WebAuthn passkey on Android

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dependencies {
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    implementation("androidx.browser:browser-auth:1.0.0-alpha03")
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    // Other dependencies
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}

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import android.content.Intent
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import android.net.Uri
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import android.os.Bundle
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import android.util.Log
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import androidx.activity.enableEdgeToEdge
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import androidx.activity.result.ActivityResultLauncher
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import androidx.annotation.OptIn
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import androidx.appcompat.app.AppCompatActivity
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import androidx.browser.auth.AuthTabIntent
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import androidx.browser.auth.ExperimentalAuthTab
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// MARK: - Configuration Constants
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const val CONST_BASE_URL = "https://example.com" // Set your backend authentication URL here
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const val CONST_SCHEME = "mgpandroid://auth" // Your custom URL scheme
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class MainActivity : AppCompatActivity() {
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    private lateinit var authTabLauncher: ActivityResultLauncher<Intent>
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    @OptIn(ExperimentalAuthTab::class)
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    override fun onCreate(savedInstanceState: Bundle?) {
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        super.onCreate(savedInstanceState)
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        enableEdgeToEdge()
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        setContentView(R.layout.activity_main)
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        // Register the Auth Tab launcher
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        authTabLauncher = AuthTabIntent.registerActivityResultLauncher(this, this::handleAuthResult)
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    }
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    override fun onNewIntent(intent: Intent) {
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        super.onNewIntent(intent)
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        // Handle intent when app is opened from CustomTabs via our custom scheme
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        intent.data?.let { uri ->
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            handleIncomingURL(uri)
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        }
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    }
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    /**
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     * Starts the web authentication session
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     */
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    @OptIn(ExperimentalAuthTab::class)
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    fun startAuthentication() {
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        val strUrl = CONST_BASE_URL + "&returnUrl=" + CONST_SCHEME
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        val authUrl = Uri.parse(strUrl)
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        // Create and launch AuthTab directly
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        val authTabIntent = AuthTabIntent.Builder().build()
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        authTabIntent.launch(authTabLauncher, authUrl, "mgpandroid")
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    }
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    /**
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     * Handle the authentication result from AuthTab
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     */
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    @OptIn(ExperimentalAuthTab::class)
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    private fun handleAuthResult(result: AuthTabIntent.AuthResult) {
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        when (result.resultCode) {
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            AuthTabIntent.RESULT_OK -> {
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                // Process the result URI
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                val callbackURL = result.resultUri
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                // Handle the callback URL received from the authentication flow
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                handleIncomingURL(callbackURL)
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            }
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            AuthTabIntent.RESULT_CANCELED -> {
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                Log.d("Authentication", "Authentication was canceled")
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            }
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            AuthTabIntent.RESULT_VERIFICATION_FAILED -> {
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                Log.e("Authentication", "Verification failed")
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            }
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            AuthTabIntent.RESULT_VERIFICATION_TIMED_OUT -> {
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                Log.e("Authentication", "Verification timed out")
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            }
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        }
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    }
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    /**
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     * Handles the URL returned from the authentication flow
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     * This handles URLs from both the AuthTab result and from CustomTabs fallback
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     */
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    private fun handleIncomingURL(url: Uri?) {
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        if (url == null) {
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            Log.e("Authentication", "No callback URL received")
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            return
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        }
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        Log.d("Authentication", "Incoming URL: $url")
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        // Ensure the URL uses the expected custom scheme
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        val scheme = url.scheme
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        if (scheme != "mgpandroid") {
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            Log.e("Authentication", "Invalid URL scheme")
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            return
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        }
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        // Extract query parameter
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        val controlStatus = url.getQueryParameter("controlStatus") ?: ""
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        // Check if authentication was successful
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        if (controlStatus == "VALIDATED") {
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            Log.d("Authentication", "Action succeeded")
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            // Handle successful authentication
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        } else {
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            // Handle authentication failure or unexpected status
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            Log.e("Authentication", "Action Failed: controlStatus=$controlStatus")
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        }
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    }
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}

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// Inside an activity or fragment
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val authButton = findViewById<Button>(R.id.authButton)
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authButton.setOnClickListener {
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    startAuthentication()
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}