/*
 * Copyright (C) 2017 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.systemui.doze;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;
import android.os.SystemProperties;
import android.os.Trace;
import android.os.UserHandle;
import android.provider.Settings;

import com.android.internal.annotations.VisibleForTesting;

/**
 * Controls the screen brightness when dozing.
 */
public class DozeScreenBrightness extends BroadcastReceiver implements DozeMachine.Part,
        SensorEventListener {
    private static final boolean DEBUG_AOD_BRIGHTNESS = SystemProperties
            .getBoolean("debug.aod_brightness", false);
    protected static final String ACTION_AOD_BRIGHTNESS =
            "com.android.systemui.doze.AOD_BRIGHTNESS";
    protected static final String BRIGHTNESS_BUCKET = "brightness_bucket";

    private final Context mContext;
    private final DozeMachine.Service mDozeService;
    private final DozeHost mDozeHost;
    private final Handler mHandler;
    private final SensorManager mSensorManager;
    private final Sensor mLightSensor;
    private final int[] mSensorToBrightness;
    private final int[] mSensorToScrimOpacity;
    private final boolean mDebuggable;

    private boolean mRegistered;
    private int mDefaultDozeBrightness;
    private boolean mPaused = false;
    private boolean mScreenOff = false;
    private int mLastSensorValue = -1;

    /**
     * Debug value used for emulating various display brightness buckets:
     *
     * {@code am broadcast -p com.android.systemui -a com.android.systemui.doze.AOD_BRIGHTNESS
     * --ei brightness_bucket 1}
     */
    private int mDebugBrightnessBucket = -1;

    @VisibleForTesting
    public DozeScreenBrightness(Context context, DozeMachine.Service service,
            SensorManager sensorManager, Sensor lightSensor, DozeHost host,
            Handler handler, int defaultDozeBrightness, int[] sensorToBrightness,
            int[] sensorToScrimOpacity, boolean debuggable) {
        mContext = context;
        mDozeService = service;
        mSensorManager = sensorManager;
        mLightSensor = lightSensor;
        mDozeHost = host;
        mHandler = handler;
        mDebuggable = debuggable;

        mDefaultDozeBrightness = defaultDozeBrightness;
        mSensorToBrightness = sensorToBrightness;
        mSensorToScrimOpacity = sensorToScrimOpacity;

        if (mDebuggable) {
            IntentFilter filter = new IntentFilter();
            filter.addAction(ACTION_AOD_BRIGHTNESS);
            mContext.registerReceiverAsUser(this, UserHandle.ALL, filter, null, handler);
        }
    }

    public DozeScreenBrightness(Context context, DozeMachine.Service service,
            SensorManager sensorManager, Sensor lightSensor, DozeHost host,
            Handler handler, AlwaysOnDisplayPolicy policy) {
        this(context, service, sensorManager, lightSensor, host, handler,
                context.getResources().getInteger(
                        com.android.internal.R.integer.config_screenBrightnessDoze),
                policy.screenBrightnessArray, policy.dimmingScrimArray, DEBUG_AOD_BRIGHTNESS);
    }

    @Override
    public void transitionTo(DozeMachine.State oldState, DozeMachine.State newState) {
        switch (newState) {
            case INITIALIZED:
                resetBrightnessToDefault();
                break;
            case DOZE_AOD:
            case DOZE_REQUEST_PULSE:
                setLightSensorEnabled(true);
                break;
            case DOZE:
                setLightSensorEnabled(false);
                resetBrightnessToDefault();
                break;
            case FINISH:
                onDestroy();
                break;
        }
        if (newState != DozeMachine.State.FINISH) {
            setScreenOff(newState == DozeMachine.State.DOZE);
            setPaused(newState == DozeMachine.State.DOZE_AOD_PAUSED);
        }
    }

    private void onDestroy() {
        setLightSensorEnabled(false);
        if (mDebuggable) {
            mContext.unregisterReceiver(this);
        }
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        Trace.beginSection("DozeScreenBrightness.onSensorChanged" + event.values[0]);
        try {
            if (mRegistered) {
                mLastSensorValue = (int) event.values[0];
                updateBrightnessAndReady(false /* force */);
            }
        } finally {
            Trace.endSection();
        }
    }

    private void updateBrightnessAndReady(boolean force) {
        if (force || mRegistered || mDebugBrightnessBucket != -1) {
            int sensorValue = mDebugBrightnessBucket == -1
                    ? mLastSensorValue : mDebugBrightnessBucket;
            int brightness = computeBrightness(sensorValue);
            boolean brightnessReady = brightness > 0;
            if (brightnessReady) {
                mDozeService.setDozeScreenBrightness(clampToUserSetting(brightness));
            }

            int scrimOpacity = -1;
            if (mPaused || mScreenOff) {
                // If AOD is paused, force the screen black until the
                // sensor reports a new brightness. This ensures that when the screen comes on
                // again, it will only show after the brightness sensor has stabilized,
                // avoiding a potential flicker.
                scrimOpacity = 255;
            } else if (brightnessReady) {
                // Only unblank scrim once brightness is ready.
                scrimOpacity = computeScrimOpacity(sensorValue);
            }
            if (scrimOpacity >= 0) {
                mDozeHost.setAodDimmingScrim(scrimOpacity / 255f);
            }
        }
    }

    private int computeScrimOpacity(int sensorValue) {
        if (sensorValue < 0 || sensorValue >= mSensorToScrimOpacity.length) {
            return -1;
        }
        return mSensorToScrimOpacity[sensorValue];
    }

    private int computeBrightness(int sensorValue) {
        if (sensorValue < 0 || sensorValue >= mSensorToBrightness.length) {
            return -1;
        }
        return mSensorToBrightness[sensorValue];
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }

    private void resetBrightnessToDefault() {
        mDozeService.setDozeScreenBrightness(clampToUserSetting(mDefaultDozeBrightness));
        mDozeHost.setAodDimmingScrim(0f);
    }

    private int clampToUserSetting(int brightness) {
        int userSetting = Settings.System.getIntForUser(mContext.getContentResolver(),
                Settings.System.SCREEN_BRIGHTNESS, Integer.MAX_VALUE,
                UserHandle.USER_CURRENT);
        return Math.min(brightness, userSetting);
    }

    private void setLightSensorEnabled(boolean enabled) {
        if (enabled && !mRegistered && mLightSensor != null) {
            // Wait until we get an event from the sensor until indicating ready.
            mRegistered = mSensorManager.registerListener(this, mLightSensor,
                    SensorManager.SENSOR_DELAY_NORMAL, mHandler);
            mLastSensorValue = -1;
        } else if (!enabled && mRegistered) {
            mSensorManager.unregisterListener(this);
            mRegistered = false;
            mLastSensorValue = -1;
            // Sensor is not enabled, hence we use the default brightness and are always ready.
        }
    }

    private void setPaused(boolean paused) {
        if (mPaused != paused) {
            mPaused = paused;
            updateBrightnessAndReady(false /* force */);
        }
    }

    private void setScreenOff(boolean screenOff) {
        if (mScreenOff != screenOff) {
            mScreenOff = screenOff;
            updateBrightnessAndReady(true /* force */);
        }
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        mDebugBrightnessBucket = intent.getIntExtra(BRIGHTNESS_BUCKET, -1);
        updateBrightnessAndReady(false /* force */);
    }
}