"use client";
import { useRef, useState, type ComponentProps, type ReactNode } from "react";
import { useFormStatus } from "react-dom";

function FormFields({ children }: { children: ReactNode }) {
  const { pending } = useFormStatus();
  return (
    <fieldset disabled={pending} style={{ display: "contents" }}>
      {children}
    </fieldset>
  );
}

/** Keeps action errors beside the submitted form, without losing entered values. */
export function ActionForm({
  action,
  children,
  ...props
}: Omit<ComponentProps<"form">, "action"> & {
  action: (data: FormData) => Promise<void | { error: string }>;
}) {
  const preserveValues = useRef(false);
  const [message, setMessage] = useState("");
  const [failed, setFailed] = useState(false);
  return (
    <form
      {...props}
      onReset={(event) => {
        if (preserveValues.current) event.preventDefault();
      }}
      onChange={() => setMessage("")}
      onKeyDown={(event) => {
        if ((event.metaKey || event.ctrlKey) && event.key === "Enter") {
          event.preventDefault();
          const button = event.currentTarget.querySelector<HTMLButtonElement>(
            'button[type="submit"]',
          );
          if (button && !button.disabled) button.click();
        }
      }}
      action={async (data) => {
        setMessage("");
        preserveValues.current = false;
        try {
          const result = await action(data);
          if (result?.error) {
            preserveValues.current = true;
            setFailed(true);
            setMessage(result.error);
            return;
          }
          setFailed(false);
          setMessage("已保存");
        } catch {
          preserveValues.current = true;
          setFailed(true);
          setMessage("操作失败，请检查输入后重试。填写内容已保留。");
        }
      }}
    >
      <FormFields>{children}</FormFields>
      {message && (
        <p
          role={failed ? "alert" : "status"}
          className={`full-span ${failed ? "error-text" : "muted"}`}
        >
          {message}
        </p>
      )}
    </form>
  );
}