/*
 * Copyright (C) 2006 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 android.app.Activity;
import android.app.AlarmManager;
import android.app.ListFragment;
import android.content.Context;
import android.content.res.XmlResourceParser;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import org.xmlpull.v1.XmlPullParserException;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TimeZone;

/**
 * The class displaying a list of time zones that match a filter string
 * such as "Africa", "Europe", etc. Choosing an item from the list will set
 * the time zone. Pressing Back without choosing from the list will not 
 * result in a change in the time zone setting.
 */
public class ZonePicker extends ListFragment {
    private static final String TAG = "ZonePicker";

    public static interface ZoneSelectionListener {
        // You can add any argument if you really need it...
        public void onZoneSelected(TimeZone tz);
    }

    private static final String KEY_ID = "id";  // value: String
    private static final String KEY_DISPLAYNAME = "name";  // value: String
    private static final String KEY_GMT = "gmt";  // value: String
    private static final String KEY_OFFSET = "offset";  // value: int (Integer)
    private static final String XMLTAG_TIMEZONE = "timezone";

    private static final int HOURS_1 = 60 * 60000;

    private static final int MENU_TIMEZONE = Menu.FIRST+1;
    private static final int MENU_ALPHABETICAL = Menu.FIRST;

    private boolean mSortedByTimezone;

    private SimpleAdapter mTimezoneSortedAdapter;
    private SimpleAdapter mAlphabeticalAdapter;

    private ZoneSelectionListener mListener;

    /**
     * Constructs an adapter with TimeZone list. Sorted by TimeZone in default.
     *
     * @param sortedByName use Name for sorting the list.
     */
    public static SimpleAdapter constructTimezoneAdapter(Context context,
            boolean sortedByName) {
        return constructTimezoneAdapter(context, sortedByName,
                android.R.layout.simple_list_item_2);
    }

    /**
     * Constructs an adapter with TimeZone list. Sorted by TimeZone in default.
     *
     * @param sortedByName use Name for sorting the list.
     */
    public static SimpleAdapter constructTimezoneAdapter(Context context,
            boolean sortedByName, int layoutId) {
        final String[] from = new String[] {KEY_DISPLAYNAME, KEY_GMT};
        final int[] to = new int[] {android.R.id.text1, android.R.id.text2};

        final String sortKey = (sortedByName ? KEY_DISPLAYNAME : KEY_OFFSET);
        final MyComparator comparator = new MyComparator(sortKey);
        final List<HashMap<String, Object>> sortedList = getZones(context);
        Collections.sort(sortedList, comparator);
        final SimpleAdapter adapter = new SimpleAdapter(context,
                sortedList,
                layoutId,
                from,
                to);

        return adapter;
    }

    /**
     * Searches {@link TimeZone} from the given {@link SimpleAdapter} object, and returns
     * the index for the TimeZone.
     *
     * @param adapter SimpleAdapter constructed by
     * {@link #constructTimezoneAdapter(Context, boolean)}.
     * @param tz TimeZone to be searched.
     * @return Index for the given TimeZone. -1 when there's no corresponding list item.
     * returned.
     */
    public static int getTimeZoneIndex(SimpleAdapter adapter, TimeZone tz) {
        final String defaultId = tz.getID();
        final int listSize = adapter.getCount();
        for (int i = 0; i < listSize; i++) {
            // Using HashMap<String, Object> induces unnecessary warning.
            final HashMap<?,?> map = (HashMap<?,?>)adapter.getItem(i);
            final String id = (String)map.get(KEY_ID);
            if (defaultId.equals(id)) {
                // If current timezone is in this list, move focus to it
                return i;
            }
        }
        return -1;
    }

    /**
     * @param item one of items in adapters. The adapter should be constructed by
     * {@link #constructTimezoneAdapter(Context, boolean)}.
     * @return TimeZone object corresponding to the item.
     */
    public static TimeZone obtainTimeZoneFromItem(Object item) {
        return TimeZone.getTimeZone((String)((Map<?, ?>)item).get(KEY_ID));
    }

    @Override
    public void onActivityCreated(Bundle savedInstanseState) {
        super.onActivityCreated(savedInstanseState);

        final Activity activity = getActivity();
        mTimezoneSortedAdapter = constructTimezoneAdapter(activity, false);
        mAlphabeticalAdapter = constructTimezoneAdapter(activity, true);

        // Sets the adapter
        setSorting(true);
        setHasOptionsMenu(true);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        menu.add(0, MENU_ALPHABETICAL, 0, R.string.zone_list_menu_sort_alphabetically)
            .setIcon(android.R.drawable.ic_menu_sort_alphabetically);
        menu.add(0, MENU_TIMEZONE, 0, R.string.zone_list_menu_sort_by_timezone)
            .setIcon(R.drawable.ic_menu_3d_globe);
        super.onCreateOptionsMenu(menu, inflater);
    }

    @Override
    public void onPrepareOptionsMenu(Menu menu) {
        if (mSortedByTimezone) {
            menu.findItem(MENU_TIMEZONE).setVisible(false);
            menu.findItem(MENU_ALPHABETICAL).setVisible(true);
        } else {
            menu.findItem(MENU_TIMEZONE).setVisible(true);
            menu.findItem(MENU_ALPHABETICAL).setVisible(false);
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {

            case MENU_TIMEZONE:
                setSorting(true);
                return true;

            case MENU_ALPHABETICAL:
                setSorting(false);
                return true;

            default:
                return false;
        }
    }

    public void setZoneSelectionListener(ZoneSelectionListener listener) {
        mListener = listener;
    }

    private void setSorting(boolean sortByTimezone) {
        final SimpleAdapter adapter =
                sortByTimezone ? mTimezoneSortedAdapter : mAlphabeticalAdapter;
        setListAdapter(adapter);
        mSortedByTimezone = sortByTimezone;
        final int defaultIndex = getTimeZoneIndex(adapter, TimeZone.getDefault());
        if (defaultIndex >= 0) {
            setSelection(defaultIndex);
        }
    }

    private static List<HashMap<String, Object>> getZones(Context context) {
        final List<HashMap<String, Object>> myData = new ArrayList<HashMap<String, Object>>();
        final long date = Calendar.getInstance().getTimeInMillis();
        try {
            XmlResourceParser xrp = context.getResources().getXml(R.xml.timezones);
            while (xrp.next() != XmlResourceParser.START_TAG)
                continue;
            xrp.next();
            while (xrp.getEventType() != XmlResourceParser.END_TAG) {
                while (xrp.getEventType() != XmlResourceParser.START_TAG) {
                    if (xrp.getEventType() == XmlResourceParser.END_DOCUMENT) {
                        return myData;
                    }
                    xrp.next();
                }
                if (xrp.getName().equals(XMLTAG_TIMEZONE)) {
                    String id = xrp.getAttributeValue(0);
                    String displayName = xrp.nextText();
                    addItem(myData, id, displayName, date);
                }
                while (xrp.getEventType() != XmlResourceParser.END_TAG) {
                    xrp.next();
                }
                xrp.next();
            }
            xrp.close();
        } catch (XmlPullParserException xppe) {
            Log.e(TAG, "Ill-formatted timezones.xml file");
        } catch (java.io.IOException ioe) {
            Log.e(TAG, "Unable to read timezones.xml file");
        }

        return myData;
    }

    private static void addItem(
            List<HashMap<String, Object>> myData, String id, String displayName, long date) {
        final HashMap<String, Object> map = new HashMap<String, Object>();
        map.put(KEY_ID, id);
        map.put(KEY_DISPLAYNAME, displayName);
        final TimeZone tz = TimeZone.getTimeZone(id);
        final int offset = tz.getOffset(date);
        final int p = Math.abs(offset);
        final StringBuilder name = new StringBuilder();
        name.append("GMT");

        if (offset < 0) {
            name.append('-');
        } else {
            name.append('+');
        }

        name.append(p / (HOURS_1));
        name.append(':');

        int min = p / 60000;
        min %= 60;

        if (min < 10) {
            name.append('0');
        }
        name.append(min);

        map.put(KEY_GMT, name.toString());
        map.put(KEY_OFFSET, offset);

        myData.add(map);
    }

    @Override
    public void onListItemClick(ListView listView, View v, int position, long id) {
        final Map<?, ?> map = (Map<?, ?>)listView.getItemAtPosition(position);
        final String tzId = (String) map.get(KEY_ID);

        // Update the system timezone value
        final Activity activity = getActivity();
        final AlarmManager alarm = (AlarmManager) activity.getSystemService(Context.ALARM_SERVICE);
        alarm.setTimeZone(tzId);
        final TimeZone tz = TimeZone.getTimeZone(tzId);
        if (mListener != null) {
            mListener.onZoneSelected(tz);
        } else {
            getActivity().onBackPressed();
        }
    }

    private static class MyComparator implements Comparator<HashMap<?, ?>> {
        private String mSortingKey;

        public MyComparator(String sortingKey) {
            mSortingKey = sortingKey;
        }

        public void setSortingKey(String sortingKey) {
            mSortingKey = sortingKey;
        }

        public int compare(HashMap<?, ?> map1, HashMap<?, ?> map2) {
            Object value1 = map1.get(mSortingKey);
            Object value2 = map2.get(mSortingKey);

            /*
             * This should never happen, but just in-case, put non-comparable
             * items at the end.
             */
            if (!isComparable(value1)) {
                return isComparable(value2) ? 1 : 0;
            } else if (!isComparable(value2)) {
                return -1;
            }

            return ((Comparable) value1).compareTo(value2);
        }

        private boolean isComparable(Object value) {
            return (value != null) && (value instanceof Comparable); 
        }
    }
}