Check-in

const SHEET_NAME = 'Sessions';

function doPost(e) {
  try {
    const d = JSON.parse(e.postData.contents);
    const s = getSheet();
    if (d.action === 'start') {
      s.appendRow([d.rowId,d.date,d.weekday,d.start,
        '','',d.type,'','','','active','',
        d.created_at,d.created_at]);
    } else {
      updateRow(s, d);
    }
    return json({ok:true});
  } catch(e) { return json({ok:false,error:e.toString()}); }
}

function doGet(e) {
  try {
    if (e.parameter.action==='get') {
      const s = getSheet();
      const rows = s.getDataRange().getValues();
      for (let i=rows.length-1;i>=1;i--) {
        if (rows[i][1]===e.parameter.date
            && rows[i][10]==='active') {
          return json({rowId:rows[i][0],
            date:rows[i][1],start:rows[i][3],
            type:rows[i][6],status:'active'});
        }
      }
    }
    return json(null);
  } catch(e) { return json(null); }
}

function updateRow(s, d) {
  const rows = s.getDataRange().getValues();
  for (let i=1;i<rows.length;i++) {
    if (rows[i][0]!==d.rowId) continue;
    const r = i+1;
    if (d.action==='stop') {
      s.getRange(r,5).setValue(d.end||'');
      s.getRange(r,6).setValue(d.duration||'');
      s.getRange(r,8).setValue(d.mood||'');
      s.getRange(r,9).setValue(d.last_food||'');
      s.getRange(r,10).setValue(d.comment||'');
      s.getRange(r,11).setValue('done');
      s.getRange(r,12).setValue(d.heartbeat_elapsed||'');
      s.getRange(r,14).setValue(d.updated_at||'');
    } else if (d.action==='heartbeat') {
      s.getRange(r,12).setValue(d.heartbeat_elapsed||'');
      s.getRange(r,14).setValue(d.updated_at||'');
    } else if (d.action==='discard') {
      s.getRange(r,11).setValue('cancelled');
      s.getRange(r,14).setValue(d.updated_at||'');
    }
    return;
  }
}

function getSheet() {
  const ss = SpreadsheetApp.getActiveSpreadsheet();
  let s = ss.getSheetByName(SHEET_NAME);
  if (!s) {
    s = ss.insertSheet(SHEET_NAME);
    s.appendRow(['rowId','date','weekday','start',
      'end','duration','type','mood','last_food',
      'comment','status','heartbeat_elapsed',
      'created_at','updated_at']);
  }
  return s;
}

function json(d) {
  return ContentService
    .createTextOutput(JSON.stringify(d))
    .setMimeType(ContentService.MimeType.JSON);
}