import type {
  FieldError,
  FieldErrors,
  FieldValues,
  Resolver,
  ResolverOptions,
  ResolverResult,
} from "react-hook-form";
import type { ZodType } from "zod/v4";

export function createZodResolver<T extends FieldValues>(
  schema: ZodType<T, unknown>,
): Resolver<T, unknown> {
  return (
    values: T,
    _context: unknown,
    _options?: ResolverOptions<T>,
  ): ResolverResult<T> => {
    const result = schema.safeParse(values);
    if (result.success) {
      return {
        values: result.data,
        errors: {},
      };
    }

    const errors: Record<
      string,
      FieldError & { params?: Record<string, unknown> }
    > = {};

    for (const issue of result.error.issues) {
      const { path, code, message, ...params } = issue;
      const key = path.join(".");

      const suffix =
        "format" in params
          ? params.format
          : "origin" in params
            ? params.origin
            : "expected" in params
              ? params.expected
              : "";

      const newCode =
        code.replace(/_([a-z])/g, (_, char) => char.toUpperCase()) +
        (suffix ? `.${suffix}` : "");

      const fieldError: FieldError & { params?: Record<string, unknown> } = {
        type: newCode,
        message: message,
        ...(Object.keys(params).length ? { params } : {}),
      };

      if (!errors[key]) {
        errors[key] = fieldError;
      }
    }

    return {
      values: {} as Record<string, never>,
      errors: errors as FieldErrors<T>,
    };
  };
}