/* @flow */

import { warn, isObject } from './util'

export default class BaseFormatter {
  _caches: { [key: string]: Array<Token> }

  constructor () {
    this._caches = Object.create(null)
  }

  interpolate (message: string, values: any): Array<any> {
    if (!values) {
      return [message]
    }
    let tokens: Array<Token> = this._caches[message]
    if (!tokens) {
      tokens = parse(message)
      this._caches[message] = tokens
    }
    return compile(tokens, values)
  }
}

type Token = {
  type: 'text' | 'named' | 'list' | 'unknown',
  value: string
}

const RE_TOKEN_LIST_VALUE: RegExp = /^(\d)+/
const RE_TOKEN_NAMED_VALUE: RegExp = /^(\w)+/

export function parse (format: string): Array<Token> {
  const tokens: Array<Token> = []
  let position: number = 0

  let text: string = ''
  while (position < format.length) {
    let char: string = format[position++]
    if (char === '{') {
      if (text) {
        tokens.push({ type: 'text', value: text })
      }

      text = ''
      let sub: string = ''
      char = format[position++]
      while (char !== '}') {
        sub += char
        char = format[position++]
      }

      const type = RE_TOKEN_LIST_VALUE.test(sub)
        ? 'list'
        : RE_TOKEN_NAMED_VALUE.test(sub)
          ? 'named'
          : 'unknown'
      tokens.push({ value: sub, type })
    } else if (char === '%') {
      // when found rails i18n syntax, skip text capture
      if (format[(position)] !== '{') {
        text += char
      }
    } else {
      text += char
    }
  }

  text && tokens.push({ type: 'text', value: text })

  return tokens
}

export function compile (tokens: Array<Token>, values: Object | Array<any>): Array<any> {
  const compiled: Array<any> = []
  let index: number = 0

  const mode: string = Array.isArray(values)
    ? 'list'
    : isObject(values)
      ? 'named'
      : 'unknown'
  if (mode === 'unknown') { return compiled }

  while (index < tokens.length) {
    const token: Token = tokens[index]
    switch (token.type) {
      case 'text':
        compiled.push(token.value)
        break
      case 'list':
        compiled.push(values[parseInt(token.value, 10)])
        break
      case 'named':
        if (mode === 'named') {
          compiled.push((values: any)[token.value])
        } else {
          if (process.env.NODE_ENV !== 'production') {
            warn(`Type of token '${token.type}' and format of value '${mode}' don't match!`)
          }
        }
        break
      case 'unknown':
        if (process.env.NODE_ENV !== 'production') {
          warn(`Detect 'unknown' type of token!`)
        }
        break
    }
    index++
  }

  return compiled
}
