// ═══════════════════════════════════════════════════
// Google Apps Script — Event Organizer (Full Version)
// ═══════════════════════════════════════════════════

function doGet(e) {
  var action = e.parameter.action;
  var sheetId = e.parameter.sheetId;
  try {
    if (action === 'getEvents')      return buildResponse({ status:'ok', events: getEventsFromSheet(sheetId) });
    if (action === 'createEvent')    return buildResponse(createCalendarAndSheetEvent({ event: JSON.parse(e.parameter.event), sheetId: sheetId, calendarName: e.parameter.calendarName||'primary' }));
    if (action === 'importCalendar') return buildResponse(importCalendarToSheet(sheetId, parseInt(e.parameter.months)||12));
    if (action === 'editEvent')      return buildResponse(editEvent(sheetId, e.parameter.calEventId, JSON.parse(e.parameter.changes)));
    if (action === 'deleteEvent')    return buildResponse(deleteEvent(sheetId, e.parameter.calEventId));
    return buildResponse({ status:'error', message:'Unknown action: '+action });
  } catch(err) {
    return buildResponse({ status:'error', message: err.message });
  }
}

// SHEET COLUMNS (10 columns)
// 1:วันที่สร้าง 2:ชื่องาน 3:วันที่งาน 4:เวลาเริ่ม
// 5:วันที่สิ้นสุด 6:เวลาสิ้นสุด 7:สถานที่
// 8:รายละเอียด 9:งานย่อย 10:Calendar Event ID

function ensureHeader(sheet) {
  if (sheet.getLastRow() === 0) {
    sheet.appendRow(['วันที่สร้าง','ชื่องาน','วันที่งาน','เวลาเริ่ม',
                     'วันที่สิ้นสุด','เวลาสิ้นสุด','สถานที่',
                     'รายละเอียด','งานย่อย','Calendar Event ID']);
    var h = sheet.getRange(1,1,1,10);
    h.setFontWeight('bold');
    h.setBackground('#2D6A4F');
    h.setFontColor('#FFFFFF');
  }
}

function getSheet(sheetId) {
  return SpreadsheetApp.openById(sheetId).getActiveSheet();
}

function getCalendar(calName) {
  if (!calName || calName === 'primary') return CalendarApp.getDefaultCalendar();
  var cals = CalendarApp.getCalendarsByName(calName);
  return cals.length > 0 ? cals[0] : CalendarApp.getDefaultCalendar();
}

// CREATE EVENT
function createCalendarAndSheetEvent(payload) {
  var ev = payload.event;
  var sheetId = payload.sheetId;
  var calName = payload.calendarName || 'primary';
  var calendar = getCalendar(calName);
  var calEventId = '';

  if (ev.date && ev.date !== 'null') {
    var startDate, endDate, calEvent;
    if (ev.isAllDay) {
      startDate = new Date(ev.date + 'T00:00:00');
      endDate   = new Date((ev.endDate || ev.date) + 'T00:00:00');
      endDate.setDate(endDate.getDate() + 1);
      calEvent = calendar.createAllDayEvent(ev.title, startDate, endDate, {
        description: (ev.description || ''),
        location: (ev.location || '')
      });
    } else {
      startDate = new Date(ev.date + 'T' + (ev.startTime || '09:00') + ':00');
      endDate   = new Date((ev.endDate || ev.date) + 'T' + (ev.endTime || ev.startTime || '10:00') + ':00');
      if (endDate <= startDate) endDate.setHours(endDate.getHours() + 1);
      var desc = (ev.description || '') + (ev.tasks && ev.tasks.length
        ? '\n\nงานย่อย:\n' + ev.tasks.map(function(t, i) { return (i+1) + '. ' + t; }).join('\n')
        : '');
      calEvent = calendar.createEvent(ev.title, startDate, endDate, {
        description: desc.trim(),
        location: (ev.location || '')
      });
    }
    calEventId = calEvent.getId();
  }

  var sheet = getSheet(sheetId);
  ensureHeader(sheet);
  var now = Utilities.formatDate(new Date(), 'Asia/Bangkok', 'dd/MM/yyyy HH:mm');
  sheet.appendRow([
    now, ev.title || '', ev.date || '', ev.startTime || '',
    ev.endDate || ev.date || '', ev.endTime || '',
    ev.location || '', ev.description || '',
    (ev.tasks || []).join(', '), calEventId
  ]);
  return { status:'ok', message:'สร้างงานสำเร็จ', calendarEventId: calEventId };
}

// IMPORT FROM CALENDAR
function importCalendarToSheet(sheetId, monthsBack) {
  var calendar = CalendarApp.getDefaultCalendar();
  var startDate = new Date();
  startDate.setMonth(startDate.getMonth() - (monthsBack || 12));
  var endDate = new Date();
  endDate.setMonth(endDate.getMonth() + 6);

  var sheet = getSheet(sheetId);
  ensureHeader(sheet);

  var lastRow = sheet.getLastRow();
  var existingIds = {};
  if (lastRow > 1) {
    var existingData = sheet.getRange(2, 10, lastRow - 1, 1).getValues();
    for (var e = 0; e < existingData.length; e++) {
      if (existingData[e][0]) existingIds[existingData[e][0]] = true;
    }
  }

  var events = calendar.getEvents(startDate, endDate);
  var added = 0;
  var now = Utilities.formatDate(new Date(), 'Asia/Bangkok', 'dd/MM/yyyy HH:mm');

  for (var j = 0; j < events.length; j++) {
    var ev = events[j];
    var id = ev.getId();
    if (existingIds[id]) continue;

    var isAllDay = ev.isAllDayEvent();
    var start = ev.getStartTime();
    var end = ev.getEndTime();

    var startDateStr = Utilities.formatDate(start, 'Asia/Bangkok', 'yyyy-MM-dd');
    var endDateStr   = Utilities.formatDate(end, 'Asia/Bangkok', 'yyyy-MM-dd');
    if (isAllDay) {
      var endAdj = new Date(end.getTime() - 86400000);
      endDateStr = Utilities.formatDate(endAdj, 'Asia/Bangkok', 'yyyy-MM-dd');
    }
    var startTime = isAllDay ? '' : Utilities.formatDate(start, 'Asia/Bangkok', 'HH:mm');
    var endTime   = isAllDay ? '' : Utilities.formatDate(end, 'Asia/Bangkok', 'HH:mm');

    sheet.appendRow([
      now, ev.getTitle(), startDateStr, startTime,
      endDateStr, endTime,
      ev.getLocation() || '', ev.getDescription() || '',
      '', id
    ]);
    existingIds[id] = true;
    added++;
  }

  return { status:'ok', added: added, message:'นำเข้าสำเร็จ ' + added + ' รายการ' };
}

// EDIT EVENT
function editEvent(sheetId, calEventId, changes) {
  var sheet = getSheet(sheetId);
  var lastRow = sheet.getLastRow();
  var rowIndex = -1;

  var normalCalEventId = normalizeId(calEventId);
  if (lastRow > 1) {
    var ids = sheet.getRange(2, 10, lastRow - 1, 1).getValues();
    for (var i = 0; i < ids.length; i++) {
      if (normalizeId(ids[i][0]) === normalCalEventId) { rowIndex = i + 2; break; }
    }
  }
  if (rowIndex === -1) return { status:'error', message:'ไม่พบงานใน Sheet (ID: ' + calEventId + ')' };

  // Read ORIGINAL row BEFORE updating — use formatCellDate to get clean strings
  var rawRow = sheet.getRange(rowIndex, 1, 1, 10).getValues()[0];
  var origDate      = formatCellDate(rawRow[2]);
  var origStartTime = String(rawRow[3] || '');
  var origEndDate   = formatCellDate(rawRow[4]);
  var origEndTime   = String(rawRow[5] || '');

  // Extract HH:MM from time fields in case they are Date objects
  origStartTime = extractHHMM(origStartTime);
  origEndTime   = extractHHMM(origEndTime);

  // Apply changes to row for Sheet update
  var row = rawRow.slice();
  if (changes.title)       row[1] = changes.title;
  if (changes.date)        row[2] = changes.date;
  if (changes.startTime)   row[3] = changes.startTime;
  if (changes.endDate)     row[4] = changes.endDate;
  if (changes.endTime)     row[5] = changes.endTime;
  if (changes.location)    row[6] = changes.location;
  if (changes.description) row[7] = changes.description;
  sheet.getRange(rowIndex, 1, 1, 10).setValues([row]);

  // Update Google Calendar using clean string values
  if (calEventId) {
    try {
      var calEvent = CalendarApp.getDefaultCalendar().getEventById(calEventId);
      if (!calEvent) {
        var cals = CalendarApp.getAllCalendars();
        for (var c = 0; c < cals.length; c++) {
          calEvent = cals[c].getEventById(calEventId);
          if (calEvent) break;
        }
      }
      if (calEvent) {
        if (changes.title)       calEvent.setTitle(changes.title);
        if (changes.location)    calEvent.setLocation(changes.location);
        if (changes.description) calEvent.setDescription(changes.description);

        if (changes.date || changes.startTime || changes.endDate || changes.endTime) {
          // Use changes first, fall back to ORIGINAL clean string values
          var useDate      = changes.date      || origDate;
          var useStartTime = changes.startTime || origStartTime || '09:00';
          var useEndDate   = changes.endDate   || changes.date || origEndDate || useDate;
          var useEndTime   = changes.endTime   || origEndTime  || useStartTime;

          // Validate date strings before building Date objects
          if (useDate && useDate.match(/^\d{4}-\d{2}-\d{2}$/)) {
            var newStart = new Date(useDate + 'T' + useStartTime + ':00');
            var newEnd   = new Date(useEndDate + 'T' + useEndTime + ':00');
            if (isNaN(newStart.getTime()) || isNaN(newEnd.getTime())) {
              // Invalid date — skip Calendar update to avoid deleting event
              Logger.log('editEvent: invalid date constructed, skipping setTime');
            } else {
              if (newEnd <= newStart) newEnd.setHours(newEnd.getHours() + 1);
              calEvent.setTime(newStart, newEnd);
            }
          }
        }
      }
    } catch(e) {
      Logger.log('editEvent Calendar error: ' + e.message);
      // Sheet was updated successfully — Calendar update failed but event not deleted
    }
  }

  return { status:'ok', message:'แก้ไขงานสำเร็จ' };
}

// Extract HH:MM from a time value that may be a full Date string or simple time string
function extractHHMM(val) {
  if (!val) return '';
  var s = String(val).trim();
  if (!s || s === 'null') return '';
  // Already HH:MM
  var simple = s.match(/^(\d{1,2}):(\d{2})/);
  if (simple) return simple[1].padStart(2,'0') + ':' + simple[2];
  // Full date string — extract time portion
  var full = s.match(/(\d{1,2}):(\d{2}):\d{2}/);
  if (full) return full[1].padStart(2,'0') + ':' + full[2];
  return '';
}

// DELETE EVENT
function deleteEvent(sheetId, calEventId) {
  var sheet = getSheet(sheetId);
  var lastRow = sheet.getLastRow();
  var rowIndex = -1;

  var normalDelId = normalizeId(calEventId);
  if (lastRow > 1) {
    var ids = sheet.getRange(2, 10, lastRow - 1, 1).getValues();
    for (var i = 0; i < ids.length; i++) {
      if (normalizeId(ids[i][0]) === normalDelId) { rowIndex = i + 2; break; }
    }
  }
  if (rowIndex === -1) return { status:'error', message:'ไม่พบงานใน Sheet' };

  sheet.deleteRow(rowIndex);

  if (calEventId) {
    try {
      var calEvent = CalendarApp.getDefaultCalendar().getEventById(calEventId);
      if (!calEvent) {
        var cals = CalendarApp.getAllCalendars();
        for (var c = 0; c < cals.length; c++) {
          calEvent = cals[c].getEventById(calEventId);
          if (calEvent) break;
        }
      }
      if (calEvent) calEvent.deleteEvent();
    } catch(e) { /* Calendar delete failed but sheet row was deleted */ }
  }

  return { status:'ok', message:'ลบงานสำเร็จ' };
}

// GET EVENTS
function getEventsFromSheet(sheetId) {
  if (!sheetId) return [];
  try {
    var sheet = getSheet(sheetId);
    var lastRow = sheet.getLastRow();
    if (lastRow <= 1) return [];
    var data = sheet.getRange(2, 1, lastRow - 1, 10).getValues();
    var results = [];
    for (var i = 0; i < data.length; i++) {
      var row = data[i];
      if (row[1]) {
        results.push({
          createdAt:  formatCellDate(row[0]),
          title:      String(row[1] || ''),
          date:       formatCellDate(row[2]),
          startTime:  String(row[3] || ''),
          endDate:    formatCellDate(row[4]),
          endTime:    String(row[5] || ''),
          location:   String(row[6] || ''),
          description:String(row[7] || ''),
          tasks:      row[8] ? String(row[8]).split(', ') : [],
          calEventId: String(row[9] || '').trim()
        });
      }
    }
    return results;
  } catch(e) { return []; }
}

// Safely format a cell value that may be a Date object or a string as YYYY-MM-DD
function formatCellDate(val) {
  if (!val) return '';
  if (val instanceof Date) {
    return Utilities.formatDate(val, 'Asia/Bangkok', 'yyyy-MM-dd');
  }
  return String(val);
}

// Normalize Calendar Event ID — strip @google.com or any @domain suffix for comparison
function normalizeId(id) {
  if (!id) return '';
  return String(id).split('@')[0].trim();
}

function buildResponse(data) {
  return ContentService.createTextOutput(JSON.stringify(data))
    .setMimeType(ContentService.MimeType.JSON);
}