Hosted wallet connector on Android (headless)

package com.fireblocks.connect

import android.annotation.SuppressLint
import android.app.Activity
import android.content.Context
import android.content.Intent
import android.graphics.Bitmap
import android.net.Uri
import android.os.Handler
import android.os.Looper
import android.util.Log
import android.view.ViewGroup
import android.webkit.JavascriptInterface
import android.webkit.WebResourceRequest
import android.webkit.WebView
import android.webkit.WebViewClient
import java.util.UUID
import org.json.JSONArray
import org.json.JSONObject

// ── Headless connect engine (Android) ────────────────────────────────────────

/**
 * Runs the hosted Fireblocks connect logic (the Dynamic SDK) inside a HIDDEN
 * [WebView], so the app can render its own native wallet list and still keep
 * every bit of connection logic in the web layer. The Android analog of iOS's
 * `FireblocksHeadlessConnect`.
 *
 * For WalletConnect-protocol wallets (MetaMask, Rainbow, Trust, …) the pairing
 * is relay-based: the engine mints a URI, we open the wallet via deeplink, the
 * user approves, and the approval resolves over a WebSocket — no visible page.
 * Wallets with no such path (Base Account passkey/email, …) come back as
 * [Result.FallbackRequired] so the caller opens the visible [FireblocksConnect].
 *
 * The app links **no wallet SDK**: it loads a URL, relays JSON messages over a
 * bridge, opens a deeplink, and renders a list. Everything wallet-specific is
 * JavaScript in the hidden WebView.
 *
 * ```kotlin
 * FireblocksHeadlessConnect.prewarm(activity)                 // at launch
 * FireblocksHeadlessConnect.connect(activity, "rainbow", "evm") { result ->
 *     when (result) {
 *         is FireblocksHeadlessConnect.Result.Success -> { /* result.wallet */ }
 *         is FireblocksHeadlessConnect.Result.FallbackRequired -> { /* visible flow */ }
 *         is FireblocksHeadlessConnect.Result.Failure -> { /* result.code */ }
 *     }
 * }
 * ```
 */
object FireblocksHeadlessConnect {

    private const val TAG = "FireblocksHeadlessConnect"

    private const val DEFAULT_ENGINE_BASE_URL = "https://connect.dynamicauth.com/headless.html"

    /**
     * The no-UI engine page. Only this page's scheme, host and port may post
     * messages to the app or load top-level in the engine WebView.
     *
     * Set this BEFORE [prewarm]/[connect], like [environmentId]: the URL is
     * resolved when the hidden WebView is first created. Point it at your own
     * deployment of the engine, never at a URL taken from untrusted input.
     */
    var engineBaseUrl: String = DEFAULT_ENGINE_BASE_URL

    /** Points Phantom's redirect at your app scheme so it returns to the app.
     *  Replace `myapp` with your scheme. */
    private const val RETURN_SCHEME = "myapp"

    /**
     * Dynamic environment ID for the engine page to use instead of the one it was
     * built with, sent as `?environmentId=<uuid>`. `null`/blank leaves the page on
     * its own default, which is the pre-existing behavior.
     *
     * Set this BEFORE [prewarm]/[connect]: the URL is resolved when the hidden
     * WebView is first created, so a later change only takes effect on the next
     * engine reload. Pass the same value to [FireblocksConnect.present] so the
     * visible fallback flow lands on the same environment.
     */
    var environmentId: String? = null

    /**
     * UI locale for the iframe app, sent as `?locale=<value>` — e.g. `"en_US"`,
     * `"es_LA"`; see the iframe app's README for the current allow-list.
     * `null`/blank leaves the page on its own default (`en_US`). Never changes
     * anything on the native side — it's forwarded as-is to the iframe app.
     *
     * Set this BEFORE [prewarm]/[connect]: same resolution timing as [environmentId].
     */
    var locale: String? = null

    /**
     * UI theme for the iframe app, sent as `?theme=<value>` — `"light"` or
     * `"dark"`. `null`/blank leaves the page on its own default (`light`).
     * Never changes anything on the native side — it's forwarded as-is to
     * the iframe app.
     *
     * Set this BEFORE [prewarm]/[connect]: same resolution timing as [environmentId].
     */
    var theme: String? = null

    /**
     * How the iframe app connects Phantom, sent as `?phantomMode=<value>` —
     * `"in-app"` (default) or `"redirect"`; see the iframe app's README.
     * `null`/blank omits the param. Forwarded as-is to the iframe app.
     *
     * Set this BEFORE [prewarm]/[connect]: same resolution timing as [environmentId].
     */
    var phantomMode: String? = null

    /**
     * The app's own https URL Phantom returns to, sent as
     * `?walletReturnUrl=<value>` and used as Phantom's `redirect_link` when
     * [phantomMode] is `"redirect"`. `null`/blank omits the param and the
     * engine falls back to `<returnScheme>://phantom-headless`. Forwarded
     * as-is.
     *
     * Set this BEFORE [prewarm]/[connect]: same resolution timing as [environmentId].
     */
    var walletReturnUrl: String? = null

    /** If the engine hasn't produced a deeplink within this window, fall back to
     *  the visible flow. Cancelled once the wallet opens. */
    private const val STARTUP_TIMEOUT_MS = 20_000L

    private const val SIGN_TIMEOUT_MS = 60_000L

    /** Longer than [SIGN_TIMEOUT_MS]: a send can involve two sequential wallet
     *  approvals (switch network, then send) rather than one, so 60s is too
     *  tight a budget to fail loud on before the user's had a fair chance to
     *  clear both prompts. */
    private const val SEND_TIMEOUT_MS = 120_000L

    /** Wallet universal-link hosts iOS/Android won't hand to the wallet app from
     *  inside a WebView (only Phantom's redirect navigates the WebView today) —
     *  the WebViewClient opens these externally. */
    private val WALLET_HOSTS = setOf(
        "phantom.app", "phantom.com",
        "link.metamask.io", "metamask.app.link",
        "link.trustwallet.com", "rnbwapp.com", "rainbow.me",
        "www.okx.com", "link.okx.com", "zerion.io",
    )

    internal fun isWalletHost(host: String): Boolean = WALLET_HOSTS.any { host == it || host.endsWith(".$it") }

    /** Bridge message types that aren't tied to a single connect() attempt, so
     *  they're exempt from the per-attempt `requestId` check in `handleMessage`.
     *  "openWallet" carries a sign/send requestId (informational), never a
     *  connect attempt id — gating it on the connect slot would drop it. */
    private val NO_REQUEST_ID_TYPES = setOf("ready", "wallets", "event", "openWallet")
    private val SIGN_TYPES = setOf("signed", "signFailed")
    private val SIGN_TX_TYPES = setOf("signedTx", "signTxFailed")
    private val SEND_TX_TYPES = setOf("sentTx", "sentTxFailed")

    /** [engineBaseUrl] plus the params the engine reads on load. */
    private fun engineUrl(): String {
        val builder = Uri.parse(engineBaseUrl)
            .buildUpon()
            .appendQueryParameter("returnScheme", RETURN_SCHEME)
        environmentId
            ?.takeIf { it.isNotBlank() }
            ?.let { builder.appendQueryParameter("environmentId", it) }
        locale
            ?.takeIf { it.isNotBlank() }
            ?.let { builder.appendQueryParameter("locale", it) }
        theme
            ?.takeIf { it.isNotBlank() }
            ?.let { builder.appendQueryParameter("theme", it) }
        phantomMode
            ?.takeIf { it.isNotBlank() }
            ?.let { builder.appendQueryParameter("phantomMode", it) }
        walletReturnUrl
            ?.takeIf { it.isNotBlank() }
            ?.let { builder.appendQueryParameter("walletReturnUrl", it) }
        return builder.build().toString()
    }

    /** A wallet in the native list, delivered live by the engine (derived from
     *  the Dynamic catalogue — no static file). */
    data class Wallet(
        val key: String,
        val name: String,
        val icon: String?,
        val chains: List<String>,
        /** "headless" → drive this engine; "fallback" → the visible flow. */
        val mode: String,
        /** Shown by default; the rest of the catalogue rides along for search. */
        val featured: Boolean,
        /**
         * The wallet's in-app-browser URL template (`{{encodedDappURI}}`), when
         * the wallet book carries one — `null` otherwise.
         *
         * NOT one of [chains]: it means "this wallet can open a URL in its own
         * browser", where it injects its providers. Some wallets are only
         * reachable that way for some chains (Phantom on EVM — see
         * [FireblocksWalletBrowser]). The template says nothing about WHICH
         * chains that browser serves, so don't infer chain support from it.
         */
        val inAppBrowser: String? = null,
    ) {
        val isMultiChain: Boolean get() = chains.size > 1
    }

    sealed class Result {
        data class Success(val wallet: WalletConnection) : Result()
        data class FallbackRequired(val reason: String) : Result()
        data class Failure(val code: String, val message: String) : Result()
    }

    sealed class SignResult {
        data class Success(val signature: String) : SignResult()
        data class Failure(val code: String, val message: String) : SignResult()
    }

    /** Result of [signTransaction], which signs without broadcasting. */
    sealed class SignTxResult {
        data class Success(val signedTransaction: String, val chain: String) : SignTxResult()
        data class Failure(val code: String, val message: String) : SignTxResult()
    }

    sealed class SendResult {
        /** [chain] is "evm", "solana", or "bitcoin" — [txHash] is the
         *  on-chain transaction hash (EVM), signature (Solana, which IS the
         *  transaction's identifier), or transaction ID (Bitcoin); either way
         *  it's already submitted. */
        data class Success(val txHash: String, val chain: String) : SendResult()
        data class Failure(val code: String, val message: String) : SendResult()
    }

    private val main = Handler(Looper.getMainLooper())
    private var appContext: Context? = null
    private var webView: WebView? = null
    private var ready = false
    private val pendingReady = mutableListOf<() -> Unit>()
    // Phantom return URLs that arrived before the page was ready (a cold start
    // or an engine reset): evaluating them then would hit an undefined headlessConnect.
    private val pendingReturnScripts = mutableListOf<String>()

    // Single in-flight attempt (mirrors the iOS engine). For production, hold
    // this in a ViewModel so it survives configuration changes / process death.
    private var handler: ((Result) -> Unit)? = null
    private var timeout: Runnable? = null

    // UUID per attempt, not a constant — a guessable/fixed request ID lets any
    // JS in this WebView forge a `connected` message for a request it never
    // made. `handleMessage` drops any message whose `requestId` doesn't match.
    // Written and read only on `main`.
    private var pendingRequestId: String? = null

    // Sign/signTx/sendTx are independent of the connect attempt above (a wallet
    // stays connected while the caller signs/sends any number of times), so
    // they get their own single-slot handler + requestId + timeout rather than
    // sharing `handler`/`pendingRequestId`/`timeout` — those three are (and
    // stay) connect-only.
    private var signHandler: ((SignResult) -> Unit)? = null
    private var signRequestId: String? = null
    private var signTimeout: Runnable? = null

    private var signTxHandler: ((SignTxResult) -> Unit)? = null
    private var signTxRequestId: String? = null
    private var signTxTimeout: Runnable? = null

    private var sendTxHandler: ((SendResult) -> Unit)? = null
    private var sendTxRequestId: String? = null
    private var sendTxTimeout: Runnable? = null

    // The origin (scheme+host+port) of the page currently committed as this
    // WebView's top-level document. `@JavascriptInterface` gives no origin, so
    // this is tracked from the WebViewClient callbacks (main thread) and
    // consulted in `handleMessage` to reject bridge messages from anything
    // other than the engine. @Volatile because it's written on `main` and read
    // on the JS-interface binder thread in `Bridge.postMessage` — a single
    // immutable reference swap, so volatility alone (no lock) is sufficient.
    @Volatile
    private var committedOrigin: Uri? = null

    private var walletsList: List<Wallet> = emptyList()
    /** Set to receive the wallet menu. Replayed immediately if already delivered. */
    var onWallets: ((List<Wallet>) -> Unit)? = null
        set(value) {
            field = value
            if (walletsList.isNotEmpty()) value?.invoke(walletsList)
        }

    // ── Public API ────────────────────────────────────────────────────────────

    /** Build + load the hidden WebView ahead of time so the first connect is
     *  fast. Safe to call more than once. */
    fun prewarm(activity: Activity) = main.post { ensureWebView(activity) }

    fun connect(
        activity: Activity,
        walletKey: String,
        chain: String?,
        onResult: (Result) -> Unit,
    ) = main.post {
        ensureWebView(activity)
        // A previous attempt is still in flight (e.g. the user opened MetaMask,
        // ignored the prompt, and is now trying another wallet). The SDK can hold
        // a stuck pending connection that blocks the next mint — reset to a fresh
        // engine so the new wallet gets a clean slate.
        if (handler != null) resetEngine()
        handler = onResult
        val requestId = UUID.randomUUID().toString()
        pendingRequestId = requestId
        scheduleStartupTimeout()
        val work = { drive(requestId, walletKey, chain) }
        if (ready) work() else pendingReady.add(work)
    }

    // Reload the hidden WebView to abandon a stuck previous attempt. The reloaded
    // page re-fires `ready` (flushing any queued connect) and re-pushes the list.
    private fun resetEngine() {
        handler = null
        pendingRequestId = null
        clearTimeout()
        ready = false
        pendingReady.clear()
        pendingReturnScripts.clear()
        webView?.reload()
    }

    /** Abort the in-flight attempt (e.g. the user backed out of the list). */
    fun cancel() = main.post {
        webView?.evaluateJavascript("window.headlessConnect && window.headlessConnect.cancel('');", null)
        clearTimeout()
        handler = null
        pendingRequestId = null
    }

    /** Sign [message] with the currently-connected wallet. Resolves once via
     *  [onResult]. Requires the engine URL to point to a build that includes
     *  sign support. Works for whatever chain the connected wallet is on
     *  (EVM or Solana) — this method doesn't know or care which. */
    fun sign(message: String, onResult: (SignResult) -> Unit) = main.post {
        signHandler?.let { finishSign(SignResult.Failure("superseded", "superseded by a new sign() call")) }
        val requestId = UUID.randomUUID().toString()
        signHandler = onResult
        signRequestId = requestId
        scheduleSignTimeout()
        val params = JSONObject().put("requestId", requestId).put("message", message)
        webView?.evaluateJavascript("window.headlessConnect && window.headlessConnect.sign($params);", null)
    }

    /**
     * Send a transaction with the currently-connected wallet — EVM, Solana, or
     * Bitcoin.
     * Resolves once via [onResult].
     *
     * The wallet signs AND broadcasts in one step: `eth_sendTransaction` for
     * EVM, `signAndSendTransaction` for Solana (the wallet-adapter-standard
     * analog every Solana wallet implements).
     *
     * [transaction] format depends on which chain the connected wallet is on
     * — this method doesn't know or care which, it's just an opaque string
     * the engine interprets:
     *  - EVM: JSON string `{"to":"0x…","value":"0x0","data":"0x","chainId":"0x1"}`
     *    — `chainId` is required; the engine verifies it against the wallet's
     *    own active network before sending (see [FireblocksConnect.sendTransaction]
     *    for the same `SendResult.Failure` codes this can surface —
     *    `chain_switch_unavailable`, `chain_not_configured`,
     *    `chain_switch_rejected`, `chain_mismatch`).
     *  - Solana: base64-encoded, pre-built `VersionedTransaction` (or legacy
     *    `Transaction`) bytes — the caller is responsible for building it (a
     *    native SOL transfer vs. an SPL-token transfer for USDC are both just
     *    "whatever instructions are already in the bytes"); the engine only
     *    signs and submits.
     *  - Bitcoin: JSON string `{"recipientAddress":"bc1…","amountSats":"12345"}`
     *    — `amountSats` is the amount in satoshis as a decimal-digit string.
     *    The wallet's own `sendBitcoin` RPC signs and broadcasts it.
     */
    fun sendTransaction(transaction: String, onResult: (SendResult) -> Unit) = dispatchSend(
        jsFunction = "sendTx",
        params = JSONObject().put("transaction", transaction),
        supersededMessage = "superseded by a new sendTransaction() call",
        unsupportedMessage = "engine build predates sendTx — redeploy connect.dynamicauth.com",
        onResult = onResult,
    )

    /** ERC-20 / SPL token for [transferAmount]: contract (or mint) [address]
     *  and the token's [decimals]. */
    data class TransferToken(val address: String, val decimals: Int)

    /**
     * Send a display-unit amount from the connected wallet — EVM or Solana.
     * Resolves once via [onResult]; the caller never builds a transaction or
     * converts to wei/lamports. The engine owns all validation, so the
     * `SendResult.Failure` codes it surfaces include `invalid_amount`,
     * `missing_recipient`, `missing_from`, `invalid_token`,
     * `invalid_network_id`, `account_not_found`, `fallback_required`,
     * `unsupported_chain`, `unsupported_wallet`, `chain_not_configured`,
     * `chain_switch_unavailable`, `chain_switch_rejected`, `chain_mismatch`,
     * `invalid_param`, `method_unavailable`, `user_rejected`, `timeout` and
     * `unsupported_engine`.
     *
     *  - [from]: address of the connected account to send from (EVM addresses
     *    match case-insensitively).
     *  - [amount]: positive decimal string in display units, e.g. `"0.01"`.
     *  - [recipient]: destination address.
     *  - [networkId]: optional. EVM: decimal chainId, e.g. `"137"`. Solana:
     *    `"mainnet-beta"` or `"devnet"`. Omitting it on EVM means the engine
     *    performs no network check and sends on whatever network the wallet is
     *    currently on.
     *  - [token]: optional ERC-20 / SPL token; omit for the native asset.
     *
     * v1 exclusions: Bitcoin returns `unsupported_chain`; Solana with Phantom
     * in redirect mode returns `unsupported_wallet`.
     */
    fun transferAmount(
        from: String,
        amount: String,
        recipient: String,
        networkId: String? = null,
        token: TransferToken? = null,
        onResult: (SendResult) -> Unit,
    ) = dispatchSend(
        jsFunction = "transferAmount",
        params = JSONObject()
            .put("from", from)
            .put("amount", amount)
            .put("recipient", recipient)
            .also { params ->
                if (networkId != null) params.put("networkId", networkId)
                if (token != null) {
                    params.put("token", JSONObject().put("address", token.address).put("decimals", token.decimals))
                }
            },
        supersededMessage = "superseded by a new transferAmount() call — the superseded transfer may still have been submitted; check the explorer before retrying.",
        unsupportedMessage = "engine build predates transferAmount — redeploy connect.dynamicauth.com",
        onResult = onResult,
    )

    private fun dispatchSend(
        jsFunction: String,
        params: JSONObject,
        supersededMessage: String,
        unsupportedMessage: String,
        onResult: (SendResult) -> Unit,
    ) = main.post {
        sendTxHandler?.let { finishSendTx(SendResult.Failure("superseded", supersededMessage)) }
        val requestId = UUID.randomUUID().toString()
        sendTxHandler = onResult
        sendTxRequestId = requestId
        sendTxTimeout = Runnable {
            finishSendTx(
                SendResult.Failure(
                    "timeout",
                    "Wallet did not respond in time — if you approved it, the transaction " +
                        "may still have been submitted; check the explorer before retrying.",
                ),
            )
        }.also { main.postDelayed(it, SEND_TIMEOUT_MS) }
        params.put("requestId", requestId)
        // `sendTx` and `transferAmount` are newer additions to the engine than
        // everything else this class calls — a deployment that predates them
        // would otherwise leave this request silently unanswered until the
        // timeout, indistinguishable from a dead wallet. Self-report
        // immediately instead, straight over the same `walletNative` channel
        // `Bridge.postMessage` already listens on.
        webView?.evaluateJavascript(
            "if (window.headlessConnect && window.headlessConnect.$jsFunction) {" +
                "  window.headlessConnect.$jsFunction($params);" +
                "} else if (window.walletNative && window.walletNative.postMessage) {" +
                "  window.walletNative.postMessage(JSON.stringify({" +
                "    type: 'sentTxFailed'," +
                "    requestId: ${JSONObject.quote(requestId)}," +
                "    code: 'unsupported_engine'," +
                "    message: ${JSONObject.quote(unsupportedMessage)}" +
                "  }));" +
                "}",
            null,
        )
    }

    /**
     * Sign a transaction with the currently-connected wallet without
     * broadcasting it. Resolves once via [onResult].
     *
     * [transaction] format depends on which chain the connected wallet is on:
     *  - EVM: JSON string `{"to":"0x…","value":"0x0","data":"0x","chainId":"0x1"}`
     *  - Solana: base64-encoded, pre-built `VersionedTransaction` (or legacy
     *    `Transaction`) bytes.
     *  - Bitcoin: JSON string
     *    `{"unsignedPsbtBase64","allowedSighash","signature"}`. The result is
     *    a base64 signed PSBT; the caller must finalize and broadcast it.
     */
    fun signTransaction(transaction: String, onResult: (SignTxResult) -> Unit) = main.post {
        signTxHandler?.let { finishSignTx(SignTxResult.Failure("superseded", "superseded by a new signTransaction() call")) }
        val requestId = UUID.randomUUID().toString()
        signTxHandler = onResult
        signTxRequestId = requestId
        signTxTimeout = Runnable {
            finishSignTx(SignTxResult.Failure("timeout", "Wallet did not respond in time"))
        }.also { main.postDelayed(it, SIGN_TIMEOUT_MS) }
        val params = JSONObject().put("requestId", requestId).put("transaction", transaction)
        webView?.evaluateJavascript(
            "if (window.headlessConnect && window.headlessConnect.signTx) {" +
                "  window.headlessConnect.signTx($params);" +
                "} else if (window.walletNative && window.walletNative.postMessage) {" +
                "  window.walletNative.postMessage(JSON.stringify({" +
                "    type: 'signTxFailed'," +
                "    requestId: ${JSONObject.quote(requestId)}," +
                "    code: 'unsupported_engine'," +
                "    message: 'engine build predates signTx — redeploy connect.dynamicauth.com'" +
                "  }));" +
                "}",
            null,
        )
    }

    /** Called when Phantom returns to the app: `<scheme>://phantom-headless`
     *  (from [FireblocksRedirectActivity]) or, when [walletReturnUrl] is set,
     *  that https link (from the activity that owns your universal link).
     *  Forwards the full URL into the WebView and lets the engine decide: in
     *  `redirect` mode it completes the connection from Phantom's payload, in
     *  `in-app` mode it ignores the payload-free tap. The engine re-checks the
     *  https link itself. Returns true if it consumed the URL. */
    fun handleReturnURL(uri: Uri): Boolean {
        val isPhantomReturn = isPhantomReturn(uri)
        if (!isPhantomReturn) return false
        val js = "window.headlessConnect && window.headlessConnect.handleReturnURL(${JSONObject.quote(uri.toString())});"
        main.post { if (ready) webView?.evaluateJavascript(js, null) else pendingReturnScripts.add(js) }
        return true
    }

    private fun isPhantomReturn(uri: Uri): Boolean {
        val isHeadlessHost = uri.host?.lowercase() == "phantom-headless"
        val configuredReturnUrl = walletReturnUrl?.trim()?.takeIf { it.isNotEmpty() }?.let(Uri::parse)
        val isReturnUrl = configuredReturnUrl != null && uri.isSameHttpsTarget(configuredReturnUrl)
        return isHeadlessHost || isReturnUrl
    }

    private fun Uri.isSameHttpsTarget(other: Uri): Boolean {
        val bothHttps = scheme.equals("https", ignoreCase = true) && other.scheme.equals("https", ignoreCase = true)
        val sameHost = host.equals(other.host, ignoreCase = true)
        val samePort = effectiveHttpsPort() == other.effectiveHttpsPort()
        val samePath = pathOrRoot() == other.pathOrRoot()
        return bothHttps && sameHost && samePort && samePath
    }

    private fun Uri.effectiveHttpsPort(): Int = if (port == -1) 443 else port

    private fun Uri.pathOrRoot(): String = path?.takeIf { it.isNotEmpty() } ?: "/"

    // ── WebView lifecycle ───────────────────────────────────────────────────

    @SuppressLint("SetJavaScriptEnabled")
    private fun ensureWebView(activity: Activity) {
        if (webView != null) return
        appContext = activity.applicationContext
        val wv = WebView(activity)
        wv.settings.javaScriptEnabled = true
        wv.settings.domStorageEnabled = true
        wv.addJavascriptInterface(Bridge(), "walletNative")
        wv.webViewClient = object : WebViewClient() {
            // The engine navigates to wallet deeplinks (Phantom's redirect); the
            // system won't open those from inside a WebView, so we do.
            override fun shouldOverrideUrlLoading(view: WebView, request: WebResourceRequest): Boolean {
                val url = request.url
                val scheme = url.scheme?.lowercase()
                if (scheme != "http" && scheme != "https") {
                    openExternally(url); return true
                }
                val host = url.host?.lowercase()
                if (host != null && isWalletHost(host)) {
                    openExternally(url); return true
                }
                // Deny-by-default: only the engine's own origin may load top-level
                // in this privileged WebView (the bridge is attached regardless of
                // what page is showing). Logged rather than silently dropped, since
                // a denial here means something unexpected tried to navigate this
                // WebView — see the Critical bridge-trust finding.
                //
                // Deliberately NOT scoped to `request.isForMainFrame()` — this also
                // denies subframe navigation. `@JavascriptInterface` exposes
                // `walletNative` to every frame in this WebView (Android gives no way
                // to restrict it to the top frame), while `committedOrigin` below
                // only ever tracks the *main*-frame origin. If this were narrowed
                // to main-frame-only, a hostile iframe could load here and post
                // forged bridge messages that `handleMessage`'s origin check would
                // wrongly accept (it'd still see the engine's own top-level
                // origin). Don't narrow this without also making the bridge
                // origin check frame-aware.
                if (!isEngineOrigin(url)) {
                    Log.w(TAG, "Denying navigation to non-engine origin: $url")
                    return true
                }
                return false
            }

            // Tracks the top-level origin currently loaded, so the bridge (which
            // gets no origin info from @JavascriptInterface) can validate against
            // it. Fires for every main-frame navigation, including the initial
            // `loadUrl` and `resetEngine()`'s reload — both same-origin already.
            override fun onPageStarted(view: WebView, url: String?, favicon: Bitmap?) {
                committedOrigin = url?.let(Uri::parse)
            }
        }
        // Keep it in the hierarchy (1×1) so its JS + relay socket keep running,
        // and DON'T call onPause() — that would suspend the socket. We rely on
        // Android keeping a short app-switch alive; for long approvals consider a
        // foreground service.
        val root = activity.findViewById<ViewGroup>(android.R.id.content)
        root.addView(wv, 1, 1)
        wv.loadUrl(engineUrl())
        webView = wv
    }

    private fun drive(requestId: String, walletKey: String, chain: String?) {
        val params = JSONObject()
            .put("requestId", requestId)
            .put("walletKey", walletKey)
        if (chain != null) params.put("chain", chain)
        webView?.evaluateJavascript("window.headlessConnect && window.headlessConnect.connect($params);", null)
    }

    private fun openExternally(uri: Uri) {
        val ctx = appContext ?: return
        try {
            ctx.startActivity(Intent(Intent.ACTION_VIEW, uri).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK))
        } catch (_: Exception) {
            // No app to handle it — the engine will surface an error/timeout.
        }
    }

    // ── Origin gating ─────────────────────────────────────────────────────────

    // Shared by the bridge (below) and the WebViewClient above: only the
    // engine's own scheme+host+port may post a message or load top-level in
    // this privileged WebView. Compared this way — not just host — so a
    // same-host page served on a different scheme/port can't slip through.
    private fun isEngineOrigin(uri: Uri?): Boolean {
        if (uri == null) return false
        // Compared against the BASE url: this gate is about origin only, so a
        // caller-supplied `environmentId` can never widen what counts as the engine.
        return sameOrigin(uri, Uri.parse(engineBaseUrl))
    }

    private fun sameOrigin(a: Uri, b: Uri): Boolean {
        val schemeA = a.scheme?.lowercase()
        val schemeB = b.scheme?.lowercase()
        if (schemeA == null || schemeA != schemeB) return false
        if (a.host?.lowercase() != b.host?.lowercase()) return false
        // Uri reports -1 for "no explicit port" — resolve that to the scheme's
        // real default so https://x.com and https://x.com:443 compare equal.
        val defaultPort = if (schemeA == "https") 443 else if (schemeA == "http") 80 else -1
        val portA = if (a.port == -1) defaultPort else a.port
        val portB = if (b.port == -1) defaultPort else b.port
        return portA == portB
    }

    // ── Bridge (JS → native) ──────────────────────────────────────────────────

    // @JavascriptInterface methods run on a binder thread, with no origin info
    // of their own. Snapshot `committedOrigin` here — on the calling thread,
    // at the moment JS posted — rather than re-reading it after hopping to
    // main, so a navigation racing the hop can't retroactively change which
    // origin this message is attributed to. committedOrigin is @Volatile, so
    // this read is safe without a lock.
    private class Bridge {
        @JavascriptInterface
        fun postMessage(json: String) {
            val origin = committedOrigin
            main.post { handleMessage(json, origin) }
        }
    }

    private fun handleMessage(json: String, origin: Uri?) {
        // Reject anything not posted by the engine's own top-level frame. Without
        // this, any JS that ends up running in this WebView — a compromised
        // script, an XSS on the hosted page, or a page the navigation gate above
        // missed — could forge a `connected` message and native would believe an
        // attacker-chosen wallet address is connected. See the Critical
        // bridge-trust finding.
        if (!isEngineOrigin(origin)) {
            Log.w(TAG, "Dropping bridge message from non-engine origin: $origin")
            return
        }
        val o = runCatching { JSONObject(json) }.getOrNull() ?: return
        val type = o.optString("type")
        // "ready"/"wallets"/"event" aren't tied to one attempt; connect's own
        // messages ("deeplink"/"opening"/"connected"/"fallback"/"error") must
        // carry the requestId of the connect() attempt in flight — sign's and
        // sendTx's messages are checked against their OWN independent
        // requestId slot below, since all three kinds of request can be
        // in flight independently of each other. Stale or forged IDs (e.g. a
        // superseded attempt's late message) are dropped rather than resolved
        // against the current handler.
        if (type !in NO_REQUEST_ID_TYPES && type !in SIGN_TYPES && type !in SIGN_TX_TYPES && type !in SEND_TX_TYPES && !matchesPendingRequest(o)) return
        if (type in SIGN_TYPES && !matchesSignRequest(o)) return
        if (type in SIGN_TX_TYPES && !matchesSignTxRequest(o)) return
        if (type in SEND_TX_TYPES && !matchesSendTxRequest(o)) return
        when (type) {
            "ready" -> {
                ready = true
                val returns = pendingReturnScripts.toList()
                pendingReturnScripts.clear()
                returns.forEach { webView?.evaluateJavascript(it, null) }
                val work = pendingReady.toList()
                pendingReady.clear()
                work.forEach { it() }
            }
            "wallets" -> {
                walletsList = parseWallets(o.optJSONArray("wallets"))
                onWallets?.invoke(walletsList)
            }
            "deeplink" -> {
                clearTimeout() // the wallet is opening; wait for the user now
                o.optString("url").takeIf { it.isNotEmpty() }?.let { openExternally(Uri.parse(it)) }
            }
            // A WalletConnect sign/send request is waiting — wake the wallet
            // app so its approval prompt surfaces (the request already went
            // over the relay; without this it sits invisibly until the user
            // opens the wallet by hand). No connect bookkeeping to touch.
            "openWallet" ->
                o.optString("url").takeIf { it.isNotEmpty() }?.let { openExternally(Uri.parse(it)) }
            "opening" -> clearTimeout()
            "connected" -> {
                // A missing/empty (or non-string — `optString` would otherwise
                // coerce e.g. a JSON number into a "successful" address) address
                // is a malformed payload, not a "connected" wallet with a blank
                // address — route it to failure instead of silently succeeding
                // (see Finding 19).
                val address = (o.opt("address") as? String)?.takeIf { it.isNotEmpty() }
                if (address == null) {
                    finish(Result.Failure("malformed_result", "connected message missing address"))
                    return
                }
                finish(
                    Result.Success(
                        WalletConnection(
                            address = address,
                            chain = o.optString("chain"),
                            walletName = o.optString("walletName"),
                            walletImage = o.optString("walletImage"),
                            sessionId = o.optString("sessionId"),
                            // Present only for session-cluster-bound wallets
                            // (Phantom) — see WalletConnection.network's docs.
                            network = o.optString("network").ifEmpty { null },
                            networkId = o.optString("networkId").ifEmpty { null },
                        ),
                    ),
                )
            }
            "fallback" -> finish(Result.FallbackRequired(o.optString("reason")))
            "error" -> finish(Result.Failure(o.optString("code", "unknown"), o.optString("message")))
            "signed" -> finishSign(SignResult.Success(o.optString("signature")))
            "signFailed" -> finishSign(SignResult.Failure(o.optString("code", "unknown"), o.optString("message")))
            "signedTx" -> finishSignTx(SignTxResult.Success(o.optString("signedTransaction"), o.optString("chain")))
            "signTxFailed" -> finishSignTx(SignTxResult.Failure(o.optString("code", "unknown"), o.optString("message")))
            "sentTx" -> finishSendTx(SendResult.Success(o.optString("txHash"), o.optString("chain")))
            "sentTxFailed" -> finishSendTx(SendResult.Failure(o.optString("code", "unknown"), o.optString("message")))
            // "event" — diagnostic timeline; hook up logging/analytics if wanted.
        }
    }

    private fun matchesPendingRequest(o: JSONObject): Boolean {
        val incoming = o.optString("requestId").takeIf { it.isNotEmpty() } ?: return false
        return incoming == pendingRequestId
    }

    private fun matchesSignRequest(o: JSONObject): Boolean {
        val incoming = o.optString("requestId").takeIf { it.isNotEmpty() } ?: return false
        return incoming == signRequestId
    }

    private fun matchesSignTxRequest(o: JSONObject): Boolean {
        val incoming = o.optString("requestId").takeIf { it.isNotEmpty() } ?: return false
        return incoming == signTxRequestId
    }

    private fun matchesSendTxRequest(o: JSONObject): Boolean {
        val incoming = o.optString("requestId").takeIf { it.isNotEmpty() } ?: return false
        return incoming == sendTxRequestId
    }

    private fun parseWallets(arr: JSONArray?): List<Wallet> {
        if (arr == null) return emptyList()
        return (0 until arr.length()).mapNotNull { i ->
            val w = arr.optJSONObject(i) ?: return@mapNotNull null
            val chains = w.optJSONArray("chains")
            Wallet(
                key = w.optString("key"),
                name = w.optString("name"),
                icon = w.optString("icon").takeIf { it.isNotEmpty() },
                chains = if (chains == null) emptyList()
                else (0 until chains.length()).map { chains.optString(it) },
                mode = w.optString("mode", "fallback"),
                featured = w.optBoolean("featured", false),
                inAppBrowser = w.optString("inAppBrowser").takeIf { it.isNotEmpty() },
            )
        }
    }

    private fun finish(result: Result) {
        val cb = handler ?: return
        handler = null
        pendingRequestId = null
        clearTimeout()
        main.post { cb(result) }
    }

    private fun scheduleStartupTimeout() {
        clearTimeout()
        timeout = Runnable {
            finish(Result.FallbackRequired("headless startup timeout"))
        }.also { main.postDelayed(it, STARTUP_TIMEOUT_MS) }
    }

    private fun finishSign(result: SignResult) {
        val cb = signHandler ?: return
        signHandler = null
        signRequestId = null
        signTimeout?.let { main.removeCallbacks(it) }
        signTimeout = null
        main.post { cb(result) }
    }

    private fun scheduleSignTimeout() {
        signTimeout?.let { main.removeCallbacks(it) }
        signTimeout = Runnable {
            finishSign(SignResult.Failure("timeout", "Wallet did not respond in time"))
        }.also { main.postDelayed(it, SIGN_TIMEOUT_MS) }
    }

    private fun finishSignTx(result: SignTxResult) {
        val cb = signTxHandler ?: return
        signTxHandler = null
        signTxRequestId = null
        signTxTimeout?.let { main.removeCallbacks(it) }
        signTxTimeout = null
        main.post { cb(result) }
    }

    private fun finishSendTx(result: SendResult) {
        val cb = sendTxHandler ?: return
        sendTxHandler = null
        sendTxRequestId = null
        sendTxTimeout?.let { main.removeCallbacks(it) }
        sendTxTimeout = null
        main.post { cb(result) }
    }

    private fun clearTimeout() {
        timeout?.let { main.removeCallbacks(it) }
        timeout = null
    }
}

package com.fireblocks.connect.sample

import android.app.Activity
import android.app.AlertDialog
import android.graphics.Color
import android.net.Uri
import android.os.Bundle
import android.view.Gravity
import android.view.View
import android.view.ViewGroup.LayoutParams.MATCH_PARENT
import android.view.ViewGroup.LayoutParams.WRAP_CONTENT
import android.widget.Button
import android.widget.EditText
import android.widget.LinearLayout
import android.widget.ProgressBar
import android.widget.RadioButton
import android.widget.RadioGroup
import android.widget.ScrollView
import android.widget.TextView
import androidx.core.widget.doAfterTextChanged
import com.fireblocks.connect.FireblocksConnect
import com.fireblocks.connect.FireblocksConnectResult
import com.fireblocks.connect.FireblocksHeadlessConnect
import com.fireblocks.connect.FireblocksHeadlessConnect.SendResult
import com.fireblocks.connect.FireblocksHeadlessConnect.SignResult
import com.fireblocks.connect.FireblocksHeadlessConnect.Wallet
import com.fireblocks.connect.FireblocksFundResult
import com.fireblocks.connect.FireblocksSendResult
import com.fireblocks.connect.FireblocksSignResult
import com.fireblocks.connect.FireblocksWalletBrowser
import com.fireblocks.connect.WalletConnection
import java.math.BigInteger

private const val BARE_ROW_ID = "bare-auth-webview"

// Base Account's passkey/email connect needs a visible page, so FallbackRequired
// is the correct answer there and a bug anywhere else.
private val EXPECTED_FALLBACK = setOf("baseaccount-evm")

/**
 * Internal connect-API comparison demo, NOT the recommended integration
 * pattern (see git history for the original headless-first / auto-fallback
 * wallet picker).
 *
 * Every wallet+chain pair the catalogue reports is listed three times, once
 * per section, and each section calls exactly one underlying API no matter
 * what that wallet/chain actually needs — so tapping a row shows, in
 * isolation, what that specific API does for that specific wallet+chain:
 *
 * 1. "Open Authenticate Webview" — [FireblocksConnect.present] with no wallet
 *    preselected; the web app's own UI runs inside a Custom Tab.
 * 2. "Connect wallet via Authenticate Webview" — same API, but with
 *    `?wallet=&chain=` preselected so it jumps straight to one wallet+chain.
 * 3. "Connect wallet via Hidden Webview" — [FireblocksHeadlessConnect.connect],
 *    the hidden no-UI WebView engine. A wallet/chain with no headless path
 *    reports back `FallbackRequired` instead of connecting — shown inline
 *    rather than auto-chaining into another flow.
 *
 * Once connected, offers sign message + send transaction so you can see the
 * full flow end-to-end — EVM (a plain JSON tx object, no chain SDK needed) or
 * Solana (a native SOL transfer; the ENGINE builds the transaction, this app
 * only picks network/recipient/amount — see `resolveSolanaTx` in
 * `src/headless.ts` for why: a Solana tx needs a live blockhash, unlike EVM's
 * self-contained {to,value,data,chainId}).
 */
class MainActivity : Activity() {

    private val hostedPageUrl = "https://connect.dynamicauth.com/"
    private val scheme = "myapp" // must match the intent-filter in AndroidManifest

    // Which Dynamic environment the hosted pages should use. `null` leaves them on
    // whatever they were built with; set a UUID here (or read one from
    // BuildConfig / a remote config) to point this build at a specific
    // environment without redeploying the web layer.
    private val environmentId: String? = null

    private var all: List<Wallet> = emptyList()
    private var connectingRowId: String? = null
    private val rowOutcomes = mutableMapOf<String, RowOutcome>()
    private var listError: String? = null
    private var connectedWallet: WalletConnection? = null

    private lateinit var status: TextView
    private lateinit var listContainer: LinearLayout
    private lateinit var connectedContainer: LinearLayout

    // Solana network toggle state — which cluster the NEXT send builds
    // against. See connectedContainer's Solana section for why the wallet
    // itself must already be set to the same one.
    private var solNetwork = "mainnet-beta"

    private data class RowOutcome(val text: String, val isExpected: Boolean)

    private data class WalletChainRow(val wallet: Wallet, val chain: String) {
        val id: String get() = "${wallet.key}-$chain"
    }

    private enum class Flow { AUTH_WEBVIEW, HIDDEN_WEBVIEW }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val root = LinearLayout(this).apply {
            orientation = LinearLayout.VERTICAL
            setPadding(40, 60, 40, 40)
            setBackgroundColor(Color.WHITE)
        }
        root.addView(TextView(this).apply {
            text = "Connect a wallet"
            textSize = 22f
            setTextColor(Color.parseColor("#0E121B"))
        })
        status = TextView(this).apply {
            textSize = 14f
            setTextColor(Color.parseColor("#606770"))
            setPadding(0, 16, 0, 16)
        }
        root.addView(status)
        connectedContainer = LinearLayout(this).apply {
            orientation = LinearLayout.VERTICAL
            visibility = View.GONE
        }
        root.addView(connectedContainer)
        listContainer = LinearLayout(this).apply { orientation = LinearLayout.VERTICAL }
        root.addView(ScrollView(this).apply { addView(listContainer) })
        setContentView(root)

        // Must be set before prewarm — the engine URL is resolved when the hidden
        // WebView is created.
        FireblocksHeadlessConnect.environmentId = environmentId
        // Pre-warm the engine so the first connect is fast, and receive the
        // wallet list it derives from the catalogue.
        FireblocksHeadlessConnect.prewarm(this)
        FireblocksHeadlessConnect.onWallets = { wallets ->
            runOnUiThread { all = wallets; renderList() }
        }
        renderList()
    }

    private fun rows(): List<WalletChainRow> =
        all.filter { it.featured }.flatMap { wallet -> chains(wallet).map { WalletChainRow(wallet, it) } }

    /** The engine's own chains, plus a synthetic "evm" for a wallet whose EVM
     *  surface only exists inside its own in-app browser (Phantom), which
     *  therefore never appears in [Wallet.chains]. */
    private fun chains(wallet: Wallet): List<String> =
        wallet.chains + if (offersInAppBrowserEvm(wallet)) listOf("evm") else emptyList()

    /**
     * Scoped to Phantom on purpose, and NOT derived from "has an in-app-browser
     * template" — a template only means the wallet can open a URL in its own
     * browser; it says nothing about which chains that browser injects a
     * provider for. The evidence for Phantom specifically is
     * `phantomevm.injectedConfig.windowLocations: ["phantom.ethereum"]`.
     */
    private fun offersInAppBrowserEvm(wallet: Wallet): Boolean =
        wallet.key.lowercase() == "phantom" &&
            wallet.inAppBrowser != null &&
            !wallet.chains.contains("evm")

    private fun renderList() {
        listContainer.removeAllViews()
        if (all.isEmpty()) {
            listContainer.addView(TextView(this).apply { text = "Loading wallets…" })
            return
        }
        listError?.let { message ->
            listContainer.addView(TextView(this).apply {
                text = message
                textSize = 12f
                setTextColor(Color.parseColor("#EA580C"))
                setPadding(0, 0, 0, 8)
            })
        }

        listContainer.addView(sectionCard(
            "Calls FireblocksConnect.present(...) with no wallet preselected — " +
                "the web app's own UI runs inside a Custom Tab.",
        ))
        listContainer.addView(demoRow("Open Authenticate Webview", BARE_ROW_ID) { openBareAuthWebview() })

        val rows = rows()
        listContainer.addView(sectionCard(
            "Calls FireblocksConnect.present(...) with ?wallet=&chain= preselected — " +
                "same Custom Tab, but jumps straight to one wallet+chain.",
        ))
        for (row in rows) listContainer.addView(walletChainRow(row, Flow.AUTH_WEBVIEW))

        listContainer.addView(sectionCard(
            "Calls FireblocksHeadlessConnect.connect(context, walletKey, chain) — the hidden " +
                "WebView engine. Wallets/chains with no headless path report back " +
                "FallbackRequired instead of connecting.",
        ))
        for (row in rows) listContainer.addView(walletChainRow(row, Flow.HIDDEN_WEBVIEW))
    }

    private fun sectionCard(text: String) = label(text).apply { setPadding(0, 32, 0, 4) }

    private fun walletChainRow(row: WalletChainRow, flow: Flow): View {
        val id = rowId(flow, row)
        return demoRow("${row.wallet.name} — ${chainLabel(row.chain)}", id) { connect(row, flow, id) }
    }

    private fun demoRow(title: String, id: String, onTap: () -> Unit): View =
        LinearLayout(this).apply {
            orientation = LinearLayout.HORIZONTAL
            gravity = Gravity.CENTER_VERTICAL
            setBackgroundColor(Color.parseColor("#F0F2F5"))
            setPadding(32, 28, 32, 28)
            isEnabled = connectingRowId == null
            setOnClickListener { onTap() }
            layoutParams = LinearLayout.LayoutParams(MATCH_PARENT, WRAP_CONTENT).apply { topMargin = 12 }
            addView(
                TextView(this@MainActivity).apply {
                    text = title
                    textSize = 14f
                    setTextColor(Color.parseColor("#0E121B"))
                },
                LinearLayout.LayoutParams(0, WRAP_CONTENT, 1f),
            )
            addView(trailing(id))
        }

    private fun trailing(id: String): View {
        val outcome = rowOutcomes[id]
        return when {
            connectingRowId == id ->
                ProgressBar(this, null, android.R.attr.progressBarStyleSmall)
            outcome != null -> TextView(this).apply {
                text = outcome.text
                textSize = 11f
                gravity = Gravity.END
                maxWidth = 420
                setTextColor(Color.parseColor(if (outcome.isExpected) "#16A34A" else "#EA580C"))
            }
            else -> TextView(this).apply {
                text = "›"
                textSize = 18f
                setTextColor(Color.parseColor("#9CA3AF"))
            }
        }
    }

    private fun rowId(flow: Flow, row: WalletChainRow) = "$flow-${row.id}"

    private fun openBareAuthWebview() {
        listError = null
        connectingRowId = BARE_ROW_ID
        renderList()
        FireblocksConnect.present(this, hostedPageUrl, scheme, environmentId) { result ->
            runOnUiThread {
                connectingRowId = null
                when (result) {
                    is FireblocksConnectResult.Success -> showConnected(result.wallet)
                    is FireblocksConnectResult.Cancelled -> renderList()
                    is FireblocksConnectResult.Error -> {
                        listError = "Couldn't connect (${result.code ?: result.reason})."
                        renderList()
                    }
                }
            }
        }
    }

    private fun connect(row: WalletChainRow, flow: Flow, id: String) {
        listError = null
        rowOutcomes.remove(id)
        connectingRowId = id
        renderList()

        when (flow) {
            Flow.AUTH_WEBVIEW -> FireblocksConnect.present(
                this,
                hostedUrl(row.wallet.key, row.chain),
                scheme,
                environmentId,
            ) { result ->
                runOnUiThread {
                    connectingRowId = null
                    when (result) {
                        is FireblocksConnectResult.Success -> showConnected(result.wallet)
                        is FireblocksConnectResult.Cancelled -> renderList()
                        is FireblocksConnectResult.Error -> {
                            rowOutcomes[id] = RowOutcome("Failed (${result.code ?: result.reason})", false)
                            renderList()
                        }
                    }
                }
            }

            Flow.HIDDEN_WEBVIEW -> FireblocksHeadlessConnect.connect(this, row.wallet.key, row.chain) { result ->
                runOnUiThread {
                    connectingRowId = null
                    when (result) {
                        is FireblocksHeadlessConnect.Result.Success -> showConnected(result.wallet)
                        is FireblocksHeadlessConnect.Result.FallbackRequired -> {
                            val expected = row.id in EXPECTED_FALLBACK
                            rowOutcomes[id] = RowOutcome(
                                if (expected) "✅ fallbackRequired\n(expected)" else "⚠️ fallbackRequired\n(unexpected)",
                                expected,
                            )
                            renderList()
                        }
                        is FireblocksHeadlessConnect.Result.Failure -> {
                            rowOutcomes[id] = RowOutcome("Failed (${result.code})", false)
                            renderList()
                        }
                    }
                }
            }
        }
    }

    /** [FireblocksConnect.present] appends redirect_uri, nonce, embedded and
     *  environmentId itself, so only the preselection goes here. */
    private fun hostedUrl(wallet: String, chain: String): String =
        Uri.parse(hostedPageUrl).buildUpon()
            .appendQueryParameter("wallet", wallet)
            .appendQueryParameter("chain", chain)
            .build()
            .toString()

    private fun chainLabel(chain: String) = when (chain) {
        "evm" -> "EVM"
        "solana" -> "SVM"
        "bitcoin" -> "BTC"
        else -> chain.uppercase()
    }

    private fun showConnected(wallet: WalletConnection) {
        connectingRowId = null
        connectedWallet = wallet
        // A session-bound network (Phantom's redirect protocol) is the only
        // network this wallet will sign for — follow it. The toggle is
        // replaced by a read-only note for such connections (renderConnected).
        wallet.network?.let { solNetwork = it }
        val addr = wallet.address.let { if (it.length > 12) "${it.take(6)}…${it.takeLast(4)}" else it }
        status.text = "${wallet.walletName}\n${wallet.chain} · $addr"
        (listContainer.parent as View).visibility = View.GONE
        connectedContainer.visibility = View.VISIBLE
        renderConnected()
    }

    private fun disconnect() {
        connectedWallet = null
        status.text = ""
        connectedContainer.visibility = View.GONE
        connectedContainer.removeAllViews()
        (listContainer.parent as View).visibility = View.VISIBLE
        renderList()
    }

    /** "Fund from Coinbase": opens the hosted page's ?intent=fundFromExchange
     *  flow in a Custom Tab. Needs no connected wallet and no signature — the
     *  user signs in to the exchange and the exchange sends the funds. The
     *  sample targets the connected wallet's address purely because that's the
     *  address on screen. See [FireblocksConnect.fundFromExchange] for why
     *  there's no headless path. */
    private fun renderFundFromExchange(wallet: WalletConnection) {
        connectedContainer.addView(label("Fund from Coinbase"))
        // Left blank on purpose: a prefilled currency narrows the hosted
        // page's balance picker down to just that currency (see its
        // preferredSources()) — fine for an integrator who already knows
        // what they want, but it means this sample would only ever show
        // USDC unless the field is cleared first. Empty shows every balance.
        val currencyField = field("Currency, e.g. USDC (optional — leave blank to see every balance)")
        connectedContainer.addView(currencyField)
        val amountField = field("Amount (e.g. 10)")
        connectedContainer.addView(amountField)

        val resultView = resultText().apply { visibility = View.GONE }
        val errorView = errorText().apply { visibility = View.GONE }
        val button = Button(this).apply {
            text = "Fund from Coinbase"
            isAllCaps = false
        }
        button.setOnClickListener {
            button.isEnabled = false
            button.text = "Waiting for Coinbase…"
            val done = {
                runOnUiThread {
                    button.isEnabled = true
                    button.text = "Fund from Coinbase"
                }
            }
            FireblocksConnect.fundFromExchange(
                context = this,
                hostedPageUrl = hostedPageUrl,
                scheme = scheme,
                to = wallet.address,
                currency = currencyField.text.toString().trim(),
                amount = amountField.text.toString().trim(),
                environmentId = environmentId,
            ) { result ->
                done()
                runOnUiThread {
                    when (result) {
                        is FireblocksFundResult.Success -> {
                            errorView.visibility = View.GONE
                            // The id is the exchange's, not a tx hash — label it
                            // so nobody pastes it into a block explorer.
                            resultView.text = "Coinbase transfer ${result.transferId}\n" +
                                "${result.amount} ${result.currency}" +
                                (result.status?.let { " · $it" } ?: "") +
                                "\nexchange id, not an on-chain hash"
                            resultView.visibility = View.VISIBLE
                        }
                        is FireblocksFundResult.Cancelled -> Unit
                        is FireblocksFundResult.Error -> {
                            resultView.visibility = View.GONE
                            errorView.text = "[${result.code ?: "unknown"}] ${result.reason}"
                            errorView.visibility = View.VISIBLE
                        }
                    }
                }
            }
        }
        connectedContainer.addView(button)
        connectedContainer.addView(resultView)
        connectedContainer.addView(errorView)
    }


    // ── Connected: sign + send ────────────────────────────────────────────────

    private fun label(text: String) = TextView(this).apply {
        this.text = text
        textSize = 12f
        setTextColor(Color.parseColor("#6B7280"))
        setPadding(0, 16, 0, 4)
    }

    private fun field(hint: String, initialText: String = ""): EditText = EditText(this).apply {
        this.hint = hint
        setText(initialText)
    }

    private fun resultText(): TextView = TextView(this).apply {
        textSize = 12f
        setTextColor(Color.parseColor("#111827"))
        setPadding(0, 8, 0, 0)
        setTextIsSelectable(true)
    }

    private fun errorText(): TextView = TextView(this).apply {
        textSize = 12f
        setTextColor(Color.parseColor("#DC2626"))
        setPadding(0, 8, 0, 0)
    }

    private fun renderConnected() {
        val wallet = connectedWallet ?: return
        connectedContainer.removeAllViews()

        // Network comes first, before anything else. Two cases:
        //  - session-bound network (Phantom's redirect protocol,
        //    wallet.network != null): the session decides what the wallet
        //    will sign for — show it read-only, no choice to offer (the
        //    engine rejects a send on the other network anyway; reconnect
        //    with the other picker option to switch).
        //  - no binding (other Solana wallets): free toggle, and everything
        //    below (sign, send) uses that choice.
        if (wallet.chain.lowercase() == "solana") {
            if (wallet.network != null) renderSolanaNetworkLocked(wallet.network)
            else renderSolanaNetworkToggle()
        }

        val signResultView = resultText().apply { visibility = View.GONE }
        val signErrorView = errorText().apply { visibility = View.GONE }
        connectedContainer.addView(Button(this).apply {
            text = "Sign a message"
            isAllCaps = false
            setOnClickListener {
                isEnabled = false
                text = "Waiting for wallet…"
                val message = "Fireblocks Android sample sign test — ${System.currentTimeMillis()}"
                val done = { signature: String?, error: String? ->
                    runOnUiThread {
                        isEnabled = true
                        text = "Sign a message"
                        if (signature != null) {
                            signErrorView.visibility = View.GONE
                            signResultView.text = "Signature: $signature"
                            signResultView.visibility = View.VISIBLE
                        } else if (error != null) {
                            signResultView.visibility = View.GONE
                            signErrorView.text = error
                            signErrorView.visibility = View.VISIBLE
                        }
                    }
                }
                // A connection made inside the WALLET's own browser (Phantom on
                // EVM) has to be signed there too — that's the only place its
                // injected provider exists; neither the headless engine nor the
                // Custom Tab flow can see it.
                val template = wallet.walletBrowserUrl
                val walletKey = wallet.walletKey
                if (template != null && walletKey != null) {
                    FireblocksWalletBrowser.signMessage(
                        context = this@MainActivity,
                        hostedPageUrl = hostedPageUrl,
                        scheme = scheme,
                        walletBrowserUrl = template,
                        walletKey = walletKey,
                        message = message,
                        expectedAddress = wallet.address,
                        environmentId = environmentId,
                    ) { result ->
                        when (result) {
                            is FireblocksSignResult.Success -> done(result.signature, null)
                            is FireblocksSignResult.Cancelled -> done(null, null)
                            is FireblocksSignResult.Error ->
                                done(null, "[${result.code ?: "unknown"}] ${result.reason}")
                        }
                    }
                    return@setOnClickListener
                }
                FireblocksHeadlessConnect.sign(message) { result ->
                    when (result) {
                        is SignResult.Success -> done(result.signature, null)
                        is SignResult.Failure -> done(null, "[${result.code}] ${result.message}")
                    }
                }
            }
        })
        connectedContainer.addView(signResultView)
        connectedContainer.addView(signErrorView)

        if (wallet.chain.lowercase() == "solana") {
            renderSolanaSend()
        } else {
            renderEvmSend()
        }

        renderFundFromExchange(wallet)

        connectedContainer.addView(Button(this).apply {
            text = "Use a different wallet"
            isAllCaps = false
            setOnClickListener {
                FireblocksHeadlessConnect.cancel()
                disconnect()
            }
        })
    }

    /// EVM send: a plain JSON tx object — no chain SDK needed to build it,
    /// unlike Solana below.
    private fun renderEvmSend() {
        connectedContainer.addView(label("Chain ID"))
        val chainIdField = field("e.g. 1 (Ethereum Mainnet)", "1")
        connectedContainer.addView(chainIdField)

        // Asset — native token, or a custom ERC-20 by contract address (e.g.
        // a token not worth curating a chain-id table for, like B3). No RPC
        // call backs this app, so decimals/symbol are typed in rather than
        // looked up — see the caution label below the fields.
        connectedContainer.addView(label("Asset"))
        val assetGroup = RadioGroup(this).apply { orientation = LinearLayout.HORIZONTAL }
        val nativeRadio = RadioButton(this).apply { id = View.generateViewId(); text = "Native"; isChecked = true }
        val customRadio = RadioButton(this).apply { id = View.generateViewId(); text = "Custom…" }
        assetGroup.addView(nativeRadio)
        assetGroup.addView(customRadio)
        connectedContainer.addView(assetGroup)

        val customTokenContainer = LinearLayout(this).apply {
            orientation = LinearLayout.VERTICAL
            visibility = View.GONE
        }
        customTokenContainer.addView(label("Token contract address (0x…)"))
        val customTokenAddressField = field("0x…")
        customTokenContainer.addView(customTokenAddressField)
        val customTokenRow = LinearLayout(this).apply { orientation = LinearLayout.HORIZONTAL }
        val customTokenSymbolField = field("Symbol, e.g. B3").apply {
            layoutParams = LinearLayout.LayoutParams(0, WRAP_CONTENT, 1f)
        }
        val customTokenDecimalsField = field("Decimals, e.g. 18", "18").apply {
            layoutParams = LinearLayout.LayoutParams(0, WRAP_CONTENT, 1f)
        }
        customTokenRow.addView(customTokenSymbolField)
        customTokenRow.addView(customTokenDecimalsField)
        customTokenContainer.addView(customTokenRow)
        customTokenContainer.addView(
            label(
                "This app makes no RPC call to verify decimals against the token " +
                    "contract — wrong decimals sends the wrong amount. Double-check on a " +
                    "block explorer before sending.",
            ),
        )
        connectedContainer.addView(customTokenContainer)

        connectedContainer.addView(label("Recipient (0x…)"))
        val toField = field("0x…", "0xc0ffee254729296a45a3885639AC7E10F9d54979")
        connectedContainer.addView(toField)

        val amountLabel = label("Amount (native token)")
        connectedContainer.addView(amountLabel)
        val amountField = field("e.g. 0.001")
        connectedContainer.addView(amountField)

        fun refreshAmountLabel() {
            amountLabel.text = if (customRadio.isChecked) {
                val symbol = customTokenSymbolField.text.toString().trim()
                "Amount (${symbol.ifEmpty { "TOKEN" }.uppercase()})"
            } else {
                "Amount (native token)"
            }
        }
        assetGroup.setOnCheckedChangeListener { _, checkedId ->
            customTokenContainer.visibility = if (checkedId == customRadio.id) View.VISIBLE else View.GONE
            refreshAmountLabel()
        }
        customTokenSymbolField.doAfterTextChanged { refreshAmountLabel() }

        val resultView = resultText().apply { visibility = View.GONE }
        val errorView = errorText().apply { visibility = View.GONE }
        val sendButton = Button(this).apply {
            text = "Send a transaction (signs + broadcasts)"
            isAllCaps = false
        }
        sendButton.setOnClickListener {
            val chainId = chainIdField.text.toString().trim().toIntOrNull()
            val recipient = toField.text.toString().trim()
            val isCustom = customRadio.isChecked
            val tokenAddress = customTokenAddressField.text.toString().trim()
            val decimals = if (isCustom) customTokenDecimalsField.text.toString().trim().toIntOrNull() else 18
            val units = decimals?.let { parseUnits(amountField.text.toString(), it) }
            val validRecipient = recipient.matches(Regex("^0x[0-9a-fA-F]{40}$"))
            val validToken = !isCustom || tokenAddress.matches(Regex("^0x[0-9a-fA-F]{40}$"))
            if (chainId == null || !validRecipient || decimals == null || units == null || !validToken) {
                errorView.text = if (isCustom) {
                    "Enter a valid chain ID, token contract address, recipient (0x + 40 hex " +
                        "chars), decimals, and amount."
                } else {
                    "Enter a valid chain ID, recipient (0x + 40 hex chars), and amount."
                }
                errorView.visibility = View.VISIBLE
                resultView.visibility = View.GONE
                return@setOnClickListener
            }
            // The `to`/`value`/`data` this send needs: a plain native transfer,
            // or an ERC-20 `transfer(address,uint256)` call against the token
            // contract when a custom asset is selected.
            val to = if (isCustom) tokenAddress else recipient
            val value = if (isCustom) "0x0" else "0x" + units.toString(16)
            val data = if (isCustom) erc20TransferCalldata(recipient, units) else "0x"
            AlertDialog.Builder(this)
                .setTitle("Send this transaction?")
                .setMessage(
                    "This sends a REAL transaction on chain $chainId and spends real gas " +
                        "from the connected wallet. This cannot be undone.",
                )
                .setNegativeButton("Cancel", null)
                .setPositiveButton("Send") { _, _ ->
                    sendButton.isEnabled = false
                    sendButton.text = "Sending…"
                    val done = { txHash: String?, error: String? ->
                        runOnUiThread {
                            sendButton.isEnabled = true
                            sendButton.text = "Send a transaction (signs + broadcasts)"
                            if (txHash != null) {
                                errorView.visibility = View.GONE
                                resultView.text = "Sent — tx hash: $txHash"
                                resultView.visibility = View.VISIBLE
                            } else if (error != null) {
                                resultView.visibility = View.GONE
                                errorView.text = error
                                errorView.visibility = View.VISIBLE
                            }
                        }
                    }
                    // Same reasoning as the sign button's wallet-browser branch:
                    // the wallet only exposes this account inside its own
                    // browser, so the send has to be confirmed there.
                    val connected = connectedWallet
                    val template = connected?.walletBrowserUrl
                    val walletKey = connected?.walletKey
                    if (connected != null && template != null && walletKey != null) {
                        FireblocksWalletBrowser.sendTransaction(
                            context = this@MainActivity,
                            hostedPageUrl = hostedPageUrl,
                            scheme = scheme,
                            walletBrowserUrl = template,
                            walletKey = walletKey,
                            to = to,
                            chainId = "0x" + chainId.toString(16),
                            expectedAddress = connected.address,
                            value = value,
                            data = data,
                            environmentId = environmentId,
                        ) { result ->
                            when (result) {
                                is FireblocksSendResult.Success -> done(result.txHash, null)
                                is FireblocksSendResult.Cancelled -> done(null, null)
                                is FireblocksSendResult.Error ->
                                    done(null, "[${result.code ?: "unknown"}] ${result.reason}")
                            }
                        }
                        return@setPositiveButton
                    }
                    val transaction = org.json.JSONObject()
                        .put("to", to)
                        .put("value", value)
                        .put("data", data)
                        .put("chainId", "0x" + chainId.toString(16))
                        .toString()
                    FireblocksHeadlessConnect.sendTransaction(transaction) { result ->
                        when (result) {
                            is SendResult.Success -> done(result.txHash, null)
                            is SendResult.Failure -> done(null, "[${result.code}] ${result.message}")
                        }
                    }
                }
                .show()
        }
        connectedContainer.addView(sendButton)
        connectedContainer.addView(resultView)
        connectedContainer.addView(errorView)
    }

    /// Solana send: a native SOL transfer. This app only picks
    /// network/recipient/amount — the ENGINE builds the actual transaction
    /// (fetches a recent blockhash from the chosen cluster, adds a System
    /// Program transfer instruction; see `resolveSolanaTx` in
    /// `src/headless.ts`). `network` only picks which cluster THIS APP asks
    /// the engine to build against — the connected wallet (e.g. Phantom)
    /// broadcasts on whatever cluster IT is configured for, so a mismatch
    /// fails with something like "blockhash not found".
    private fun renderSolanaNetworkToggle() {
        connectedContainer.addView(label("Network"))
        val networkRow = LinearLayout(this).apply { orientation = LinearLayout.HORIZONTAL }
        val mainnetButton = Button(this).apply { text = "Mainnet"; isAllCaps = false }
        val devnetButton = Button(this).apply { text = "Devnet"; isAllCaps = false }
        fun refreshNetworkButtons() {
            mainnetButton.setBackgroundColor(
                Color.parseColor(if (solNetwork == "mainnet-beta") "#2563EB" else "#F0F2F5"),
            )
            mainnetButton.setTextColor(Color.parseColor(if (solNetwork == "mainnet-beta") "#FFFFFF" else "#0E121B"))
            devnetButton.setBackgroundColor(
                Color.parseColor(if (solNetwork == "devnet") "#2563EB" else "#F0F2F5"),
            )
            devnetButton.setTextColor(Color.parseColor(if (solNetwork == "devnet") "#FFFFFF" else "#0E121B"))
        }
        refreshNetworkButtons()
        mainnetButton.setOnClickListener { solNetwork = "mainnet-beta"; refreshNetworkButtons() }
        devnetButton.setOnClickListener { solNetwork = "devnet"; refreshNetworkButtons() }
        networkRow.addView(mainnetButton, LinearLayout.LayoutParams(0, WRAP_CONTENT, 1f))
        networkRow.addView(devnetButton, LinearLayout.LayoutParams(0, WRAP_CONTENT, 1f))
        connectedContainer.addView(networkRow)
    }

    /// Read-only replacement for [renderSolanaNetworkToggle] when the wallet
    /// session is BOUND to a network (Phantom's redirect protocol): the
    /// session decides what the wallet will sign for, so there's no choice
    /// to offer — switching means reconnecting with the other picker option
    /// in the wallet list.
    private fun renderSolanaNetworkLocked(network: String) {
        connectedContainer.addView(TextView(this).apply {
            text = "🔒 Network: ${if (network == "devnet") "Devnet" else "Mainnet"} — chosen at " +
                "connect. Reconnect to switch."
            textSize = 12f
            setTextColor(Color.parseColor("#6B7280"))
            setBackgroundColor(Color.parseColor("#F0F2F5"))
            setPadding(24, 20, 24, 20)
        })
    }

    private fun renderSolanaSend() {
        connectedContainer.addView(label("Recipient (base58 Solana address)"))
        val toField = field("Base58 Solana address")
        connectedContainer.addView(toField)

        connectedContainer.addView(label("Amount (SOL)"))
        val amountField = field("e.g. 0.01")
        connectedContainer.addView(amountField)

        connectedContainer.addView(TextView(this).apply {
            text = "Make sure the connected wallet is also set to the same network — this " +
                "app can't switch it for you."
            textSize = 11f
            setTextColor(Color.parseColor("#9CA3AF"))
            setPadding(0, 8, 0, 0)
        })

        val resultView = resultText().apply { visibility = View.GONE }
        val errorView = errorText().apply { visibility = View.GONE }
        val sendButton = Button(this).apply {
            text = "Send SOL (signs + broadcasts)"
            isAllCaps = false
        }
        sendButton.setOnClickListener {
            val to = toField.text.toString().trim()
            val lamports = parseUnits(amountField.text.toString(), 9)
            if (!to.matches(Regex("^[1-9A-HJ-NP-Za-km-z]{32,44}$")) || lamports == null) {
                errorView.text = "Enter a valid Solana recipient address and amount."
                errorView.visibility = View.VISIBLE
                resultView.visibility = View.GONE
                return@setOnClickListener
            }
            val network = solNetwork
            AlertDialog.Builder(this)
                .setTitle("Send this transaction?")
                .setMessage(
                    "This sends a REAL SOL transfer on Solana " +
                        (if (network == "mainnet-beta") "Mainnet" else "Devnet") +
                        " and spends real SOL for network fees from the connected wallet. " +
                        "This cannot be undone.",
                )
                .setNegativeButton("Cancel", null)
                .setPositiveButton("Send") { _, _ ->
                    sendButton.isEnabled = false
                    sendButton.text = "Sending…"
                    val transaction = org.json.JSONObject()
                        .put("to", to)
                        .put("lamports", lamports.toString())
                        .put("network", network)
                        .toString()
                    FireblocksHeadlessConnect.sendTransaction(transaction) { result ->
                        runOnUiThread {
                            sendButton.isEnabled = true
                            sendButton.text = "Send SOL (signs + broadcasts)"
                            when (result) {
                                is SendResult.Success -> {
                                    errorView.visibility = View.GONE
                                    resultView.text = "Sent — signature: ${result.txHash}"
                                    resultView.visibility = View.VISIBLE
                                }
                                is SendResult.Failure -> {
                                    resultView.visibility = View.GONE
                                    errorView.text = "[${result.code}] ${result.message}"
                                    errorView.visibility = View.VISIBLE
                                }
                            }
                        }
                    }
                }
                .show()
        }
        connectedContainer.addView(sendButton)
        connectedContainer.addView(resultView)
        connectedContainer.addView(errorView)
    }

    /// Parses a decimal-string amount (e.g. "10.5") into the smallest unit for
    /// a token with [decimals] decimal places, as a [BigInteger] — no
    /// floating point, so precision never gets lost the way `Double` would
    /// with large amounts. Returns `null` for empty/malformed input, too many
    /// fractional digits, or a zero amount. Mirrors `_parseUnits` in the
    /// Flutter sample's `example_screen.dart`.
    private fun parseUnits(input: String, decimals: Int): BigInteger? {
        val trimmed = input.trim()
        if (trimmed.isEmpty() || !Regex("^\\d+(\\.\\d+)?$").matches(trimmed)) return null
        val parts = trimmed.split(".")
        val whole = parts[0]
        val frac = if (parts.size > 1) parts[1] else ""
        if (frac.length > decimals) return null
        val value = (whole + frac.padEnd(decimals, '0')).toBigIntegerOrNull() ?: return null
        return if (value == BigInteger.ZERO) null else value
    }

    /// Encodes an ERC-20 `transfer(address,uint256)` call: 4-byte selector
    /// (`0xa9059cbb`) + the recipient left-padded to 32 bytes + the amount
    /// left-padded to 32 bytes. Mirrors `_erc20TransferCalldata` in the
    /// Flutter sample's `example_screen.dart`.
    private fun erc20TransferCalldata(recipient: String, amount: BigInteger): String {
        val addressWord = recipient.removePrefix("0x").lowercase().padStart(64, '0')
        val amountWord = amount.toString(16).padStart(64, '0')
        return "0xa9059cbb$addressWord$amountWord"
    }
}