/* 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.browser

import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Bundle
import android.view.Gravity
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.annotation.CallSuper
import androidx.coordinatorlayout.widget.CoordinatorLayout
import androidx.core.net.toUri
import androidx.core.view.isVisible
import androidx.fragment.app.Fragment
import androidx.fragment.app.activityViewModels
import androidx.lifecycle.lifecycleScope
import androidx.navigation.fragment.findNavController
import com.google.android.material.snackbar.Snackbar
import kotlinx.android.synthetic.main.fragment_browser.*
import kotlinx.android.synthetic.main.fragment_browser.view.*
import kotlinx.coroutines.Dispatchers.IO
import kotlinx.coroutines.Dispatchers.Main
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.Job
import kotlinx.coroutines.MainScope
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.mapNotNull
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import mozilla.appservices.places.BookmarkRoot
import mozilla.components.browser.session.Session
import mozilla.components.browser.session.SessionManager
import mozilla.components.browser.state.action.ContentAction
import mozilla.components.browser.state.selector.findTabOrCustomTabOrSelectedTab
import mozilla.components.browser.state.state.SessionState
import mozilla.components.browser.state.state.content.DownloadState
import mozilla.components.browser.state.store.BrowserStore
import mozilla.components.browser.thumbnails.BrowserThumbnails
import mozilla.components.concept.engine.prompt.ShareData
import mozilla.components.feature.accounts.FxaCapability
import mozilla.components.feature.accounts.FxaWebChannelFeature
import mozilla.components.feature.app.links.AppLinksFeature
import mozilla.components.feature.contextmenu.ContextMenuCandidate
import mozilla.components.feature.contextmenu.ContextMenuFeature
import mozilla.components.feature.downloads.AbstractFetchDownloadService
import mozilla.components.feature.downloads.DownloadsFeature
import mozilla.components.feature.downloads.manager.FetchDownloadManager
import mozilla.components.feature.intent.ext.EXTRA_SESSION_ID
import mozilla.components.feature.media.fullscreen.MediaFullscreenOrientationFeature
import mozilla.components.feature.prompts.PromptFeature
import mozilla.components.feature.prompts.share.ShareDelegate
import mozilla.components.feature.readerview.ReaderViewFeature
import mozilla.components.feature.session.FullScreenFeature
import mozilla.components.feature.session.PictureInPictureFeature
import mozilla.components.feature.session.SessionFeature
import mozilla.components.feature.session.SessionUseCases
import mozilla.components.feature.session.SwipeRefreshFeature
import mozilla.components.feature.session.behavior.EngineViewBottomBehavior
import mozilla.components.feature.sitepermissions.SitePermissions
import mozilla.components.feature.sitepermissions.SitePermissionsFeature
import mozilla.components.feature.sitepermissions.SitePermissionsRules
import mozilla.components.lib.state.ext.flowScoped
import mozilla.components.service.sync.logins.DefaultLoginValidationDelegate
import mozilla.components.support.base.feature.PermissionsFeature
import mozilla.components.support.base.feature.UserInteractionHandler
import mozilla.components.support.base.feature.ViewBoundFeatureWrapper
import mozilla.components.support.ktx.android.view.exitImmersiveModeIfNeeded
import mozilla.components.support.ktx.android.view.hideKeyboard
import mozilla.components.support.ktx.kotlinx.coroutines.flow.ifChanged
import org.mozilla.fenix.FeatureFlags
import org.mozilla.fenix.HomeActivity
import org.mozilla.fenix.IntentReceiverActivity
import org.mozilla.fenix.NavGraphDirections
import org.mozilla.fenix.R
import org.mozilla.fenix.browser.readermode.DefaultReaderModeController
import org.mozilla.fenix.components.FenixSnackbar
import org.mozilla.fenix.components.FindInPageIntegration
import org.mozilla.fenix.components.StoreProvider
import org.mozilla.fenix.components.metrics.Event
import org.mozilla.fenix.components.toolbar.BrowserFragmentState
import org.mozilla.fenix.components.toolbar.BrowserFragmentStore
import org.mozilla.fenix.components.toolbar.BrowserInteractor
import org.mozilla.fenix.components.toolbar.BrowserToolbarView
import org.mozilla.fenix.components.toolbar.BrowserToolbarViewInteractor
import org.mozilla.fenix.components.toolbar.DefaultBrowserToolbarController
import org.mozilla.fenix.components.toolbar.SwipeRefreshScrollingViewBehavior
import org.mozilla.fenix.components.toolbar.ToolbarIntegration
import org.mozilla.fenix.downloads.DownloadService
import org.mozilla.fenix.downloads.DynamicDownloadDialog
import org.mozilla.fenix.ext.components
import org.mozilla.fenix.ext.enterToImmersiveMode
import org.mozilla.fenix.ext.hideToolbar
import org.mozilla.fenix.ext.metrics
import org.mozilla.fenix.ext.nav
import org.mozilla.fenix.ext.requireComponents
import org.mozilla.fenix.ext.sessionsOfType
import org.mozilla.fenix.ext.settings
import org.mozilla.fenix.home.SharedViewModel
import org.mozilla.fenix.tabtray.TabTrayDialogFragment
import org.mozilla.fenix.theme.ThemeManager
import org.mozilla.fenix.utils.allowUndo
import org.mozilla.fenix.wifi.SitePermissionsWifiIntegration
import java.lang.ref.WeakReference

/**
 * Base fragment extended by [BrowserFragment].
 * This class only contains shared code focused on the main browsing content.
 * UI code specific to the app or to custom tabs can be found in the subclasses.
 */
@ExperimentalCoroutinesApi
@Suppress("TooManyFunctions", "LargeClass")
abstract class BaseBrowserFragment : Fragment(), UserInteractionHandler, SessionManager.Observer {
    protected lateinit var browserFragmentStore: BrowserFragmentStore
    private lateinit var browserAnimator: BrowserAnimator

    private var _browserInteractor: BrowserToolbarViewInteractor? = null
    protected val browserInteractor: BrowserToolbarViewInteractor
        get() = _browserInteractor!!

    private var _browserToolbarView: BrowserToolbarView? = null
    protected val browserToolbarView: BrowserToolbarView
        get() = _browserToolbarView!!

    private val sessionManager: SessionManager
        get() = requireComponents.core.sessionManager

    protected val readerViewFeature = ViewBoundFeatureWrapper<ReaderViewFeature>()

    private val sessionFeature = ViewBoundFeatureWrapper<SessionFeature>()
    private val contextMenuFeature = ViewBoundFeatureWrapper<ContextMenuFeature>()
    private val downloadsFeature = ViewBoundFeatureWrapper<DownloadsFeature>()
    private val appLinksFeature = ViewBoundFeatureWrapper<AppLinksFeature>()
    private val promptsFeature = ViewBoundFeatureWrapper<PromptFeature>()
    private val findInPageIntegration = ViewBoundFeatureWrapper<FindInPageIntegration>()
    private val thumbnailsFeature = ViewBoundFeatureWrapper<BrowserThumbnails>()
    private val toolbarIntegration = ViewBoundFeatureWrapper<ToolbarIntegration>()
    private val sitePermissionsFeature = ViewBoundFeatureWrapper<SitePermissionsFeature>()
    private val fullScreenFeature = ViewBoundFeatureWrapper<FullScreenFeature>()
    private val swipeRefreshFeature = ViewBoundFeatureWrapper<SwipeRefreshFeature>()
    private val webchannelIntegration = ViewBoundFeatureWrapper<FxaWebChannelFeature>()
    private val sitePermissionWifiIntegration = ViewBoundFeatureWrapper<SitePermissionsWifiIntegration>()
    private var fullScreenMediaFeature = ViewBoundFeatureWrapper<MediaFullscreenOrientationFeature>()
    private var pipFeature: PictureInPictureFeature? = null

    var customTabSessionId: String? = null

    private var browserInitialized: Boolean = false
    private var initUIJob: Job? = null
    protected var webAppToolbarShouldBeVisible = true

    private val sharedViewModel: SharedViewModel by activityViewModels()

    @CallSuper
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        require(arguments != null)
        customTabSessionId = arguments?.getString(EXTRA_SESSION_ID)

        val view = inflater.inflate(R.layout.fragment_browser, container, false)

        val activity = activity as HomeActivity
        activity.themeManager.applyStatusBarTheme(activity)

        browserFragmentStore = StoreProvider.get(this) {
            BrowserFragmentStore(
                BrowserFragmentState()
            )
        }

        return view
    }

    final override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        browserInitialized = initializeUI(view) != null
    }

    @Suppress("ComplexMethod", "LongMethod")
    @CallSuper
    protected open fun initializeUI(view: View): Session? {
        val context = requireContext()
        val sessionManager = context.components.core.sessionManager
        val store = context.components.core.store

        val toolbarHeight = resources.getDimensionPixelSize(R.dimen.browser_toolbar_height)

        browserAnimator = BrowserAnimator(
            fragment = WeakReference(this),
            engineView = WeakReference(engineView),
            swipeRefresh = WeakReference(swipeRefresh),
            viewLifecycleScope = viewLifecycleOwner.lifecycleScope,
            arguments = requireArguments()
        ).apply {
            beginAnimateInIfNecessary()
        }

        return getSessionById()?.also { session ->
            val browserToolbarController = DefaultBrowserToolbarController(
                activity = requireActivity(),
                navController = findNavController(),
                readerModeController = DefaultReaderModeController(
                    readerViewFeature,
                    view.readerViewControlsBar,
                    isPrivate = (activity as HomeActivity).browsingModeManager.mode.isPrivate
                ),
                sessionManager = requireComponents.core.sessionManager,
                findInPageLauncher = { findInPageIntegration.withFeature { it.launch() } },
                engineView = engineView,
                swipeRefresh = swipeRefresh,
                browserAnimator = browserAnimator,
                customTabSession = customTabSessionId?.let { sessionManager.findSessionById(it) },
                openInFenixIntent = Intent(context, IntentReceiverActivity::class.java).apply {
                    action = Intent.ACTION_VIEW
                    putExtra(HomeActivity.OPEN_TO_BROWSER, true)
                },
                bookmarkTapped = { viewLifecycleOwner.lifecycleScope.launch { bookmarkTapped(it) } },
                scope = viewLifecycleOwner.lifecycleScope,
                tabCollectionStorage = requireComponents.core.tabCollectionStorage,
                topSiteStorage = requireComponents.core.topSiteStorage,
                sharedViewModel = sharedViewModel,
                onTabCounterClicked = {
                    TabTrayDialogFragment.show(parentFragmentManager)
                },
                onCloseTab = {
                    val snapshot = sessionManager.createSessionSnapshot(it)
                    val state = snapshot.engineSession?.saveState()
                    val isSelected =
                        it.id == context.components.core.store.state.selectedTabId ?: false

                    val snackbarMessage = if (snapshot.session.private) {
                        requireContext().getString(R.string.snackbar_private_tab_closed)
                    } else {
                        requireContext().getString(R.string.snackbar_tab_closed)
                    }

                    viewLifecycleOwner.lifecycleScope.allowUndo(
                        requireView(),
                        snackbarMessage,
                        requireContext().getString(R.string.snackbar_deleted_undo),
                        {
                            sessionManager.add(
                                snapshot.session,
                                isSelected,
                                engineSessionState = state
                            )
                        },
                        operation = { }
                    )
                }
            )

            _browserInteractor = BrowserInteractor(
                browserToolbarController = browserToolbarController
            )

            _browserToolbarView = BrowserToolbarView(
                container = view.browserLayout,
                shouldUseBottomToolbar = context.settings().shouldUseBottomToolbar,
                interactor = browserInteractor,
                customTabSession = customTabSessionId?.let { sessionManager.findSessionById(it) },
                lifecycleOwner = viewLifecycleOwner
            )

            thumbnailsFeature.set(
                feature = BrowserThumbnails(context, view.engineView, store),
                owner = this,
                view = view
            )

            toolbarIntegration.set(
                feature = browserToolbarView.toolbarIntegration,
                owner = this,
                view = view
            )

            findInPageIntegration.set(
                feature = FindInPageIntegration(
                    store = store,
                    sessionId = customTabSessionId,
                    stub = view.stubFindInPage,
                    engineView = view.engineView,
                    toolbar = browserToolbarView.view
                ),
                owner = this,
                view = view
            )

            browserToolbarView.view.display.setOnSiteSecurityClickedListener {
                showQuickSettingsDialog()
            }

            browserToolbarView.view.display.setOnTrackingProtectionClickedListener {
                context.metrics.track(Event.TrackingProtectionIconPressed)
                showTrackingProtectionPanel()
            }

            contextMenuFeature.set(
                feature = ContextMenuFeature(
                    fragmentManager = parentFragmentManager,
                    store = store,
                    candidates = getContextMenuCandidates(context, view),
                    engineView = view.engineView,
                    useCases = context.components.useCases.contextMenuUseCases,
                    tabId = customTabSessionId
                ),
                owner = this,
                view = view
            )

            fullScreenMediaFeature.set(
                feature = MediaFullscreenOrientationFeature(
                    requireActivity(),
                    context.components.core.store
                ),
                owner = this,
                view = view
            )

            val downloadFeature = DownloadsFeature(
                context.applicationContext,
                store = store,
                useCases = context.components.useCases.downloadUseCases,
                fragmentManager = childFragmentManager,
                tabId = customTabSessionId,
                downloadManager = FetchDownloadManager(
                    context.applicationContext,
                    store,
                    DownloadService::class
                ),
                promptsStyling = DownloadsFeature.PromptsStyling(
                    gravity = Gravity.BOTTOM,
                    shouldWidthMatchParent = true,
                    positiveButtonBackgroundColor = ThemeManager.resolveAttribute(
                        R.attr.accent,
                        context
                    ),
                    positiveButtonTextColor = ThemeManager.resolveAttribute(
                        R.attr.contrastText,
                        context
                    ),
                    positiveButtonRadius = (resources.getDimensionPixelSize(R.dimen.tab_corner_radius)).toFloat()
                ),
                onNeedToRequestPermissions = { permissions ->
                    requestPermissions(permissions, REQUEST_CODE_DOWNLOAD_PERMISSIONS)
                }
            )

            downloadFeature.onDownloadStopped = { downloadState, _, downloadJobStatus ->
                // If the download is just paused, don't show any in-app notification
                if (downloadJobStatus == AbstractFetchDownloadService.DownloadJobStatus.COMPLETED ||
                    downloadJobStatus == AbstractFetchDownloadService.DownloadJobStatus.FAILED
                ) {

                    saveDownloadDialogState(session, downloadState, downloadJobStatus)

                    DynamicDownloadDialog(
                        container = view.browserLayout,
                        downloadState = downloadState,
                        didFail = downloadJobStatus == AbstractFetchDownloadService.DownloadJobStatus.FAILED,
                        tryAgain = downloadFeature::tryAgain,
                        onCannotOpenFile = {
                            FenixSnackbar.make(
                                view = view,
                                duration = Snackbar.LENGTH_SHORT,
                                isDisplayedWithBrowserToolbar = true
                            )
                                .setText(context.getString(R.string.mozac_feature_downloads_could_not_open_file))
                                .show()
                        },
                        view = view.viewDynamicDownloadDialog,
                        toolbarHeight = toolbarHeight,
                        onDismiss = { sharedViewModel.downloadDialogState.remove(session.id) }
                    ).show()
                    browserToolbarView.expand()
                }
            }

            downloadsFeature.set(
                downloadFeature,
                owner = this,
                view = view
            )

            resumeDownloadDialogState(session, store, view, context, toolbarHeight)

            pipFeature = PictureInPictureFeature(
                store = store,
                activity = requireActivity(),
                crashReporting = context.components.analytics.crashReporter,
                tabId = customTabSessionId
            )

            appLinksFeature.set(
                feature = AppLinksFeature(
                    context,
                    sessionManager = sessionManager,
                    sessionId = customTabSessionId,
                    fragmentManager = parentFragmentManager,
                    launchInApp = { context.settings().openLinksInExternalApp }
                ),
                owner = this,
                view = view
            )

            promptsFeature.set(
                feature = PromptFeature(
                    fragment = this,
                    store = store,
                    customTabId = customTabSessionId,
                    fragmentManager = parentFragmentManager,
                    loginValidationDelegate = DefaultLoginValidationDelegate(
                        context.components.core.lazyPasswordsStorage
                    ),
                    isSaveLoginEnabled = {
                        context.settings().shouldPromptToSaveLogins
                    },
                    shareDelegate = object : ShareDelegate {
                        override fun showShareSheet(
                            context: Context,
                            shareData: ShareData,
                            onDismiss: () -> Unit,
                            onSuccess: () -> Unit
                        ) {
                            val directions = NavGraphDirections.actionGlobalShareFragment(
                                data = arrayOf(shareData),
                                showPage = true,
                                sessionId = getSessionById()?.id
                            )
                            findNavController().navigate(directions)
                        }
                    },
                    onNeedToRequestPermissions = { permissions ->
                        requestPermissions(permissions, REQUEST_CODE_PROMPT_PERMISSIONS)
                    }),
                owner = this,
                view = view
            )

            sessionFeature.set(
                feature = SessionFeature(
                    sessionManager,
                    SessionUseCases(sessionManager),
                    view.engineView,
                    customTabSessionId
                ),
                owner = this,
                view = view
            )

            val accentHighContrastColor =
                ThemeManager.resolveAttribute(R.attr.accentHighContrast, context)

            sitePermissionsFeature.set(
                feature = SitePermissionsFeature(
                    context = context,
                    storage = context.components.core.permissionStorage.permissionsStorage,
                    sessionManager = sessionManager,
                    fragmentManager = parentFragmentManager,
                    promptsStyling = SitePermissionsFeature.PromptsStyling(
                        gravity = getAppropriateLayoutGravity(),
                        shouldWidthMatchParent = true,
                        positiveButtonBackgroundColor = accentHighContrastColor,
                        positiveButtonTextColor = R.color.photonWhite
                    ),
                    sessionId = customTabSessionId,
                    onNeedToRequestPermissions = { permissions ->
                        requestPermissions(permissions, REQUEST_CODE_APP_PERMISSIONS)
                    },
                    onShouldShowRequestPermissionRationale = { shouldShowRequestPermissionRationale(it) }),
                owner = this,
                view = view
            )

            sitePermissionWifiIntegration.set(
                feature = SitePermissionsWifiIntegration(
                    settings = context.settings(),
                    wifiConnectionMonitor = context.components.wifiConnectionMonitor
                ),
                owner = this,
                view = view
            )

            context.settings().setSitePermissionSettingListener(viewLifecycleOwner) {
                // If the user connects to WIFI while on the BrowserFragment, this will update the
                // SitePermissionsRules (specifically autoplay) accordingly
                this.context?.let { assignSitePermissionsRules(it) }
            }
            assignSitePermissionsRules(context)

            fullScreenFeature.set(
                feature = FullScreenFeature(
                    sessionManager,
                    SessionUseCases(sessionManager),
                    customTabSessionId,
                    ::viewportFitChange,
                    ::fullScreenChanged
                ),
                owner = this,
                view = view
            )

            session.register(observer = object : Session.Observer {
                override fun onNavigationStateChanged(
                    session: Session,
                    canGoBack: Boolean,
                    canGoForward: Boolean
                ) {
                    // Once https://bugzilla.mozilla.org/show_bug.cgi?id=1626338 is fixed, we can
                    // rely solely on `onLoadRequest` entirely, but as it stands that is not called
                    // for history navigation (back or forward).
                    browserToolbarView.expand()
                }

                override fun onLoadRequest(
                    session: Session,
                    url: String,
                    triggeredByRedirect: Boolean,
                    triggeredByWebContent: Boolean
                ) {
                    browserToolbarView.expand()
                }
            }, owner = viewLifecycleOwner)

            sessionManager.register(observer = object : SessionManager.Observer {
                override fun onSessionSelected(session: Session) {
                    fullScreenChanged(false)
                    browserToolbarView.expand()
                }
            }, owner = viewLifecycleOwner)

            store.flowScoped(viewLifecycleOwner) { flow ->
                flow.mapNotNull { state -> state.findTabOrCustomTabOrSelectedTab(customTabSessionId) }
                    .ifChanged { tab -> tab.content.pictureInPictureEnabled }
                    .collect { tab -> pipModeChanged(tab) }
            }

            @Suppress("ConstantConditionIf")
            if (FeatureFlags.pullToRefreshEnabled) {
                val primaryTextColor =
                    ThemeManager.resolveAttribute(R.attr.primaryText, context)
                view.swipeRefresh.setColorSchemeColors(primaryTextColor)
                swipeRefreshFeature.set(
                    feature = SwipeRefreshFeature(
                        sessionManager,
                        context.components.useCases.sessionUseCases.reload,
                        view.swipeRefresh,
                        customTabSessionId
                    ),
                    owner = this,
                    view = view
                )
            } else {
                // Disable pull to refresh
                view.swipeRefresh.setOnChildScrollUpCallback { _, _ -> true }
            }

            @Suppress("ConstantConditionIf")
            if (!FeatureFlags.asFeatureWebChannelsDisabled) {
                webchannelIntegration.set(
                    feature = FxaWebChannelFeature(
                        requireContext(),
                        customTabSessionId,
                        requireComponents.core.engine,
                        requireComponents.core.store,
                        requireComponents.backgroundServices.accountManager,
                        requireComponents.backgroundServices.serverConfig,
                        setOf(FxaCapability.CHOOSE_WHAT_TO_SYNC)
                    ),
                    owner = this,
                    view = view
                )
            }

            initializeEngineView(toolbarHeight)
        }
    }

    /**
     * Preserves current state of the [DynamicDownloadDialog] to persist through tab changes and
     * other fragments navigation.
     * */
    private fun saveDownloadDialogState(
        session: Session,
        downloadState: DownloadState,
        downloadJobStatus: AbstractFetchDownloadService.DownloadJobStatus
    ) {
        sharedViewModel.downloadDialogState[session.id] = Pair(
            downloadState,
            downloadJobStatus == AbstractFetchDownloadService.DownloadJobStatus.FAILED
        )
    }

    /**
     * Re-initializes [DynamicDownloadDialog] if the user hasn't dismissed the dialog
     * before navigating away from it's original tab.
     * onTryAgain it will use [ContentAction.UpdateDownloadAction] to re-enqueue the former failed
     * download, because [DownloadsFeature] clears any queued downloads onStop.
     * */
    private fun resumeDownloadDialogState(
        session: Session,
        store: BrowserStore,
        view: View,
        context: Context,
        toolbarHeight: Int
    ) {
        val savedDownloadState =
            sharedViewModel.downloadDialogState[session.id] ?: return

        val onTryAgain: (Long) -> Unit = {
            savedDownloadState.first?.let { dlState ->
                store.dispatch(
                    ContentAction.UpdateDownloadAction(
                        session.id, dlState.copy(skipConfirmation = true)
                    )
                )
            }
        }

        val onCannotOpenFile = {
            FenixSnackbar.make(
                view = view,
                duration = Snackbar.LENGTH_SHORT,
                isDisplayedWithBrowserToolbar = true
            )
                .setText(context.getString(R.string.mozac_feature_downloads_could_not_open_file))
                .show()
        }

        val onDismiss: () -> Unit =
            { sharedViewModel.downloadDialogState.remove(session.id) }

        DynamicDownloadDialog(
            container = view.browserLayout,
            downloadState = savedDownloadState.first,
            didFail = savedDownloadState.second,
            tryAgain = onTryAgain,
            onCannotOpenFile = onCannotOpenFile,
            view = view.viewDynamicDownloadDialog,
            toolbarHeight = toolbarHeight,
            onDismiss = onDismiss
        ).show()

        browserToolbarView.expand()
    }

    private fun initializeEngineView(toolbarHeight: Int) {
        engineView.setDynamicToolbarMaxHeight(toolbarHeight)

        val behavior = if (requireContext().settings().shouldUseBottomToolbar) {
            EngineViewBottomBehavior(context, null)
        } else {
            SwipeRefreshScrollingViewBehavior(requireContext(), null, engineView, browserToolbarView)
        }

        (swipeRefresh.layoutParams as CoordinatorLayout.LayoutParams).behavior = behavior
    }

    /**
     * Returns a list of context menu items [ContextMenuCandidate] for the context menu
     */
    protected abstract fun getContextMenuCandidates(
        context: Context,
        view: View
    ): List<ContextMenuCandidate>

    @CallSuper
    override fun onSessionSelected(session: Session) {
        (activity as HomeActivity).updateThemeForSession(session)
        if (!browserInitialized) {
            // Initializing a new coroutineScope to avoid ConcurrentModificationException in ObserverRegistry
            // This will be removed when ObserverRegistry is deprecated by browser-state.
            initUIJob = MainScope().launch {
                view?.let {
                    browserInitialized = initializeUI(it) != null
                }
            }
        }
    }

    @CallSuper
    override fun onStart() {
        super.onStart()
        requireComponents.core.sessionManager.register(this, this, autoPause = true)
        sitePermissionWifiIntegration.get()?.maybeAddWifiConnectedListener()
    }

    @CallSuper
    override fun onResume() {
        super.onResume()
        val components = requireComponents

        val preferredColorScheme = components.core.getPreferredColorScheme()
        if (components.core.engine.settings.preferredColorScheme != preferredColorScheme) {
            components.core.engine.settings.preferredColorScheme = preferredColorScheme
            components.useCases.sessionUseCases.reload()
        }
        hideToolbar()
    }

    @CallSuper
    final override fun onPause() {
        super.onPause()
        val session = requireComponents.core.store.state.findTabOrCustomTabOrSelectedTab(customTabSessionId)
        // If we didn't enter PiP, exit full screen on pause
        if (session?.content?.pictureInPictureEnabled == false && fullScreenFeature.onBackPressed()) {
            fullScreenChanged(false)
        }
        if (findNavController().currentDestination?.id != R.id.searchFragment) {
            view?.hideKeyboard()
        }
    }

    @CallSuper
    override fun onStop() {
        super.onStop()
        initUIJob?.cancel()
    }

    @CallSuper
    override fun onBackPressed(): Boolean {
        return findInPageIntegration.onBackPressed() ||
                fullScreenFeature.onBackPressed() ||
                sessionFeature.onBackPressed() ||
                removeSessionIfNeeded()
    }

    /**
     * Saves the external app session ID to be restored later in [onViewStateRestored].
     */
    final override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        outState.putString(KEY_CUSTOM_TAB_SESSION_ID, customTabSessionId)
    }

    /**
     * Retrieves the external app session ID saved by [onSaveInstanceState].
     */
    final override fun onViewStateRestored(savedInstanceState: Bundle?) {
        super.onViewStateRestored(savedInstanceState)
        savedInstanceState?.getString(KEY_CUSTOM_TAB_SESSION_ID)?.let {
            if (requireComponents.core.sessionManager.findSessionById(it)?.customTabConfig != null) {
                customTabSessionId = it
            }
        }
    }

    /**
     * Forwards permission grant results to one of the features.
     */
    final override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>,
        grantResults: IntArray
    ) {
        val feature: PermissionsFeature? = when (requestCode) {
            REQUEST_CODE_DOWNLOAD_PERMISSIONS -> downloadsFeature.get()
            REQUEST_CODE_PROMPT_PERMISSIONS -> promptsFeature.get()
            REQUEST_CODE_APP_PERMISSIONS -> sitePermissionsFeature.get()
            else -> null
        }
        feature?.onPermissionsResult(permissions, grantResults)
    }

    /**
     * Forwards activity results to the prompt feature.
     */
    final override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        promptsFeature.withFeature { it.onActivityResult(requestCode, resultCode, data) }
    }

    /**
     * Removes the session if it was opened by an ACTION_VIEW intent
     * or if it has a parent session and no more history
     */
    protected open fun removeSessionIfNeeded(): Boolean {
        getSessionById()?.let { session ->
            val sessionManager = requireComponents.core.sessionManager
            if (session.source == Session.Source.ACTION_VIEW) {
                activity?.finish()
                sessionManager.remove(session)
            } else {
                val isLastSession =
                    sessionManager.sessionsOfType(private = session.private).count() == 1
                if (session.hasParentSession) {
                    sessionManager.remove(session, true)
                }
                val goToOverview = isLastSession || !session.hasParentSession
                return !goToOverview
            }
        }
        return false
    }

    protected abstract fun navToQuickSettingsSheet(
        session: Session,
        sitePermissions: SitePermissions?
    )

    protected abstract fun navToTrackingProtectionPanel(session: Session)

    /**
     * Returns the layout [android.view.Gravity] for the quick settings and ETP dialog.
     */
    protected fun getAppropriateLayoutGravity(): Int =
        if (context?.settings()?.shouldUseBottomToolbar == true) Gravity.BOTTOM else Gravity.TOP

    /**
     * Updates the site permissions rules based on user settings.
     */
    private fun assignSitePermissionsRules(context: Context) {
        val settings = context.settings()

        val rules: SitePermissionsRules = settings.getSitePermissionsCustomSettingsRules()

        sitePermissionsFeature.withFeature {
            it.sitePermissionsRules = rules
        }
    }

    /**
     * Displays the quick settings dialog,
     * which lets the user control tracking protection and site settings.
     */
    private fun showQuickSettingsDialog() {
        val session = getSessionById() ?: return
        viewLifecycleOwner.lifecycleScope.launch(Main) {
            val sitePermissions: SitePermissions? = withContext(IO) {
                session.url.toUri().host?.let { host ->
                    val storage = requireContext().components.core.permissionStorage
                    storage.findSitePermissionsBy(host)
                }
            }

            view?.let {
                navToQuickSettingsSheet(session, sitePermissions)
            }
        }
    }

    private fun showTrackingProtectionPanel() {
        val session = getSessionById() ?: return
        view?.let {
            navToTrackingProtectionPanel(session)
        }
    }

    /**
     * Returns the current session.
     */
    protected fun getSessionById(): Session? {
        val sessionManager = context?.components?.core?.sessionManager ?: return null
        val localCustomTabId = customTabSessionId
        return if (localCustomTabId != null) {
            sessionManager.findSessionById(localCustomTabId)
        } else {
            sessionManager.selectedSession
        }
    }

    private suspend fun bookmarkTapped(session: Session) = withContext(IO) {
        val bookmarksStorage = requireComponents.core.bookmarksStorage
        val existing =
            bookmarksStorage.getBookmarksWithUrl(session.url).firstOrNull { it.url == session.url }
        if (existing != null) {
            // Bookmark exists, go to edit fragment
            withContext(Main) {
                nav(
                    R.id.browserFragment,
                    BrowserFragmentDirections.actionGlobalBookmarkEditFragment(existing.guid, true)
                )
            }
        } else {
            // Save bookmark, then go to edit fragment
            val guid = bookmarksStorage.addItem(
                BookmarkRoot.Mobile.id,
                url = session.url,
                title = session.title,
                position = null
            )

            withContext(Main) {
                requireComponents.analytics.metrics.track(Event.AddBookmark)

                view?.let { view ->
                    FenixSnackbar.make(
                        view = view,
                        duration = FenixSnackbar.LENGTH_LONG,
                        isDisplayedWithBrowserToolbar = true
                    )
                        .setText(getString(R.string.bookmark_saved_snackbar))
                        .setAction(getString(R.string.edit_bookmark_snackbar_action)) {
                            nav(
                                R.id.browserFragment,
                                BrowserFragmentDirections.actionGlobalBookmarkEditFragment(guid, true)
                            )
                        }
                        .show()
                }
            }
        }
    }

    override fun onHomePressed() = pipFeature?.onHomePressed() ?: false

    /**
     * Exit fullscreen mode when exiting PIP mode
     */
    private fun pipModeChanged(session: SessionState) {
        if (!session.content.pictureInPictureEnabled && session.content.fullScreen) {
            onBackPressed()
            fullScreenChanged(false)
        }
    }

    final override fun onPictureInPictureModeChanged(enabled: Boolean) {
        pipFeature?.onPictureInPictureModeChanged(enabled)
    }

    private fun viewportFitChange(layoutInDisplayCutoutMode: Int) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
            val layoutParams = activity?.window?.attributes
            layoutParams?.layoutInDisplayCutoutMode = layoutInDisplayCutoutMode
            activity?.window?.attributes = layoutParams
        }
    }

    private fun fullScreenChanged(inFullScreen: Boolean) {
        if (inFullScreen) {
            // Close find in page bar if opened
            findInPageIntegration.onBackPressed()
            FenixSnackbar.make(
                    view = requireView(),
                    duration = Snackbar.LENGTH_SHORT,
                    isDisplayedWithBrowserToolbar = false
                )
                .setText(getString(R.string.full_screen_notification))
                .show()
            activity?.enterToImmersiveMode()
            browserToolbarView.view.isVisible = false

            engineView.setDynamicToolbarMaxHeight(0)
            browserToolbarView.expand()
            // Without this, fullscreen has a margin at the top.
            engineView.setVerticalClipping(0)
        } else {
            activity?.exitImmersiveModeIfNeeded()
            (activity as? HomeActivity)?.let { activity ->
                activity.themeManager.applyStatusBarTheme(activity)
            }
            if (webAppToolbarShouldBeVisible) {
                browserToolbarView.view.isVisible = true
                val toolbarHeight = resources.getDimensionPixelSize(R.dimen.browser_toolbar_height)
                engineView.setDynamicToolbarMaxHeight(toolbarHeight)
            }
        }
    }

    /*
     * Dereference these views when the fragment view is destroyed to prevent memory leaks
     */
    override fun onDestroyView() {
        super.onDestroyView()
        _browserToolbarView = null
        _browserInteractor = null
    }

    companion object {
        private const val KEY_CUSTOM_TAB_SESSION_ID = "custom_tab_session_id"
        private const val REQUEST_CODE_DOWNLOAD_PERMISSIONS = 1
        private const val REQUEST_CODE_PROMPT_PERMISSIONS = 2
        private const val REQUEST_CODE_APP_PERMISSIONS = 3
        private const val SNACKBAR_ELEVATION = 80f
    }
}
