/*
 * Copyright (C) 2016 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.internal.app;

import android.annotation.IntDef;
import android.annotation.NonNull;
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.os.UserHandle;
import android.provider.Settings.Secure;
import android.util.Slog;

import com.android.internal.R;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Calendar;
import java.util.Locale;

/**
 * Controller for managing Night display settings.
 * <p/>
 * Night display tints your screen red at night. This makes it easier to look at your screen in
 * dim light and may help you fall asleep more easily.
 */
public final class NightDisplayController {

    private static final String TAG = "NightDisplayController";
    private static final boolean DEBUG = false;

    /** @hide */
    @Retention(RetentionPolicy.SOURCE)
    @IntDef({ AUTO_MODE_DISABLED, AUTO_MODE_CUSTOM, AUTO_MODE_TWILIGHT })
    public @interface AutoMode {}

    /**
     * Auto mode value to prevent Night display from being automatically activated. It can still
     * be activated manually via {@link #setActivated(boolean)}.
     *
     * @see #setAutoMode(int)
     */
    public static final int AUTO_MODE_DISABLED = 0;
    /**
     * Auto mode value to automatically activate Night display at a specific start and end time.
     *
     * @see #setAutoMode(int)
     * @see #setCustomStartTime(LocalTime)
     * @see #setCustomEndTime(LocalTime)
     */
    public static final int AUTO_MODE_CUSTOM = 1;
    /**
     * Auto mode value to automatically activate Night display from sunset to sunrise.
     *
     * @see #setAutoMode(int)
     */
    public static final int AUTO_MODE_TWILIGHT = 2;

    private final Context mContext;
    private final int mUserId;

    private final ContentObserver mContentObserver;

    private Callback mCallback;

    public NightDisplayController(@NonNull Context context) {
        this(context, UserHandle.myUserId());
    }

    public NightDisplayController(@NonNull Context context, int userId) {
        mContext = context.getApplicationContext();
        mUserId = userId;

        mContentObserver = new ContentObserver(new Handler(Looper.getMainLooper())) {
            @Override
            public void onChange(boolean selfChange, Uri uri) {
                super.onChange(selfChange, uri);

                final String setting = uri == null ? null : uri.getLastPathSegment();
                if (setting != null) {
                    onSettingChanged(setting);
                }
            }
        };
    }

    /**
     * Returns {@code true} when Night display is activated (the display is tinted red).
     */
    public boolean isActivated() {
        return Secure.getIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_ACTIVATED, 0, mUserId) == 1;
    }

    /**
     * Sets whether Night display should be activated.
     *
     * @param activated {@code true} if Night display should be activated
     * @return {@code true} if the activated value was set successfully
     */
    public boolean setActivated(boolean activated) {
        return Secure.putIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_ACTIVATED, activated ? 1 : 0, mUserId);
    }

    /**
     * Returns the current auto mode value controlling when Night display will be automatically
     * activated. One of {@link #AUTO_MODE_DISABLED}, {@link #AUTO_MODE_CUSTOM}, or
     * {@link #AUTO_MODE_TWILIGHT}.
     */
    public @AutoMode int getAutoMode() {
        int autoMode = Secure.getIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_AUTO_MODE, -1, mUserId);
        if (autoMode == -1) {
            if (DEBUG) {
                Slog.d(TAG, "Using default value for setting: " + Secure.NIGHT_DISPLAY_AUTO_MODE);
            }
            autoMode = mContext.getResources().getInteger(
                    R.integer.config_defaultNightDisplayAutoMode);
        }

        if (autoMode != AUTO_MODE_DISABLED
                && autoMode != AUTO_MODE_CUSTOM
                && autoMode != AUTO_MODE_TWILIGHT) {
            Slog.e(TAG, "Invalid autoMode: " + autoMode);
            autoMode = AUTO_MODE_DISABLED;
        }

        return autoMode;
    }

    /**
     * Sets the current auto mode value controlling when Night display will be automatically
     * activated. One of {@link #AUTO_MODE_DISABLED}, {@link #AUTO_MODE_CUSTOM}, or
     * {@link #AUTO_MODE_TWILIGHT}.
     *
     * @param autoMode the new auto mode to use
     * @return {@code true} if new auto mode was set successfully
     */
    public boolean setAutoMode(@AutoMode int autoMode) {
        if (autoMode != AUTO_MODE_DISABLED
                && autoMode != AUTO_MODE_CUSTOM
                && autoMode != AUTO_MODE_TWILIGHT) {
            throw new IllegalArgumentException("Invalid autoMode: " + autoMode);
        }

        return Secure.putIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_AUTO_MODE, autoMode, mUserId);
    }

    /**
     * Returns the local time when Night display will be automatically activated when using
     * {@link #AUTO_MODE_CUSTOM}.
     */
    public @NonNull LocalTime getCustomStartTime() {
        int startTimeValue = Secure.getIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_CUSTOM_START_TIME, -1, mUserId);
        if (startTimeValue == -1) {
            if (DEBUG) {
                Slog.d(TAG, "Using default value for setting: "
                        + Secure.NIGHT_DISPLAY_CUSTOM_START_TIME);
            }
            startTimeValue = mContext.getResources().getInteger(
                    R.integer.config_defaultNightDisplayCustomStartTime);
        }

        return LocalTime.valueOf(startTimeValue);
    }

    /**
     * Sets the local time when Night display will be automatically activated when using
     * {@link #AUTO_MODE_CUSTOM}.
     *
     * @param startTime the local time to automatically activate Night display
     * @return {@code true} if the new custom start time was set successfully
     */
    public boolean setCustomStartTime(@NonNull LocalTime startTime) {
        if (startTime == null) {
            throw new IllegalArgumentException("startTime cannot be null");
        }
        return Secure.putIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_CUSTOM_START_TIME, startTime.toMillis(), mUserId);
    }

    /**
     * Returns the local time when Night display will be automatically deactivated when using
     * {@link #AUTO_MODE_CUSTOM}.
     */
    public @NonNull LocalTime getCustomEndTime() {
        int endTimeValue = Secure.getIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_CUSTOM_END_TIME, -1, mUserId);
        if (endTimeValue == -1) {
            if (DEBUG) {
                Slog.d(TAG, "Using default value for setting: "
                        + Secure.NIGHT_DISPLAY_CUSTOM_END_TIME);
            }
            endTimeValue = mContext.getResources().getInteger(
                    R.integer.config_defaultNightDisplayCustomEndTime);
        }

        return LocalTime.valueOf(endTimeValue);
    }

    /**
     * Sets the local time when Night display will be automatically deactivated when using
     * {@link #AUTO_MODE_CUSTOM}.
     *
     * @param endTime the local time to automatically deactivate Night display
     * @return {@code true} if the new custom end time was set successfully
     */
    public boolean setCustomEndTime(@NonNull LocalTime endTime) {
        if (endTime == null) {
            throw new IllegalArgumentException("endTime cannot be null");
        }
        return Secure.putIntForUser(mContext.getContentResolver(),
                Secure.NIGHT_DISPLAY_CUSTOM_END_TIME, endTime.toMillis(), mUserId);
    }

    private void onSettingChanged(@NonNull String setting) {
        if (DEBUG) {
            Slog.d(TAG, "onSettingChanged: " + setting);
        }

        if (mCallback != null) {
            switch (setting) {
                case Secure.NIGHT_DISPLAY_ACTIVATED:
                    mCallback.onActivated(isActivated());
                    break;
                case Secure.NIGHT_DISPLAY_AUTO_MODE:
                    mCallback.onAutoModeChanged(getAutoMode());
                    break;
                case Secure.NIGHT_DISPLAY_CUSTOM_START_TIME:
                    mCallback.onCustomStartTimeChanged(getCustomStartTime());
                    break;
                case Secure.NIGHT_DISPLAY_CUSTOM_END_TIME:
                    mCallback.onCustomEndTimeChanged(getCustomEndTime());
                    break;
            }
        }
    }

    /**
     * Register a callback to be invoked whenever the Night display settings are changed.
     */
    public void setListener(Callback callback) {
        final Callback oldCallback = mCallback;
        if (oldCallback != callback) {
            mCallback = callback;

            if (callback == null) {
                // Stop listening for changes now that there IS NOT a listener.
                mContext.getContentResolver().unregisterContentObserver(mContentObserver);
            } else if (oldCallback == null) {
                // Start listening for changes now that there IS a listener.
                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);
            }
        }
    }

    /**
     * Returns {@code true} if Night display is supported by the device.
     */
    public static boolean isAvailable(Context context) {
        return context.getResources().getBoolean(R.bool.config_nightDisplayAvailable);
    }

    /**
     * A time without a time-zone or date.
     */
    public static class LocalTime {

        /**
         * The hour of the day from 0 - 23.
         */
        public final int hourOfDay;
        /**
         * The minute within the hour from 0 - 59.
         */
        public final int minute;

        public LocalTime(int hourOfDay, int minute) {
            if (hourOfDay < 0 || hourOfDay > 23) {
                throw new IllegalArgumentException("Invalid hourOfDay: " + hourOfDay);
            } else if (minute < 0 || minute > 59) {
                throw new IllegalArgumentException("Invalid minute: " + minute);
            }

            this.hourOfDay = hourOfDay;
            this.minute = minute;
        }

        /**
         * Returns the first date time corresponding to this local time that occurs before the
         * provided date time.
         *
         * @param time the date time to compare against
         * @return the prior date time corresponding to this local time
         */
        public Calendar getDateTimeBefore(Calendar time) {
            final Calendar c = Calendar.getInstance();
            c.set(Calendar.YEAR, time.get(Calendar.YEAR));
            c.set(Calendar.DAY_OF_YEAR, time.get(Calendar.DAY_OF_YEAR));

            c.set(Calendar.HOUR_OF_DAY, hourOfDay);
            c.set(Calendar.MINUTE, minute);
            c.set(Calendar.SECOND, 0);
            c.set(Calendar.MILLISECOND, 0);

            // Check if the local time has past, if so return the same time tomorrow.
            if (c.after(time)) {
                c.add(Calendar.DATE, -1);
            }

            return c;
        }

        /**
         * Returns the first date time corresponding to this local time that occurs after the
         * provided date time.
         *
         * @param time the date time to compare against
         * @return the next date time corresponding to this local time
         */
        public Calendar getDateTimeAfter(Calendar time) {
            final Calendar c = Calendar.getInstance();
            c.set(Calendar.YEAR, time.get(Calendar.YEAR));
            c.set(Calendar.DAY_OF_YEAR, time.get(Calendar.DAY_OF_YEAR));

            c.set(Calendar.HOUR_OF_DAY, hourOfDay);
            c.set(Calendar.MINUTE, minute);
            c.set(Calendar.SECOND, 0);
            c.set(Calendar.MILLISECOND, 0);

            // Check if the local time has past, if so return the same time tomorrow.
            if (c.before(time)) {
                c.add(Calendar.DATE, 1);
            }

            return c;
        }

        /**
         * Returns a local time corresponding the given number of milliseconds from midnight.
         *
         * @param millis the number of milliseconds from midnight
         * @return the corresponding local time
         */
        private static LocalTime valueOf(int millis) {
            final int hourOfDay = (millis / 3600000) % 24;
            final int minutes = (millis / 60000) % 60;
            return new LocalTime(hourOfDay, minutes);
        }

        /**
         * Returns the local time represented as milliseconds from midnight.
         */
        private int toMillis() {
            return hourOfDay * 3600000 + minute * 60000;
        }

        @Override
        public String toString() {
            return String.format(Locale.US, "%02d:%02d", hourOfDay, minute);
        }
    }

    /**
     * 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) {}
    }
}