/**
 * @OnlyCurrentDoc
 * 心智圖資料雲端儲存 Google Apps Script (ES5 相容版)
 * 作者: 阿剛老師 (修改 by Gemini)
 * 功能: 接收來自心智圖工具的資料，並存儲/讀取/刪除在綁定的 Google 試算表中。
 */

// --- 常數設定 ---
var SHEET_LIST_NAME = '心智圖列表';
var SHEET_DATA_NAME = '心智圖資料';
var LIST_HEADERS = ['心智圖名稱', '上傳者', '更新時間', '資料ID'];
var DATA_HEADERS = ['資料ID', '心智圖內容 (JSON)'];

/**
 * 當此 Script 作為 Web App 接收到 GET 請求時執行
 */
function doGet(e) {
  try {
    var action = e.parameter.action;
    var ss = setupSheets();
    var listSheet = ss.listSheet;
    var dataSheet = ss.dataSheet;

    if (action === 'getList') {
      var listData = listSheet.getDataRange().getValues();
      listData.shift(); // 移除標頭
      var result = [];
      for (var i = 0; i < listData.length; i++) {
        result.push({
          name: listData[i][0],
          uploader: listData[i][1],
          updateTime: listData[i][2],
          id: listData[i][3]
        });
      }
      return createJsonResponse({ status: 'success', data: result.reverse() });

    } else if (action === 'getMap' && e.parameter.id) {
      var dataId = e.parameter.id;
      var dataSheetData = dataSheet.getDataRange().getValues();
      dataSheetData.shift(); // 移除標頭
      var foundRow = null;
      for (var j = 0; j < dataSheetData.length; j++) {
        if (dataSheetData[j][0] === dataId) {
          foundRow = dataSheetData[j];
          break;
        }
      }
      if (foundRow) {
        return createJsonResponse({ status: 'success', data: foundRow[1] });
      } else {
        throw new Error('找不到對應的資料ID: ' + dataId);
      }

    } else {
      throw new Error('無效的操作或缺少參數 (action=getList 或 action=getMap&id=...)');
    }

  } catch (error) {
    return createJsonResponse({ status: 'error', message: error.message });
  }
}

/**
 * 當此 Script 作為 Web App 接收到 POST 請求時執行
 */
function doPost(e) {
  try {
    var ss = setupSheets();
    var listSheet = ss.listSheet;
    var dataSheet = ss.dataSheet;

    if (!e || !e.postData || !e.postData.contents) {
      throw new Error('無效的請求資料。');
    }
    var postData = JSON.parse(e.postData.contents);
    var action = postData.action || 'save'; // 預設 action 為 'save'

    if (action === 'save') {
      return handleSave(postData, listSheet, dataSheet);
    } else if (action === 'deleteMap') {
      return handleDelete(postData, listSheet, dataSheet);
    } else {
      throw new Error('無效的 POST 操作。');
    }

  } catch (error) {
    return createJsonResponse({ status: 'error', message: error.message, stack: error.stack });
  }
}

/**
 * 處理儲存心智圖的邏輯
 */
function handleSave(postData, listSheet, dataSheet) {
  var mindMapName = postData.name;
  var mindMapContent = postData.content;
  var uploader = postData.uploader || '';

  if (!mindMapName || !mindMapContent) {
    throw new Error('傳入的資料格式不正確，缺少 \'name\' 或 \'content\'.');
  }

  var listData = listSheet.getDataRange().getValues();
  var nameExists = false;
  for (var i = 1; i < listData.length; i++) {
    if (listData[i][0] === mindMapName) {
      nameExists = true;
      break;
    }
  }

  var now = new Date();

  if (nameExists) {
    // If name exists, append timestamp to make it unique
    var timestamp = Utilities.formatDate(now, Session.getScriptTimeZone(), " (yyyy-MM-dd HH:mm:ss)");
    mindMapName += timestamp;
  }

  // Always create a new entry
  var dataId = generateUUID();
  listSheet.appendRow([mindMapName, uploader, now, dataId]);
  dataSheet.appendRow([dataId, mindMapContent]);
  return createJsonResponse({ status: 'success', message: "心智圖 '" + mindMapName + "' 已成功新增。" });
}

/**
 * 處理刪除心智圖的邏輯
 */
function handleDelete(postData, listSheet, dataSheet) {
  var dataId = postData.id;
  if (!dataId) {
    throw new Error('缺少要刪除的資料ID。');
  }

  var listData = listSheet.getDataRange().getValues();
  var listRowToDelete = -1;
  for (var i = 1; i < listData.length; i++) {
    if (listData[i][3] === dataId) {
      listRowToDelete = i + 1;
      break;
    }
  }

  if (listRowToDelete > -1) {
    listSheet.deleteRow(listRowToDelete);
  }

  var dataSheetData = dataSheet.getDataRange().getValues();
  var dataRowToDelete = -1;
  for (var j = 1; j < dataSheetData.length; j++) {
    if (dataSheetData[j][0] === dataId) {
      dataRowToDelete = j + 1;
      break;
    }
  }

  if (dataRowToDelete > -1) {
    dataSheet.deleteRow(dataRowToDelete);
  }
  
  if (listRowToDelete > -1 || dataRowToDelete > -1) {
      return createJsonResponse({ status: 'success', message: '資料已成功刪除。' });
  } else {
      throw new Error('在試算表中找不到要刪除的資料ID: ' + dataId);
  }
}

/**
 * 檢查並初始化所需的工作表和標頭
 */
function setupSheets() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var listSheet = ss.getSheetByName(SHEET_LIST_NAME);
  if (!listSheet) {
    listSheet = ss.insertSheet(SHEET_LIST_NAME);
    listSheet.appendRow(LIST_HEADERS);
    listSheet.setFrozenRows(1);
    listSheet.getRange('A:D').applyRowBanding();
    listSheet.setColumnWidth(1, 250);
    listSheet.setColumnWidth(2, 150);
    listSheet.setColumnWidth(3, 200);
    listSheet.setColumnWidth(4, 300);
  }

  var dataSheet = ss.getSheetByName(SHEET_DATA_NAME);
  if (!dataSheet) {
    dataSheet = ss.insertSheet(SHEET_DATA_NAME);
    dataSheet.appendRow(DATA_HEADERS);
    dataSheet.setFrozenRows(1);
    dataSheet.setColumnWidth(1, 300);
    dataSheet.setColumnWidth(2, 800);
  }
  
  return { listSheet: listSheet, dataSheet: dataSheet };
}

/**
 * 產生一個簡易的唯一ID (UUID v4)
 */
function generateUUID() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
}

/**
 * 建立一個標準的 JSON 回應
 */
function createJsonResponse(data) {
  return ContentService.createTextOutput(JSON.stringify(data))
    .setMimeType(ContentService.MimeType.JSON);
}