/*
 * 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.launcher3.util;

import static android.view.Display.DEFAULT_DISPLAY;
import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION;

import static com.android.launcher3.Utilities.dpiFromPx;
import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
import static com.android.launcher3.util.Executors.UI_HELPER_EXECUTOR;
import static com.android.launcher3.util.WindowManagerCompat.MIN_TABLET_WIDTH;

import static java.util.Collections.emptyMap;

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.content.ComponentCallbacks;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.res.Configuration;
import android.graphics.Point;
import android.hardware.display.DisplayManager;
import android.hardware.display.DisplayManager.DisplayListener;
import android.os.Build;
import android.text.TextUtils;
import android.util.ArrayMap;
import android.util.ArraySet;
import android.util.Log;
import android.view.Display;

import androidx.annotation.AnyThread;
import androidx.annotation.UiThread;
import androidx.annotation.WorkerThread;

import com.android.launcher3.Utilities;
import com.android.launcher3.uioverrides.ApiWrapper;

import java.util.ArrayList;
import java.util.Map;
import java.util.Objects;
import java.util.Set;

/**
 * Utility class to cache properties of default display to avoid a system RPC on every call.
 */
@SuppressLint("NewApi")
public class DisplayController implements DisplayListener, ComponentCallbacks, SafeCloseable {

    private static final String TAG = "DisplayController";

    public static final MainThreadInitializedObject<DisplayController> INSTANCE =
            new MainThreadInitializedObject<>(DisplayController::new);

    public static final int CHANGE_ACTIVE_SCREEN = 1 << 0;
    public static final int CHANGE_ROTATION = 1 << 1;
    public static final int CHANGE_FRAME_DELAY = 1 << 2;
    public static final int CHANGE_DENSITY = 1 << 3;
    public static final int CHANGE_SUPPORTED_BOUNDS = 1 << 4;

    public static final int CHANGE_ALL = CHANGE_ACTIVE_SCREEN | CHANGE_ROTATION
            | CHANGE_FRAME_DELAY | CHANGE_DENSITY | CHANGE_SUPPORTED_BOUNDS;

    private final Context mContext;
    private final DisplayManager mDM;

    // Null for SDK < S
    private final Context mWindowContext;
    // The callback in this listener updates DeviceProfile, which other listeners might depend on
    private DisplayInfoChangeListener mPriorityListener;
    private final ArrayList<DisplayInfoChangeListener> mListeners = new ArrayList<>();

    private Info mInfo;
    private boolean mDestroyed = false;

    private DisplayController(Context context) {
        mContext = context;
        mDM = context.getSystemService(DisplayManager.class);

        Display display = mDM.getDisplay(DEFAULT_DISPLAY);
        if (Utilities.ATLEAST_S) {
            mWindowContext = mContext.createWindowContext(display, TYPE_APPLICATION, null);
            mWindowContext.registerComponentCallbacks(this);
        } else {
            mWindowContext = null;
            SimpleBroadcastReceiver configChangeReceiver =
                    new SimpleBroadcastReceiver(this::onConfigChanged);
            mContext.registerReceiver(configChangeReceiver,
                    new IntentFilter(Intent.ACTION_CONFIGURATION_CHANGED));
        }
        mInfo = new Info(getDisplayInfoContext(display), display,
                getInternalDisplays(mDM), emptyMap());
        mDM.registerDisplayListener(this, UI_HELPER_EXECUTOR.getHandler());
    }

    private static ArrayMap<String, PortraitSize> getInternalDisplays(
            DisplayManager displayManager) {
        Display[] displays = displayManager.getDisplays();
        ArrayMap<String, PortraitSize> internalDisplays = new ArrayMap<>();
        for (Display display : displays) {
            if (ApiWrapper.isInternalDisplay(display)) {
                Point size = new Point();
                display.getRealSize(size);
                internalDisplays.put(ApiWrapper.getUniqueId(display),
                        new PortraitSize(size.x, size.y));
            }
        }
        return internalDisplays;
    }

    @Override
    public void close() {
        mDestroyed = true;
        if (mWindowContext != null) {
            mWindowContext.unregisterComponentCallbacks(this);
        } else {
            // TODO: unregister broadcast receiver
        }
        mDM.unregisterDisplayListener(this);
    }

    @Override
    public final void onDisplayAdded(int displayId) { }

    @Override
    public final void onDisplayRemoved(int displayId) { }

    @WorkerThread
    @Override
    public final void onDisplayChanged(int displayId) {
        if (displayId != DEFAULT_DISPLAY) {
            return;
        }
        Display display = mDM.getDisplay(DEFAULT_DISPLAY);
        if (display == null) {
            return;
        }
        if (Utilities.ATLEAST_S) {
            // Only check for refresh rate. Everything else comes from component callbacks
            if (getSingleFrameMs(display) == mInfo.singleFrameMs) {
                return;
            }
        }
        handleInfoChange(display);
    }

    public static int getSingleFrameMs(Context context) {
        return INSTANCE.get(context).getInfo().singleFrameMs;
    }

    /**
     * Interface for listening for display changes
     */
    public interface DisplayInfoChangeListener {

        /**
         * Invoked when display info has changed.
         * @param context updated context associated with the display.
         * @param info updated display information.
         * @param flags bitmask indicating type of change.
         */
        void onDisplayInfoChanged(Context context, Info info, int flags);
    }

    /**
     * Only used for pre-S
     */
    private void onConfigChanged(Intent intent) {
        if (mDestroyed) {
            return;
        }
        Configuration config = mContext.getResources().getConfiguration();
        if (mInfo.fontScale != config.fontScale || mInfo.densityDpi != config.densityDpi) {
            Log.d(TAG, "Configuration changed, notifying listeners");
            Display display = mDM.getDisplay(DEFAULT_DISPLAY);
            if (display != null) {
                handleInfoChange(display);
            }
        }
    }

    @UiThread
    @Override
    @TargetApi(Build.VERSION_CODES.S)
    public final void onConfigurationChanged(Configuration config) {
        Display display = mWindowContext.getDisplay();
        if (config.densityDpi != mInfo.densityDpi
                || config.fontScale != mInfo.fontScale
                || display.getRotation() != mInfo.rotation
                || !mInfo.mScreenSizeDp.equals(
                        new PortraitSize(config.screenHeightDp, config.screenWidthDp))) {
            handleInfoChange(display);
        }
    }

    @Override
    public final void onLowMemory() { }

    public void setPriorityListener(DisplayInfoChangeListener listener) {
        mPriorityListener = listener;
    }

    public void addChangeListener(DisplayInfoChangeListener listener) {
        mListeners.add(listener);
    }

    public void removeChangeListener(DisplayInfoChangeListener listener) {
        mListeners.remove(listener);
    }

    public Info getInfo() {
        return mInfo;
    }

    private Context getDisplayInfoContext(Display display) {
        return Utilities.ATLEAST_S ? mWindowContext : mContext.createDisplayContext(display);
    }

    @AnyThread
    private void handleInfoChange(Display display) {
        Info oldInfo = mInfo;

        Context displayContext = getDisplayInfoContext(display);
        Info newInfo = new Info(displayContext, display,
                oldInfo.mInternalDisplays, oldInfo.mPerDisplayBounds);

        if (newInfo.densityDpi != oldInfo.densityDpi || newInfo.fontScale != oldInfo.fontScale) {
            // Cache may not be valid anymore, recreate without cache
            newInfo = new Info(displayContext, display, getInternalDisplays(mDM), emptyMap());
        }

        int change = 0;
        if (!newInfo.displayId.equals(oldInfo.displayId)) {
            change |= CHANGE_ACTIVE_SCREEN;
        }
        if (newInfo.rotation != oldInfo.rotation) {
            change |= CHANGE_ROTATION;
        }
        if (newInfo.singleFrameMs != oldInfo.singleFrameMs) {
            change |= CHANGE_FRAME_DELAY;
        }
        if (newInfo.densityDpi != oldInfo.densityDpi || newInfo.fontScale != oldInfo.fontScale) {
            change |= CHANGE_DENSITY;
        }
        if (!newInfo.supportedBounds.equals(oldInfo.supportedBounds)) {
            change |= CHANGE_SUPPORTED_BOUNDS;

            PortraitSize realSize = new PortraitSize(newInfo.currentSize.x, newInfo.currentSize.y);
            PortraitSize expectedSize = oldInfo.mInternalDisplays.get(
                    ApiWrapper.getUniqueId(display));
            if (newInfo.supportedBounds.size() != oldInfo.supportedBounds.size()) {
                Log.e("b/198965093",
                        "Inconsistent number of displays"
                                + "\ndisplay state: " + display.getState()
                                + "\noldInfo.supportedBounds: " + oldInfo.supportedBounds
                                + "\nnewInfo.supportedBounds: " + newInfo.supportedBounds);
            }
            if (!realSize.equals(expectedSize) && display.getState() == Display.STATE_OFF) {
                Log.e("b/198965093", "Display size changed while display is off, ignoring change");
                return;
            }
        }

        if (change != 0) {
            mInfo = newInfo;
            final int flags = change;
            MAIN_EXECUTOR.execute(() -> notifyChange(displayContext, flags));
        }
    }

    private void notifyChange(Context context, int flags) {
        if (mPriorityListener != null) {
            mPriorityListener.onDisplayInfoChanged(context, mInfo, flags);
        }
        for (int i = mListeners.size() - 1; i >= 0; i--) {
            mListeners.get(i).onDisplayInfoChanged(context, mInfo, flags);
        }
    }

    public static class Info {

        public final int singleFrameMs;

        // Configuration properties
        public final int rotation;
        public final float fontScale;
        public final int densityDpi;

        private final PortraitSize mScreenSizeDp;

        public final Point currentSize;

        public String displayId;
        public final Set<WindowBounds> supportedBounds = new ArraySet<>();
        private final Map<String, Set<WindowBounds>> mPerDisplayBounds = new ArrayMap<>();
        private final ArrayMap<String, PortraitSize> mInternalDisplays;

        public Info(Context context, Display display) {
            this(context, display, new ArrayMap<>(), emptyMap());
        }

        private Info(Context context, Display display,
                ArrayMap<String, PortraitSize> internalDisplays,
                Map<String, Set<WindowBounds>> perDisplayBoundsCache) {
            mInternalDisplays = internalDisplays;
            rotation = display.getRotation();

            Configuration config = context.getResources().getConfiguration();
            fontScale = config.fontScale;
            densityDpi = config.densityDpi;
            mScreenSizeDp = new PortraitSize(config.screenHeightDp, config.screenWidthDp);

            singleFrameMs = getSingleFrameMs(display);
            currentSize = new Point();
            display.getRealSize(currentSize);

            displayId = ApiWrapper.getUniqueId(display);
            Set<WindowBounds> currentSupportedBounds =
                    getSupportedBoundsForDisplay(display, currentSize);
            mPerDisplayBounds.put(displayId, currentSupportedBounds);
            supportedBounds.addAll(currentSupportedBounds);

            if (ApiWrapper.isInternalDisplay(display) && internalDisplays.size() > 1) {
                int displayCount = internalDisplays.size();
                for (int i = 0; i < displayCount; i++) {
                    String displayKey = internalDisplays.keyAt(i);
                    if (TextUtils.equals(displayId, displayKey)) {
                        continue;
                    }

                    Set<WindowBounds> displayBounds = perDisplayBoundsCache.get(displayKey);
                    if (displayBounds == null) {
                        // We assume densityDpi is the same across all internal displays
                        displayBounds = WindowManagerCompat.estimateDisplayProfiles(
                                context, internalDisplays.valueAt(i), densityDpi,
                                ApiWrapper.TASKBAR_DRAWN_IN_PROCESS);
                    }

                    supportedBounds.addAll(displayBounds);
                    mPerDisplayBounds.put(displayKey, displayBounds);
                }
            }
        }

        private static Set<WindowBounds> getSupportedBoundsForDisplay(Display display, Point size) {
            Point smallestSize = new Point();
            Point largestSize = new Point();
            display.getCurrentSizeRange(smallestSize, largestSize);

            int portraitWidth = Math.min(size.x, size.y);
            int portraitHeight = Math.max(size.x, size.y);
            Set<WindowBounds> result = new ArraySet<>();
            result.add(new WindowBounds(portraitWidth, portraitHeight,
                    smallestSize.x, largestSize.y));
            result.add(new WindowBounds(portraitHeight, portraitWidth,
                    largestSize.x, smallestSize.y));
            return result;
        }

        /**
         * Returns true if the bounds represent a tablet
         */
        public boolean isTablet(WindowBounds bounds) {
            return dpiFromPx(Math.min(bounds.bounds.width(), bounds.bounds.height()),
                    densityDpi) >= MIN_TABLET_WIDTH;
        }
    }

    /**
     * Utility class to hold a size information in an orientation independent way
     */
    public static class PortraitSize {
        public final int width, height;

        public PortraitSize(int w, int h) {
            width = Math.min(w, h);
            height = Math.max(w, h);
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            PortraitSize that = (PortraitSize) o;
            return width == that.width && height == that.height;
        }

        @Override
        public int hashCode() {
            return Objects.hash(width, height);
        }
    }

    private static int getSingleFrameMs(Display display) {
        float refreshRate = display.getRefreshRate();
        return refreshRate > 0 ? (int) (1000 / refreshRate) : 16;
    }
}