/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.launcher3

import android.app.admin.DevicePolicyManager
import android.content.Context
import android.content.Intent
import android.content.pm.ShortcutInfo
import android.os.UserHandle
import android.text.TextUtils
import android.util.Log
import android.util.Pair
import androidx.annotation.WorkerThread
import com.android.launcher3.celllayout.CellPosMapper
import com.android.launcher3.icons.IconCache
import com.android.launcher3.model.AddWorkspaceItemsTask
import com.android.launcher3.model.AllAppsList
import com.android.launcher3.model.BaseLauncherBinder
import com.android.launcher3.model.BgDataModel
import com.android.launcher3.model.CacheDataUpdatedTask
import com.android.launcher3.model.ItemInstallQueue
import com.android.launcher3.model.LoaderTask
import com.android.launcher3.model.ModelDbController
import com.android.launcher3.model.ModelDelegate
import com.android.launcher3.model.ModelLauncherCallbacks
import com.android.launcher3.model.ModelTaskController
import com.android.launcher3.model.ModelWriter
import com.android.launcher3.model.PackageUpdatedTask
import com.android.launcher3.model.ReloadStringCacheTask
import com.android.launcher3.model.ShortcutsChangedTask
import com.android.launcher3.model.UserLockStateChangedTask
import com.android.launcher3.model.WidgetsFilterDataProvider
import com.android.launcher3.model.data.ItemInfo
import com.android.launcher3.model.data.WorkspaceItemInfo
import com.android.launcher3.pm.UserCache
import com.android.launcher3.shortcuts.ShortcutRequest
import com.android.launcher3.testing.shared.TestProtocol.sDebugTracing
import com.android.launcher3.util.Executors.MAIN_EXECUTOR
import com.android.launcher3.util.Executors.MODEL_EXECUTOR
import com.android.launcher3.util.PackageManagerHelper
import com.android.launcher3.util.PackageUserKey
import com.android.launcher3.util.Preconditions
import java.io.FileDescriptor
import java.io.PrintWriter
import java.util.concurrent.CancellationException
import java.util.function.Consumer

/**
 * Maintains in-memory state of the Launcher. It is expected that there should be only one
 * LauncherModel object held in a static. Also provide APIs for updating the database state for the
 * Launcher.
 */
class LauncherModel(
    private val context: Context,
    private val mApp: LauncherAppState,
    private val iconCache: IconCache,
    private val widgetsFilterDataProvider: WidgetsFilterDataProvider,
    appFilter: AppFilter,
    mPmHelper: PackageManagerHelper,
    isPrimaryInstance: Boolean,
) {

    private val mCallbacksList = ArrayList<BgDataModel.Callbacks>(1)

    // < only access in worker thread >
    private val mBgAllAppsList = AllAppsList(iconCache, appFilter)

    /**
     * All the static data should be accessed on the background thread, A lock should be acquired on
     * this object when accessing any data from this model.
     */
    private val mBgDataModel = BgDataModel()

    val modelDelegate: ModelDelegate =
        ModelDelegate.newInstance(
            context,
            mApp,
            mPmHelper,
            mBgAllAppsList,
            mBgDataModel,
            isPrimaryInstance,
        )

    val modelDbController = ModelDbController(context)

    private val mLock = Any()

    private var mLoaderTask: LoaderTask? = null
    private var mIsLoaderTaskRunning = false

    // only allow this once per reboot to reload work apps
    private var mShouldReloadWorkProfile = true

    // Indicates whether the current model data is valid or not.
    // We start off with everything not loaded. After that, we assume that
    // our monitoring of the package manager provides all updates and we never
    // need to do a requery. This is only ever touched from the loader thread.
    private var mModelLoaded = false
    private var mModelDestroyed = false

    fun isModelLoaded() =
        synchronized(mLock) { mModelLoaded && mLoaderTask == null && !mModelDestroyed }

    /**
     * Returns the ID for the last model load. If the load ID doesn't match for a transaction, the
     * transaction should be ignored.
     */
    var lastLoadId: Int = -1
        private set

    // Runnable to check if the shortcuts permission has changed.
    private val mDataValidationCheck = Runnable {
        if (mModelLoaded) {
            modelDelegate.validateData()
        }
    }

    fun newModelCallbacks() = ModelLauncherCallbacks(this::enqueueModelUpdateTask)

    /** Adds the provided items to the workspace. */
    fun addAndBindAddedWorkspaceItems(itemList: List<Pair<ItemInfo?, Any?>?>) {
        callbacks.forEach { it.preAddApps() }
        enqueueModelUpdateTask(AddWorkspaceItemsTask(itemList))
    }

    fun getWriter(
        verifyChanges: Boolean,
        cellPosMapper: CellPosMapper?,
        owner: BgDataModel.Callbacks?,
    ) = ModelWriter(mApp.context, this, mBgDataModel, verifyChanges, cellPosMapper, owner)

    /** Returns the [WidgetsFilterDataProvider] that manages widget filters. */
    fun getWidgetsFilterDataProvider(): WidgetsFilterDataProvider {
        return widgetsFilterDataProvider
    }

    /** Called when the icon for an app changes, outside of package event */
    @WorkerThread
    fun onAppIconChanged(packageName: String, user: UserHandle) {
        // Update the icon for the calendar package
        enqueueModelUpdateTask(PackageUpdatedTask(PackageUpdatedTask.OP_UPDATE, user, packageName))
        ShortcutRequest(context, user).forPackage(packageName).query(ShortcutRequest.PINNED).let {
            if (it.isNotEmpty()) {
                enqueueModelUpdateTask(ShortcutsChangedTask(packageName, it, user, false))
            }
        }
    }

    /** Called when the workspace items have drastically changed */
    fun onWorkspaceUiChanged() {
        MODEL_EXECUTOR.execute(modelDelegate::workspaceLoadComplete)
    }

    /** Called when the model is destroyed */
    fun destroy() {
        mModelDestroyed = true
        MODEL_EXECUTOR.execute {
            modelDelegate.destroy()
            widgetsFilterDataProvider.destroy()
        }
    }

    fun onBroadcastIntent(intent: Intent) {
        if (DEBUG_RECEIVER || sDebugTracing) Log.d(TAG, "onReceive intent=$intent")
        when (intent.action) {
            Intent.ACTION_LOCALE_CHANGED,
            LauncherAppState.ACTION_FORCE_ROLOAD ->
                // If we have changed locale we need to clear out the labels in all apps/workspace.
                forceReload()
            DevicePolicyManager.ACTION_DEVICE_POLICY_RESOURCE_UPDATED ->
                enqueueModelUpdateTask(ReloadStringCacheTask(this.modelDelegate))
        }
    }

    /**
     * Called then there use a user event
     *
     * @see UserCache.addUserEventListener
     */
    fun onUserEvent(user: UserHandle, action: String) {
        when (action) {
            Intent.ACTION_MANAGED_PROFILE_AVAILABLE -> {
                if (mShouldReloadWorkProfile) {
                    forceReload()
                } else {
                    enqueueModelUpdateTask(
                        PackageUpdatedTask(PackageUpdatedTask.OP_USER_AVAILABILITY_CHANGE, user)
                    )
                }
                mShouldReloadWorkProfile = false
            }
            Intent.ACTION_MANAGED_PROFILE_UNAVAILABLE -> {
                mShouldReloadWorkProfile = false
                enqueueModelUpdateTask(
                    PackageUpdatedTask(PackageUpdatedTask.OP_USER_AVAILABILITY_CHANGE, user)
                )
            }
            UserCache.ACTION_PROFILE_LOCKED ->
                enqueueModelUpdateTask(UserLockStateChangedTask(user, false))
            UserCache.ACTION_PROFILE_UNLOCKED ->
                enqueueModelUpdateTask(UserLockStateChangedTask(user, true))
            Intent.ACTION_MANAGED_PROFILE_REMOVED -> {
                LauncherPrefs.get(mApp.context).put(LauncherPrefs.WORK_EDU_STEP, 0)
                forceReload()
            }
            UserCache.ACTION_PROFILE_ADDED,
            UserCache.ACTION_PROFILE_REMOVED -> forceReload()
            UserCache.ACTION_PROFILE_AVAILABLE,
            UserCache.ACTION_PROFILE_UNAVAILABLE -> {
                // This broadcast is only available when android.os.Flags.allowPrivateProfile() is
                // set. For Work-profile this broadcast will be sent in addition to
                // ACTION_MANAGED_PROFILE_AVAILABLE/UNAVAILABLE. So effectively, this if block only
                // handles the non-work profile case.
                enqueueModelUpdateTask(
                    PackageUpdatedTask(PackageUpdatedTask.OP_USER_AVAILABILITY_CHANGE, user)
                )
            }
        }
    }

    /**
     * Reloads the workspace items from the DB and re-binds the workspace. This should generally not
     * be called as DB updates are automatically followed by UI update
     */
    fun forceReload() {
        synchronized(mLock) {
            // Stop any existing loaders first, so they don't set mModelLoaded to true later
            stopLoader()
            mModelLoaded = false
        }
        rebindCallbacks()
    }

    /** Rebinds all existing callbacks with already loaded model */
    fun rebindCallbacks() {
        if (hasCallbacks()) {
            startLoader()
        }
    }

    /** Removes an existing callback */
    fun removeCallbacks(callbacks: BgDataModel.Callbacks) {
        synchronized(mCallbacksList) {
            Preconditions.assertUIThread()
            if (mCallbacksList.remove(callbacks)) {
                if (stopLoader()) {
                    // Rebind existing callbacks
                    startLoader()
                }
            }
        }
    }

    /**
     * Adds a callbacks to receive model updates
     *
     * @return true if workspace load was performed synchronously
     */
    fun addCallbacksAndLoad(callbacks: BgDataModel.Callbacks): Boolean {
        synchronized(mLock) {
            addCallbacks(callbacks)
            return startLoader(arrayOf(callbacks))
        }
    }

    /** Adds a callbacks to receive model updates */
    fun addCallbacks(callbacks: BgDataModel.Callbacks) {
        Preconditions.assertUIThread()
        synchronized(mCallbacksList) { mCallbacksList.add(callbacks) }
    }

    /**
     * Starts the loader. Tries to bind {@params synchronousBindPage} synchronously if possible.
     *
     * @return true if the page could be bound synchronously.
     */
    fun startLoader() = startLoader(arrayOf())

    private fun startLoader(newCallbacks: Array<BgDataModel.Callbacks>): Boolean {
        // Enable queue before starting loader. It will get disabled in Launcher#finishBindingItems
        ItemInstallQueue.INSTANCE.get(context).pauseModelPush(ItemInstallQueue.FLAG_LOADER_RUNNING)
        synchronized(mLock) {
            // If there is already one running, tell it to stop.
            val wasRunning = stopLoader()
            val bindDirectly = mModelLoaded && !mIsLoaderTaskRunning
            val bindAllCallbacks = wasRunning || !bindDirectly || newCallbacks.isEmpty()
            val callbacksList = if (bindAllCallbacks) callbacks else newCallbacks
            if (callbacksList.isNotEmpty()) {
                // Clear any pending bind-runnables from the synchronized load process.
                callbacksList.forEach { MAIN_EXECUTOR.execute(it::clearPendingBinds) }

                val launcherBinder =
                    BaseLauncherBinder(mApp, mBgDataModel, mBgAllAppsList, callbacksList)
                if (bindDirectly) {
                    // Divide the set of loaded items into those that we are binding synchronously,
                    // and everything else that is to be bound normally (asynchronously).
                    launcherBinder.bindWorkspace(bindAllCallbacks, /* isBindSync= */ true)
                    // For now, continue posting the binding of AllApps as there are other
                    // issues that arise from that.
                    launcherBinder.bindAllApps()
                    launcherBinder.bindDeepShortcuts()
                    launcherBinder.bindWidgets()
                    return true
                } else {
                    mLoaderTask =
                        LoaderTask(
                            mApp,
                            mBgAllAppsList,
                            mBgDataModel,
                            this.modelDelegate,
                            launcherBinder,
                            widgetsFilterDataProvider,
                        )

                    // Always post the loader task, instead of running directly
                    // (even on same thread) so that we exit any nested synchronized blocks
                    MODEL_EXECUTOR.post(mLoaderTask)
                }
            }
        }
        return false
    }

    /**
     * If there is already a loader task running, tell it to stop.
     *
     * @return true if an existing loader was stopped.
     */
    private fun stopLoader(): Boolean {
        synchronized(mLock) {
            val oldTask: LoaderTask? = mLoaderTask
            mLoaderTask = null
            if (oldTask != null) {
                oldTask.stopLocked()
                return true
            }
            return false
        }
    }

    /**
     * Loads the model if not loaded
     *
     * @param callback called with the data model upon successful load or null on model thread.
     */
    fun loadAsync(callback: Consumer<BgDataModel?>) {
        synchronized(mLock) {
            if (!mModelLoaded && !mIsLoaderTaskRunning) {
                startLoader()
            }
        }
        MODEL_EXECUTOR.post { callback.accept(if (isModelLoaded()) mBgDataModel else null) }
    }

    inner class LoaderTransaction(task: LoaderTask) : AutoCloseable {
        private var mTask: LoaderTask? = null

        init {
            synchronized(mLock) {
                if (mLoaderTask !== task) {
                    throw CancellationException("Loader already stopped")
                }
                this@LauncherModel.lastLoadId++
                mTask = task
                mIsLoaderTaskRunning = true
                mModelLoaded = false
            }
        }

        fun commit() {
            synchronized(mLock) {
                // Everything loaded bind the data.
                mModelLoaded = true
            }
        }

        override fun close() {
            synchronized(mLock) {
                // If we are still the last one to be scheduled, remove ourselves.
                if (mLoaderTask === mTask) {
                    mLoaderTask = null
                }
                mIsLoaderTaskRunning = false
            }
        }
    }

    @Throws(CancellationException::class)
    fun beginLoader(task: LoaderTask) = LoaderTransaction(task)

    /**
     * Refreshes the cached shortcuts if the shortcut permission has changed. Current implementation
     * simply reloads the workspace, but it can be optimized to use partial updates similar to
     * [UserCache]
     */
    fun validateModelDataOnResume() {
        MODEL_EXECUTOR.handler.removeCallbacks(mDataValidationCheck)
        MODEL_EXECUTOR.post(mDataValidationCheck)
    }

    /** Called when the icons for packages have been updated in the icon cache. */
    fun onPackageIconsUpdated(updatedPackages: HashSet<String?>, user: UserHandle) {
        // If any package icon has changed (app was updated while launcher was dead),
        // update the corresponding shortcuts.
        enqueueModelUpdateTask(
            CacheDataUpdatedTask(CacheDataUpdatedTask.OP_CACHE_UPDATE, user, updatedPackages)
        )
    }

    /** Called when the labels for the widgets has updated in the icon cache. */
    fun onWidgetLabelsUpdated(updatedPackages: HashSet<String?>, user: UserHandle) {
        enqueueModelUpdateTask { taskController, dataModel, _ ->
            dataModel.widgetsModel.onPackageIconsUpdated(updatedPackages, user, mApp)
            taskController.bindUpdatedWidgets(dataModel)
        }
    }

    /** Called when the widget filters are refreshed and available to bind to the model. */
    fun onWidgetFiltersLoaded() {
        enqueueModelUpdateTask { taskController, dataModel, _ ->
            dataModel.widgetsModel.updateWidgetFilters(widgetsFilterDataProvider)
            taskController.bindUpdatedWidgets(dataModel)
        }
    }

    fun enqueueModelUpdateTask(task: ModelUpdateTask) {
        if (mModelDestroyed) {
            return
        }
        MODEL_EXECUTOR.execute {
            if (!isModelLoaded()) {
                // Loader has not yet run.
                return@execute
            }
            task.execute(
                ModelTaskController(mApp, mBgDataModel, mBgAllAppsList, this, MAIN_EXECUTOR),
                mBgDataModel,
                mBgAllAppsList,
            )
        }
    }

    /**
     * A task to be executed on the current callbacks on the UI thread. If there is no current
     * callbacks, the task is ignored.
     */
    fun interface CallbackTask {
        fun execute(callbacks: BgDataModel.Callbacks)
    }

    fun interface ModelUpdateTask {
        fun execute(taskController: ModelTaskController, dataModel: BgDataModel, apps: AllAppsList)
    }

    fun updateAndBindWorkspaceItem(si: WorkspaceItemInfo, info: ShortcutInfo) {
        enqueueModelUpdateTask { taskController, _, _ ->
            si.updateFromDeepShortcutInfo(info, context)
            iconCache.getShortcutIcon(si, info)
            taskController.getModelWriter().updateItemInDatabase(si)
            taskController.bindUpdatedWorkspaceItems(listOf(si))
        }
    }

    fun refreshAndBindWidgetsAndShortcuts(packageUser: PackageUserKey?) {
        enqueueModelUpdateTask { taskController, dataModel, _ ->
            dataModel.widgetsModel.update(taskController.app, packageUser)
            taskController.bindUpdatedWidgets(dataModel)
        }
    }

    fun dumpState(prefix: String?, fd: FileDescriptor?, writer: PrintWriter, args: Array<String?>) {
        if (args.isNotEmpty() && TextUtils.equals(args[0], "--all")) {
            writer.println(prefix + "All apps list: size=" + mBgAllAppsList.data.size)
            for (info in mBgAllAppsList.data) {
                writer.println(
                    "$prefix   title=\"${info.title}\" bitmapIcon=${info.bitmap.icon} componentName=${info.targetPackage}"
                )
            }
            writer.println()
        }
        modelDelegate.dump(prefix, fd, writer, args)
        mBgDataModel.dump(prefix, fd, writer, args)
    }

    /** Returns true if there are any callbacks attached to the model */
    fun hasCallbacks() = synchronized(mCallbacksList) { mCallbacksList.isNotEmpty() }

    /** Returns an array of currently attached callbacks */
    val callbacks: Array<BgDataModel.Callbacks>
        get() {
            synchronized(mCallbacksList) {
                return mCallbacksList.toTypedArray<BgDataModel.Callbacks>()
            }
        }

    companion object {
        private const val DEBUG_RECEIVER = false

        const val TAG = "Launcher.Model"
    }
}