#!/usr/bin/env node
const spawn = require('child_process').spawn;
const colors = require('colors');
const prompt = require('prompt');
const fetch = require('node-fetch');
const htmlChars = require('./htmlChars');
const { YTKEY } = require('./config');

let data = {ids: [], titles: [], descriptions: [], channels: [], durations: []};

const clearOutput = () => console.clear();

const showError = (msg) => console.log(colors.red('Error'), ' - ', msg);

const showMsg = (msg) => console.log(colors.green(msg));

const showOsd = () => {
  data.ids.forEach((id, i) => {
    console.log(`${colors.yellow(i+1)}. ${colors.cyan(data.titles[i])} ${colors.green('['+data.durations[i]+']')} ${colors.red(data.channels[i])}`);
  });
  console.log('');
};

const showPlaying = n => console.log(`${colors.green('Currently playing:\n------------------')}\n${colors.yellow('Title:')} ${colors.cyan(data.titles[n])}\n${colors.yellow('Description:')} ${colors.cyan(data.descriptions[n])}\n${colors.yellow('Channel:')} ${colors.cyan(data.channels[n])}\n${colors.yellow('Length:')} ${colors.cyan(data.durations[n])}\n`);

const showPlaylist = (r,n) => console.log(r.map(x=>x===n?(colors.yellow(x+'. '+data.titles[x-1])):(colors.cyan(x+'. '+data.titles[x-1]))).join('\n'),'\n');

const showHelp = () => console.log(colors.green('YT audio player\n---------------\n1. Type song name and press [ENTER] to search it in YT\n2. Type result number and press [ENTER] to play the song\n3. Type a range of songs (ex. [2-5]) to play them in a row\n4. Type [r(nr)] (ex. [r2]) to find songs related to chosen result\n5. Type [h] and press [ENTER] to see this help page\n6. Type [q] and press [ENTER] to quit YT audio player\n'));

const apiUrl = 'https://www.googleapis.com/youtube/v3';

const searchUrl = q => `${apiUrl}/search?part=snippet&maxResults=20&q=${q}&type=video&key=${YTKEY}`;

const detailsUrl = a => `${apiUrl}/videos?part=contentDetails&id=${a.join(',')}&key=${YTKEY}`;

const relatedUrl = i => `${apiUrl}/search?part=snippet&maxResults=20&relatedToVideoId=${i}&type=video&key=${YTKEY}`;

const isSongRange = q => q.match(/^[0-9]+-[0-9]+$/);

const isSongName = q => q.match(/.{3,}/);

const isRelated = q => q.match(/^r[0-9]+$/) && parseInt(q.replace('r','')) <= data.ids.length;

const isSongNumber = q => q.match(/^[0-9]+$/) && parseInt(q) <= data.ids.length;

const playNr = (n) => spawn('mpv', ['--no-video', '--msg-level=all=no,statusline=status', `https://www.youtube.com/watch?v=${data.ids[parseInt(n)]}`], { stdio: 'inherit' });

const playNext = (r, n) => {
  clearOutput();
  showMsg('Playlist:\n---------');
  showPlaylist(r, n);
  showPlaying(n-1);

  const player = playNr(n-1);

  player.on('close', () => {
    if (n < r[r.length-1]){
      playNext(r, n+1);
    } else {
      clearOutput();
      showOsd();
      showPrompt();
    }
  });
};

const handleSongRange = (q) => {
  if (data.ids.length > 0) {
    const [a,b] = q.split('-').map(n=>parseInt(n));
    if (a<b){
      const range = [...Array(b-a+1).keys()].map(n=>n+a);
      playNext(range, range[0]);
    } else {
      clearOutput();
      showOsd();
      showError('invalid range, try again');
      showPrompt();
    }
  } else {
    clearOutput();
    showError('first search for the videos');
    showPrompt();
  }
};

const handleSongName = q => getSongs(q);

const handleRelated = q => {
  return getRelated(parseInt(q.replace('r','')) - 1);
}

const handleSongNumber = (q) => {
  const nr = parseInt(q) - 1;
  clearOutput();
  showPlaying(nr);
  const player = playNr(nr);
  player.on('close', () => {
    clearOutput();
    showOsd();
    showPrompt();
  });
};

const handleHelp = () => {
  clearOutput();
  showHelp();
  showPrompt();
};

const handleQuit = () => {
  clearOutput();
  showMsg('Quiting YT audio player...');
  return 0;
};

const handleWrongInput = () => {
  clearOutput();
  showOsd();
  showError('wrong input');
  showPrompt();
};

const formatTime = i => i.contentDetails.duration.replace(/(PT|S)/g,'').split(/[A-Z]/g).map(d => d.padStart(2, '0')).join(':');

const getJson = (url) => fetch(url).then(res => res.json()).catch(e => console.log(e));

const getSongs = (q) => getJson(searchUrl(q)).then(json => presentResults(json));

const getRelated = (n) => getJson(relatedUrl(data.ids[n])).then(json => presentResults(json));

const getDurations = (ids) => getJson(detailsUrl(ids)).then(json => json.items.map(formatTime));

const presentResults = (results) => {
  const items = results.items.filter(i => i.snippet);
  data.titles = items.map(i => decode(i.snippet.title));
  data.descriptions = items.map(i => decode(i.snippet.description));
  data.channels = items.map(i => decode(i.snippet.channelTitle));
  data.ids = items.map(i => i.id.videoId);
  getDurations(data.ids).then(durations => {
    data.durations = durations;
    clearOutput();
    showOsd();
    showPrompt();
  });
};

const decode = t => t.replace(new RegExp(`/${Object.keys(htmlChars).join('|')}/gi`), (m) => htmlChars[m]);

const handlePrompt = (err, { query }) => {
  if (err) {
    console.log(err);
    return 1;
  }

  if (isSongRange(query)) {
    handleSongRange(query);
  } else if (isRelated(query)) {
    handleRelated(query);
  } else if (isSongName(query)) {
    handleSongName(query);
  } else if (isSongNumber(query)) {
    handleSongNumber(query);
  } else if (query === 'h') {
    handleHelp();
  } else if (query === 'q') {
    handleQuit();
  } else {
    handleWrongInput();
  }
};

const showPrompt = () => {
  prompt.message = "";
  prompt.delimiter = "";
  prompt.start();
  prompt.get({
    name: 'query',
    description: 'YT Search ([h]elp, [q]uit):',
    required: true,
  }, handlePrompt);
}

clearOutput();
showPrompt();