/**
 * A valid, Base64-encoded JWT.
 *
 * Inspired by validator.js' [JWT
 * module](https://github.com/validatorjs/validator.js/blob/master/src/lib/isJWT.js).
 *
 * @since 0.0.2
 */
import { Kind, Kind2, URIS, URIS2, HKT2 } from 'fp-ts/HKT'
import * as D from 'io-ts/Decoder'
import * as Enc from 'io-ts/Encoder'
import * as Eq_ from 'fp-ts/Eq'
import * as G from 'io-ts/Guard'
import * as Str from 'fp-ts/string'
import * as TD from 'io-ts/TaskDecoder'
import * as t from 'io-ts/Type'
import { pipe } from 'fp-ts/function'
import * as fc from 'fast-check'

import * as Arb from '../internal/ArbitraryBase'
import { isBase64Url } from './Base64Url'
import { base64Encode, urlifyBase64 } from '../internal/util'

/**
 * @since 0.0.2
 * @internal
 */
interface JWTBrand {
  readonly JWT: unique symbol
}

/**
 * A valid, Base64-encoded JWT.
 *
 * Inspired by validator.js' [JWT
 * module](https://github.com/validatorjs/validator.js/blob/master/src/lib/isJWT.js).
 *
 * @since 0.0.2
 * @category Model
 */
export type JWT = string & JWTBrand

/**
 * @since 0.0.2
 * @category Model
 */
export type SchemableParams<S> = HKT2<S, string, JWT>

/**
 * @since 0.0.2
 * @category Model
 */
export type SchemableParams1<S extends URIS> = Kind<S, JWT>

/**
 * @since 0.0.2
 * @category Model
 */
export type SchemableParams2<S extends URIS2> = Kind2<S, string, JWT>

/**
 * @since 0.0.2
 * @category Model
 */
export type SchemableParams2C<S extends URIS2> = Kind2<S, unknown, JWT>

/**
 * @since 0.0.2
 * @category Refinements
 */
export const isJWT = (s: string): s is JWT => {
  const dotSplit = s.split('.')
  const len = dotSplit.length

  if (len > 3 || len < 2) {
    return false
  }

  return dotSplit.reduce((acc, currElem) => acc && isBase64Url(currElem), true)
}

/**
 * @since 0.0.2
 * @category Instances
 */
export const Decoder: SchemableParams2C<D.URI> = pipe(D.string, D.refine(isJWT, 'JWT'))

/**
 * @since 0.0.2
 * @category Instances
 */
export const Eq: SchemableParams1<Eq_.URI> = Str.Eq

/**
 * @since 0.0.2
 * @category Instances
 */
export const Guard: SchemableParams1<G.URI> = pipe(G.string, G.refine(isJWT))

/**
 * @since 0.0.2
 * @category Instances
 */
export const TaskDecoder: SchemableParams2C<TD.URI> = pipe(
  TD.string,
  TD.refine(isJWT, 'JWT')
)

/**
 * @since 0.0.2
 * @category Instances
 */
export const Type: SchemableParams1<t.URI> = pipe(t.string, t.refine(isJWT, 'JWT'))

/**
 * @since 0.0.3
 * @category Instances
 */
export const Encoder: SchemableParams2<Enc.URI> = Enc.id()

/**
 * Note: This will produce unsigned JWTs, with `alg: "none"`.
 *
 * @since 0.0.3
 * @category Instances
 */
export const Arbitrary: SchemableParams1<Arb.URI> = fc.object().map(json => {
  const header = urlifyBase64(base64Encode(JSON.stringify({ alg: 'none', typ: 'JWT' })))
  const payload = urlifyBase64(base64Encode(JSON.stringify(json)))
  const signature = ''
  return [header, payload, signature].join('.')
}) as Arb.Arbitrary<JWT>