var WORK_EMAIL = 'martin.ruiz@wellsfargo.com';
var WORK_LABEL = 'Fwd To Work';
var MAILBOX = '[Mailbox]';
var ARCHIVE_PREFIX = '>';
var MAILBOX_ARCHIVE_REGEX = new RegExp('^\\[Mailbox\\]/' + ARCHIVE_PREFIX);
var MAILBOX_REGEX = new RegExp(/^\[Mailbox\]\/\>/);
var TODO_LABEL = 'Todo';
var TODO_EMAIL = 'me@wunderlist.com';
var MESSAGE_URL_BASE = 'https://mail.google.com/mail/u/0/#all/';
var SPAM_LABEL = 'Spam';

/**
 * A simple wrapper for GmailApp API so I can minimize the
 * number of API calls and keep it below the service limit.
 * 10,000 calls is the limit.  Using this wrapper I cache
 * the results and reuse across function calls.
 * https://developers.google.com/apps-script/class_gmailapp
 */
var Gmail = (function () {
  var labels = GmailApp.getUserLabels();
  var labelMap = {};
  
  for (var i in labels) {
    var label = labels[i];
    labelMap[label.getName()] = label;
  }
  
  var getLabelByName = function (labelName) {
    return labelMap[labelName];
  };
  
  return {
    getUserLabels: function () { return labelMap; },
    getUserLabelByName: getLabelByName
  };
})();

/**
 * Archive, Forwards and markAsSpam are called every minute
 */
function runMailboxCompanion() {
  doArchive();
  forwardToWork();
  sendTodo();
  markAsSpam();
}

/**
 * archives messages in [Mailbox]/>labelName to
 * labelName.  It also sets the message as read.
 * Note that I use '>' to signal which labels to
 * archive.
 */
function archiveMessages(labelName) {
  var label, archiveLabel, page, mailboxLabel;
 
  mailboxLabel = MAILBOX + '/' + ARCHIVE_PREFIX + labelName;
  
  label = Gmail.getUserLabelByName(mailboxLabel);
  // create labelName if it doesn't already exist
  archiveLabel = Gmail.getUserLabelByName(labelName);
  if (!archiveLabel) {
    archiveLabel = GmailApp.createLabel(labelName);
  }
  
  page = null;

  while(!page || page.length == 100) {
    page = label.getThreads(0, 100);
    if (page.length > 0) {
      archiveLabel.addToThreads(page);
      label.removeFromThreads(page);
      GmailApp.markThreadsRead(page);
    }
  }
}

function doArchive() {
  var labelName, labels;
  
  labels = Gmail.getUserLabels();

  // find and archive all labels in [Mailbox] with '>' prefix
  for (labelName in labels) {
    if (MAILBOX_ARCHIVE_REGEX.test(labelName)) {
      labelName = labelName.replace(MAILBOX_ARCHIVE_REGEX,'');
      archiveMessages(labelName);
    }
  }
}

/**
 * forward messages in [Mailbox]/labelName to email 'address'
 */
function forwardMessage(labelName, address) {
  var label, threads, message;
  
  label = Gmail.getUserLabelByName(MAILBOX + '/' + labelName);
  threads = label.getThreads();

  for (var i in threads) {
    message = threads[i].getMessages()[0];
    message.forward(address);
    label.removeFromThread(threads[i]);
  }
}

/**
 * I use this to forward emails to work
 */
function forwardToWork() {
  forwardMessage(WORK_LABEL, WORK_EMAIL);
}

/**
 * I use this to forward my email todo to wunderlist
 * Task = email.subject, Description = email.url
 */
function sendTodo() {
  var label, threads, message, messageURL;
  
  label = Gmail.getUserLabelByName(MAILBOX + '/' + TODO_LABEL);
  threads = label.getThreads();

  for (var i in threads) {
    message = threads[i].getMessages()[0];
    messageURL = MESSAGE_URL_BASE + message.getId();
    GmailApp.sendEmail(TODO_EMAIL, message.getSubject(), messageURL);
    label.removeFromThread(threads[i]);
  }
}

/**
 * Move messages in [Mailbox]/Spam to Spam label
 */
function markAsSpam() {
  var label, threads, spam;
  
  spam = MAILBOX + '/' + SPAM_LABEL;
  
  label = Gmail.getUserLabelByName(spam);
  
  if (!label) {
    label = GmailApp.createLabel(spam);
  }
  
  threads = label.getThreads();

  for (var i in threads) {
    threads[i].moveToSpam();
    label.removeFromThread(threads[i]);
  }  
}