counts.js

var HIGH_PRI = 'is%3Aopen+is%3Aissue+label%3A%22High+Pri%22',
    MEDIUM_PRI = 'is%3Aopen+is%3Aissue+label%3A%22Medium+Pri%22',
    LOW_PRI = 'is%3Aopen+is%3Aissue+label%3A%22Low+Pri%22',
    documentID = 'GOOGLE_DOCUMENT_ID';

function getIssueCount(query, open) {
  var page = UrlFetchApp.fetch('https://github.com/adobe-photoshop/spaces-design/issues?q=' + query),
      content = page.getContentText(),
      reg = open === false ?  /(\d{1,}) Closed/ : /(\d{1,}) Open/,
      count = parseInt(content.match(reg)[1]);
  
  return count;
}

function getDate() {
  var now = new Date(),
      year = now.getFullYear(), 
      month = now.getMonth()+1,
      day = now.getDate();
  
  // To be accepted by Github, month and day must have 0 padding.
  month = month < 10 ? "0" + month : month;
  day = day < 10 ? "0" + day : day;
  
  return [year, month, day].join('-');
}

function updateIssueCounts() {
  var today = getDate(),
      highPriCount = getIssueCount(HIGH_PRI),
      mediumPriCount = getIssueCount(MEDIUM_PRI),
      lowPriCount = getIssueCount(LOW_PRI),
      newCount = getIssueCount('is%3Aissue++created%3A'+today),
      closedCount = getIssueCount('is%3Aissue++state%3Aclosed+updated%3A'+today, false),
      sheet = SpreadsheetApp.openById(documentID);

  sheet.appendRow([new Date(), highPriCount, mediumPriCount, lowPriCount, newCount, closedCount]);
}

function onOpen() {
  var ui = SpreadsheetApp.getUi();
  ui.createMenu('Git Hub')
      .addItem('Update Now', 'updateIssueCounts')
      .addToUi();
}

trigger.png