Google Apps Script Backend

const SSID = "example_1OkGswUREJEt81JKxhTIEowt-Rknp7cLJKDNELFgKTxEQ";

function doPost(e) {
  try {
    const data = JSON.parse(e.postData.contents);
    
    validateData(data);
    
    // Process and store data
    const result = logTimeEntry(data);

    // Return with CORS headers for downstream apps
    if (result) {
      return ContentService
      .createTextOutput(JSON.stringify({success: true, id: result}))
      .setMimeType(ContentService.MimeType.JSON)
      .setHeaders({
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'POST',
        'Access-Control-Allow-Headers': 'Content-Type'
      });
    }
    
    throw new Error("No result from logTimeEntry");
  } catch (error) {
    // Return with CORS headers for downstream apps
    return ContentService
      .createTextOutput(JSON.stringify({error: "Processing failed"}))
      .setMimeType(ContentService.MimeType.JSON)
      .setHeaders({
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'POST',
        'Access-Control-Allow-Headers': 'Content-Type'
      });
  }
}

function validateData(data) {
    // Validate required fields
    if (!data.date || !data.category || !data.startTime || data.endTime) {
     throw new Error("Missing required fields");
    }
    // validate time
    if (  data.startTime > data.endTime) {
      throw new Error("Start time cannot be after end time");
    }
    if (isNaN(start.getTime())) {
      throw new Error("Invalid start time format");
    }
    
    if (isNaN(end.getTime())) {
      throw new Error("Invalid end time format");
    }

    // validate date
    if (data.date) {
      entryDate = new Date(data.date);
      if (isNaN(entryDate.getTime())) {
        throw new Error("Invalid date format");
      }
    }
}

function logTimeEntry(data) {
  try{
     var ss = SpreadsheetApp.openById(SSID);
     var sheet = ss.getSheetByName("Sheet1");

     // Get date - Already validated
     // Use what is provided in payload.  If missing, defaults to today's date
     const entryDate = data.date ? new Date(data.date) : new Date(); 
  
     // Calculate duration
     const start = new Date(data.startTime);
     const end = new Date(data.endTime || new Date());
     const durationMinutes = Math.round((end - start) / (1000 * 60));
     const durationHours = (durationMinutes / 60).toFixed(2);
     
     // Prepare row data
     const rowData = [
       entryDate,                 // Date
       start.toTimeString(),      // Start
       end.toTimeString(),        // End
       durationMinutes,           // Duration
       parseFloat(durationHours), // Duration in Hours
       data.category,             // Category
       data.task,                 // Task
       data.client || '',         // use for Client/Context field (may not always be a 'client')
       data.notes || ''           // Notes
     ];
     
     // Append to sheet
     sheet.appendRow(rowData);
     
     return sheet.getLastRow();

  } catch (error) {
    console.error('Error in logTimeEntry:', error.message);
    throw error; // throw to be caught by doPost
  }
}