(function() {
// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Beancount transaction exporter for Patreon
// Usage:
// On your credit card / Paypal exports, bill everything to the SourceAccount.
// The exports from this script will move the money to the corect sub-accounts.
//
// Open your https://patreon.com/pledges page, go to "Billing History", and
// select the correct year. Open the developer tools, paste in this script, and
// then type:
//
//   exportPage()
//
// This will create one console log per transaction on the page (which may be
// more than one per month in some circumstances).
let AccountPrefix = 'Expenses:Entertainment:Patreon:';
let SourceAccount = 'Expenses:Entertainment:Patreon:Pledges';

// turns "/username" into "Username"
function toAccountName(href) {
  const u = new URL(href);
  let p = u.pathname;
  if (p === '/user') {
    return 'U' + u.search.slice(3);
  }
  if (/_/.test(p)) {
    p = p.replace(/_/g, '');
  }
  return p.slice(1, 2).toUpperCase() + p.slice(2);
}

// turns "$5.00" into "5.00 USD"
function toCurrency(amount) {
  if (amount.startsWith('$')) {
    return amount.slice(1) + ' USD';
  } else if (amount.startsWith('£')) {
    return amount.slice(1) + ' GBP';
  } else if (amount.startsWith('€')) {
    return amount.slice(1) + ' EUR';
  } else {
    throw 'unimplemented currency code: ' + amount;
  }
}

var monthNames = [
  'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August',
  'September', 'October', 'November', 'December'
];
// TODO - check other locales.
function textToISOTextDate(text) {
  const split = text.split(' ');
  const monthIdx = monthNames.indexOf(split[0]);
  if (monthIdx === -1) {
    throw 'Failed to parse date: ' + text;
  }
  const dayText = split[1].replace(/,/g, '');
  const yearText = split[2];
  const monthText =
      (monthIdx +
       1).toLocaleString('en-US', {minimumIntegerDigits: 2, style: 'decimal'});

  // Sanity check result
  const result = `${yearText}-${monthText}-${dayText}`;
  if (isNaN(Date.parse(result))) {
    throw 'Failed to parse date: \'' + text + '\' got \'' + result + '\'';
  }
  return result;
}

// @param [pledges-historical-desktop-layout-row]
function exportRow(el) {
  if (el.childElementCount !== 5) {
    throw 'row layout has changed';
  }
  // Get username
  const userLink = el.children[0].querySelector('a').href;
  const acct = toAccountName(userLink);
  // Get amount
  const successEl = el.children[3].querySelector('[color="success"]');
  if (!successEl) {
    return ';' + acct + ' ; Transaction not success';
  }
  const amountContainerEl =
      successEl.parentElement.parentElement.previousElementSibling,
        amountText = amountContainerEl.firstElementChild.innerText;
  const currency = toCurrency(amountText);

  return [acct, currency];
}

// @param [data-tag="pledges-historical-group"]
function exportTransaction(el) {
  const headerEl = el.children[0], listEl = el.children[1];
  const listContainer = listEl.querySelector(
      '[data-tag="pledges-historical-desktop-layout-rows-container"]');
  if (!listContainer) {
    throw 'layout has changed';
  }

  // header > left section > color dark > text
  const pageDateText = headerEl.firstElementChild.firstElementChild.innerText;
  const ourDateText = textToISOTextDate(pageDateText);
  // header > right section > color dark
  const totalEl = headerEl.lastElementChild.firstElementChild;
  // split into two text elements
  const totalText = totalEl.childNodes[1].data;
  const totalCurrency = '-' + toCurrency(totalText);

  let resultHeader =
      `${ourDateText} * "Patreon Pledges for ${pageDateText}" ""`;
  let rows = [];
  for (let i = 0; i < listContainer.childElementCount; i++) {
    let rowEl = listContainer.childNodes[i];
    let rowContainer = rowEl.querySelector(
        '[data-tag="pledges-historical-desktop-layout-row"]');
    rows.push(exportRow(rowContainer));
  }
  rows =
      rows.map((it) => ('\t' + AccountPrefix + it[0].padEnd(18 - 1) + ' ' + it[1]));

  const finalText = [
    resultHeader,
    '\t' + SourceAccount + '  ' + totalCurrency
  ].concat(rows).join('\n');

  return finalText;
}
window.exportTransaction = () => console.log(exportTransaction());

function exportPage() {
  let transactions = [];
  document.querySelectorAll('[data-tag="pledges-historical-group"]')
      .forEach((el) => {
        transactions.push(exportTransaction(el));
      });
  return transactions.reverse().join('\n\n');
}
window.exportPage = () => console.log(exportPage());
})();