export interface Cause<E extends Constraint, D extends Constraint> extends
  declareConstructor<
    Cause_.Cause<E["Type"]>,
    Cause_.Cause<E["Encoded"]>,
    readonly [E, D],
    CauseIso<E, D>
  >
{
  readonly "Rebuild": Cause<E, D>
  readonly error: E
  readonly defect: D
}

/**
 * Iso representation used for `Cause` schemas: an ordered array of
 * `CauseReasonIso` values.
 *
 * **When to use**
 *
 * Use when working with the ISO shape of a `Cause` schema, such as `toIso`
 * optics or codecs that expose a cause as its ordered array of encoded reasons.
 *
 * @see {@link Cause} for constructing schemas for full Cause values
 * @see {@link CauseReasonIso} for the ISO shape of each array element
 *
 * @category Cause
 * @since 4.0.0
 */
export type CauseIso<E extends Constraint, D extends Constraint> = ReadonlyArray<CauseReasonIso<E, D>>

/**
 * Creates a schema for `Cause` values using separate schemas for typed failures
 * and unexpected defects.
 *
 * **When to use**
 *
 * Use to validate, transform, or serialize Effect failure causes when typed
 * failures and unexpected defects need separate schemas.
 *
 * **Details**
 *
 * The `error` schema is applied to `Fail` reasons and the `defect` schema is
 * applied to `Die` reasons. Interrupt reasons do not use either schema and
 * carry only an optional fiber id.
 *
 * @see {@link CauseReason} for the schema used by each individual cause reason
 * @see {@link CauseIso} for the ordered array representation used by the schema ISO
 *
 * @category Cause
 * @since 3.10.0
 */
export function Cause<E extends Constraint, D extends Constraint>(error: E, defect: D): Cause<E, D> {
  const schema = declareConstructor<Cause_.Cause<E["Type"]>, Cause_.Cause<E["Encoded"]>, CauseIso<E, D>>()(
    [error, defect],
    ([error, defect]) => {
      const failures = ArraySchema(CauseReason(error, defect))
      return (input, ast, options) => {
        if (!Cause_.isCause(input)) {
          return Effect.fail(new SchemaIssue.InvalidType(ast, Option_.some(input)))
        }
        return Effect.mapBothEager(SchemaParser.decodeUnknownEffect(failures)(input.reasons, options), {
          onSuccess: Cause_.fromReasons,
          onFailure: (issue) =>
            new SchemaIssue.Composite(ast, Option_.some(input), [new SchemaIssue.Pointer(["failures"], issue)])
        })
      }
    },
    {
      typeConstructor: {
        _tag: "effect/Cause"
      },
      generation: {
        runtime: `Schema.Cause(?, ?)`,
        Type: `Cause.Cause<?, ?>`,
        importDeclaration: `import * as Cause from "effect/Cause"`
      },
      expected: "Cause",
      toCodec: ([error, defect]) =>
        link<Cause_.Cause<E["Encoded"]>>()(
          ArraySchema(CauseReason(error, defect)),
          SchemaTransformation.transform({
            decode: Cause_.fromReasons,
            encode: ({ reasons: failures }) => failures
          })
        ),
      toArbitrary: ([error, defect]) => causeToArbitrary(error, defect),
      toEquivalence: ([error, defect]) => causeToEquivalence(error, defect),
      toFormatter: ([error, defect]) => causeToFormatter(error, defect)
    }
  )
  return make(schema.ast, { error, defect })
}