import { of, Observable, from } from 'rxjs';
import {
  IValidator,
  isAsyncValidator,
  createAsyncValidator,
  ValidatorContext,
} from '..';
import { switchMap } from 'rxjs/operators';
import { markForRequired, isRequiredValidator } from '../validators';

/**
 * 条件校验，条件函数返回true时才会执行校验，否则直接视为校验通过
 * @param condition
 */
export function when<V = unknown>(
  condition: (ctx: ValidatorContext<V>) => boolean
) {
  return (validator: IValidator<V>) => {
    const next: IValidator<V> = isAsyncValidator(validator)
      ? createAsyncValidator<V>((value, context) => {
          return condition(context)
            ? validator.validator(value, context)
            : null;
        })
      : (value: V, context: ValidatorContext<V>) => {
          return condition(context) ? validator(value, context) : null;
        };
    isRequiredValidator(validator) && markForRequired(next);
    return next;
  };
}

/**
 * ValidatorMiddlewares.when的异步版本，接收异步的条件函数
 * @param condition
 */
export function whenAsync<V = unknown>(
  condition: (
    formValue: ValidatorContext<V>
  ) => Promise<boolean> | Observable<boolean>
) {
  return (validator: IValidator<V>) => {
    const next = createAsyncValidator<V>((value, context) => {
      return from(condition(context)).pipe(
        switchMap(shouldValidate => {
          if (shouldValidate) {
            return isAsyncValidator(validator)
              ? validator.validator(value, context) || of(null)
              : of(validator(value, context));
          }
          return of(null);
        })
      );
    });
    isRequiredValidator(validator) && markForRequired(next);
    return next;
  };
}