Google Sheets script for my ops keystone, inspired by http://sebastianmarshall.com/key-points-week-one

Code.gs

var config = {
  templateSheetName: 'TEMPLATE',
  dateFormat: 'ddd M/d',
  sheetTitlePrefix: 'Week ',
  daysPerSheet: 7,
  showLatestOnLeft: true,
  dateHeaderRow: 1,
};

// Get the first sheet from the given spreadsheet. 
// If no spreadsheet is passed, defaults to active spreadsheet.
function getFirstSheet(ss) {
  var ss = ss || SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  return sheet;
}

// Get the sheet labeled 'TEMPLATE'.
function getTemplateSheet(ss) {
  var ss = ss || SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName(config.templateSheetName);
  return sheet;
}

// Return a record {row, column, value, cell} of the first non-frozen cell.
function getFirstNonFrozenCol(sheet) {
  var sheet = sheet || SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();

  var frozenCols = sheet.getFrozenColumns();
  var totalCols = sheet.getLastColumn();
  if (totalCols === frozenCols) {
    throw new Error('getFirstNonFrozenCol: sheet ' + sheet.getSheetName() +
      ' has no non-frozen columns');
  }

  var row = config.dateHeaderRow;
  var column = frozenCols + 1;
  var cell = sheet.getRange(row, column, 1, 1);
  var value = cell.getValue();
  
  return {row: row, column: column, value: value, cell: cell};
}

// Get the most recent date column from the given sheet.
// Returns a Date object.
function getLatestDateCell(sheet) {
  // If the most recent date is on the left, then we can just return the
  // first non-frozen cell.
  if (config.showLatestOnLeft) {
    return getFirstNonFrozenCol(sheet);
  }

  var lastCol = sheet.getLastColumn();
  var cell = sheet.getRange(config.dateHeaderRow, lastCol, 1, 1);
  var value = cell.getValue();

  return {row: config.dateHeaderRow, column: lastCol, cell: cell, value: value};
}

// Parse the week number from a sheet title.
// e.g. "Week 15" -> 15
function parseWeekNumber(str) {
  var re = new RegExp('^' + config.sheetTitlePrefix + '([0-9]+)');
  var match = str.match(re);
  if (!match || match.length < 2) {
    throw new Error('parseWeekNumber: could not parse week from title '.concat(str));
  }
  var week = parseInt(match[1], 10);
  return week;
}

// Create a new weekly sheet, and set it to the active sheet.
function addWeeklySheet(ss) {
  var ss = ss || SpreadsheetApp.getActiveSpreadsheet();
  var sheet = getFirstSheet(ss);

  // Get the week number from the latest sheet's title.
  var lastWeek = parseWeekNumber(sheet.getSheetName());
  var week = lastWeek + 1;
  var name = config.sheetTitlePrefix.concat(week);

  // Get the date range from the latest sheet's leftmost column.
  var lastDate = getLatestDateCell(sheet);
  if (!(lastDate.value instanceof Date)) {
    throw new Error('addWeeklySheet: expected Date object, got ' + lastDate.value);
  }
  var dates = generateNextDates(lastDate.value, config.daysPerSheet);

  // Show dates from left to right.
  if (config.showLatestOnLeft) {
    dates.reverse();
  }

  ss.insertSheet(name, 0, {template: getTemplateSheet()});
  var newSheet = getFirstSheet(ss);
  return addDates(newSheet, dates);
}

// Takes a Date object and a number of days to generate, and returns
// a list of Date objects representing that many days afterwards.
function generateNextDates(start, n) {
  var startMs = start.getTime();
  var MS_PER_DAY = 1000 * 60 * 60 * 24;
  var result = [];

  for (var i = 1; i < n + 1; i += 1) {
    var delta = i * MS_PER_DAY;
    var date = new Date(startMs + delta);
    result.push(date);
  }

  return result;
}

// Insert the given range of dates in the non-frozen header cells of the
// given sheet.
function addDates(sheet, dates) {
  var lastCol = sheet.getLastColumn();
  var available = lastCol - sheet.getFrozenColumns();
  if (available < dates.length) {
    sheet.insertColumnsAfter(lastCol, dates.length - available);
  }
  var range = sheet.getRange(1, sheet.getFrozenColumns() + 1, 1, dates.length);
  range.setValues([dates]).setNumberFormat(config.dateFormat);
  return sheet;
}

// Create menu.
function onOpen(e) {
  SpreadsheetApp.getUi()
  .createMenu('Keystone')
  .addItem('Add weekly sheet', 'addWeeklySheet')
  .addToUi();
}