/*
 * 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.tool;

import android.content.Context;
import android.database.Cursor;
import android.os.Environment;
import android.text.TextUtils;
import android.text.format.DateFormat;
import android.util.Log;

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

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;

/**
 * 备份工具类，用于将笔记导出为文本文件。
 */
public class BackupUtils {
    private static final String TAG = "BackupUtils";

    // 单例模式相关
    private static BackupUtils sInstance;

    /**
     * 获取 BackupUtils 的单例实例。
     *
     * @param context 上下文
     * @return BackupUtils 实例
     */
    public static synchronized BackupUtils getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new BackupUtils(context);
        }
        return sInstance;
    }

    /**
     * 定义备份和恢复状态的常量。
     */
    public static final int STATE_SD_CARD_UNMOUONTED = 0; // SD 卡未挂载
    public static final int STATE_BACKUP_FILE_NOT_EXIST = 1; // 备份文件不存在
    public static final int STATE_DATA_DESTROIED = 2; // 数据格式不正确
    public static final int STATE_SYSTEM_ERROR = 3; // 系统错误
    public static final int STATE_SUCCESS = 4; // 成功

    private TextExport mTextExport;

    private BackupUtils(Context context) {
        mTextExport = new TextExport(context);
    }

    /**
     * 检查外部存储是否可用。
     *
     * @return 如果外部存储可用则返回 true，否则返回 false
     */
    private static boolean externalStorageAvailable() {
        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
    }

    /**
     * 将笔记导出为文本文件。
     *
     * @return 导出结果的状态码
     */
    public int exportToText() {
        return mTextExport.exportToText();
    }

    /**
     * 获取导出的文本文件名。
     *
     * @return 文件名
     */
    public String getExportedTextFileName() {
        return mTextExport.mFileName;
    }

    /**
     * 获取导出的文本文件目录。
     *
     * @return 文件目录
     */
    public String getExportedTextFileDir() {
        return mTextExport.mFileDirectory;
    }

    /**
     * 内部类，用于处理笔记导出到文本文件的具体逻辑。
     */
    private static class TextExport {
        // 查询笔记时使用的列
        private static final String[] NOTE_PROJECTION = {
                NoteColumns.ID,
                NoteColumns.MODIFIED_DATE,
                NoteColumns.SNIPPET,
                NoteColumns.TYPE
        };

        // 查询数据时使用的列
        private static final String[] DATA_PROJECTION = {
                DataColumns.CONTENT,
                DataColumns.MIME_TYPE,
                DataColumns.DATA1,
                DataColumns.DATA2,
                DataColumns.DATA3,
                DataColumns.DATA4,
        };

        private final String[] TEXT_FORMAT;
        private Context mContext;
        private String mFileName;
        private String mFileDirectory;

        public TextExport(Context context) {
            TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
            mContext = context;
            mFileName = "";
            mFileDirectory = "";
        }

        /**
         * 根据 ID 获取格式化字符串。
         *
         * @param id 格式 ID
         * @return 格式化字符串
         */
        private String getFormat(int id) {
            return TEXT_FORMAT[id];
        }

        /**
         * 将指定文件夹中的笔记导出为文本。
         *
         * @param folderId 文件夹 ID
         * @param ps       PrintStream 对象
         */
        private void exportFolderToText(String folderId, PrintStream ps) {
            Cursor notesCursor = mContext.getContentResolver().query(
                    Notes.CONTENT_NOTE_URI,
                    NOTE_PROJECTION,
                    NoteColumns.PARENT_ID + "=?",
                    new String[]{folderId},
                    null);

            if (notesCursor != null) {
                if (notesCursor.moveToFirst()) {
                    do {
                        ps.println(String.format(getFormat(1), DateFormat.format(
                                mContext.getString(R.string.format_datetime_mdhm),
                                notesCursor.getLong(1))));
                        String noteId = notesCursor.getString(0);
                        exportNoteToText(noteId, ps);
                    } while (notesCursor.moveToNext());
                }
                notesCursor.close();
            }
        }

        /**
         * 将指定笔记导出为文本。
         *
         * @param noteId 笔记 ID
         * @param ps     PrintStream 对象
         */
        private void exportNoteToText(String noteId, PrintStream ps) {
            Cursor dataCursor = mContext.getContentResolver().query(
                    Notes.CONTENT_DATA_URI,
                    DATA_PROJECTION,
                    DataColumns.NOTE_ID + "=?",
                    new String[]{noteId},
                    null);

            if (dataCursor != null) {
                if (dataCursor.moveToFirst()) {
                    do {
                        String mimeType = dataCursor.getString(1);
                        if (DataConstants.CALL_NOTE.equals(mimeType)) {
                            String phoneNumber = dataCursor.getString(4);
                            long callDate = dataCursor.getLong(2);
                            String location = dataCursor.getString(0);

                            if (!TextUtils.isEmpty(phoneNumber)) {
                                ps.println(String.format(getFormat(2), phoneNumber));
                            }
                            ps.println(String.format(getFormat(2), DateFormat.format(
                                    mContext.getString(R.string.format_datetime_mdhm),
                                    callDate)));
                            if (!TextUtils.isEmpty(location)) {
                                ps.println(String.format(getFormat(2), location));
                            }
                        } else if (DataConstants.NOTE.equals(mimeType)) {
                            String content = dataCursor.getString(0);
                            if (!TextUtils.isEmpty(content)) {
                                ps.println(String.format(getFormat(2), content));
                            }
                        }
                    } while (dataCursor.moveToNext());
                }
                dataCursor.close();
            }
            try {
                ps.write(new byte[]{Character.LINE_SEPARATOR, Character.LETTER_NUMBER});
            } catch (IOException e) {
                Log.e(TAG, e.toString());
            }
        }

        /**
         * 将笔记导出为用户可读的文本文件。
         *
         * @return 导出结果的状态码
         */
        public int exportToText() {
            if (!externalStorageAvailable()) {
                Log.d(TAG, "Media was not mounted");
                return STATE_SD_CARD_UNMOUONTED;
            }

            PrintStream ps = getExportToTextPrintStream();
            if (ps == null) {
                Log.e(TAG, "get print stream error");
                return STATE_SYSTEM_ERROR;
            }

            // 导出文件夹及其包含的笔记
            Cursor folderCursor = mContext.getContentResolver().query(
                    Notes.CONTENT_NOTE_URI,
                    NOTE_PROJECTION,
                    "(" + NoteColumns.TYPE + "=" + Notes.TYPE_FOLDER + " AND "
                            + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER + ") OR "
                            + NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER,
                    null,
                    null);

            if (folderCursor != null) {
                if (folderCursor.moveToFirst()) {
                    do {
                        String folderName = "";
                        if (folderCursor.getLong(0) == Notes.ID_CALL_RECORD_FOLDER) {
                            folderName = mContext.getString(R.string.call_record_folder_name);
                        } else {
                            folderName = folderCursor.getString(2);
                        }
                        if (!TextUtils.isEmpty(folderName)) {
                            ps.println(String.format(getFormat(0), folderName));
                        }
                        String folderId = folderCursor.getString(0);
                        exportFolderToText(folderId, ps);
                    } while (folderCursor.moveToNext());
                }
                folderCursor.close();
            }

            // 导出根文件夹中的笔记
            Cursor noteCursor = mContext.getContentResolver().query(
                    Notes.CONTENT_NOTE_URI,
                    NOTE_PROJECTION,
                    NoteColumns.TYPE + "=" + Notes.TYPE_NOTE + " AND " + NoteColumns.PARENT_ID
                            + "=0",
                    null,
                    null);

            if (noteCursor != null) {
                if (noteCursor.moveToFirst()) {
                    do {
                        ps.println(String.format(getFormat(1), DateFormat.format(
                                mContext.getString(R.string.format_datetime_mdhm),
                                noteCursor.getLong(1))));
                        String noteId = noteCursor.getString(0);
                        exportNoteToText(noteId, ps);
                    } while (noteCursor.moveToNext());
                }
                noteCursor.close();
            }
            ps.close();

            return STATE_SUCCESS;
        }

        /**
         * 获取指向导出文件的 PrintStream 对象。
         *
         * @return PrintStream 对象
         */
        private PrintStream getExportToTextPrintStream() {
            File file = generateFileMountedOnSDcard(mContext, R.string.file_path,
                    R.string.file_name_txt_format);
            if (file == null) {
                Log.e(TAG, "create file to exported failed");
                return null;
            }
            mFileName = file.getName();
            mFileDirectory = mContext.getString(R.string.file_path);
            PrintStream ps = null;
            try {
                FileOutputStream fos = new FileOutputStream(file);
                ps = new PrintStream(fos);
            } catch (FileNotFoundException | NullPointerException e) {
                e.printStackTrace();
                return null;
            }
            return ps;
        }
    }

    /**
     * 在 SD 卡上生成用于存储导出数据的文件。
     *
     * @param context 上下文
     * @param filePathResId 文件路径资源 ID
     * @param fileNameFormatResId 文件名格式资源 ID
     * @return 生成的文件对象
     */
    private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
        StringBuilder sb = new StringBuilder();
        sb.append(Environment.getExternalStorageDirectory());
        sb.append(context.getString(filePathResId));
        File filedir = new File(sb.toString());
        sb.append(context.getString(
                fileNameFormatResId,
                DateFormat.format(context.getString(R.string.format_date_ymd),
                        System.currentTimeMillis())));
        File file = new File(sb.toString());

        try {
            if (!filedir.exists()) {
                filedir.mkdir();
            }
            if (!file.exists()) {
                file.createNewFile();
            }
            return file;
        } catch (SecurityException | IOException e) {
            e.printStackTrace();
        }

        return null;
    }
}