const { readFileSync, writeFileSync } = require('node:fs')
const { EOL } = require('node:os')
const { resolve } = require('node:path')

const dotenv = require('dotenv')

const { EXIT } = require('./consts')
const CLI = require('./cli')

const help_message = "Produce an .env file appropriate for stress testing."

const cli = CLI({
  grammar: [
    [["--help"], "Show this help message"],
    [["--inenv", "ENV"], "Environment file path to read", ".env"],
    [["--outenv", "ENV"], "Environment file path to write", ".stress.env"],
    [["--dbuser", "DBUSER"], "Database username", "postgres"],
    [["--dbpass", "DBPASS"], "Database password", "postgres123"],
    [["--dbhost", "DBHOST"], "Database hostname", "localhost"],
    [["--dbport", "DBPORT"], "Database port", "5432"],
    [["--dbname", "DBNAME"], "Database name", "lamassu_stress"],
  ],
})

const help = (exit_code) => {
  console.log("Usage: lamassu-server-stress-testing env ARGS...")
  console.log(help_message)
  cli.help()
  return exit_code
}

const env_read = (path) => {
  const envstr = readFileSync(path, { encoding: 'utf8' })
  return dotenv.parse(envstr)
  //const entries = envstr
  //  .split(EOL)
  //  .flatMap((line) => {
  //    line = line.trimStart()
  //    const i = line.indexOf('=')
  //
  //    if (line.startsWith('#') || i <= 0)
  //      return []
  //
  //    const varname = line.substring(0, i)
  //    const value = line.substring(i + 1)
  //    return [[varname, value]]
  //  })
  //return Object.fromEntries(entries)
}

const env_write = (envvars, path) => {
  const envcontent = Object.entries(envvars)
    .map(([varname, value]) => [varname, value].join('='))
    .join(EOL) + EOL
  writeFileSync(path, envcontent)
}

const run = async (args) => {
  const [err, options, positional] = cli.parse(args)
  if (err) {
    console.error(err)
    return help(EXIT.BADARGS)
  }

  if (options.help)
    return help(EXIT.OK)

  if (positional.length > 0) {
    console.error("Unknown arguments:", positional)
    return help(EXIT.BADARGS)
  }

  const inenvpath = resolve(process.cwd(), options.inenv ?? ".env")
  const inenvvars = env_read(inenvpath)

  const outenvpath = resolve(process.cwd(), options.outenv ?? ".stress.env")
  const outenvvars = {
    ...inenvvars,
    POSTGRES_USER: options.dbuser ?? "postgres",
    POSTGRES_PASSWORD: options.dbpass ?? "postgres123",
    POSTGRES_HOST: options.dbhost ?? "localhost",
    POSTGRES_PORT: options.dbport ?? "5432",
    POSTGRES_DB: options.dbname ?? "lamassu_stress",
  }
  env_write(outenvvars, outenvpath)

  return EXIT.OK
}

module.exports = {
  help_message,
  run,
}