import { readFileSync, writeFileSync, statSync, copyFileSync } from 'fs'
import { resolve } from 'path'
import { homedir } from 'os'

import yaml from 'js-yaml'
import CronParser from 'cron-parser'

import { Backend, Config } from './types'
import { makeArrayIfIsNot, makeObjectKeysLowercase, rand } from './utils'

export enum LocationFromPrefixes {
  Filesystem,
  DockerVolume,
}

export const normalizeAndCheckBackends = (config: Config) => {
  config.backends = makeObjectKeysLowercase(config.backends)

  for (const [name, { type, path, key, ...rest }] of Object.entries(config.backends)) {
    if (!type || !path) throw new Error(`The backend "${name}" is missing some required attributes`)

    const tmp: any = {
      type,
      path,
      key: key || rand(128),
    }
    for (const [key, value] of Object.entries(rest)) tmp[key.toUpperCase()] = value

    config.backends[name] = tmp as Backend
  }
}

export const normalizeAndCheckLocations = (config: Config) => {
  config.locations = makeObjectKeysLowercase(config.locations)
  const backends = Object.keys(config.backends)

  const checkDestination = (backend: string, location: string) => {
    if (!backends.includes(backend)) throw new Error(`Cannot find the backend "${backend}" for "${location}"`)
  }

  for (const [name, { from, to, cron, ...rest }] of Object.entries(config.locations)) {
    if (!from) throw new Error(`The location "${name.blue}" is missing the "${'from'.underline.red}" source folder. See https://git.io/Jf0xw`)
    if (!to || (Array.isArray(to) && !to.length))
      throw new Error(`The location "${name.blue}" has no backend "${'to'.underline.red}" to save the backups. See https://git.io/Jf0xw`)

    for (const t of makeArrayIfIsNot(to)) checkDestination(t, name)

    if (cron) {
      try {
        CronParser.parseExpression(cron)
      } catch {
        throw new Error(`The location "${name.blue}" has an invalid ${'cron'.underline.red} entry. See https://git.io/Jf0xP`)
      }
    }
  }
}

const findConfigFile = (custom: string): string => {
  const config = '.autorestic.yml'
  const paths = [resolve(custom || ''), resolve('./' + config), homedir() + '/' + config]
  for (const path of paths) {
    try {
      const file = statSync(path)
      if (file.isFile()) return path
    } catch (e) {}
  }
  throw new Error('Config file not found')
}

export let CONFIG_FILE: string = ''

export const init = (custom: string): Config => {
  const file = findConfigFile(custom)
  CONFIG_FILE = file

  const parsed = yaml.safeLoad(readFileSync(CONFIG_FILE).toString())
  if (!parsed || typeof parsed === 'string') throw new Error('Could not parse the config file')
  const raw: Config = makeObjectKeysLowercase(parsed)

  const current = JSON.stringify(raw)

  normalizeAndCheckBackends(raw)
  normalizeAndCheckLocations(raw)

  const changed = JSON.stringify(raw) !== current

  if (changed) {
    const OLD_CONFIG_FILE = CONFIG_FILE + '.old'
    copyFileSync(CONFIG_FILE, OLD_CONFIG_FILE)
    writeFileSync(CONFIG_FILE, yaml.safeDump(raw))
    console.log(
      '\n' +
        '⚠️ MOVED OLD CONFIG FILE TO: ⚠️'.red.underline.bold +
        '\n' +
        OLD_CONFIG_FILE +
        '\n' +
        'What? Why? '.grey +
        'https://git.io/Jf0xK'.underline.grey +
        '\n'
    )
  }

  return raw
}