/*
 * 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;

/**
 * 便签应用的内容提供者（ContentProvider）
 * 负责管理便签数据的CRUD操作，包括搜索功能
 */
public class NotesProvider extends ContentProvider {
    /**
     * URI匹配器，用于匹配不同的URI请求，根据URI类型执行相应的操作
     */
    private static final UriMatcher mMatcher;

    /**
     * 数据库帮助类实例，用于获取数据库连接
     */
    private NotesDatabaseHelper mHelper;

    /**
     * 日志标签，用于日志输出
     */
    private static final String TAG = "NotesProvider";

    /**
     * URI匹配类型常量定义，用于区分不同的URI请求类型
     */
    private static final int URI_NOTE            = 1;      // 操作便签表（所有记录）
    private static final int URI_NOTE_ITEM       = 2;      // 操作便签表（单条记录）
    private static final int URI_DATA            = 3;      // 操作数据表（所有记录）
    private static final int URI_DATA_ITEM       = 4;      // 操作数据表（单条记录）
    private static final int URI_SEARCH          = 5;      // 搜索操作
    private static final int URI_SEARCH_SUGGEST  = 6;      // 搜索建议操作

    /**
     * 静态初始化块，配置URI匹配规则
     * 为不同类型的URI请求配置对应的匹配类型
     */
    static {
        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        // 匹配便签表的URI
        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
        // 匹配数据表的URI
        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
        // 匹配搜索相关的URI
        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
    }

    /**
     * 搜索查询的投影（列）定义
     * x'0A' 在SQLite中代表 '\n' 字符
     * 对于搜索结果中的标题和内容，我们将修剪 '\n' 和空白字符以显示更多信息
     */
    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;

    /**
     * 便签片段搜索查询的SQL语句
     * 搜索条件：便签片段包含关键词，且不在回收站中，类型为普通便签
     */
    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;

    /**
     * 初始化内容提供者
     * @return 如果初始化成功返回true，否则返回false
     */
    @Override
    public boolean onCreate() {
        mHelper = NotesDatabaseHelper.getInstance(getContext());
        return true;
    }

    /**
     * 查询数据
     * @param uri 要查询的URI
     * @param projection 要返回的列，null表示所有列
     * @param selection 查询条件，null表示无条件
     * @param selectionArgs 查询条件参数
     * @param sortOrder 排序方式，null表示默认排序
     * @return 包含查询结果的Cursor对象
     */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
                        String sortOrder) {
        Cursor c = null;
        SQLiteDatabase db = mHelper.getReadableDatabase();
        String id = null;

        // 根据URI类型执行不同的查询操作
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 查询所有便签
                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
                        sortOrder);
                break;
            case URI_NOTE_ITEM:
                // 查询单条便签记录
                id = uri.getPathSegments().get(1);
                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_DATA:
                // 查询所有数据记录
                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
                        sortOrder);
                break;
            case URI_DATA_ITEM:
                // 查询单条数据记录
                id = uri.getPathSegments().get(1);
                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_SEARCH:
            case URI_SEARCH_SUGGEST:
                // 处理搜索和搜索建议请求
                if (sortOrder != null || projection != null) {
                    throw new IllegalArgumentException(
                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
                }

                String searchString = null;
                // 根据URI类型获取搜索关键词
                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
                    if (uri.getPathSegments().size() > 1) {
                        searchString = uri.getPathSegments().get(1);
                    }
                } else {
                    searchString = uri.getQueryParameter("pattern");
                }

                // 如果搜索关键词为空，返回null
                if (TextUtils.isEmpty(searchString)) {
                    return null;
                }

                try {
                    // 构造模糊查询字符串
                    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);
        }

        // 设置内容观察者，以便在数据变化时通知相关组件
        if (c != null) {
            c.setNotificationUri(getContext().getContentResolver(), uri);
        }
        return c;
    }

    /**
     * 插入数据
     * @param uri 要插入数据的URI
     * @param values 要插入的数据值
     * @return 新插入数据的URI
     */
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = mHelper.getWritableDatabase();
        long dataId = 0, noteId = 0, insertedId = 0;

        // 根据URI类型执行不同的插入操作
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 插入便签数据
                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
                break;
            case URI_DATA:
                // 插入数据表记录
                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);
        }

        // 通知便签URI的数据变化
        if (noteId > 0) {
            getContext().getContentResolver().notifyChange(
                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
        }

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

        // 返回新插入数据的URI
        return ContentUris.withAppendedId(uri, insertedId);
    }

    /**
     * 删除数据
     * @param uri 要删除数据的URI
     * @param selection 删除条件，null表示无条件
     * @param selectionArgs 删除条件参数
     * @return 被删除的行数
     */
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int count = 0;
        String id = null;
        SQLiteDatabase db = mHelper.getWritableDatabase();
        boolean deleteData = false;

        // 根据URI类型执行不同的删除操作
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 删除便签记录（不删除ID小于0的系统文件夹）
                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
                count = db.delete(TABLE.NOTE, selection, selectionArgs);
                break;
            case URI_NOTE_ITEM:
                // 删除单条便签记录
                id = uri.getPathSegments().get(1);
                /**
                 * ID小于0的是系统文件夹，不允许删除（移动到回收站）
                 */
                long noteId = Long.valueOf(id);
                if (noteId <= 0) {
                    break;
                }
                count = db.delete(TABLE.NOTE,
                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
                break;
            case URI_DATA:
                // 删除数据记录
                count = db.delete(TABLE.DATA, selection, selectionArgs);
                deleteData = true;
                break;
            case URI_DATA_ITEM:
                // 删除单条数据记录
                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);
        }

        // 如果成功删除数据，发送数据变化通知
        if (count > 0) {
            if (deleteData) {
                // 如果删除的是数据表记录，通知便签URI数据变化
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            // 通知当前URI数据变化
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    /**
     * 更新数据
     * @param uri 要更新数据的URI
     * @param values 更新的数据值
     * @param selection 更新条件，null表示无条件
     * @param selectionArgs 更新条件参数
     * @return 被更新的行数
     */
    @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;

        // 根据URI类型执行不同的更新操作
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 更新便签记录，增加版本号
                increaseNoteVersion(-1, selection, selectionArgs);
                count = db.update(TABLE.NOTE, values, selection, selectionArgs);
                break;
            case URI_NOTE_ITEM:
                // 更新单条便签记录，增加版本号
                id = uri.getPathSegments().get(1);
                increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
                count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs);
                break;
            case URI_DATA:
                // 更新数据记录
                count = db.update(TABLE.DATA, values, selection, selectionArgs);
                updateData = true;
                break;
            case URI_DATA_ITEM:
                // 更新单条数据记录
                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);
        }

        // 如果成功更新数据，发送数据变化通知
        if (count > 0) {
            if (updateData) {
                // 如果更新的是数据表记录，通知便签URI数据变化
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            // 通知当前URI数据变化
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    /**
     * 解析查询/更新条件
     * 将原始条件转换为SQL语句中的AND条件
     * @param selection 原始条件字符串
     * @return 格式化后的条件字符串
     */
    private String parseSelection(String selection) {
        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
    }

    /**
     * 增加便签版本号
     * 当便签被修改时，调用此方法增加版本号
     * @param id 便签ID，如果id>0则更新指定便签，否则更新所有匹配条件的便签
     * @param selection 更新条件
     * @param selectionArgs 更新条件参数
     */
    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 ");

        // 构造WHERE子句
        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;
            // 替换预编译语句中的占位符
            for (String args : selectionArgs) {
                selectString = selectString.replaceFirst("\\?", args);
            }
            sql.append(selectString);
        }

        // 执行SQL语句更新版本号
        mHelper.getWritableDatabase().execSQL(sql.toString());
    }

    /**
     * 返回指定URI的MIME类型
     * @param uri 要获取MIME类型的URI
     * @return MIME类型字符串
     */
    @Override
    public String getType(Uri uri) {
        // TODO: 实现此方法，返回合适的MIME类型
        return null;
    }
}