export class Enum extends Base {
  readonly _tag = "Enum"
  readonly enums: ReadonlyArray<readonly [string, string | number]>

  constructor(
    enums: ReadonlyArray<readonly [string, string | number]>,
    annotations?: Schema.Annotations.Annotations,
    checks?: Checks,
    encoding?: Encoding,
    context?: Context
  ) {
    super(annotations, checks, encoding, context)
    this.enums = enums
  }
  /** @internal */
  getParser() {
    const values = new Set<unknown>(this.enums.map(([, v]) => v))
    return fromRefinement(
      this,
      (input): input is typeof this.enums[number][1] => values.has(input)
    )
  }
  /** @internal */
  toCodecStringTree(): AST {
    if (this.enums.some(([_, v]) => typeof v === "number")) {
      const coercions = Object.fromEntries(this.enums.map(([_, v]) => [globalThis.String(v), v]))
      return replaceEncoding(this, [
        new Link(
          new Union(Object.keys(coercions).map((k) => new Literal(k)), "anyOf"),
          new SchemaTransformation.Transformation(
            SchemaGetter.transform((s) => coercions[s]),
            SchemaGetter.String()
          )
        )
      ])
    }
    return this
  }
  /** @internal */
  getExpected(): string {
    return this.enums.map(([_, value]) => JSON.stringify(value)).join(" | ")
  }
}