import { readFile } from 'node:fs/promises'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import test from 'brittle'

const __dirname = path.dirname(fileURLToPath(import.meta.url))

async function loadTelnetFns() {
  const body = await readFile(path.join(__dirname, '../src/telnet.js'), 'utf8')
  const fn = new Function(
    `${body}
return {
  TELNET_IAC,
  TELNET_DO,
  TELNET_DONT,
  TELNET_WILL,
  TELNET_WONT,
  TELNET_SB,
  TELNET_SE,
  TELNET_OPT_ECHO,
  TELNET_OPT_NAWS,
  TELNET_OPT_TTYPE,
  bareTelnetNewParseState,
  bareTelnetParseChunk,
  bareTelnetMakeNego,
  bareTelnetHandleNeg,
  bareTelnetHandleSB,
  bareTelnetEncodeNAWS,
  bareTelnetEncodeTTYPEIs
}`
  )
  return fn()
}

test('telnet parser separates data and negotiation records', async (t) => {
  const tel = await loadTelnetFns()
  const st = tel.bareTelnetNewParseState()
  const data = new Uint8Array([65, tel.TELNET_IAC, tel.TELNET_WILL, tel.TELNET_OPT_ECHO, 66])
  const out = tel.bareTelnetParseChunk(st, data)
  t.is(new TextDecoder().decode(out.data), 'AB')
  t.is(out.commands.length, 1)
  t.is(out.commands[0].kind, 'neg')
  t.is(out.commands[0].cmd, tel.TELNET_WILL)
  t.is(out.commands[0].opt, tel.TELNET_OPT_ECHO)
})

test('telnet negotiation responds to DO NAWS with WILL + SB NAWS', async (t) => {
  const tel = await loadTelnetFns()
  const nego = tel.bareTelnetMakeNego({ nawsCols: 120, nawsRows: 40, ttype: 'xterm' })
  const r = tel.bareTelnetHandleNeg(nego, tel.TELNET_DO, tel.TELNET_OPT_NAWS)
  t.ok(r.responses.length >= 2)
  t.is(r.responses[0][0], tel.TELNET_IAC)
  t.is(r.responses[0][1], tel.TELNET_WILL)
  t.is(r.responses[0][2], tel.TELNET_OPT_NAWS)
})

test('telnet subnegotiation SEND TTYPE returns IS TTYPE', async (t) => {
  const tel = await loadTelnetFns()
  const nego = tel.bareTelnetMakeNego({ ttype: 'xterm-256color' })
  const r = tel.bareTelnetHandleSB(nego, tel.TELNET_OPT_TTYPE, new Uint8Array([1]))
  t.ok(r.responses.length >= 1)
  const sb = r.responses[0]
  t.is(sb[0], tel.TELNET_IAC)
  t.is(sb[1], tel.TELNET_SB)
  t.is(sb[2], tel.TELNET_OPT_TTYPE)
})