import { Arr, memoizeFunction, Result } from 'ts-data-forge';
import { type Type } from '../type.mjs';
import {
  createAssertFn,
  createCastFn,
  createIsFn,
  createPrimitiveValidationError,
  prependIndexToValidationErrors,
  type ValidationError,
} from '../utils/index.mjs';

export const array = <A,>(
  elementType: Type<A>,
  options?: Partial<
    Readonly<{
      typeName: string;
      defaultValue: readonly A[];
    }>
  >,
): Type<readonly A[]> => {
  type T = readonly A[];

  const typeName = options?.typeName ?? `${elementType.typeName}[]`;

  const getDefaultValue = memoizeFunction((): T => options?.defaultValue ?? []);

  const validate: Type<T>['validate'] = (a) => {
    if (!Arr.isArray(a)) {
      return Result.err([
        createPrimitiveValidationError({
          actualValue: a,
          expectedType: 'array',
          typeName,
          details: undefined,
        }),
      ]);
    }

    const errors: readonly ValidationError[] = Arr.generate(function* () {
      for (const [index, el] of a.entries()) {
        const res = elementType.validate(el);

        if (Result.isErr(res)) {
          yield* prependIndexToValidationErrors(res.value, index);
        }
      }
    });

    if (Arr.isNonEmpty(errors)) {
      return Result.err(errors);
    }

    // eslint-disable-next-line total-functions/no-unsafe-type-assertion
    return Result.ok(a as T);
  };

  const fill: Type<T>['fill'] = (a) =>
    !Arr.isArray(a) ? getDefaultValue() : a.map((e) => elementType.fill(e));

  const prune = (a: T): T => a.map((e) => elementType.prune(e));

  return {
    typeName,
    get defaultValue() {
      return getDefaultValue();
    },
    fill,
    prune,
    validate,
    is: createIsFn(validate),
    assertIs: createAssertFn(validate),
    cast: createCastFn(validate),
  };
};