javiercejudo/modelico

import {always} from '../U'
import {typeSymbol} from '../symbols'
import Base from './Base'

const enumeratorsReducer = (acc, code) => Object.assign(acc, {[code]: {code}})

const reviverFactory = enumerators => (
  k,
  v,
  path = [],
  {default: def} = {}
) => {
  const enumerator = enumerators[v]

  if (enumerator !== undefined) {
    return enumerator
  }

  if (def !== undefined) {
    const defEnumerator = enumerators[def]

    if (defEnumerator !== undefined) {
      return defEnumerator
    }
  }

  throw TypeError(
    `missing enumerator "${v}" without valid default at "${path.join(' → ')}"`
  )
}

const maybeReviverFactory = enumerators => {
  const reviver = reviverFactory(enumerators)

  return (k, v, path) =>
    enumerators[v] === undefined ? null : reviver(k, v, path)
}

class Enum extends Base {
  constructor(input, Ctor = Enum, displayName = Ctor.displayName) {
    const enumerators = Array.isArray(input)
      ? input.reduce(enumeratorsReducer, {})
      : input

    if (Ctor !== Enum) {
      Ctor.displayName = displayName
      Object.freeze(Ctor)
    }

    super(Ctor)

    Object.getOwnPropertyNames(enumerators).forEach(enumerator => {
      this[enumerator] = always(enumerators[enumerator])
      enumerators[enumerator][typeSymbol] = always(this)
      enumerators[enumerator].toJSON = always(enumerator)
      enumerators[enumerator].equals = other =>
        enumerators[enumerator] === other
    })

    Object.defineProperty(this, 'metadata', {
      value: always(
        Object.freeze({
          type: this,
          enumerators,
          reviver: reviverFactory(enumerators),
          maybeReviver: maybeReviverFactory(enumerators)
        })
      )
    })
  }

  static fromObject(...args) {
    return new Enum(...args)
  }

  static fromArray(...args) {
    return new Enum(...args)
  }
}

Object.defineProperty(Enum, 'displayName', {
  value: 'Enum',
  writable: true
})

export default Enum