/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.fenix

import android.annotation.SuppressLint
import android.os.Build
import android.os.Build.VERSION.SDK_INT
import android.os.StrictMode
import android.util.Log.INFO
import androidx.annotation.CallSuper
import androidx.appcompat.app.AppCompatDelegate
import androidx.core.content.getSystemService
import androidx.work.Configuration.Builder
import androidx.work.Configuration.Provider
import kotlinx.coroutines.Deferred
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.async
import kotlinx.coroutines.launch
import mozilla.appservices.Megazord
import mozilla.components.browser.state.action.SystemAction
import mozilla.components.browser.state.selector.selectedTab
import mozilla.components.concept.base.crash.Breadcrumb
import mozilla.components.concept.push.PushProcessor
import mozilla.components.feature.addons.update.GlobalAddonDependencyProvider
import mozilla.components.lib.crash.CrashReporter
import mozilla.components.service.glean.Glean
import mozilla.components.service.glean.config.Configuration
import mozilla.components.service.glean.net.ConceptFetchHttpUploader
import mozilla.components.support.base.facts.register
import mozilla.components.support.base.log.Log
import mozilla.components.support.base.log.logger.Logger
import mozilla.components.support.ktx.android.content.isMainProcess
import mozilla.components.support.ktx.android.content.runOnlyInMainProcess
import mozilla.components.support.locale.LocaleAwareApplication
import mozilla.components.support.rusthttp.RustHttpConfig
import mozilla.components.support.rustlog.RustLog
import mozilla.components.support.utils.logElapsedTime
import mozilla.components.support.webextensions.WebExtensionSupport
import org.mozilla.fenix.GleanMetrics.PerfStartup
import org.mozilla.fenix.components.Components
import org.mozilla.fenix.components.metrics.MetricServiceType
import org.mozilla.fenix.components.metrics.SecurePrefsTelemetry
import org.mozilla.fenix.ext.settings
import org.mozilla.fenix.perf.ProfilerMarkerFactProcessor
import org.mozilla.fenix.perf.StartupTimeline
import org.mozilla.fenix.perf.StorageStatsMetrics
import org.mozilla.fenix.perf.runBlockingIncrement
import org.mozilla.fenix.push.PushFxaIntegration
import org.mozilla.fenix.push.WebPushEngineIntegration
import org.mozilla.fenix.session.PerformanceActivityLifecycleCallbacks
import org.mozilla.fenix.session.VisibilityLifecycleCallback
import org.mozilla.fenix.utils.BrowsersCache
import java.util.concurrent.TimeUnit

/**
 *The main application class for Fenix. Records data to measure initialization performance.
 *  Installs [CrashReporter], initializes [Glean]  in fenix builds and setup Megazord in the main process.
 */
@Suppress("Registered", "TooManyFunctions", "LargeClass")
open class FenixApplication : LocaleAwareApplication(), Provider {
    init {
        recordOnInit() // DO NOT MOVE ANYTHING ABOVE HERE: the timing of this measurement is critical.
    }

    private val logger = Logger("FenixApplication")

    open val components by lazy { Components(this) }

    var visibilityLifecycleCallback: VisibilityLifecycleCallback? = null
        private set

    override fun onCreate() {
        val methodDurationTimerId = PerfStartup.applicationOnCreate.start() // DO NOT MOVE ANYTHING ABOVE HERE.
        super.onCreate()

        setupInAllProcesses()

        if (!isMainProcess()) {
            // If this is not the main process then do not continue with the initialization here. Everything that
            // follows only needs to be done in our app's main process and should not be done in other processes like
            // a GeckoView child process or the crash handling process. Most importantly we never want to end up in a
            // situation where we create a GeckoRuntime from the Gecko child process.
            return
        }

        if (Config.channel.isFenix) {
            // We need to always initialize Glean and do it early here.
            // Note that we are only initializing Glean here for "fenix" builds. "fennec" builds
            // will initialize in MigratingFenixApplication because we first need to migrate the
            // user's choice from Fennec.
            initializeGlean()
        }

        setupInMainProcessOnly()

        // We use start/stop instead of measure so we don't measure outside the main process.
        PerfStartup.applicationOnCreate.stopAndAccumulate(methodDurationTimerId) // DO NOT MOVE ANYTHING BELOW HERE.
    }

    protected open fun initializeGlean() {
        val telemetryEnabled = settings().isTelemetryEnabled

        logger.debug("Initializing Glean (uploadEnabled=$telemetryEnabled, isFennec=${Config.channel.isFennec})")

        Glean.initialize(
            applicationContext = this,
            configuration = Configuration(
                channel = BuildConfig.BUILD_TYPE,
                httpClient = ConceptFetchHttpUploader(
                    lazy(LazyThreadSafetyMode.NONE) { components.core.client }
                )),
            uploadEnabled = telemetryEnabled
        )
    }

    @CallSuper
    open fun setupInAllProcesses() {
        setupCrashReporting()

        // We want the log messages of all builds to go to Android logcat
        Log.addSink(FenixLogSink(logsDebug = Config.channel.isDebug))
    }

    @CallSuper
    open fun setupInMainProcessOnly() {
        ProfilerMarkerFactProcessor.create { components.core.engine.profiler }.register()

        run {
            // Attention: Do not invoke any code from a-s in this scope.
            val megazordSetup = setupMegazord()

            setDayNightTheme()
            components.strictMode.enableStrictMode(true)
            warmBrowsersCache()

            // Make sure the engine is initialized and ready to use.
            components.strictMode.resetAfter(StrictMode.allowThreadDiskReads()) {
                components.core.engine.warmUp()
            }
            initializeWebExtensionSupport()
            restoreBrowserState()
            restoreDownloads()

            // Just to make sure it is impossible for any application-services pieces
            // to invoke parts of itself that require complete megazord initialization
            // before that process completes, we wait here, if necessary.
            if (!megazordSetup.isCompleted) {
                runBlockingIncrement { megazordSetup.await() }
            }
        }

        setupLeakCanary()
        startMetricsIfEnabled()
        setupPush()

        visibilityLifecycleCallback = VisibilityLifecycleCallback(getSystemService())
        registerActivityLifecycleCallbacks(visibilityLifecycleCallback)

        // Storage maintenance disabled, for now, as it was interfering with background migrations.
        // See https://github.com/mozilla-mobile/fenix/issues/7227 for context.
        // if ((System.currentTimeMillis() - settings().lastPlacesStorageMaintenance) > ONE_DAY_MILLIS) {
        //    runStorageMaintenance()
        // }

        initVisualCompletenessQueueAndQueueTasks()

        components.appStartupTelemetry.onFenixApplicationOnCreate()
    }

    private fun restoreBrowserState() = GlobalScope.launch(Dispatchers.Main) {
        val store = components.core.store
        val sessionStorage = components.core.sessionStorage

        components.useCases.tabsUseCases.restore(sessionStorage, settings().getTabTimeout())

        // Now that we have restored our previous state (if there's one) let's setup auto saving the state while
        // the app is used.
        sessionStorage.autoSave(store)
            .periodicallyInForeground(interval = 30, unit = TimeUnit.SECONDS)
            .whenGoingToBackground()
            .whenSessionsChange()
    }

    private fun restoreDownloads() {
        components.useCases.downloadUseCases.restoreDownloads()
    }

    private fun initVisualCompletenessQueueAndQueueTasks() {
        val queue = components.performance.visualCompletenessQueue.queue

        fun initQueue() {
            registerActivityLifecycleCallbacks(PerformanceActivityLifecycleCallbacks(queue))
        }

        fun queueInitStorageAndServices() {
            components.performance.visualCompletenessQueue.queue.runIfReadyOrQueue {
                GlobalScope.launch(Dispatchers.IO) {
                    logger.info("Running post-visual completeness tasks...")
                    logElapsedTime(logger, "Storage initialization") {
                        components.core.historyStorage.warmUp()
                        components.core.bookmarksStorage.warmUp()
                        components.core.passwordsStorage.warmUp()
                    }

                    SecurePrefsTelemetry(this@FenixApplication, components.analytics.experiments).startTests()
                }
                // Account manager initialization needs to happen on the main thread.
                GlobalScope.launch(Dispatchers.Main) {
                    logElapsedTime(logger, "Kicking-off account manager") {
                        components.backgroundServices.accountManager
                    }
                }
            }
        }

        fun queueMetrics() {
            if (SDK_INT >= Build.VERSION_CODES.O) { // required by StorageStatsMetrics.
                queue.runIfReadyOrQueue {
                    // Because it may be slow to capture the storage stats, it might be preferred to
                    // create a WorkManager task for this metric, however, I ran out of
                    // implementation time and WorkManager is harder to test.
                    StorageStatsMetrics.report(this.applicationContext)
                }
            }
        }

        fun queueReviewPrompt() {
            GlobalScope.launch(Dispatchers.IO) {
                components.reviewPromptController.trackApplicationLaunch()
            }
        }

        initQueue()

        // We init these items in the visual completeness queue to avoid them initing in the critical
        // startup path, before the UI finishes drawing (i.e. visual completeness).
        queueInitStorageAndServices()
        queueMetrics()
        queueReviewPrompt()
    }

    private fun startMetricsIfEnabled() {
        if (settings().isTelemetryEnabled) {
            components.analytics.metrics.start(MetricServiceType.Data)
        }

        if (settings().isMarketingTelemetryEnabled) {
            components.analytics.metrics.start(MetricServiceType.Marketing)
        }
    }

    // See https://github.com/mozilla-mobile/fenix/issues/7227 for context.
    // To re-enable this, we need to do so in a way that won't interfere with any startup operations
    // which acquire reserved+ sqlite lock. Currently, Fennec migrations need to write to storage
    // on startup, and since they run in a background service we can't simply order these operations.
    private fun runStorageMaintenance() {
        GlobalScope.launch(Dispatchers.IO) {
            // Bookmarks and history storage sit on top of the same db file so we only need to
            // run maintenance on one - arbitrarily using bookmarks.
            components.core.bookmarksStorage.runMaintenance()
        }
        settings().lastPlacesStorageMaintenance = System.currentTimeMillis()
    }

    protected open fun setupLeakCanary() {
        // no-op, LeakCanary is disabled by default
    }

    open fun updateLeakCanaryState(isEnabled: Boolean) {
        // no-op, LeakCanary is disabled by default
    }

    private fun setupPush() {
        // Sets the PushFeature as the singleton instance for push messages to go to.
        // We need the push feature setup here to deliver messages in the case where the service
        // starts up the app first.
        components.push.feature?.let {
            Logger.info("AutoPushFeature is configured, initializing it...")

            // Install the AutoPush singleton to receive messages.
            PushProcessor.install(it)

            WebPushEngineIntegration(components.core.engine, it).start()

            // Perform a one-time initialization of the account manager if a message is received.
            PushFxaIntegration(it, lazy { components.backgroundServices.accountManager }).launch()

            // Initialize the service. This could potentially be done in a coroutine in the future.
            it.initialize()
        }
    }

    private fun setupCrashReporting() {
        components
            .analytics
            .crashReporter
            .install(this)
    }

    /**
     * Initiate Megazord sequence! Megazord Battle Mode!
     *
     * The application-services combined libraries are known as the "megazord". We use the default `full`
     * megazord - it contains everything that fenix needs, and (currently) nothing more.
     *
     * Documentation on what megazords are, and why they're needed:
     * - https://github.com/mozilla/application-services/blob/master/docs/design/megazords.md
     * - https://mozilla.github.io/application-services/docs/applications/consuming-megazord-libraries.html
     */
    private fun setupMegazord(): Deferred<Unit> {
        // Note: Megazord.init() must be called as soon as possible ...
        Megazord.init()

        return GlobalScope.async(Dispatchers.IO) {
            // ... but RustHttpConfig.setClient() and RustLog.enable() can be called later.
            RustHttpConfig.setClient(lazy { components.core.client })
            RustLog.enable(components.analytics.crashReporter)
            // We want to ensure Nimbus is initialized as early as possible so we can
            // experiment on features close to startup.
            // But we need viaduct (the RustHttp client) to be ready before we do.
            components.analytics.experiments.initialize()
        }
    }

    override fun onTrimMemory(level: Int) {
        super.onTrimMemory(level)

        // Additional logging and breadcrumb to debug memory issues:
        // https://github.com/mozilla-mobile/fenix/issues/12731

        logger.info("onTrimMemory(), level=$level, main=${isMainProcess()}")

        components.analytics.crashReporter.recordCrashBreadcrumb(Breadcrumb(
            category = "Memory",
            message = "onTrimMemory()",
            data = mapOf(
                "level" to level.toString(),
                "main" to isMainProcess().toString()
            ),
            level = Breadcrumb.Level.INFO
        ))

        runOnlyInMainProcess {
            components.core.icons.onTrimMemory(level)

            // We want to be judicious in passing low mamory messages to
            // android-components, because it is (at time of writing) hardcoded
            // to drop tab states (and any user data in them) as soon as we
            // reach "moderate" memory pressure on the system, even if the
            // browser is in no danger of being killed. See
            // https://github.com/mozilla-mobile/android-components/blob/38186676d46c555b5a24268e5fa361e45e57102c/components/browser/session/src/main/java/mozilla/components/browser/session/engine/middleware/TrimMemoryMiddleware.kt#L53-L64
            // for the relvant android-components code and
            // https://stuff.mit.edu/afs/sipb/project/android/docs/reference/android/content/ComponentCallbacks2.html
            // for the list of memory pressure levels.
            val settings = this.settings()
            if (settings.shouldRelinquishMemoryUnderPressure) {
                // We will give up our RAM when asked nicely
                components.core.store.dispatch(SystemAction.LowMemoryAction(level))
            }
            // Otherwise we will die for our RAM, if pressed.
        }
    }

    @SuppressLint("WrongConstant")
    // Suppressing erroneous lint warning about using MODE_NIGHT_AUTO_BATTERY, a likely library bug
    private fun setDayNightTheme() {
        val settings = this.settings()
        when {
            settings.shouldUseLightTheme -> {
                AppCompatDelegate.setDefaultNightMode(
                    AppCompatDelegate.MODE_NIGHT_NO
                )
            }
            settings.shouldUseDarkTheme -> {
                AppCompatDelegate.setDefaultNightMode(
                    AppCompatDelegate.MODE_NIGHT_YES
                )
            }
            SDK_INT < Build.VERSION_CODES.P && settings.shouldUseAutoBatteryTheme -> {
                AppCompatDelegate.setDefaultNightMode(
                    AppCompatDelegate.MODE_NIGHT_AUTO_BATTERY
                )
            }
            SDK_INT >= Build.VERSION_CODES.P && settings.shouldFollowDeviceTheme -> {
                AppCompatDelegate.setDefaultNightMode(
                    AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
                )
            }
            // First run of app no default set, set the default to Follow System for 28+ and Normal Mode otherwise
            else -> {
                if (SDK_INT >= Build.VERSION_CODES.P) {
                    AppCompatDelegate.setDefaultNightMode(
                        AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
                    )
                    settings.shouldFollowDeviceTheme = true
                } else {
                    AppCompatDelegate.setDefaultNightMode(
                        AppCompatDelegate.MODE_NIGHT_NO
                    )
                    settings.shouldUseLightTheme = true
                }
            }
        }
    }

    private fun warmBrowsersCache() {
        // We avoid blocking the main thread for BrowsersCache on startup by loading it on
        // background thread.
        GlobalScope.launch(Dispatchers.Default) {
            BrowsersCache.all(this@FenixApplication)
        }
    }

    private fun initializeWebExtensionSupport() {
        try {
            GlobalAddonDependencyProvider.initialize(
                components.addonManager,
                components.addonUpdater,
                onCrash = { exception ->
                    components.analytics.crashReporter.submitCaughtException(exception)
                }
            )
            WebExtensionSupport.initialize(
                components.core.engine,
                components.core.store,
                onNewTabOverride = {
                    _, engineSession, url ->
                        val shouldCreatePrivateSession =
                            components.core.store.state.selectedTab?.content?.private
                                ?: components.settings.openLinksInAPrivateTab

                        if (shouldCreatePrivateSession) {
                            components.useCases.tabsUseCases.addPrivateTab(
                                url = url,
                                selectTab = true,
                                engineSession = engineSession
                            )
                        } else {
                            components.useCases.tabsUseCases.addTab(
                                url = url,
                                selectTab = true,
                                engineSession = engineSession
                            )
                        }
                },
                onCloseTabOverride = {
                    _, sessionId -> components.useCases.tabsUseCases.removeTab(sessionId)
                },
                onSelectTabOverride = {
                    _, sessionId -> components.useCases.tabsUseCases.selectTab(sessionId)
                },
                onExtensionsLoaded = { extensions ->
                    components.addonUpdater.registerForFutureUpdates(extensions)
                    components.supportedAddonsChecker.registerForChecks()
                },
                onUpdatePermissionRequest = components.addonUpdater::onUpdatePermissionRequest
            )
        } catch (e: UnsupportedOperationException) {
            Logger.error("Failed to initialize web extension support", e)
        }
    }

    protected fun recordOnInit() {
        // This gets called by more than one process. Ideally we'd only run this in the main process
        // but the code to check which process we're in crashes because the Context isn't valid yet.
        //
        // This method is not covered by our internal crash reporting: be very careful when modifying it.
        StartupTimeline.onApplicationInit() // DO NOT MOVE ANYTHING ABOVE HERE: the timing is critical.
    }

    override fun onConfigurationChanged(config: android.content.res.Configuration) {
        // Workaround for androidx appcompat issue where follow system day/night mode config changes
        // are not triggered when also using createConfigurationContext like we do in LocaleManager
        // https://issuetracker.google.com/issues/143570309#comment3
        applicationContext.resources.configuration.uiMode = config.uiMode

        if (isMainProcess()) {
            // We can only do this on the main process as resetAfter will access components.core, which
            // will initialize the engine and create an additional GeckoRuntime from the Gecko
            // child process, causing a crash.

            // There's a strict mode violation in A-Cs LocaleAwareApplication which
            // reads from shared prefs: https://github.com/mozilla-mobile/android-components/issues/8816
            components.strictMode.resetAfter(StrictMode.allowThreadDiskReads()) {
                super.onConfigurationChanged(config)
            }
        } else {
            super.onConfigurationChanged(config)
        }
    }

    override fun getWorkManagerConfiguration() = Builder().setMinimumLoggingLevel(INFO).build()
}