/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * 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 net.micode.notes.data;

import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.DataConstants;
import net.micode.notes.data.Notes.NoteColumns;

/**
 * 笔记数据库帮助类,用于管理笔记数据库的创建和升级
 */
public class NotesDatabaseHelper extends SQLiteOpenHelper {
    // 数据库名称
    private static final String DB_NAME = "note.db";

    // 数据库版本号
    private static final int DB_VERSION = 4;

    /**
     * 数据库表名常量接口
     */
    public interface TABLE {
        public static final String NOTE = "note";  // 笔记表
        public static final String DATA = "data";  // 数据表
    }

    private static final String TAG = "NotesDatabaseHelper";

    // 单例模式实例
    private static NotesDatabaseHelper mInstance;

    /**
     * 创建笔记表的SQL语句
     * 包含笔记的基本信息:ID、父ID、提醒时间、背景色、创建时间等
     */
    private static final String CREATE_NOTE_TABLE_SQL =
        "CREATE TABLE " + TABLE.NOTE + "(" +
            NoteColumns.ID + " INTEGER PRIMARY KEY," +
            NoteColumns.PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.ALERTED_DATE + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.BG_COLOR_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
            NoteColumns.HAS_ATTACHMENT + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
            NoteColumns.NOTES_COUNT + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.SNIPPET + " TEXT NOT NULL DEFAULT ''," +
            NoteColumns.TYPE + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.WIDGET_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.WIDGET_TYPE + " INTEGER NOT NULL DEFAULT -1," +
            NoteColumns.SYNC_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.LOCAL_MODIFIED + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.ORIGIN_PARENT_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.GTASK_ID + " TEXT NOT NULL DEFAULT ''," +
            NoteColumns.VERSION + " INTEGER NOT NULL DEFAULT 0" +
        ")";

    /**
     * 创建数据表的SQL语句
     * 存储笔记的具体内容数据
     */
    private static final String CREATE_DATA_TABLE_SQL =
        "CREATE TABLE " + TABLE.DATA + "(" +
            DataColumns.ID + " INTEGER PRIMARY KEY," +
            DataColumns.MIME_TYPE + " TEXT NOT NULL," +
            DataColumns.NOTE_ID + " INTEGER NOT NULL DEFAULT 0," +
            NoteColumns.CREATED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
            NoteColumns.MODIFIED_DATE + " INTEGER NOT NULL DEFAULT (strftime('%s','now') * 1000)," +
            DataColumns.CONTENT + " TEXT NOT NULL DEFAULT ''," +
            DataColumns.DATA1 + " INTEGER," +
            DataColumns.DATA2 + " INTEGER," +
            DataColumns.DATA3 + " TEXT NOT NULL DEFAULT ''," +
            DataColumns.DATA4 + " TEXT NOT NULL DEFAULT ''," +
            DataColumns.DATA5 + " TEXT NOT NULL DEFAULT ''" +
        ")";

    /**
     * 创建数据表NOTE_ID索引的SQL语句
     */
    private static final String CREATE_DATA_NOTE_ID_INDEX_SQL =
        "CREATE INDEX IF NOT EXISTS note_id_index ON " +
        TABLE.DATA + "(" + DataColumns.NOTE_ID + ");";

    /**
     * 当笔记移动到文件夹时增加文件夹笔记计数的触发器
     */
    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER increase_folder_count_on_update "+
        " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
        "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
        " END";

    /**
     * 当笔记从文件夹移出时减少文件夹笔记计数的触发器
     */
    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER decrease_folder_count_on_update " +
        " AFTER UPDATE OF " + NoteColumns.PARENT_ID + " ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
        "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
        "  AND " + NoteColumns.NOTES_COUNT + ">0" + ";" +
        " END";

    /**
     * 当向文件夹插入新笔记时增加文件夹笔记计数的触发器
     */
    private static final String NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER =
        "CREATE TRIGGER increase_folder_count_on_insert " +
        " AFTER INSERT ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + " + 1" +
        "  WHERE " + NoteColumns.ID + "=new." + NoteColumns.PARENT_ID + ";" +
        " END";

    /**
     * 当从文件夹删除笔记时减少文件夹笔记计数的触发器
     */
    private static final String NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER =
        "CREATE TRIGGER decrease_folder_count_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE +
        " BEGIN " +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.NOTES_COUNT + "=" + NoteColumns.NOTES_COUNT + "-1" +
        "  WHERE " + NoteColumns.ID + "=old." + NoteColumns.PARENT_ID +
        "  AND " + NoteColumns.NOTES_COUNT + ">0;" +
        " END";

    /**
     * 当插入NOTE类型的数据时更新笔记内容的触发器
     */
    private static final String DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER =
        "CREATE TRIGGER update_note_content_on_insert " +
        " AFTER INSERT ON " + TABLE.DATA +
        " WHEN new." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
        "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
        " END";

    /**
     * 当NOTE类型的数据更新时更新笔记内容的触发器
     */
    private static final String DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER =
        "CREATE TRIGGER update_note_content_on_update " +
        " AFTER UPDATE ON " + TABLE.DATA +
        " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.SNIPPET + "=new." + DataColumns.CONTENT +
        "  WHERE " + NoteColumns.ID + "=new." + DataColumns.NOTE_ID + ";" +
        " END";

    /**
     * 当NOTE类型的数据删除时更新笔记内容的触发器
     */
    private static final String DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER =
        "CREATE TRIGGER update_note_content_on_delete " +
        " AFTER delete ON " + TABLE.DATA +
        " WHEN old." + DataColumns.MIME_TYPE + "='" + DataConstants.NOTE + "'" +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.SNIPPET + "=''" +
        "  WHERE " + NoteColumns.ID + "=old." + DataColumns.NOTE_ID + ";" +
        " END";

    /**
     * 当笔记被删除时删除相关数据的触发器
     */
    private static final String NOTE_DELETE_DATA_ON_DELETE_TRIGGER =
        "CREATE TRIGGER delete_data_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE +
        " BEGIN" +
        "  DELETE FROM " + TABLE.DATA +
        "   WHERE " + DataColumns.NOTE_ID + "=old." + NoteColumns.ID + ";" +
        " END";

    /**
     * 当文件夹被删除时删除其下所有笔记的触发器
     */
    private static final String FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER =
        "CREATE TRIGGER folder_delete_notes_on_delete " +
        " AFTER DELETE ON " + TABLE.NOTE +
        " BEGIN" +
        "  DELETE FROM " + TABLE.NOTE +
        "   WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
        " END";

    /**
     * 当文件夹被移到回收站时移动其下所有笔记的触发器
     */
    private static final String FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER =
        "CREATE TRIGGER folder_move_notes_on_trash " +
        " AFTER UPDATE ON " + TABLE.NOTE +
        " WHEN new." + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
        " BEGIN" +
        "  UPDATE " + TABLE.NOTE +
        "   SET " + NoteColumns.PARENT_ID + "=" + Notes.ID_TRASH_FOLER +
        "  WHERE " + NoteColumns.PARENT_ID + "=old." + NoteColumns.ID + ";" +
        " END";

    /**
     * 构造函数
     * @param context 上下文对象
     */
    public NotesDatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    /**
     * 创建笔记表
     * @param db 数据库对象
     */
    public void createNoteTable(SQLiteDatabase db) {
        db.execSQL(CREATE_NOTE_TABLE_SQL);
        reCreateNoteTableTriggers(db);
        createSystemFolder(db);
        Log.d(TAG, "note table has been created");
    }

    /**
     * 重新创建笔记表的所有触发器
     * @param db 数据库对象
     */
    private void reCreateNoteTableTriggers(SQLiteDatabase db) {
        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_update");
        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_update");
        db.execSQL("DROP TRIGGER IF EXISTS decrease_folder_count_on_delete");
        db.execSQL("DROP TRIGGER IF EXISTS delete_data_on_delete");
        db.execSQL("DROP TRIGGER IF EXISTS increase_folder_count_on_insert");
        db.execSQL("DROP TRIGGER IF EXISTS folder_delete_notes_on_delete");
        db.execSQL("DROP TRIGGER IF EXISTS folder_move_notes_on_trash");

        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_UPDATE_TRIGGER);
        db.execSQL(NOTE_DECREASE_FOLDER_COUNT_ON_DELETE_TRIGGER);
        db.execSQL(NOTE_DELETE_DATA_ON_DELETE_TRIGGER);
        db.execSQL(NOTE_INCREASE_FOLDER_COUNT_ON_INSERT_TRIGGER);
        db.execSQL(FOLDER_DELETE_NOTES_ON_DELETE_TRIGGER);
        db.execSQL(FOLDER_MOVE_NOTES_ON_TRASH_TRIGGER);
    }

    /**
     * 创建系统文件夹
     * @param db 数据库对象
     */
    private void createSystemFolder(SQLiteDatabase db) {
        ContentValues values = new ContentValues();

        /**
         * 创建通话记录文件夹
         */
        values.put(NoteColumns.ID, Notes.ID_CALL_RECORD_FOLDER);
        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
        db.insert(TABLE.NOTE, null, values);

        /**
         * 创建根文件夹(默认文件夹)
         */
        values.clear();
        values.put(NoteColumns.ID, Notes.ID_ROOT_FOLDER);
        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
        db.insert(TABLE.NOTE, null, values);

        /**
         * 创建临时文件夹(用于移动笔记)
         */
        values.clear();
        values.put(NoteColumns.ID, Notes.ID_TEMPARAY_FOLDER);
        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
        db.insert(TABLE.NOTE, null, values);

        /**
         * 创建回收站文件夹
         */
        values.clear();
        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
        db.insert(TABLE.NOTE, null, values);
    }

    /**
     * 创建数据表
     * @param db 数据库对象
     */
    public void createDataTable(SQLiteDatabase db) {
        db.execSQL(CREATE_DATA_TABLE_SQL);
        reCreateDataTableTriggers(db);
        db.execSQL(CREATE_DATA_NOTE_ID_INDEX_SQL);
        Log.d(TAG, "data table has been created");
    }

    /**
     * 重新创建数据表的所有触发器
     * @param db 数据库对象
     */
    private void reCreateDataTableTriggers(SQLiteDatabase db) {
        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_insert");
        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_update");
        db.execSQL("DROP TRIGGER IF EXISTS update_note_content_on_delete");

        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_INSERT_TRIGGER);
        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_UPDATE_TRIGGER);
        db.execSQL(DATA_UPDATE_NOTE_CONTENT_ON_DELETE_TRIGGER);
    }

    /**
     * 获取NotesDatabaseHelper的单例
     * @param context 上下文对象
     * @return NotesDatabaseHelper实例
     */
    static synchronized NotesDatabaseHelper getInstance(Context context) {
        if (mInstance == null) {
            mInstance = new NotesDatabaseHelper(context);
        }
        return mInstance;
    }

    /**
     * 数据库创建回调
     * @param db 数据库对象
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
        createNoteTable(db);
        createDataTable(db);
    }

    /**
     * 数据库升级回调
     * @param db 数据库对象
     * @param oldVersion 旧版本号
     * @param newVersion 新版本号
     */
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        boolean reCreateTriggers = false;
        boolean skipV2 = false;

        if (oldVersion == 1) {
            upgradeToV2(db);
            skipV2 = true; // 此升级包含从v2到v3的升级
            oldVersion++;
        }

        if (oldVersion == 2 && !skipV2) {
            upgradeToV3(db);
            reCreateTriggers = true;
            oldVersion++;
        }

        if (oldVersion == 3) {
            upgradeToV4(db);
            oldVersion++;
        }

        if (reCreateTriggers) {
            reCreateNoteTableTriggers(db);
            reCreateDataTableTriggers(db);
        }

        if (oldVersion != newVersion) {
            throw new IllegalStateException("Upgrade notes database to version " + newVersion
                    + "fails");
        }
    }

    /**
     * 升级到版本2
     * @param db 数据库对象
     */
    private void upgradeToV2(SQLiteDatabase db) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE.NOTE);
        db.execSQL("DROP TABLE IF EXISTS " + TABLE.DATA);
        createNoteTable(db);
        createDataTable(db);
    }

    /**
     * 升级到版本3
     * @param db 数据库对象
     */
    private void upgradeToV3(SQLiteDatabase db) {
        // 删除未使用的触发器
        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_insert");
        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_delete");
        db.execSQL("DROP TRIGGER IF EXISTS update_note_modified_date_on_update");
        // 添加gtask_id列
        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.GTASK_ID
                + " TEXT NOT NULL DEFAULT ''");
        // 添加回收站系统文件夹
        ContentValues values = new ContentValues();
        values.put(NoteColumns.ID, Notes.ID_TRASH_FOLER);
        values.put(NoteColumns.TYPE, Notes.TYPE_SYSTEM);
        db.insert(TABLE.NOTE, null, values);
    }

    /**
     * 升级到版本4
     * @param db 数据库对象
     */
    private void upgradeToV4(SQLiteDatabase db) {
        db.execSQL("ALTER TABLE " + TABLE.NOTE + " ADD COLUMN " + NoteColumns.VERSION
                + " INTEGER NOT NULL DEFAULT 0");
    }
}