function doPost(e) {
  var data = JSON.parse(e.postData.contents);
  var payload = data.payload || {};

  // ---------- helpers ----------
  function escapeHtml(str) {
    if (str === null || str === undefined) return '';
    return String(str)
      .replace(/&/g, '&')
      .replace(//g, '>')
      .replace(/"/g, '"')
      .replace(/'/g, ''');
  }

  function formatNumber(val) {
    var n = Number(val);
    if (isNaN(n)) return escapeHtml(val);
    return n.toLocaleString('en-IN');
  }

  function formatINR(val) {
    var n = Number(val);
    if (isNaN(n)) return escapeHtml(val);
    return '₹' + n.toLocaleString('en-IN', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
  }

  var excelAttached = false;

  // ---------- build campus rows ----------
  var campusRowsHtml = '';
  if (payload.campuses && payload.campuses.length > 0) {
    var shown = payload.campuses.slice(0, 10);
    for (var i = 0; i < shown.length; i++) {
      var c = shown[i];
      campusRowsHtml +=
        '' +
        '' + escapeHtml(c.name) + '' +
        '' + formatNumber(c.students) + '' +
        '' + formatINR(c.collected) + '' +
        '' + formatINR(c.outstanding) + '' +
        '';
    }
    if (payload.campuses.length > 10) {
      campusRowsHtml +=
        '' +
        '+ ' + (payload.campuses.length - 10) + ' more campus(es) — full detail in attached Excel' +
        '';
    }
  }

  // ---------- card helper (2-up on desktop, stacks on mobile) ----------
  function card(label, value, color) {
    return (
      '' +
      '' +
      '
' +
      '
' + escapeHtml(label) + '
' +
      '
' + value + '
' +
      '
'
    );
  }

  // ---------- HTML email body ----------
  var htmlBody =
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'
' +

'' +

// header
'' +

// content
'' +

// footer
'' +

'
' +
'
VYSAMOX ERP
' +
'
Performance & Financial Report  •  ' + escapeHtml(new Date().toLocaleString('en-IN')) + '
' +
'
' +

'
Financial Summary
' +
'' +
  card('Total Collections', formatINR(data.totalCollected), '#10b981') +
  card('Outstanding Balance', formatINR(data.totalOutstanding), '#ef4444') +
'' +
  card('Cash Collected', formatINR(data.cashCollected)) +
  card('Bank Collected', formatINR(data.bankCollected)) +
'' +

'
Students & Campuses
' +
'' +
  card('Total Admissions', formatNumber(data.studentCount)) +
  card('Active Campuses', formatNumber(data.campusCount)) +
'' +
  card('Audit Events Today', formatNumber(data.auditCount)) +
  card('Offline Sync Queue', formatNumber(data.syncQueueCount)) +
'';

  if (campusRowsHtml) {
    htmlBody +=
'
Campus-wise Breakdown
' +
'' +
'' +
'' +
'' +
'' +
'' +
'' +
'' + campusRowsHtml + '' +
'
Campus
Students
Collected
Outstanding
';
  }

  // Excel generation
  var excelBlob;
  var ss;
  try {
    ss = SpreadsheetApp.create('VYSAMOX_System_Report_Temp');
    var sheet1 = ss.getActiveSheet();
    sheet1.setName('Financials & Campuses');

    sheet1.appendRow(['VYSAMOX ERP SYSTEM PERFORMANCE REPORT']);
    sheet1.appendRow(['Report Date:', new Date().toLocaleString('en-IN')]);
    sheet1.appendRow([]);

    sheet1.appendRow(['KEY PERFORMANCE METRICS']);
    sheet1.appendRow(['Metric', 'Value']);
    sheet1.appendRow(['Total Collections', Number(data.totalCollected) || data.totalCollected]);
    sheet1.appendRow(['Total Outstanding', Number(data.totalOutstanding) || data.totalOutstanding]);
    sheet1.appendRow(['Cash Collected', Number(data.cashCollected) || data.cashCollected]);
    sheet1.appendRow(['Bank Collected', Number(data.bankCollected) || data.bankCollected]);
    sheet1.appendRow(['Total Admissions', data.studentCount]);
    sheet1.appendRow(['Active Campuses', data.campusCount]);
    sheet1.appendRow(['Security Audit logs today', data.auditCount]);
    sheet1.appendRow(['Background Sync Queue count', data.syncQueueCount]);

    sheet1.getRange('A1:B1').merge().setFontWeight('bold').setFontSize(14).setBackground('#4f46e5').setFontColor('#ffffff');
    sheet1.getRange('A4:B4').merge().setFontWeight('bold').setFontSize(11).setBackground('#f1f5f9');
    sheet1.getRange('A5:B5').setFontWeight('bold');

    if (payload.campuses && payload.campuses.length > 0) {
      sheet1.appendRow([]);
      sheet1.appendRow([]);
      sheet1.appendRow(['CAMPUS-WISE BREAKDOWN']);
      sheet1.appendRow(['Campus Name', 'Student Count', 'Collected Fee', 'Outstanding Balance']);
      for (var j = 0; j < payload.campuses.length; j++) {
        var camp = payload.campuses[j];
        sheet1.appendRow([camp.name, camp.students, camp.collected, camp.outstanding]);
      }
      var campStartRow = sheet1.getLastRow() - payload.campuses.length - 1;
      sheet1.getRange('A' + campStartRow + ':D' + campStartRow).merge().setFontWeight('bold').setFontSize(11).setBackground('#f1f5f9');
      sheet1.getRange('A' + (campStartRow + 1) + ':D' + (campStartRow + 1)).setFontWeight('bold');
    }

    sheet1.autoResizeColumns(1, 4);

    if (payload.recentAudits && payload.recentAudits.length > 0) {
      var sheet2 = ss.insertSheet('Recent Audit Logs');
      sheet2.appendRow(['RECENT AUDIT LOGS (TODAY)']);
      sheet2.appendRow(['Time', 'Operator', 'Module', 'Action', 'Status', 'Remarks']);
      for (var k = 0; k < payload.recentAudits.length; k++) {
        var log = payload.recentAudits[k];
        sheet2.appendRow([log.timestamp, log.user, log.module, log.action, log.status, log.remarks]);
      }
      sheet2.getRange('A1:F1').merge().setFontWeight('bold').setFontSize(12).setBackground('#3b82f6').setFontColor('#ffffff');
      sheet2.getRange('A2:F2').setFontWeight('bold');
      sheet2.autoResizeColumns(1, 6);
    }

    if (payload.unsyncedQueue && payload.unsyncedQueue.length > 0) {
      var sheet3 = ss.insertSheet('Unsynced Background Queue');
      sheet3.appendRow(['UNSYNCED OFFLINE OPERATIONS QUEUE']);
      sheet3.appendRow(['Operation ID', 'Collection', 'Action', 'Description Label', 'Queue Status', 'Added Time']);
      for (var l = 0; l < payload.unsyncedQueue.length; l++) {
        var op = payload.unsyncedQueue[l];
        sheet3.appendRow([op.id, op.collectionName, op.action, op.label, op.status, op.timestamp]);
      }
      sheet3.getRange('A1:F1').merge().setFontWeight('bold').setFontSize(12).setBackground('#e11d48').setFontColor('#ffffff');
      sheet3.getRange('A2:F2').setFontWeight('bold');
      sheet3.autoResizeColumns(1, 6);
    }

    SpreadsheetApp.flush();

    var url = 'https://docs.google.com/spreadsheets/d/' + ss.getId() + '/export?format=xlsx';
    var response = UrlFetchApp.fetch(url, {
      headers: {
        Authorization: 'Bearer ' + ScriptApp.getOAuthToken(),
        MuteHttpExceptions: true
      }
    });
    excelBlob = response.getBlob().setName('VYSAMOX_System_Performance_Report_' + new Date().toLocaleDateString('en-IN') + '.xlsx');
    excelAttached = true;
  } catch (err) {
    Logger.log('Excel Generation Error: ' + err.message);
    excelAttached = false;
  }

  if (excelAttached) {
    htmlBody += '
Note: The full detail reports are attached as a professional multi-sheet Excel (.xlsx) file.
';
  } else {
    htmlBody += '
⚠ The Excel detail report could not be generated this run. Figures above reflect the latest available summary.
';
  }

  htmlBody +=
'
' +
'
Generated automatically by VYSAMOX ERP Security & Analytics System.
' +
'
© ' + new Date().getFullYear() + ' VYSAMOX. All rights reserved.
' +
'
' + // email-container
'
' + // outer
'';

  // ---------- send ----------
  var emailOptions = {
    to: data.recipient,
    subject: '📊 VYSAMOX ERP - System Performance Report Summary',
    htmlBody: htmlBody
  };

  if (excelBlob) {
    emailOptions.attachments = [excelBlob];
  }

  MailApp.sendEmail(emailOptions);

  if (ss) {
    try {
      DriveApp.getFileById(ss.getId()).setTrashed(true);
    } catch (e) {}
  }

  return ContentService.createTextOutput(JSON.stringify({ status: 'success', excelAttached: excelAttached }))
    .setMimeType(ContentService.MimeType.JSON);
}