server.js

import { serve } from 'https://deno.land/std@0.136.0/http/server.ts';
import { serveFile } from 'https://deno.land/std@0.136.0/http/file_server.ts';
import { existsSync } from 'https://deno.land/std@0.136.0/fs/mod.ts';
import { parse as parseYaml } from 'https://deno.land/std@0.136.0/encoding/yaml.ts';
import { compile as etaCompile, config as etaConfig } from 'https://deno.land/x/eta@v1.12.3/mod.ts';

const log = (msg) => {
  console.log(`${(new Date()).toISOString()} ${msg}`);
};
const debug = (Deno.env.get('DEBUG') === '1');

const epoch = new Date('2022-05-11T16:00:00Z');
const todaysPuzzleIndex = () => Math.ceil((new Date() - epoch) / 86400000);
const todaysPuzzle = () => todaysPuzzleIndex().toString().padStart(3, '0');

const indexHtmlContents = new TextDecoder().decode(await Deno.readFile('page/index.html'));
const indexTemplate = etaCompile(indexHtmlContents);

const analytics = (req) => {
  const cookies = req.headers.get('Cookie');
  if (cookies === null) return '';
  const dict = {};
  for (const s of cookies.split(';')) {
    const i = s.indexOf('=');
    const key = decodeURIComponent(s.substring(0, i).trim());
    const value = decodeURIComponent(s.substring(i + 1));
    dict[key] = value;
  }
  if (!dict['lang']) return '';
  return `${dict['lang']} ${dict['sfx']} ${dict['dark']} ${dict['highcon']} ${dict['notation']}`;
};

const NOTE_OFFS = [9, 11, 0, 2, 4, 5, 7];
const SCALE_OFFS = [0, 2, 4, 5, 7, 9, 11];

const midiPitch = (s) => {
  const i = s.charCodeAt(0) - 'A'.charCodeAt(0);
  const acci = (s[1] === '#' ? 1 : s[1] === 'b' ? -1 : 0);
  const oct = s.charCodeAt(acci === 0 ? 1 : 2) - '0'.charCodeAt(0);
  return 12 +
    NOTE_OFFS[i] +
    oct * 12 +
    acci;
};
const bend = (s) => {
  const i = s.indexOf('/');
  if (i === -1) return 1;
  return parseFloat(s.substring(i + 1)) / 440;
};

const getPuzzleId = (index) => {
  const lastChar = index[index.length-1];
  let suffix = '';
  let id = 0;
  if (lastChar < '0' || lastChar > '9') {
    suffix = index.toString().substring(3, index.length);
    id = parseInt(index.toString().substring(0, 3));
  } else {
    id = parseInt(index.toString().padStart(3, '0'));
  }
  return [id, suffix]
}

const noSuchPuzzle = () => new Response('No such puzzle > <\n', { status: 404 });

const servePuzzle = async (req, puzzleId, checkToday) => {
  const today = todaysPuzzle();
  if (puzzleId === undefined) puzzleId = today;

  const file = `puzzles/${puzzleId}.yml`;
  if (!existsSync(file)) return noSuchPuzzle();

  const puzzleContents = parseYaml(
    new TextDecoder().decode(await Deno.readFile(file))
  );

  puzzleContents.id = puzzleId;

  for (const note of puzzleContents.tune) {
    const noteName = note[0].toString();
    let noteValue = parseInt(noteName[0]);
    if (noteName.indexOf('-') !== -1) noteValue -= 7;
    if (noteName.indexOf('+') !== -1) noteValue += 7;
    if (noteName.indexOf('b') !== -1) noteValue -= 0.1;
    if (noteName.indexOf('#') !== -1) noteValue += 0.1;
    if (noteName.indexOf('*') !== -1) noteValue += 100;
    note[0] = noteValue;
  }

  // Accidentals in absolute notation
  const tunePitchBase = puzzleContents.tunePitchBase;
  const acciStyles = [];
  const note = tunePitchBase.charCodeAt(0) - 'A'.charCodeAt(0);
  const acci = (tunePitchBase[1] === 'b' ? -1 : 
                tunePitchBase[1] === '#' ? 1 : 0);
  for (let s = 1; s <= 7; s++) {
    acciStyles.push(`body.nota-alpha .fg > .bubble.solf-${s} > div.content:before { content: '${String.fromCharCode('A'.charCodeAt(0) + (note + s - 1) % 7)}'; }`);
  }
  for (let s = 1; s <= 7; s++) {
    const value = NOTE_OFFS[note] + acci + SCALE_OFFS[s - 1];
    const diff = (value - NOTE_OFFS[(note + s - 1) % 7] + 12) % 12;
    let accis = undefined;
    if (diff === 1) accis = ['\\266f', '\\266e', '\\2715'];
    else if (diff === 11) accis = ['\\266d', '\\266d\\266d', '\\266e'];
    if (accis) {
      acciStyles.push(`body.nota-alpha .bubble:not(.outline).solf-${s} > * > .accidental::before { content: '${accis[0]}'; }`);
      acciStyles.push(`body.nota-alpha .bubble:not(.outline).solf-${s} > .flat > .accidental::before { content: '${accis[1]}'; }`);
      acciStyles.push(`body.nota-alpha .bubble:not(.outline).solf-${s} > .sharp > .accidental::before { content: '${accis[2]}'; }`);
    }
  }
  puzzleContents.acciStyles = acciStyles.join('\n');

  puzzleContents.tuneNoteBase = puzzleContents.tunePitchBase[0];
  puzzleContents.tunePitchBend = bend(puzzleContents.tunePitchBase);
  puzzleContents.tunePitchBase = midiPitch(puzzleContents.tunePitchBase);

  const i18n = {};
  for (const lang of ['zh-Hans', 'en']) {
    const langContents = puzzleContents[lang];
    i18n[lang] = langContents;
  }
  puzzleContents.i18nVars = i18n;

  const isDaily = !!puzzleId.match(/^[0-9]{3,}[-]*[a-zA-Z]*[0-9]*[a-zA-Z]*$/g);
  puzzleContents.guideToToday =
    (checkToday && isDaily && parseInt(puzzleId) < parseInt(today));
  puzzleContents.isDaily = isDaily;
  puzzleContents.todayDaily = today;

  const puzzleNames = Deno.readDirSync("./puzzles/");
  const validPuzzleIds = []
  for (const entry of puzzleNames) {
    if (entry.isDirectory) continue;
    const fileName = entry.name;
    const isValid = !!fileName.match(/^[0-9]{3,}[-]*[a-zA-Z]*[0-9]*[a-zA-Z]*\.yml$/g);
    if (!isValid) continue;
    let index = fileName.substring(0, fileName.length - 4);  // remove the file extension '.yml'
    let decomposition = getPuzzleId(index);
    if (decomposition[0] > todaysPuzzleIndex()) continue; // should not show the future puzzles.
    validPuzzleIds.push(index);
  }
  puzzleContents.availablePuzzleIds = validPuzzleIds;

  log(`puzzle ${puzzleId} ${analytics(req)} from ${req.headers.get('x-real-ip')}`);
  const pageContents = indexTemplate(puzzleContents, etaConfig);
  return new Response(pageContents, {
    status: 200,
    headers: {
      'Content-Type': 'text/html; charset=utf-8',
    },
  });
};

const handler = async (req) => {
  const url = new URL(req.url);
  if (req.method === 'GET') {
    if (url.pathname === '/') {
      return servePuzzle(req, undefined, false);
    }
    if (url.pathname === '/favicon.ico') {
      return serveFile(req, 'favicon.png');
    }
    if (url.pathname.startsWith('/static/')) {
      const fileName = url.pathname.substring('/static/'.length);
      return serveFile(req, 'page/' + fileName);
    }
    if (url.pathname.startsWith('/reveal/')) {
      const fileName = url.pathname.substring('/reveal/'.length);
      return serveFile(req, 'puzzles/reveal/' + fileName);
    }
    if (url.pathname.startsWith('/revealimage/')) {
      const fileName = url.pathname.substring('/revealimage/'.length);
      return serveFile(req, 'puzzles/revealimage/' + fileName);
    }
    if (url.pathname.startsWith('/hintimage/')) {
      const fileName = url.pathname.substring('/hintimage/'.length);
      return serveFile(req, 'puzzles/hintimage/' + fileName);
    }
    // Custom puzzle
    if (url.pathname.match(/^\/[A-Za-z0-9-]+$/g)) {
      const puzzleId = url.pathname.substring(1);
      if (!debug && parseInt(puzzleId) > todaysPuzzleIndex())
        return noSuchPuzzle();
      return servePuzzle(req, puzzleId, url.search !== '?past');
    }
  } else if (req.method === 'POST') {
    // Analytics
    if (url.pathname === '/analytics') {
      try {
        const body = await req.formData();
        log(`analy ${body.get('puzzle')} from ${req.headers.get('x-real-ip')} ${body.get('t')} ${analytics(req)}`);
      } catch {
        return new Response('', { status: 400 });
      }
      return new Response('', { status: 200 });
    }
  }
  return new Response('Void space, please return\n', { status: 404 });
};

const port = 2222;
log(`http://localhost:${port}/`);
await serve(handler, { port });