const rl = require('readline');

const list_mock = [
  '1',
  '2',
  '3',
  '4',
  '5',
  '6',
  '7',
  '8',
  '9',
  '10',
  '11',
  '12',
  '13',
  '14',
  '15',
  '16',
  '17',
  '18',
  '19',
  '20',
  '21',
  '22',
  '23',
  '24',
  '25',
  '26',
  '27',
  '28',
  '29',
  '30',
  '31',
  '32',
  '33',
  '34',
  '35',
  '36',
  '37',
  '38',
  '39',
  '40',
  '41',
  '42',
  '43',
  '44',
  '45',
  '46',
  '47',
  '48',
  '49',
  '50'
]

let active = 0; scroll = 0; draw = { t: 'p', v: ['Loading Notes App...'] }, appTitle = '', menu = ''
const pr = t => process.stdout.write(t)
const cls = () => console.clear()
const cursor = {
  hide: () => pr('\u001B[?25l'),
  show: () => pr('\u001B[?25h')
}

// =========== DRAW APP =============

const drawApp = () => {
  const lines = process.stdout.rows
  const columns = process.stdout.columns
  // process.stdout.write('\x1Bc')
  cls()
  for (var i = 0; i < lines - 1; i++) {
    const dist = t => [Math.floor((columns - t) / 2), Math.ceil((columns - t) / 2) - 2]
    switch(i){
      case 0:
        pr('╔'+'═'.repeat(columns - 2)+'╗')
        break
      case 1:
        pr('║'+' '.repeat(dist(appTitle.length)[0])+appTitle+' '.repeat(dist(appTitle.length)[1])+'║')
        break
      case 2:
        pr('╠'+'═'.repeat(columns - 2) +'╣')
        break
      case lines - 3:
        pr('╟'+'─'.repeat(columns - 2) +'╢')
        break
      case lines - 2:
        pr('║'+' '+menu.substring(0,columns-4)+' '.repeat(columns-menu.length-3)+'║')
        break
      default:
        const max = Math.max(...(draw.v.map(el => el.length)))
        if (draw.t === 'p') {
          if (i === (Math.floor((lines - draw.v.length) / 2) - 2)){
            pr('║'+' '.repeat(dist(max+4)[0])+'┌'+'─'.repeat(max+2)+'┐'+' '.repeat(dist(max+4)[1])+'║')
          } else if (i === (Math.floor((lines + draw.v.length) / 2) + 1)) {
            pr('║'+' '.repeat(dist(max+4)[0])+'└'+'─'.repeat(max+2)+'┘'+' '.repeat(dist(max+4)[1])+'║')
          } else if (i === (Math.floor((lines - draw.v.length) / 2) - 1) || i === (Math.floor((lines + draw.v.length) / 2))) {
            pr('║'+' '.repeat(dist(max+4)[0])+'│'+' '.repeat(max+2)+'│'+' '.repeat(dist(max+4)[1])+'║')
          } else if (i < (Math.floor((lines - draw.v.length) / 2) - 1) || (i > (Math.floor((lines + draw.v.length) / 2)))) {
            pr('║'+' '.repeat(columns - 2)+'║')
          } else {
            const n = i - (Math.floor((lines - draw.v.length) / 2))
            const t = draw.v[n]
            const s = [Math.floor((max+2-t.length) / 2), Math.ceil((max+2-t.length) / 2)]
            pr('║'+' '.repeat(dist(max+4)[0])+'│'+' '.repeat(s[0])+t+' '.repeat(s[1])+'│'+' '.repeat(dist(max+4)[1])+'║')
          }
        } else if (draw.t === 'l') {
          const l = draw.v[i-3+scroll] && draw.v[i-3+scroll].substring(0,columns-4)

          pr(l
            ? ('║'+(active===i-3+scroll?'\x1b[7m ':' ')+l+' '.repeat(columns-l.length-3)+'\x1b[0m║')
            : ('║'+' '.repeat(columns - 2)+'║')
          )
        }
    }
  }

  pr('╚'+'═'.repeat(columns - 2)+'╝')
}

// ============ GET KEY =================

const getKey = () => {
  rl.emitKeypressEvents(process.stdin);
  process.stdin.setRawMode(true);
  process.stdin.on('keypress', (_, key) => {
    const lines = process.stdout.rows
    switch(key.name) {
      case 'up':
      case 'k':
        active > 0 && active--
        active < scroll && scroll--
        drawApp()
        break
      case 'down':
      case 'j':
        if (draw.t === 'l') {
          active < draw.v.length - 1 && active++
          active - scroll > lines - 7 && scroll++
          drawApp()
        }
        break
      case 'return':
      case 'o':
        // draw = { t: 'p', v: ['popup test'] }
        // draw = { t: 'p', v: ['popup test', 'aaaaaaa'] }
        draw = { t: 'p', v: ['popup test', '', `This will display note nr ${active + 1}.`] }
        drawApp()
        // process.stdout.write(draw.v[active]);
        break
      case 'q':
        cursor.show()
        console.clear()
        pr('Bye!\n\n')
        process.exit()
      default:
    }
  })
}

// ============ EXECUTION ================

cls()
cursor.hide()
process.stdout.on('resize', drawApp);

appTitle = "Notes App"
menu = '[Q]uit   [↓/j] Down   [↑/k] Up   [Enter/o] Open'
draw = { t: 'l', v: list_mock }

drawApp()
getKey()