/*
 * 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.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Intent;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.text.TextUtils;
import android.util.Log;

import net.micode.notes.R;
import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE;


/**
 * 笔记内容提供者
 * 负责处理笔记和数据的CRUD操作，提供ContentProvider接口
 * 支持搜索和搜索建议功能
 */
public class NotesProvider extends ContentProvider {

    private static final UriMatcher mMatcher;  // URI匹配器，用于解析不同类型的URI请求

    // 数据库帮助类实例，负责获取读写数据库
    private NotesDatabaseHelper mHelper;

    private static final String TAG = "NotesProvider";  // 日志标签

    // URI匹配码：笔记列表
    private static final int URI_NOTE            = 1;
    // URI匹配码：单个笔记
    private static final int URI_NOTE_ITEM       = 2;
    // URI匹配码：数据列表
    private static final int URI_DATA            = 3;
    // URI匹配码：单个数据项
    private static final int URI_DATA_ITEM       = 4;


    // URI匹配码：搜索
    private static final int URI_SEARCH          = 5;
    // URI匹配码：搜索建议
    private static final int URI_SEARCH_SUGGEST  = 6;

    /**
     * 静态初始化块 - 配置URI匹配规则
     */
    static {
        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        // 笔记集合URI
        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
        // 单个笔记URI（带ID）
        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
        // 笔记数据集合URI
        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
        // 单个笔记数据URI（带ID）
        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
        // 搜索URI
        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
        // 搜索建议URI（两种形式）
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
    }

    /**
     * 笔记搜索投影字段。
     * x'0A' 代表 SQLite 中的换行符；搜索时去掉换行与空格，便于列表展示更多内容。
     */
    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
        + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","
        + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","
        + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
        + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;

    /**
     * 笔记片段搜索查询语句
     * 只搜索非回收站中的普通笔记，根据内容片段进行模糊匹配
     */
    private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
        + " FROM " + TABLE.NOTE
        + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
        + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
        + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;

    /**
     * 内容提供者创建时调用
     * 初始化数据库帮助类实例
     */
    @Override
    public boolean onCreate() {
        mHelper = NotesDatabaseHelper.getInstance(getContext());
        return true;
    }

    /**
     * 查询方法 - 处理对笔记和数据的查询请求
     * @param uri 请求的URI
     * @param projection 查询的列
     * @param selection 查询条件
     * @param selectionArgs 查询条件参数
     * @param sortOrder 排序方式
     * @return 查询结果游标
     */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder) {
        Cursor c = null;
        SQLiteDatabase db = mHelper.getReadableDatabase();
        String id = null;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:  // 查询笔记集合
                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
                        sortOrder);
                break;

            case URI_NOTE_ITEM:  // 查询单个笔记
                id = uri.getPathSegments().get(1);
                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_DATA:  // 查询笔记数据集合
                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
                        sortOrder);
                break;
            case URI_DATA_ITEM:  // 查询单个笔记数据
                id = uri.getPathSegments().get(1);
                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_SEARCH:  // 搜索请求
            case URI_SEARCH_SUGGEST:  // 搜索建议请求
                if (sortOrder != null || projection != null) {
                    throw new IllegalArgumentException(
                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
                }

                String searchString = null;
                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
                    if (uri.getPathSegments().size() > 1) {
                        searchString = uri.getPathSegments().get(1);
                    }
                } else {
                    searchString = uri.getQueryParameter("pattern");
                }

                if (TextUtils.isEmpty(searchString)) {
                    return null;
                }

                try {
                    searchString = String.format("%%%s%%", searchString);
                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
                            new String[] { searchString });
                } catch (IllegalStateException ex) {
                    Log.e(TAG, "got exception: " + ex.toString());
                }
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        if (c != null) {
            // 通知游标所关联的 URI，用于后续数据变更时自动刷新
            c.setNotificationUri(getContext().getContentResolver(), uri);
        }
        return c;
    }

    /**
     * 插入方法 - 处理对笔记和数据的插入请求
     * @param uri 请求的URI
     * @param values 要插入的数据
     * @return 插入后的资源URI
     */
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = mHelper.getWritableDatabase();
        long dataId = 0, noteId = 0, insertedId = 0;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:  // 插入笔记
                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
                break;
            case URI_DATA:  // 插入笔记数据
                if (values.containsKey(DataColumns.NOTE_ID)) {
                    noteId = values.getAsLong(DataColumns.NOTE_ID);
                } else {
                    Log.d(TAG, "Wrong data format without note id:" + values.toString());
                }
                insertedId = dataId = db.insert(TABLE.DATA, null, values);
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        // 通知笔记 URI 变化（noteId>0 时）
        if (noteId > 0) {
            getContext().getContentResolver().notifyChange(
                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
        }

        // 通知数据 URI 变化（dataId>0 时）
        if (dataId > 0) {
            getContext().getContentResolver().notifyChange(
                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
        }

        return ContentUris.withAppendedId(uri, insertedId);
    }

    /**
     * 删除方法 - 处理对笔记和数据的删除请求
     * @param uri 请求的URI
     * @param selection 删除条件
     * @param selectionArgs 删除条件参数
     * @return 删除的行数
     */
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int count = 0;
        String id = null;
        SQLiteDatabase db = mHelper.getWritableDatabase();
        boolean deleteData = false;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
                count = db.delete(TABLE.NOTE, selection, selectionArgs);
                break;
            case URI_NOTE_ITEM:
                id = uri.getPathSegments().get(1);
                /**
                 * ID that smaller than 0 is system folder which is not allowed to
                 * trash
                 * ID小于0的是系统文件夹，不允许删除
                 */
                long noteId = Long.valueOf(id);
                if (noteId <= 0) {
                    break;
                }
                count = db.delete(TABLE.NOTE,
                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
                break;
            case URI_DATA:
                count = db.delete(TABLE.DATA, selection, selectionArgs);
                deleteData = true;
                break;
            case URI_DATA_ITEM:
                id = uri.getPathSegments().get(1);
                count = db.delete(TABLE.DATA,
                        DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
                deleteData = true;
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        if (count > 0) {
            if (deleteData) {
                // 数据行删除会影响笔记摘要，通知笔记 URI
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    /**
     * 更新数据库中的数据
     * @param uri 要更新的内容URI
     * @param values 要更新的列值
     * @param selection 更新条件
     * @param selectionArgs 更新条件参数
     * @return 更新的行数
     */
    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        int count = 0;
        String id = null;
        SQLiteDatabase db = mHelper.getWritableDatabase();
        boolean updateData = false;  // 是否更新了数据内容
        
        switch (mMatcher.match(uri)) {
            case URI_NOTE:  // 更新所有笔记
                increaseNoteVersion(-1, selection, selectionArgs);  // 增加笔记版本号
                count = db.update(TABLE.NOTE, values, selection, selectionArgs);
                break;
            case URI_NOTE_ITEM:  // 更新单个笔记
                id = uri.getPathSegments().get(1);
                increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);  // 增加笔记版本号
                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs);
                break;
            case URI_DATA:  // 更新所有笔记数据
                count = db.update(TABLE.DATA, values, selection, selectionArgs);
                updateData = true;
                break;
            case URI_DATA_ITEM:  // 更新单个笔记数据
                id = uri.getPathSegments().get(1);
                count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs);
                updateData = true;
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }

        if (count > 0) {
            if (updateData) {
                // 数据行更新影响笔记摘要，通知笔记 URI
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            // 通知URI的观察者数据已更改
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    /**
     * 拼接 WHERE 子句，如果传入 selection 非空则加上 AND (...)。
     *
     * @param selection 选择条件
     * @return 格式化后的选择条件
     */
    private String parseSelection(String selection) {
        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ")" : "");
    }

    /**
     * 增加笔记版本号，用于标记被修改过。
     * 用于记录笔记的修改版本，支持并发更新场景
     * @param id 笔记ID；小于0表示不按ID过滤，仅使用 selection
     * @param selection 选择条件
     * @param selectionArgs 选择参数
     */
    private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
        StringBuilder sql = new StringBuilder(120);
        sql.append("UPDATE ");
        sql.append(TABLE.NOTE);
        sql.append(" SET ");
        sql.append(NoteColumns.VERSION);
        sql.append("=" + NoteColumns.VERSION + "+1 ");

        if (id > 0 || !TextUtils.isEmpty(selection)) {
            sql.append(" WHERE ");
        }
        if (id > 0) {
            sql.append(NoteColumns.ID + "=" + String.valueOf(id));
        }
        if (!TextUtils.isEmpty(selection)) {
            String selectString = id > 0 ? parseSelection(selection) : selection;
            for (String args : selectionArgs) {
                selectString = selectString.replaceFirst("\\?", args);
            }
            sql.append(selectString);
        }

        mHelper.getWritableDatabase().execSQL(sql.toString());
    }

    /**
     * 获取内容URI对应的MIME类型
     * @param uri 内容URI
     * @return MIME类型 - 目前未完全实现，返回null
     */
    @Override
    public String getType(Uri uri) {
        // TODO Auto-generated method stub
        return null;
    }

}
