import {
  log,
}         from '../config.js'

import languageMonitor from 'language-monitor'

type LanguageCode = 'chinese'
                  | 'danish'
                  | 'norwegian'
                  | 'japanese'
                  | 'dutch'
                  | 'swedish'
                  | 'cebuano'
                  | 'tagalog'
                  | 'german'
                  | 'indonesian'
                  | 'turkish'
                  | 'korean'
                  | 'portuguese'
                  | 'azeri'
                  | 'english'
                  | 'estonian'
                  | 'latin'
                  | 'slovene'
                  | 'swahili'
                  | 'hungarian'
                  | 'spanish'
                  | 'lithuanian'
                  | 'finnish'
                  | 'hawaiian'
                  | 'icelandic'
                  | 'italian'

interface GuessedLanguage {
  code: LanguageCode,
  rate: number,
}

function detectLanguage (text: string, limit?: number): GuessedLanguage[] {
  return languageMonitor(text, limit)
}

function includeLanguage (
  resultList: GuessedLanguage[],
  language: LanguageCode,
  threshold = 0.1,
) {
  const minThreshold = (min: number) => (result: GuessedLanguage) => result.rate > min
  const toCode = (result: GuessedLanguage) => result.code

  return resultList
    .filter(minThreshold(threshold))
    .map(toCode)
    .includes(language)
}

export type LanguageMatcherOptions = LanguageCode | LanguageCode[]

type MatchLanguageFunction = (text: string) => boolean

function languageMatcher (
  options: LanguageMatcherOptions,
): MatchLanguageFunction {
  log.verbose('WechatyQnAMaker', 'languageMatcher(%s)', JSON.stringify(options))

  let codeList: LanguageCode[]

  if (Array.isArray(options)) {
    codeList = options
  } else {
    codeList = [ options ]
  }

  return function matchLanguage (text: string) {
    const resultList = detectLanguage(text)
    return codeList.some(code => includeLanguage(resultList, code))
  }

}

export {
  detectLanguage,
  languageMatcher,
  includeLanguage,
}