/*
 * 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.Build;
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.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

public class BackupUtils {
    private static final String TAG = "BackupUtils";
    // Singleton stuff
    private static BackupUtils sInstance;

    public static synchronized BackupUtils getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new BackupUtils(context);
        }
        return sInstance;
    }

    /**
     * Following states are signs to represents backup or restore
     * status
     */
    // Currently, the sdcard is not mounted
    public static final int STATE_SD_CARD_UNMOUONTED           = 0;
    // The backup file not exist
    public static final int STATE_BACKUP_FILE_NOT_EXIST        = 1;
    // The data is not well formated, may be changed by other programs
    public static final int STATE_DATA_DESTROIED               = 2;
    // Some run-time exception which causes restore or backup fails
    public static final int STATE_SYSTEM_ERROR                 = 3;
    // Backup or restore success
    public static final int STATE_SUCCESS                      = 4;
    // Permission denied
    public static final int STATE_PERMISSION_DENIED            = 5;

    private TextExport mTextExport;

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

    private static boolean externalStorageAvailable() {
        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
    }

    public int exportToText() {
        return mTextExport.exportToText();
    }

    public String getExportedTextFileName() {
        return mTextExport.mFileName;
    }

    public String getExportedTextFileDir() {
        return mTextExport.mFileDirectory;
    }

    private static class TextExport {
        private static final String[] NOTE_PROJECTION = {
                NoteColumns.ID,
                NoteColumns.MODIFIED_DATE,
                NoteColumns.SNIPPET,
                NoteColumns.TYPE,
                NoteColumns.PARENT_ID
        };

        private static final int NOTE_COLUMN_ID = 0;
        private static final int NOTE_COLUMN_MODIFIED_DATE = 1;
        private static final int NOTE_COLUMN_SNIPPET = 2;
        private static final int NOTE_COLUMN_TYPE = 3;
        private static final int NOTE_COLUMN_PARENT_ID = 4;

        private static final String[] DATA_PROJECTION = {
                DataColumns.CONTENT,
                DataColumns.MIME_TYPE,
                DataColumns.DATA1,
                DataColumns.DATA2,
                DataColumns.DATA3,
                DataColumns.DATA4,
        };

        private static final int DATA_COLUMN_CONTENT = 0;
        private static final int DATA_COLUMN_MIME_TYPE = 1;
        private static final int DATA_COLUMN_CALL_DATE = 2;
        private static final int DATA_COLUMN_PHONE_NUMBER = 4;

        private final String [] TEXT_FORMAT;
        private static final int FORMAT_FOLDER_NAME          = 0;
        private static final int FORMAT_NOTE_DATE            = 1;
        private static final int FORMAT_NOTE_CONTENT         = 2;

        private Context mContext;
        private String mFileName;
        private String mFileDirectory;
        private BufferedWriter mWriter;
        private int mNotesCount;
        private int mFoldersCount;

        public TextExport(Context context) {
            TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
            mContext = context;
            mFileName = "";
            mFileDirectory = "";
            mNotesCount = 0;
            mFoldersCount = 0;
        }

        private String getFormat(int id) {
            return TEXT_FORMAT[id];
        }

        /**
         * Export notes to text file
         */
        public int exportToText() {
            if (!externalStorageAvailable()) {
                Log.d(TAG, "Media was not mounted");
                return STATE_SD_CARD_UNMOUONTED;
            }

            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 STATE_SYSTEM_ERROR;
            }
            
            mFileName = file.getName();
            mFileDirectory = mContext.getString(R.string.file_path);
            
            // 使用try-with-resources确保资源释放
            try (BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8))) {
                mWriter = writer;
                
                // 导出文件夹和笔记
                exportFoldersAndNotes();
                
                // 写入导出统计信息
                writeExportSummary();
                
                Log.d(TAG, "Export successful. Exported " + mFoldersCount + " folders and " + mNotesCount + " notes.");
                return STATE_SUCCESS;
            } catch (IOException e) {
                Log.e(TAG, "Error during export: " + e.getMessage(), e);
                return STATE_SYSTEM_ERROR;
            }
        }
        
        /**
         * 写入导出摘要信息
         */
        private void writeExportSummary() throws IOException {
            mWriter.write("\n");
            mWriter.write("==============================\n");
            mWriter.write(mContext.getString(R.string.export_summary) + "\n");
            mWriter.write(mContext.getString(R.string.export_date) + ": " 
                    + DateFormat.format(mContext.getString(R.string.format_datetime_ymdhm), System.currentTimeMillis()) + "\n");
            mWriter.write(mContext.getString(R.string.folder_count) + ": " + mFoldersCount + "\n");
            mWriter.write(mContext.getString(R.string.note_count) + ": " + mNotesCount + "\n");
            mWriter.write("==============================\n");
        }
        
        /**
         * 导出所有文件夹和笔记
         */
        private void exportFoldersAndNotes() throws IOException {
            // 首先导出文件夹和其中的笔记
            exportFolders();
            
            // 导出根文件夹中的笔记
            exportRootNotes();
        }
        
        /**
         * 导出所有文件夹
         */
        private void exportFolders() throws IOException {
            // 查询所有文件夹
            String selection = "(" + NoteColumns.TYPE + "=" + Notes.TYPE_FOLDER + " AND "
                    + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER + ") OR "
                    + NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER;
            
            try (Cursor folderCursor = mContext.getContentResolver().query(
                    Notes.CONTENT_NOTE_URI,
                    NOTE_PROJECTION,
                    selection, null, null)) {
                
                if (folderCursor != null && folderCursor.moveToFirst()) {
                    do {
                        mFoldersCount++;
                        exportFolder(folderCursor);
                    } while (folderCursor.moveToNext());
                }
            }
        }
        
        /**
         * 导出单个文件夹及其包含的笔记
         */
        private void exportFolder(Cursor folderCursor) throws IOException {
            String folderId = folderCursor.getString(NOTE_COLUMN_ID);
            String folderName;
            
            if(folderCursor.getLong(NOTE_COLUMN_ID) == Notes.ID_CALL_RECORD_FOLDER) {
                folderName = mContext.getString(R.string.call_record_folder_name);
            } else {
                folderName = folderCursor.getString(NOTE_COLUMN_SNIPPET);
            }
            
            if (!TextUtils.isEmpty(folderName)) {
                mWriter.write(String.format(getFormat(FORMAT_FOLDER_NAME), folderName));
                mWriter.newLine();
            }
            
            // 导出文件夹中的笔记
            exportNotesInFolder(folderId);
            
            // 添加文件夹分隔线
            mWriter.write("\n");
        }
        
        /**
         * 导出指定文件夹中的所有笔记
         */
        private void exportNotesInFolder(String folderId) throws IOException {
            try (Cursor notesCursor = mContext.getContentResolver().query(Notes.CONTENT_NOTE_URI,
                    NOTE_PROJECTION, NoteColumns.PARENT_ID + "=?", new String[] { folderId }, null)) {
                
                if (notesCursor != null && notesCursor.moveToFirst()) {
                    do {
                        mNotesCount++;
                        exportNote(notesCursor);
                    } while (notesCursor.moveToNext());
                }
            }
        }
        
        /**
         * 导出根文件夹中的笔记
         */
        private void exportRootNotes() throws IOException {
            try (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 && noteCursor.moveToFirst()) {
                    do {
                        mNotesCount++;
                        exportNote(noteCursor);
                    } while (noteCursor.moveToNext());
                }
            }
        }
        
        /**
         * 导出单个笔记
         */
        private void exportNote(Cursor noteCursor) throws IOException {
            // 打印笔记的最后修改日期
            mWriter.write(String.format(getFormat(FORMAT_NOTE_DATE), 
                    DateFormat.format(mContext.getString(R.string.format_datetime_mdhm),
                            noteCursor.getLong(NOTE_COLUMN_MODIFIED_DATE))));
            mWriter.newLine();
            
            // 查询并导出笔记的数据
            String noteId = noteCursor.getString(NOTE_COLUMN_ID);
            exportNoteData(noteId);
            
            // 添加笔记分隔线
            mWriter.write("\n");
        }
        
        /**
         * 导出笔记的所有数据
         */
        private void exportNoteData(String noteId) throws IOException {
            try (Cursor dataCursor = mContext.getContentResolver().query(Notes.CONTENT_DATA_URI,
                    DATA_PROJECTION, DataColumns.NOTE_ID + "=?", new String[] { noteId }, null)) {
                
                if (dataCursor != null && dataCursor.moveToFirst()) {
                    do {
                        String mimeType = dataCursor.getString(DATA_COLUMN_MIME_TYPE);
                        if (DataConstants.CALL_NOTE.equals(mimeType)) {
                            exportCallNote(dataCursor);
                        } else if (DataConstants.NOTE.equals(mimeType)) {
                            exportTextNote(dataCursor);
                        }
                    } while (dataCursor.moveToNext());
                }
            }
        }
        
        /**
         * 导出通话记录笔记
         */
        private void exportCallNote(Cursor dataCursor) throws IOException {
            // 打印电话号码
            String phoneNumber = dataCursor.getString(DATA_COLUMN_PHONE_NUMBER);
            long callDate = dataCursor.getLong(DATA_COLUMN_CALL_DATE);
            String location = dataCursor.getString(DATA_COLUMN_CONTENT);

            if (!TextUtils.isEmpty(phoneNumber)) {
                mWriter.write(String.format(getFormat(FORMAT_NOTE_CONTENT), phoneNumber));
                mWriter.newLine();
            }
            
            // 打印通话日期
            mWriter.write(String.format(getFormat(FORMAT_NOTE_CONTENT), 
                    DateFormat.format(mContext.getString(R.string.format_datetime_mdhm), callDate)));
            mWriter.newLine();
            
            // 打印通话附件位置
            if (!TextUtils.isEmpty(location)) {
                mWriter.write(String.format(getFormat(FORMAT_NOTE_CONTENT), location));
                mWriter.newLine();
            }
        }
        
        /**
         * 导出文本笔记
         */
        private void exportTextNote(Cursor dataCursor) throws IOException {
            String content = dataCursor.getString(DATA_COLUMN_CONTENT);
            if (!TextUtils.isEmpty(content)) {
                mWriter.write(String.format(getFormat(FORMAT_NOTE_CONTENT), content));
                mWriter.newLine();
            }
        }

        /**
         * Generate the text file to store imported data
         */
        private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
            StringBuilder sb = new StringBuilder();
            
            // 适配Android 10+的存储访问
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                sb.append(context.getExternalFilesDir(null));
            } else {
                sb.append(Environment.getExternalStorageDirectory());
            }
            
            sb.append(context.getString(filePathResId));
            File filedir = new File(sb.toString());
            
            // 确保目录存在
            if (!filedir.exists() && !filedir.mkdirs()) {
                Log.e(TAG, "Failed to create directory: " + filedir.getAbsolutePath());
                return null;
            }
            
            // 构建文件名
            sb.append(context.getString(
                    fileNameFormatResId,
                    DateFormat.format(context.getString(R.string.format_date_ymd),
                            System.currentTimeMillis())));
            File file = new File(sb.toString());

            try {
                if (!file.exists() && !file.createNewFile()) {
                    Log.e(TAG, "Failed to create file: " + file.getAbsolutePath());
                    return null;
                }
                return file;
            } catch (SecurityException | IOException e) {
                Log.e(TAG, "Error creating file: " + e.getMessage(), e);
                return null;
            }
        }
    }
}