/*
 * Copyright (C) 2010 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;

import static android.provider.Settings.System.SCREEN_OFF_TIMEOUT;

import android.app.ActivityManagerNative;
import android.app.admin.DevicePolicyManager;
import android.content.ContentResolver;
import android.content.Context;
import android.content.res.Configuration;
import android.database.ContentObserver;
import android.os.Bundle;
import android.os.Handler;
import android.os.RemoteException;
import android.preference.CheckBoxPreference;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceScreen;
import android.provider.Settings;
import android.util.Log;

import java.util.ArrayList;

public class DisplaySettings extends SettingsPreferenceFragment implements
        Preference.OnPreferenceChangeListener {
    private static final String TAG = "DisplaySettings";

    /** If there is no setting in the provider, use this. */
    private static final int FALLBACK_SCREEN_TIMEOUT_VALUE = 30000;

    private static final String KEY_SCREEN_TIMEOUT = "screen_timeout";
    private static final String KEY_ACCELEROMETER = "accelerometer";
    private static final String KEY_FONT_SIZE = "font_size";

    private CheckBoxPreference mAccelerometer;
    private ListPreference mFontSizePref;

    private final Configuration mCurConfig = new Configuration();
    
    private ListPreference mScreenTimeoutPreference;

    private ContentObserver mAccelerometerRotationObserver = new ContentObserver(new Handler()) {
        @Override
        public void onChange(boolean selfChange) {
            updateAccelerometerRotationCheckbox();
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ContentResolver resolver = getActivity().getContentResolver();

        addPreferencesFromResource(R.xml.display_settings);

        mAccelerometer = (CheckBoxPreference) findPreference(KEY_ACCELEROMETER);
        mAccelerometer.setPersistent(false);

        mScreenTimeoutPreference = (ListPreference) findPreference(KEY_SCREEN_TIMEOUT);
        final long currentTimeout = Settings.System.getLong(resolver, SCREEN_OFF_TIMEOUT,
                FALLBACK_SCREEN_TIMEOUT_VALUE);
        mScreenTimeoutPreference.setValue(String.valueOf(currentTimeout));
        mScreenTimeoutPreference.setOnPreferenceChangeListener(this);
        disableUnusableTimeouts(mScreenTimeoutPreference);
        updateTimeoutPreferenceDescription(mScreenTimeoutPreference,
                R.string.screen_timeout_summary, currentTimeout);

        mFontSizePref = (ListPreference) findPreference(KEY_FONT_SIZE);
        mFontSizePref.setOnPreferenceChangeListener(this);
    }

    private void updateTimeoutPreferenceDescription(
            ListPreference pref,
            int summaryStrings,
            long currentTimeout) {
        updateTimeoutPreferenceDescription(pref, summaryStrings, 0, currentTimeout);
    }

    private void updateTimeoutPreferenceDescription(
            ListPreference pref,
            int summaryStrings,
            int zeroString,
            long currentTimeout) {
        String summary;
        if (currentTimeout == 0) {
            summary = pref.getContext().getString(zeroString);
        } else {
            final CharSequence[] entries = pref.getEntries();
            final CharSequence[] values = pref.getEntryValues();
            int best = 0;
            for (int i = 0; i < values.length; i++) {
                long timeout = Long.valueOf(values[i].toString());
                if (currentTimeout >= timeout) {
                    best = i;
                }
            }
            summary = pref.getContext().getString(summaryStrings, entries[best]);
        }
        pref.setSummary(summary);
    }

    private void disableUnusableTimeouts(ListPreference screenTimeoutPreference) {
        final DevicePolicyManager dpm =
                (DevicePolicyManager) getActivity().getSystemService(
                Context.DEVICE_POLICY_SERVICE);
        final long maxTimeout = dpm != null ? dpm.getMaximumTimeToLock(null) : 0;
        if (maxTimeout == 0) {
            return; // policy not enforced
        }
        final CharSequence[] entries = screenTimeoutPreference.getEntries();
        final CharSequence[] values = screenTimeoutPreference.getEntryValues();
        ArrayList<CharSequence> revisedEntries = new ArrayList<CharSequence>();
        ArrayList<CharSequence> revisedValues = new ArrayList<CharSequence>();
        for (int i = 0; i < values.length; i++) {
            long timeout = Long.valueOf(values[i].toString());
            if (timeout <= maxTimeout) {
                revisedEntries.add(entries[i]);
                revisedValues.add(values[i]);
            }
        }
        if (revisedEntries.size() != entries.length || revisedValues.size() != values.length) {
            screenTimeoutPreference.setEntries(
                    revisedEntries.toArray(new CharSequence[revisedEntries.size()]));
            screenTimeoutPreference.setEntryValues(
                    revisedValues.toArray(new CharSequence[revisedValues.size()]));
            final int userPreference = Integer.valueOf(screenTimeoutPreference.getValue());
            if (userPreference <= maxTimeout) {
                screenTimeoutPreference.setValue(String.valueOf(userPreference));
            } else {
                // There will be no highlighted selection since nothing in the list matches
                // maxTimeout. The user can still select anything less than maxTimeout.
                // TODO: maybe append maxTimeout to the list and mark selected.
            }
        }
        screenTimeoutPreference.setEnabled(revisedEntries.size() > 0);
    }

    int floatToIndex(float val, int resid) {
        String[] indices = getResources().getStringArray(resid);
        float lastVal = Float.parseFloat(indices[0]);
        for (int i=1; i<indices.length; i++) {
            float thisVal = Float.parseFloat(indices[i]);
            if (val < (lastVal + (thisVal-lastVal)*.5f)) {
                return i-1;
            }
            lastVal = thisVal;
        }
        return indices.length-1;
    }
    
    public void readFontSizePreference(ListPreference pref) {
        try {
            mCurConfig.updateFrom(ActivityManagerNative.getDefault().getConfiguration());
        } catch (RemoteException e) {
            Log.w(TAG, "Unable to retrieve font size");
        }
        pref.setValueIndex(floatToIndex(mCurConfig.fontScale, R.array.entryvalues_font_size));
    }
    
    @Override
    public void onResume() {
        super.onResume();

        updateState();
        getContentResolver().registerContentObserver(
                Settings.System.getUriFor(Settings.System.ACCELEROMETER_ROTATION), true,
                mAccelerometerRotationObserver);
    }

    @Override
    public void onPause() {
        super.onPause();

        getContentResolver().unregisterContentObserver(mAccelerometerRotationObserver);
    }

    private void updateState() {
        updateAccelerometerRotationCheckbox();
        readFontSizePreference(mFontSizePref);
    }

    private void updateAccelerometerRotationCheckbox() {
        mAccelerometer.setChecked(Settings.System.getInt(
                getContentResolver(),
                Settings.System.ACCELEROMETER_ROTATION, 0) != 0);
    }

    public void writeFontSizePreference(Object objValue) {
        try {
            mCurConfig.fontScale = Float.parseFloat(objValue.toString());
            ActivityManagerNative.getDefault().updatePersistentConfiguration(mCurConfig);
        } catch (RemoteException e) {
            Log.w(TAG, "Unable to save font size");
        }
    }
    
    @Override
    public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
        if (preference == mAccelerometer) {
            Settings.System.putInt(getContentResolver(),
                    Settings.System.ACCELEROMETER_ROTATION,
                    mAccelerometer.isChecked() ? 1 : 0);
        }
        return super.onPreferenceTreeClick(preferenceScreen, preference);
    }

    public boolean onPreferenceChange(Preference preference, Object objValue) {
        final String key = preference.getKey();
        if (KEY_SCREEN_TIMEOUT.equals(key)) {
            int value = Integer.parseInt((String) objValue);
            try {
                Settings.System.putInt(getContentResolver(),
                        SCREEN_OFF_TIMEOUT, value);
                updateTimeoutPreferenceDescription(mScreenTimeoutPreference,
                        R.string.screen_timeout_summary, value);
            } catch (NumberFormatException e) {
                Log.e(TAG, "could not persist screen timeout setting", e);
            }
        }
        if (KEY_FONT_SIZE.equals(key)) {
            writeFontSizePreference(objValue);
        }

        return true;
    }
}