/*
 * 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.email.provider;

import com.android.email.Email;
import com.android.email.R;
import com.android.email.activity.MessageCompose;
import com.android.email.activity.MessageView;
import com.android.email.data.ThrottlingCursorLoader;
import com.android.email.provider.EmailContent.Message;
import com.android.email.provider.EmailContent.MessageColumns;

import android.app.Activity;
import android.app.PendingIntent;
import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.content.Loader;
import android.database.Cursor;
import android.graphics.Paint.Align;
import android.graphics.Typeface;
import android.net.Uri;
import android.net.Uri.Builder;
import android.os.Bundle;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.TextUtils.TruncateAt;
import android.text.format.DateUtils;
import android.text.style.StyleSpan;
import android.util.Log;
import android.widget.RemoteViews;
import android.widget.RemoteViewsService;

import java.util.HashMap;
import java.util.List;

public class WidgetProvider extends AppWidgetProvider {
    private static final String TAG = "WidgetProvider";

    /**
     * When handling clicks in a widget ListView, a single PendingIntent template is provided to
     * RemoteViews, and the individual "on click" actions are distinguished via a "fillInIntent"
     * on each list element; when a click is received, this "fillInIntent" is merged with the
     * PendingIntent using Intent.fillIn().  Since this mechanism does NOT preserve the Extras
     * Bundle, we instead encode information about the action (e.g. view, reply, etc.) and its
     * arguments (e.g. messageId, mailboxId, etc.) in an Uri which is added to the Intent via
     * Intent.setDataAndType()
     *
     * The mime type MUST be set in the Intent, even though we do not use it; therefore, it's value
     * is entirely arbitrary.
     *
     * Our "command" Uri is NOT used by the system in any manner, and is therefore constrained only
     * in the requirement that it be syntactically valid.
     *
     * We use the following convention for our commands:
     *     widget://command/<command>/<arg1>[/<arg2>]
     */
    private static final String WIDGET_DATA_MIME_TYPE = "com.android.email/widget_data";
    private static final Uri COMMAND_URI = Uri.parse("widget://command");

    // Command names and Uri's built upon COMMAND_URI
    private static final String COMMAND_NAME_SWITCH_LIST_VIEW = "switch_list_view";
    private static final Uri COMMAND_URI_SWITCH_LIST_VIEW =
        COMMAND_URI.buildUpon().appendPath(COMMAND_NAME_SWITCH_LIST_VIEW).build();
    private static final String COMMAND_NAME_VIEW_MESSAGE = "view_message";
    private static final Uri COMMAND_URI_VIEW_MESSAGE =
        COMMAND_URI.buildUpon().appendPath(COMMAND_NAME_VIEW_MESSAGE).build();

    private static final int TOTAL_COUNT_UNKNOWN = -1;
    private static final int MAX_MESSAGE_LIST_COUNT = 25;

    private static final String SORT_DESCENDING = MessageColumns.TIMESTAMP + " DESC";

    // Map holding our instantiated widgets, accessed by widget id
    private static HashMap<Integer, EmailWidget> sWidgetMap = new HashMap<Integer, EmailWidget>();
    private static AppWidgetManager sWidgetManager;
    private static Context sContext;
    private static ContentResolver sResolver;
    private static TextPaint sDatePaint = new TextPaint();

    /**
     * Types of views that we're prepared to show in the widget - all mail, unread mail, and starred
     * mail; we rotate between them.  Each ViewType is composed of a selection string and a title.
     */
    public enum ViewType {
        ALL_MAIL(null, R.string.widget_all_mail),
        UNREAD(MessageColumns.FLAG_READ + "=0", R.string.widget_unread),
        STARRED(MessageColumns.FLAG_FAVORITE + "=1", R.string.widget_starred);

        private final String selection;
        private final int titleResource;
        private String title;

        ViewType(String _selection, int _titleResource) {
            selection = _selection;
            titleResource = _titleResource;
        }

        public String getTitle(Context context) {
            if (title == null) {
                title = context.getString(titleResource);
            }
            return title;
        }
    }

    static class EmailWidget implements RemoteViewsService.RemoteViewsFactory {
        // The widget identifier
        private final int mWidgetId;

        // The cursor underlying the message list for this widget; this must only be modified while
        // holding mCursorLock
        private volatile Cursor mCursor;
        // A lock on our cursor, which is used in the UI thread while inflating views, and by
        // our Loader in the background
        private final Object mCursorLock = new Object();
        // Number of records in the cursor
        private int mCursorCount = TOTAL_COUNT_UNKNOWN;
        // The widget's loader (derived from ThrottlingCursorLoader)
        private WidgetLoader mLoader;

        // The current view type (all mail, unread, or starred for now)
        private ViewType mViewType = ViewType.ALL_MAIL;

        // The projection to be used by the WidgetLoader
        public static final String[] WIDGET_PROJECTION = new String[] {
            EmailContent.RECORD_ID, MessageColumns.DISPLAY_NAME, MessageColumns.TIMESTAMP,
            MessageColumns.SUBJECT, MessageColumns.FLAG_READ, MessageColumns.FLAG_FAVORITE,
            MessageColumns.FLAG_ATTACHMENT, MessageColumns.MAILBOX_KEY, MessageColumns.SNIPPET,
            MessageColumns.ACCOUNT_KEY
            };
        public static final int WIDGET_COLUMN_ID = 0;
        public static final int WIDGET_COLUMN_DISPLAY_NAME = 1;
        public static final int WIDGET_COLUMN_TIMESTAMP = 2;
        public static final int WIDGET_COLUMN_SUBJECT = 3;
        public static final int WIDGET_COLUMN_FLAG_READ = 4;
        public static final int WIDGET_COLUMN_FLAG_FAVORITE = 5;
        public static final int WIDGET_COLUMN_FLAG_ATTACHMENT = 6;
        public static final int WIDGET_COLUMN_MAILBOX_KEY = 7;
        public static final int WIDGET_COLUMN_SNIPPET = 8;
        public static final int WIDGET_COLUMN_ACCOUNT_KEY = 9;

        public EmailWidget(int _widgetId) {
            super();
            if (Email.DEBUG) {
                Log.d(TAG, "Creating EmailWidget with id = " + _widgetId);
            }
            mWidgetId = _widgetId;
            mLoader = new WidgetLoader();
            if (sDatePaint == null) {
                sDatePaint = new TextPaint();
                sDatePaint.setTypeface(Typeface.DEFAULT);
                sDatePaint.setTextSize(14);
                sDatePaint.setAntiAlias(true);
                sDatePaint.setTextAlign(Align.RIGHT);
            }
        }

        /**
         * The ThrottlingCursorLoader does all of the heavy lifting in managing the data loading
         * task; all we need is to register a listener so that we're notified when the load is
         * complete.
         */
        final class WidgetLoader extends ThrottlingCursorLoader {
            protected WidgetLoader() {
                super(sContext, Message.CONTENT_URI, WIDGET_PROJECTION, mViewType.selection, null,
                        SORT_DESCENDING);
                registerListener(0, new OnLoadCompleteListener<Cursor>() {
                    @Override
                    public void onLoadComplete(Loader<Cursor> loader, Cursor cursor) {
                        synchronized (mCursorLock) {
                            // Save away the cursor
                            mCursor = cursor;
                            // Reset the notification Uri to our Message table notifier URI
                            mCursor.setNotificationUri(sResolver, Message.NOTIFIER_URI);
                            // Save away the count (for display)
                            mCursorCount = mCursor.getCount();
                            if (Email.DEBUG) {
                                Log.d(TAG, "onLoadComplete, count = " + cursor.getCount());
                            }
                        }
                        RemoteViews views =
                            new RemoteViews(sContext.getPackageName(), R.layout.widget);
                        views.setTextViewText(R.id.widget_title,
                                mViewType.getTitle(sContext) + " ("  + mCursorCount + ")");
                        sWidgetManager.partiallyUpdateAppWidget(mWidgetId, views);
                        sWidgetManager.notifyAppWidgetViewDataChanged(mWidgetId, R.id.message_list);
                    }
                });
                startLoading();
            }

            /**
             * Convenience method that stops existing loading (if any), sets a (possibly new)
             * selection criterion, and starts loading
             *
             * @param selection a valid query selection argument
             */
            void startLoadingWithSelection(String selection) {
                stopLoading();
                setSelection(selection);
                startLoading();
            }
        }

        /**
         * Switch to the next widget view (cycles all -> unread -> starred)
         */
        public void switchToNextView() {
            switch(mViewType) {
                case ALL_MAIL:
                    mViewType = ViewType.UNREAD;
                    break;
                case UNREAD:
                    mViewType = ViewType.STARRED;
                    break;
                case STARRED:
                    mViewType = ViewType.ALL_MAIL;
                    break;
            }
            synchronized(mCursorLock) {
                mCursorCount = TOTAL_COUNT_UNKNOWN;
                invalidateCursorLocked();
                mLoader.startLoadingWithSelection(mViewType.selection);
            }
        }

        /**
         * Invalidates the current cursor and tells the UI that the underlying data has changed.
         * This method must be called while holding mCursorLock
         */
        private void invalidateCursorLocked() {
            mCursor = null;
            sWidgetManager.notifyAppWidgetViewDataChanged(mWidgetId, R.id.message_list);
        }

        private void setStyleSpan(SpannableString str, int typeface) {
            int length = str.length();
            str.setSpan(new StyleSpan(typeface), 0, length, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        }

        private CharSequence formattedText(String str, int typeface) {
            if (str == null) {
                return "";
            }
            SpannableString ss = new SpannableString(str);
            setStyleSpan(ss, typeface);
            return ss;
        }

        private CharSequence formattedTextFromCursor(Cursor c, int column, int typeface) {
            return formattedText(mCursor.getString(column), typeface);
        }


        /**
         * Convenience method for creating an onClickPendingIntent that executes a command via
         * our command Uri.  Used for the "next view" command; appends the widget id to the command
         * Uri.
         *
         * @param views The RemoteViews we're inflating
         * @param buttonId the id of the button view
         * @param data the command Uri
         */
        private void setCommandIntent(RemoteViews views, int buttonId, Uri data) {
            Intent intent = new Intent(sContext, WidgetService.class);
            intent.setDataAndType(ContentUris.withAppendedId(data, mWidgetId),
                    WIDGET_DATA_MIME_TYPE);
            PendingIntent pendingIntent = PendingIntent.getService(sContext, 0, intent,
                    PendingIntent.FLAG_UPDATE_CURRENT);
            views.setOnClickPendingIntent(buttonId, pendingIntent);
        }

        /**
         * Convenience method for creating an onClickPendingIntent that launches another activity
         * directly.  Used for the "Compose" button
         *
         * @param views The RemoteViews we're inflating
         * @param buttonId the id of the button view
         * @param activityClass the class of the activity to be launched
         */
        private void setActivityIntent(RemoteViews views, int buttonId,
                Class<? extends Activity> activityClass) {
            Intent intent = new Intent(sContext, activityClass);
            PendingIntent pendingIntent = PendingIntent.getActivity(sContext, 0, intent, 0);
            views.setOnClickPendingIntent(buttonId, pendingIntent);
        }

        /**
         * Convenience method for constructing a fillInIntent for a given list view element.
         * Appends the command and any arguments to a base Uri.
         *
         * @param views the RemoteViews we are inflating
         * @param viewId the id of the view
         * @param baseUri the base uri for the command
         * @param args any arguments to the command
         */
        private void setFillInIntent(RemoteViews views, int viewId, Uri baseUri, String ... args) {
            Intent intent = new Intent();
            Builder builder = baseUri.buildUpon();
            for (String arg: args) {
                builder.appendPath(arg);
            }
            intent.setDataAndType(builder.build(), WIDGET_DATA_MIME_TYPE);
            views.setOnClickFillInIntent(viewId, intent);
        }

        /**
         * Update the "header" of the widget (i.e. everything that doesn't include the scrolling
         * message list)
         */
        private void updateHeader() {
            if (Email.DEBUG) {
                Log.d(TAG, "updateWidget " + mWidgetId);
            }

            // Get the widget layout
            RemoteViews views = new RemoteViews(sContext.getPackageName(), R.layout.widget);

            // Set up the list with an adapter
            Intent intent = new Intent(sContext, WidgetService.class);
            intent.setData(Uri.parse(intent.toUri(Intent.URI_INTENT_SCHEME)));
            intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mWidgetId);
            views.setRemoteAdapter(R.id.message_list, intent);

            // Set up the title (view type + count of messages)
            views.setTextViewText(R.id.widget_title,
                    mViewType.getTitle(sContext) + " ("  + mCursorCount + ")");

             // Set up "new" button (compose new message) and "next view" button
            setActivityIntent(views, R.id.widget_compose, MessageCompose.class);
            setCommandIntent(views, R.id.widget_logo, COMMAND_URI_SWITCH_LIST_VIEW);

            // Use a bare intent for our template; we need to fill everything in
            intent = new Intent(sContext, WidgetService.class);
            PendingIntent pendingIntent =
                PendingIntent.getService(sContext, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);
            views.setPendingIntentTemplate(R.id.message_list, pendingIntent);

            // And finally update the widget
            sWidgetManager.updateAppWidget(mWidgetId, views);
        }

        /* (non-Javadoc)
         * @see android.widget.RemoteViewsService.RemoteViewsFactory#getViewAt(int)
         */
        public RemoteViews getViewAt(int position) {
            // Use the cursor to set up the widget
            synchronized (mCursorLock) {
                if (mCursor == null || !mCursor.moveToPosition(position)) {
                    return getLoadingView();
                }
                RemoteViews views =
                    new RemoteViews(sContext.getPackageName(), R.layout.widget_list_item);

                // Typeface for from, subject, and date (normal/bold) depends on whether the message
                // is read/unread
                int typeface = (mCursor.getInt(WIDGET_COLUMN_FLAG_READ) == 0) ? Typeface.BOLD
                        : Typeface.NORMAL;
                views.setTextViewText(R.id.widget_from,
                        formattedTextFromCursor(mCursor, WIDGET_COLUMN_DISPLAY_NAME, typeface));
                views.setTextViewText(R.id.widget_subject,
                        formattedTextFromCursor(mCursor, WIDGET_COLUMN_SUBJECT, typeface));

                long timestamp = mCursor.getLong(WIDGET_COLUMN_TIMESTAMP);
                // Get a nicely formatted date string (relative to today)
                String date = DateUtils.getRelativeTimeSpanString(sContext, timestamp).toString();
                views.setTextViewText(R.id.widget_date, TextUtils.ellipsize(date, sDatePaint, 64,
                        TruncateAt.END));

                // Set button intents for view, reply, and delete
                String messageId = mCursor.getString(WIDGET_COLUMN_ID);
                String mailboxId = mCursor.getString(WIDGET_COLUMN_MAILBOX_KEY);
                setFillInIntent(views, R.id.widget_message, COMMAND_URI_VIEW_MESSAGE, messageId,
                        mailboxId);

                return views;
            }
        }

        @Override
        public int getCount() {
            if (mCursor == null) return 0;
            return Math.min(mCursor.getCount(), MAX_MESSAGE_LIST_COUNT);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public RemoteViews getLoadingView() {
            RemoteViews view = new RemoteViews(sContext.getPackageName(), R.layout.widget_loading);
            view.setTextViewText(R.id.loading_text, sContext.getString(R.string.widget_loading));
            return view;
        }

        @Override
        public int getViewTypeCount() {
            // Regular list view and the "loading" view
            return 2;
        }

        @Override
        public boolean hasStableIds() {
            return true;
        }

        @Override
        public void onDataSetChanged() {
        }

        @Override
        public void onDestroy() {
            if (mLoader != null) {
                mLoader.stopLoading();
            }
            sWidgetMap.remove(mWidgetId);
        }

        @Override
        public void onCreate() {
        }
    }

    private static synchronized void update(Context context, AppWidgetManager widgetManager,
            int[] appWidgetIds) {
        for (int widgetId: appWidgetIds) {
            getOrCreateWidget(widgetId).updateHeader();
        }
    }

    private static EmailWidget getOrCreateWidget(int widgetId) {
        EmailWidget widget = sWidgetMap.get(widgetId);
        if (widget == null) {
            if (Email.DEBUG) {
                Log.d(TAG, "Creating EmailWidget for id #" + widgetId);
            }
            widget = new EmailWidget(widgetId);
            sWidgetMap.put(widgetId, widget);
        }
        return widget;
    }

    @Override
    public void onDisabled(Context context) {
        super.onDisabled(context);
        if (Email.DEBUG) {
            Log.d(TAG, "onDisabled");
        }
        context.stopService(new Intent(context, WidgetService.class));
    }

    @Override
    public void onEnabled(final Context context) {
        super.onEnabled(context);
        if (Email.DEBUG) {
            Log.d(TAG, "onEnabled");
        }
        context.startService(new Intent(context, WidgetService.class));
    }

    @Override
    public void onReceive(final Context context, Intent intent) {
        String action = intent.getAction();
        if (AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) {
            Bundle extras = intent.getExtras();
            if (extras != null) {
                final int[] appWidgetIds = extras.getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS);
                if (appWidgetIds != null && appWidgetIds.length > 0) {
                    if (sWidgetManager == null) {
                        sWidgetManager = AppWidgetManager.getInstance(context);
                        sContext = context.getApplicationContext();
                        sResolver = sContext.getContentResolver();
                    }
                    context.startService(new Intent(context, WidgetService.class));
                    update(sContext, sWidgetManager, appWidgetIds);
                }
            }
        } else if (AppWidgetManager.ACTION_APPWIDGET_DELETED.equals(action)) {
            Bundle extras = intent.getExtras();
            if (extras != null && extras.containsKey(AppWidgetManager.EXTRA_APPWIDGET_ID)) {
                final int widgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID);
                // Find the widget in the map
                EmailWidget widget = sWidgetMap.get(widgetId);
                if (widget != null) {
                    // Stop loading and remove the widget from the map
                    widget.onDestroy();
                }
            }
        }
    }

    /**
     * We use the WidgetService for two purposes:
     *  1) To provide a widget factory for RemoteViews, and
     *  2) To process our command Uri's (i.e. take actions on user clicks)
     */
    public static class WidgetService extends RemoteViewsService {
        @Override
        public RemoteViewsFactory onGetViewFactory(Intent intent) {
            // Which widget do we want (nice alliteration, huh?)
            int widgetId = intent.getIntExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);
            if (widgetId == -1) return null;
            // Find the existing widget or create it
            EmailWidget widget = sWidgetMap.get(widgetId);
            if (widget == null) {
                throw new IllegalStateException("onGetViewFactory, widget does not exist");
            }
            return widget;
        }

        @Override
        public void startActivity(Intent intent) {
            // Since we're not calling startActivity from an Activity, we need the new task flag
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
            super.startActivity(intent);
        }

        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {
            Uri data = intent.getData();
            if (Email.DEBUG) {
                Log.d(TAG, "Executing: " + data);
            }
            if (data == null) return Service.START_NOT_STICKY;
            List<String> pathSegments = data.getPathSegments();
            // Our path segments are <command>, <arg1> [, <arg2>]
            // First, a quick check of Uri validity
            if (pathSegments.size() < 2) {
                throw new IllegalArgumentException();
            }
            String command = pathSegments.get(0);
            // Ignore unknown action names
            try {
                long arg1 = Long.parseLong(pathSegments.get(1));
                if (COMMAND_NAME_VIEW_MESSAGE.equals(command)) {
                    // "view", <message id>, <mailbox id>
                    Intent i = MessageView.getActionViewIntent(this, arg1,
                            Long.parseLong(pathSegments.get(2)));
                    startActivity(i);
                } else if (COMMAND_NAME_SWITCH_LIST_VIEW.equals(command)) {
                    // "next_view", <widget id>
                    EmailWidget widget = sWidgetMap.get((int)arg1);
                    if (widget != null) {
                        widget.switchToNextView();
                    }
                }
            } catch (NumberFormatException e) {
                // Shouldn't happen as we construct all of the Uri's
            }
            return Service.START_NOT_STICKY;
        }

    }
}