/*
 * 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 android.hardware.display;

import android.annotation.NonNull;
import android.annotation.UserIdInt;
import android.app.ActivityManager;
import android.content.ContentResolver;
import android.content.Context;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.Handler;
import android.os.Looper;
import android.provider.Settings.Secure;

import java.time.LocalTime;

/**
 * @hide
 */
public class NightDisplayListener {

    private final Context mContext;
    private final ColorDisplayManager mManager;
    private final Handler mHandler;
    private final ContentObserver mContentObserver;
    private final int mUserId;

    private Callback mCallback;

    public NightDisplayListener(@NonNull Context context) {
        this(context, ActivityManager.getCurrentUser(), new Handler(Looper.getMainLooper()));
    }

    public NightDisplayListener(@NonNull Context context, @NonNull Handler handler) {
        this(context, ActivityManager.getCurrentUser(), handler);
    }

    public NightDisplayListener(@NonNull Context context, @UserIdInt int userId,
            @NonNull Handler handler) {
        mContext = context.getApplicationContext();
        mManager = mContext.getSystemService(ColorDisplayManager.class);
        mUserId = userId;

        mHandler = handler;
        mContentObserver = new ContentObserver(mHandler) {
            @Override
            public void onChange(boolean selfChange, Uri uri) {
                super.onChange(selfChange, uri);
                final String setting = uri == null ? null : uri.getLastPathSegment();
                if (setting != null && mCallback != null) {
                    switch (setting) {
                        case Secure.NIGHT_DISPLAY_ACTIVATED:
                            mCallback.onActivated(mManager.isNightDisplayActivated());
                            break;
                        case Secure.NIGHT_DISPLAY_AUTO_MODE:
                            mCallback.onAutoModeChanged(mManager.getNightDisplayAutoMode());
                            break;
                        case Secure.NIGHT_DISPLAY_CUSTOM_START_TIME:
                            mCallback.onCustomStartTimeChanged(
                                    mManager.getNightDisplayCustomStartTime());
                            break;
                        case Secure.NIGHT_DISPLAY_CUSTOM_END_TIME:
                            mCallback.onCustomEndTimeChanged(
                                    mManager.getNightDisplayCustomEndTime());
                            break;
                        case Secure.NIGHT_DISPLAY_COLOR_TEMPERATURE:
                            mCallback.onColorTemperatureChanged(
                                    mManager.getNightDisplayColorTemperature());
                            break;
                    }
                }
            }
        };
    }

    /**
     * Register a callback to be invoked whenever the Night display settings are changed.
     */
    public void setCallback(Callback callback) {
        if (Looper.myLooper() != mHandler.getLooper()) {
            mHandler.post(() -> setCallbackInternal(callback));
        }
        setCallbackInternal(callback);
    }

    private void setCallbackInternal(Callback newCallback) {
        final Callback oldCallback = mCallback;
        if (oldCallback != newCallback) {
            mCallback = newCallback;
            if (mCallback == null) {
                mContext.getContentResolver().unregisterContentObserver(mContentObserver);
            } else if (oldCallback == null) {
                final ContentResolver cr = mContext.getContentResolver();
                cr.registerContentObserver(Secure.getUriFor(Secure.NIGHT_DISPLAY_ACTIVATED),
                        false /* notifyForDescendants */, mContentObserver, mUserId);
                cr.registerContentObserver(Secure.getUriFor(Secure.NIGHT_DISPLAY_AUTO_MODE),
                        false /* notifyForDescendants */, mContentObserver, mUserId);
                cr.registerContentObserver(
                        Secure.getUriFor(Secure.NIGHT_DISPLAY_CUSTOM_START_TIME),
                        false /* notifyForDescendants */, mContentObserver, mUserId);
                cr.registerContentObserver(
                        Secure.getUriFor(Secure.NIGHT_DISPLAY_CUSTOM_END_TIME),
                        false /* notifyForDescendants */, mContentObserver, mUserId);
                cr.registerContentObserver(
                        Secure.getUriFor(Secure.NIGHT_DISPLAY_COLOR_TEMPERATURE),
                        false /* notifyForDescendants */, mContentObserver, mUserId);
            }
        }
    }

    /**
     * Callback invoked whenever the Night display settings are changed.
     */
    public interface Callback {

        /**
         * Callback invoked when the activated state changes.
         *
         * @param activated {@code true} if Night display is activated
         */
        default void onActivated(boolean activated) {
        }

        /**
         * Callback invoked when the auto mode changes.
         *
         * @param autoMode the auto mode to use
         */
        default void onAutoModeChanged(int autoMode) {
        }

        /**
         * Callback invoked when the time to automatically activate Night display changes.
         *
         * @param startTime the local time to automatically activate Night display
         */
        default void onCustomStartTimeChanged(LocalTime startTime) {
        }

        /**
         * Callback invoked when the time to automatically deactivate Night display changes.
         *
         * @param endTime the local time to automatically deactivate Night display
         */
        default void onCustomEndTimeChanged(LocalTime endTime) {
        }

        /**
         * Callback invoked when the color temperature changes.
         *
         * @param colorTemperature the color temperature to tint the screen
         */
        default void onColorTemperatureChanged(int colorTemperature) {
        }
    }
}