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/*
* Copyright 2019 Allan Wang
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.pitchedapps.frost.utils
import android.content.Context
import android.hardware.fingerprint.FingerprintManager
import android.os.Build
import androidx.biometric.BiometricPrompt
import androidx.fragment.app.FragmentActivity
import ca.allanwang.kau.utils.string
import com.pitchedapps.frost.R
import kotlinx.coroutines.CompletableDeferred
import java.util.concurrent.Executor
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors
typealias BiometricDeferred = CompletableDeferred<BiometricPrompt.CryptoObject?>
/**
* Container for [BiometricPrompt]
* Inspired by coroutine's CommonPool
*/
object BiometricUtils {
private val executor: Executor
get() = pool ?: getOrCreatePoolSync()
@Volatile
private var pool: ExecutorService? = null
private var lastUnlockTime = -1L
private const val UNLOCK_TIME_INTERVAL = 15 * 60 * 1000
/**
* Checks if biometric authentication is possible
* Currently, this means checking for enrolled fingerprints
*/
@Suppress("DEPRECATION")
fun isSupported(context: Context): Boolean {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) return false
val fingerprintManager =
context.getSystemService(FingerprintManager::class.java) ?: return false
return fingerprintManager.isHardwareDetected && fingerprintManager.hasEnrolledFingerprints()
}
private fun getOrCreatePoolSync(): Executor =
pool ?: Executors.newSingleThreadExecutor().also { pool = it }
private fun shouldPrompt(context: Context): Boolean {
return Prefs.biometricsEnabled && System.currentTimeMillis() - lastUnlockTime > UNLOCK_TIME_INTERVAL
}
/**
* Generates a prompt dialog and attempt to return an auth object.
* Note that the underlying request will call [androidx.fragment.app.FragmentTransaction.commit],
* so this cannot happen after onSaveInstanceState.
*/
fun authenticate(activity: FragmentActivity, force: Boolean = false): BiometricDeferred {
val deferred: BiometricDeferred = CompletableDeferred()
if (!force && !shouldPrompt(activity)) {
deferred.complete(null)
return deferred
}
val info = BiometricPrompt.PromptInfo.Builder()
.setTitle(activity.string(R.string.biometrics_prompt_title))
.setNegativeButtonText(activity.string(R.string.kau_cancel))
.build()
BiometricPrompt(activity, executor, Callback(activity, deferred)).authenticate(info)
return deferred
}
private class Callback(val activity: FragmentActivity, val deferred: BiometricDeferred) :
BiometricPrompt.AuthenticationCallback() {
override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
deferred.cancel()
activity.finish()
}
override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
lastUnlockTime = System.currentTimeMillis()
deferred.complete(result.cryptoObject)
}
override fun onAuthenticationFailed() {
deferred.cancel()
activity.finish()
}
}
/**
* For completeness we provide a shutdown function.
* In practice, we initialize the executor only when it is first used,
* and keep it alive throughout the app lifecycle, as it will be used an arbitrary number of times,
* with unknown frequency
*/
@Synchronized
fun shutdown() {
pool?.shutdown()
pool = null
}
}
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