Automatically updating a Google Sheet with data from Google Analytics for regular reporting

gistfile1.js

function fetchMyQuery() {
  // our query object
  var query = {
    "optionalArgs": {
      "dimensions": "ga:source",
      "filters": "ga:medium==referral",
      "sort": "-ga:pageviews",
      "max-results": "50"
    },
    "ids": "ga:82426939",
    "metrics": "ga:pageviews,ga:sessionDuration,ga:exits",
    "start-date": "7daysAgo",
    "end-date": "yesterday"
  };
  
  // one line! get GA results
  var results = Analytics.Data.Ga.get(query.ids, query['start-date'], query['end-date'], query.metrics, query.optionalArgs);
  
  // get a Sheet object - you can replace the sheet name with any other named sheet in your spreadsheet
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet1");
  outputToSpreadsheet(results, sheet); 
}

function outputToSpreadsheet(results, sheet) {
  // Print the headers.
  var headerNames = [];
  for (var i = 0, header; header = results.getColumnHeaders()[i]; ++i) {
    headerNames.push(header.getName());
  }
  sheet.getRange(1, 1, 1, headerNames.length)
      .setValues([headerNames]);

  // Print the rows of data.
  sheet.getRange(2, 1, results.getRows().length, headerNames.length)
      .setValues(results.getRows());
}