atomTemplate.html

<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="ja">
  <title>pastakのKindle本購入履歴</title>
  <updated><?= getLastUpdated().toISOString() ?></updated>
  <author>
    <name>Pasta-K</name>
  </author>
  <id>https://docs.google.com/spreadsheets/d/1870lEluCFFovzkXKCOLrfjQnj2kdMbVs-CSVDaQghnk/</id>
     <?
 for(var i=0;i<20;i++){
 if(!getRowData(i)[1]) continue;
  ?>
  <entry>
  <title><?= getRowData(i)[2] ?></title>
  <link href="<?= getRowData(i)[3] ?>tag=pastalablog-22"/>
  <id><?= getRowData(i)[3] ?></id>
  <published><?= getRowData(i)[1].toISOString() ?></published>
  <updated><?= getRowData(i)[1].toISOString() ?></updated>
  </entry>
 <? } // End For ?>
</feed>

Code.gs

var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Sheet1');
var range;

function parseURLQuery (url) {
  var o = {};
  var t = url.split('?')[1].split('&');
  t.forEach(function (a) {
    var t = a.split('=');
    o[t[0]] = t[1]
  })
  return o;
}

// https://stackoverflow.com/questions/25735677/remove-duplicates-values-in-array-google-apps-script/25740182#25740182
function removeDups(array) {
  var outArray = [];
  array.sort(lowerCase);
  function lowerCase(a,b){
    return a[0].toLowerCase()>b[0].toLowerCase() ? 1 : -1;// sort function that does not "see" letter case
  }
  outArray.push(array[0]);
  for(var n in array){
    if(outArray[outArray.length-1][0].toLowerCase()!=array[n][0].toLowerCase()){
      outArray.push(array[n]);
    }
  }
  return outArray;
}

function getLastUpdated() {
  return sheet.getRange('B2').getValue();
}

function getRowData(rowNum){
 return range.getValues()[rowNum];
}

function doGet() {
 range = sheet.getRange(2, 1, 20, 20);
 // テンプレート呼び出し(rssTemplate.html)
 var output = HtmlService.createTemplateFromFile('atomTemplate');
 var result= output.evaluate();
 
// コンテントタイプ指定
 return ContentService.createTextOutput(result.getContent())
 .setMimeType(ContentService.MimeType.XML);
}

function myFunction() {
  var threads = GmailApp.search('subject:(Amazon.co.jp ご注文の確認) Kindle本 ご購入ありがとうございます。', 0, 20);
  var mails = GmailApp.getMessagesForThreads(threads);
  var lastMailId = sheet.getRange('A2').getValue();
  
  var info = [];
  var amazonRegexp = /^https?:\/\/www\.amazon\.co\.jp\/dp\/([\W\w\d]+)\//;
  
  for(var i=0;i < mails.length;i++){
   var msg = mails[i][0];
   var date = msg.getDate();
   var id = msg.getSubject().replace('Amazon.co.jp ご注文の確認 ',''); 
   
   if (id === lastMailId) break;
   
   var doc = Xml.parse(msg.getBody(), true);
   var bodyHtml = doc.html.body.toXmlString();
   doc = XmlService.parse(bodyHtml);
   var xml = doc.getRootElement();
   var booksInfo = removeDups(
        HTMLParser.getElementsByTagName(xml, 'a')
        .map(function (a) { return [a.getAttribute('href').getValue(), a] })
        .map(function (a) { return [decodeURIComponent(parseURLQuery(a[0])['U']), a[1]] })
        .filter(function (a) { return amazonRegexp.test(a[0]) })
        .map(function (a) { return [a[0].replace(/ref=.+$/, ''),a[1]] })
        .map(function (a) { return [a[0],a[1], a[0].replace(amazonRegexp, '$1')] })
        .map(function (a) { return [a[0], a[1].getText(), id, date, a[2]] })
      );
   info.push(booksInfo);
  }
  info.reverse().forEach(function (booksInfo) {
    for (var j = 0; j < booksInfo.length;j++) {
     sheet.insertRowBefore(2);
     sheet.getRange(2, 1, 1, 5).setValues([
       [booksInfo[j][2], booksInfo[j][3], booksInfo[j][1], booksInfo[j][0], booksInfo[j][4]]
     ]);
   }
  }) 
}