/*
 * Copyright (C) 2014 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.settings.fuelgauge;

import android.content.ContentResolver;
import android.content.Context;
import android.content.res.Resources;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.PowerManager;
import android.provider.Settings.Global;
import android.support.annotation.VisibleForTesting;
import android.util.Log;
import android.widget.Switch;

import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
import com.android.settings.R;
import com.android.settings.SettingsActivity;
import com.android.settings.SettingsPreferenceFragment;
import com.android.settings.Utils;
import com.android.settings.dashboard.conditional.BatterySaverCondition;
import com.android.settings.dashboard.conditional.ConditionManager;
import com.android.settings.notification.SettingPref;
import com.android.settings.widget.SwitchBar;

public class BatterySaverSettings extends SettingsPreferenceFragment
        implements SwitchBar.OnSwitchChangeListener, BatterySaverReceiver.BatterySaverListener {
    private static final String TAG = "BatterySaverSettings";
    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
    private static final String KEY_TURN_ON_AUTOMATICALLY = "turn_on_automatically";
    private static final long WAIT_FOR_SWITCH_ANIM = 500;

    private final Handler mHandler = new Handler();
    private final SettingsObserver mSettingsObserver = new SettingsObserver(mHandler);

    @VisibleForTesting
    SwitchBar mSwitchBar;
    private Context mContext;
    private boolean mCreated;
    private SettingPref mTriggerPref;
    private Switch mSwitch;
    private boolean mValidListener;
    private PowerManager mPowerManager;
    private BatterySaverReceiver mReceiver;

    @Override
    public int getMetricsCategory() {
        return MetricsEvent.FUELGAUGE_BATTERY_SAVER;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (mCreated) {
            mSwitchBar.show();
            return;
        }
        mCreated = true;
        addPreferencesFromResource(R.xml.battery_saver_settings);
        mFooterPreferenceMixin.createFooterPreference()
                .setTitle(com.android.internal.R.string.battery_saver_description);
        mContext = getActivity();
        mSwitchBar = ((SettingsActivity) mContext).getSwitchBar();
        mSwitch = mSwitchBar.getSwitch();
        mSwitchBar.show();

        mTriggerPref = new SettingPref(SettingPref.TYPE_GLOBAL, KEY_TURN_ON_AUTOMATICALLY,
                Global.LOW_POWER_MODE_TRIGGER_LEVEL,
                0, /*default*/
                getResources().getIntArray(R.array.battery_saver_trigger_values)) {
            @Override
            protected String getCaption(Resources res, int value) {
                if (value > 0 && value < 100) {
                    return res.getString(R.string.battery_saver_turn_on_automatically_pct,
                                         Utils.formatPercentage(value));
                }
                return res.getString(R.string.battery_saver_turn_on_automatically_never);
            }
        };
        mTriggerPref.init(this);

        mPowerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        mReceiver = new BatterySaverReceiver(mContext);
        mReceiver.setBatterySaverListener(this);
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        mSwitchBar.hide();
    }

    @Override
    public void onResume() {
        super.onResume();
        mSettingsObserver.setListening(true);
        mReceiver.setListening(true);
        if (!mValidListener) {
            mSwitchBar.addOnSwitchChangeListener(this);
            mValidListener = true;
        }
        updateSwitch();
    }

    @Override
    public void onPause() {
        super.onPause();
        mSettingsObserver.setListening(false);
        mReceiver.setListening(false);
        if (mValidListener) {
            mSwitchBar.removeOnSwitchChangeListener(this);
            mValidListener = false;
        }
    }

    @Override
    public void onSwitchChanged(Switch switchView, boolean isChecked) {
        mHandler.removeCallbacks(mStartMode);
        if (isChecked) {
            mHandler.postDelayed(mStartMode, WAIT_FOR_SWITCH_ANIM);
        } else {
            if (DEBUG) Log.d(TAG, "Stopping low power mode from settings");
            trySetPowerSaveMode(false);
        }
    }

    private void trySetPowerSaveMode(boolean mode) {
        if (!mPowerManager.setPowerSaveMode(mode)) {
            if (DEBUG) Log.d(TAG, "Setting mode failed, fallback to current value");
            mHandler.post(mUpdateSwitch);
        }
        // TODO: Remove once broadcast is in place.
        ConditionManager.get(getContext()).getCondition(BatterySaverCondition.class).refreshState();
    }

    private void updateSwitch() {
        final boolean mode = mPowerManager.isPowerSaveMode();
        if (DEBUG) Log.d(TAG, "updateSwitch: isChecked=" + mSwitch.isChecked() + " mode=" + mode);
        if (mode == mSwitch.isChecked()) return;

        // set listener to null so that that code below doesn't trigger onCheckedChanged()
        if (mValidListener) {
            mSwitchBar.removeOnSwitchChangeListener(this);
        }
        mSwitch.setChecked(mode);
        if (mValidListener) {
            mSwitchBar.addOnSwitchChangeListener(this);
        }
    }

    private final Runnable mUpdateSwitch = new Runnable() {
        @Override
        public void run() {
            updateSwitch();
        }
    };

    private final Runnable mStartMode = new Runnable() {
        @Override
        public void run() {
            AsyncTask.execute(new Runnable() {
                @Override
                public void run() {
                    if (DEBUG) Log.d(TAG, "Starting low power mode from settings");
                    trySetPowerSaveMode(true);
                }
            });
        }
    };

    @Override
    public void onPowerSaveModeChanged() {
        mHandler.post(mUpdateSwitch);
    }

    @Override
    public void onBatteryChanged(boolean pluggedIn) {
        mSwitchBar.setEnabled(!pluggedIn);
    }

    private final class SettingsObserver extends ContentObserver {
        private final Uri LOW_POWER_MODE_TRIGGER_LEVEL_URI
                = Global.getUriFor(Global.LOW_POWER_MODE_TRIGGER_LEVEL);

        public SettingsObserver(Handler handler) {
            super(handler);
        }

        @Override
        public void onChange(boolean selfChange, Uri uri) {
            if (LOW_POWER_MODE_TRIGGER_LEVEL_URI.equals(uri)) {
                mTriggerPref.update(mContext);
            }
        }

        public void setListening(boolean listening) {
            final ContentResolver cr = getContentResolver();
            if (listening) {
                cr.registerContentObserver(LOW_POWER_MODE_TRIGGER_LEVEL_URI, false, this);
            } else {
                cr.unregisterContentObserver(this);
            }
        }
    }
}