/*
 * Copyright (C) 2019 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.server.telecom;

import android.annotation.IntRange;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.app.UiModeManager;
import android.telecom.Log;
import android.util.LocalLog;

import com.android.internal.util.IndentingPrintWriter;

import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.PriorityQueue;
import java.util.function.Function;
import java.util.stream.Collectors;

/**
 * Tracks the package names of apps which enter end exit car mode.
 */
public class CarModeTracker {
    /**
     * Data class holding information about apps which have requested to enter car mode.
     */
    private class CarModeApp {
        private final boolean mAutomotiveProjection;
        private final @IntRange(from = 0) int mPriority;
        private @NonNull String mPackageName;

        public CarModeApp(@NonNull String packageName) {
            this(true, 0, packageName);
        }

        public CarModeApp(int priority, @NonNull String packageName) {
            this(false, priority, packageName);
        }

        private CarModeApp(boolean automotiveProjection, int priority, @NonNull String packageName) {
            mAutomotiveProjection = automotiveProjection;
            mPriority = priority;
            mPackageName = Objects.requireNonNull(packageName);
        }

        public boolean hasSetAutomotiveProjection() {
            return mAutomotiveProjection;
        }

        /**
         * The priority at which the app requested to enter car mode.
         * Will be the same as the one specified when {@link UiModeManager#enableCarMode(int, int)}
         * was called, or {@link UiModeManager#DEFAULT_PRIORITY} if no priority was specified.
         * @return The priority.
         */
        public int getPriority() {
            return mPriority;
        }

        /**
         * @return The package name of the app which requested to enter car mode/set projection.
         */
        public String getPackageName() {
            return mPackageName;
        }

        public void setPackageName(String packageName) {
            mPackageName = packageName;
        }

        public String toString() {
            return String.format("[%s, %s]",
                    mAutomotiveProjection ? "PROJECTION SET" : mPriority,
                    mPackageName);
        }
    }

    /**
     * Priority list of apps which have entered or exited car mode, ordered first by whether the app
     * has set automotive projection, and then by highest priority.  Where items have the same
     * priority, order is arbitrary, but we only allow one item in the queue per priority.
     */
    private PriorityQueue<CarModeApp> mCarModeApps = new PriorityQueue<>(2,
            // Natural ordering of booleans is False, True. Natural ordering of ints is increasing.
            Comparator.comparing(CarModeApp::hasSetAutomotiveProjection)
                    .thenComparing(CarModeApp::getPriority)
                    .reversed());

    private final LocalLog mCarModeChangeLog = new LocalLog(20);

    /**
     * Handles a request to enter car mode by a package name.
     * @param priority The priority at which car mode is entered.
     * @param packageName The package name of the app entering car mode.
     */
    public void handleEnterCarMode(@IntRange(from = 0) int priority, @NonNull String packageName) {
        if (mCarModeApps.stream().anyMatch(c -> c.getPriority() == priority)) {
            Log.w(this, "handleEnterCarMode: already in car mode at priority %d (apps: %s)",
                    priority, getCarModePriorityString());
            return;
        }

        if (mCarModeApps.stream().anyMatch(c -> c.getPackageName().equals(packageName))) {
            Log.w(this, "handleEnterCarMode: %s is already in car mode (apps: %s)",
                    packageName, getCarModePriorityString());
            return;
        }

        Log.i(this, "handleEnterCarMode: packageName=%s, priority=%d", packageName, priority);
        mCarModeChangeLog.log("enterCarMode: packageName=" + packageName + ", priority="
                + priority);
        mCarModeApps.add(new CarModeApp(priority, packageName));
    }

    /**
     * Handles a request to exist car mode at a priority level.
     * @param priority The priority level.
     * @param packageName The packagename of the app requesting the change.
     */
    public void handleExitCarMode(@IntRange(from = 0) int priority, @NonNull String packageName) {
        if (!mCarModeApps.stream().anyMatch(c -> c.getPriority() == priority)) {
            Log.w(this, "handleExitCarMode: not in car mode at priority %d (apps=%s)",
                    priority, getCarModePriorityString());
            return;
        }

        if (priority != UiModeManager.DEFAULT_PRIORITY && !mCarModeApps.stream().anyMatch(
                c -> c.getPackageName().equals(packageName) && c.getPriority() == priority)) {
            Log.w(this, "handleExitCarMode: %s didn't enter car mode at priority %d (apps=%s)",
                    packageName, priority, getCarModePriorityString());
            return;
        }

        Log.i(this, "handleExitCarMode: packageName=%s, priority=%d", packageName, priority);
        mCarModeChangeLog.log("exitCarMode: packageName=" + packageName + ", priority="
                + priority);
        mCarModeApps.removeIf(c -> c.getPriority() == priority);
    }

    public void handleSetAutomotiveProjection(@NonNull String packageName) {
        Optional<CarModeApp> projectingApp = mCarModeApps.stream()
                .filter(CarModeApp::hasSetAutomotiveProjection)
                .findAny();
        // No app with automotive projection? Easy peasy, just add it.
        if (!projectingApp.isPresent()) {
            Log.i(this, "handleSetAutomotiveProjection: %s", packageName);
            mCarModeChangeLog.log("setAutomotiveProjection: packageName=" + packageName);
            mCarModeApps.add(new CarModeApp(packageName));
            return;
        }
        // Otherwise an app already has automotive projection set. Is it the same app?
        if (packageName.equals(projectingApp.get().getPackageName())) {
            Log.w(this, "handleSetAutomotiveProjection: %s already the automotive projection app",
                    packageName);
            return;
        }
        // We have a new app for automotive projection. As a shortcut just reuse the same object by
        // overwriting the package name.
        Log.i(this, "handleSetAutomotiveProjection: %s replacing %s as automotive projection app",
                packageName, projectingApp.get().getPackageName());
        mCarModeChangeLog.log("setAutomotiveProjection: " + packageName + " replaces "
                + projectingApp.get().getPackageName());
        projectingApp.get().setPackageName(packageName);
    }

    public void handleReleaseAutomotiveProjection() {
        Optional<String> projectingPackage = mCarModeApps.stream()
                .filter(CarModeApp::hasSetAutomotiveProjection)
                .map(CarModeApp::getPackageName)
                .findAny();
        if (!projectingPackage.isPresent()) {
            Log.w(this, "handleReleaseAutomotiveProjection: no current automotive projection app");
            return;
        }
        Log.i(this, "handleReleaseAutomotiveProjection: %s", projectingPackage.get());
        mCarModeChangeLog.log("releaseAutomotiveProjection: packageName="
                + projectingPackage.get());
        mCarModeApps.removeIf(CarModeApp::hasSetAutomotiveProjection);
    }

    /**
     * Force-removes a package from the car mode tracking list, no matter at which priority.
     *
     * This handles the case where packages are disabled or uninstalled. In those case, remove them
     * from the tracking list so they don't cause a leak.
     * @param packageName Package name of the app to force-remove
     */
    public void forceRemove(@NonNull String packageName) {
        // We must account for the possibility that the app has set both car mode AND projection.
        List<CarModeApp> forcedApp = mCarModeApps.stream()
                .filter(c -> c.getPackageName().equals(packageName))
                .collect(Collectors.toList());
        if (forcedApp.isEmpty()) {
            Log.i(this, "Package %s is not tracked.", packageName);
            return;
        }
        for (CarModeApp app : forcedApp) {
            String logString = "forceRemove: " + app;
            Log.i(this, logString);
            mCarModeChangeLog.log(logString);
        }
        mCarModeApps.removeIf(c -> c.getPackageName().equals(packageName));
    }

    /**
     * Retrieves a list of the apps which are currently in car mode, ordered by priority such that
     * the highest priority app is first.
     * @return List of apps in car mode.
     */
    public @NonNull List<String> getCarModeApps() {
        return mCarModeApps
                .stream()
                .sorted(mCarModeApps.comparator())
                .map(CarModeApp::getPackageName)
                .collect(Collectors.toList());
    }

    private @NonNull String getCarModePriorityString() {
        return mCarModeApps
                .stream()
                .sorted(mCarModeApps.comparator())
                .map(CarModeApp::toString)
                .collect(Collectors.joining(", "));
    }

    /**
     * Gets the app which is currently in car mode.  This is the highest priority app which has
     * entered car mode.
     * @return The app which is in car mode.
     */
    public @Nullable String getCurrentCarModePackage() {
        CarModeApp app = mCarModeApps.peek();
        return app == null ? null : app.getPackageName();
    }

    /**
     * @return {@code true} if the device is in car mode, {@code false} otherwise.
     */
    public boolean isInCarMode() {
        return !mCarModeApps.isEmpty();
    }

    /**
     * Dumps the state of the car mode tracker to the specified print writer.
     * @param pw
     */
    public void dump(IndentingPrintWriter pw) {
        pw.println("CarModeTracker:");
        pw.increaseIndent();

        pw.println("Current car mode apps:");
        pw.increaseIndent();
        for (CarModeApp app : mCarModeApps) {
            pw.print("[");
            pw.print(app.hasSetAutomotiveProjection() ? "PROJECTION SET" : app.getPriority());
            pw.print("] ");
            pw.println(app.getPackageName());
        }
        pw.decreaseIndent();

        pw.println("Car mode history:");
        pw.increaseIndent();
        mCarModeChangeLog.dump(pw);
        pw.decreaseIndent();

        pw.decreaseIndent();
    }
}