"use client";

import { useActionState } from "react";

import { Button } from "@/components/ui/button";
import { Checkbox } from "@/components/ui/checkbox";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";

import { registerAction, type RegisterState } from "./actions";

const initialRegisterState: RegisterState = { attempt: 0 };

export function RegisterForm() {
  const [state, formAction, pending] = useActionState(
    registerAction,
    initialRegisterState,
  );

  // Bumping the key on each attempt forces uncontrolled inputs to remount with
  // the echoed defaultValue from the server — otherwise React's <form action>
  // semantics would wipe them after a failed submit.
  const attemptKey = state.attempt;

  return (
    <form action={formAction} className="space-y-4">
      <div className="grid gap-4 sm:grid-cols-2">
        <FormField
          key={`firstName-${attemptKey}`}
          id="firstName"
          name="firstName"
          label="Vorname"
          autoComplete="given-name"
          required
          defaultValue={state.values?.firstName ?? ""}
          error={state.errors?.firstName?.[0]}
        />
        <FormField
          key={`lastName-${attemptKey}`}
          id="lastName"
          name="lastName"
          label="Nachname"
          autoComplete="family-name"
          required
          defaultValue={state.values?.lastName ?? ""}
          error={state.errors?.lastName?.[0]}
        />
      </div>

      <FormField
        key={`email-${attemptKey}`}
        id="email"
        name="email"
        type="email"
        label="E-Mail"
        autoComplete="email"
        required
        defaultValue={state.values?.email ?? ""}
        error={state.errors?.email?.[0]}
      />

      <FormField
        key={`password-${attemptKey}`}
        id="password"
        name="password"
        type="password"
        label="Passwort"
        autoComplete="new-password"
        required
        helperText="Mindestens 8 Zeichen."
        error={state.errors?.password?.[0]}
      />

      <div className="flex items-start gap-3 pt-2">
        <Checkbox
          key={`acceptPrivacyPolicy-${attemptKey}`}
          id="acceptPrivacyPolicy"
          name="acceptPrivacyPolicy"
          required
          defaultChecked={state.values?.acceptPrivacyPolicy === true}
          aria-invalid={!!state.errors?.acceptPrivacyPolicy?.[0]}
          aria-describedby={
            state.errors?.acceptPrivacyPolicy?.[0]
              ? "acceptPrivacyPolicy-error"
              : undefined
          }
        />
        <div className="grid gap-1 leading-none">
          <Label htmlFor="acceptPrivacyPolicy" className="text-sm font-normal">
            Ich habe die{" "}
            <a
              href="/datenschutz"
              className="underline"
              target="_blank"
              rel="noreferrer"
            >
              Datenschutzerklärung
            </a>{" "}
            gelesen und akzeptiere sie.
          </Label>
          {state.errors?.acceptPrivacyPolicy?.[0] && (
            <p
              id="acceptPrivacyPolicy-error"
              role="alert"
              aria-live="polite"
              className="text-xs text-destructive"
            >
              {state.errors.acceptPrivacyPolicy[0]}
            </p>
          )}
        </div>
      </div>

      {state.errors?._form?.[0] && (
        <p
          role="alert"
          aria-live="polite"
          className="rounded-md border border-destructive/50 bg-destructive/10 p-3 text-sm text-destructive"
        >
          {state.errors._form[0]}
        </p>
      )}

      <Button type="submit" className="w-full" disabled={pending}>
        {pending ? "Wird erstellt…" : "Account erstellen"}
      </Button>
    </form>
  );
}

function FormField({
  id,
  name,
  label,
  type = "text",
  required,
  autoComplete,
  helperText,
  defaultValue,
  error,
}: {
  id: string;
  name: string;
  label: string;
  type?: string;
  required?: boolean;
  autoComplete?: string;
  helperText?: string;
  defaultValue?: string;
  error?: string;
}) {
  const errorId = error ? `${id}-error` : undefined;
  const helperId = !error && helperText ? `${id}-helper` : undefined;
  return (
    <div className="space-y-1.5">
      <Label htmlFor={id}>{label}</Label>
      <Input
        id={id}
        name={name}
        type={type}
        required={required}
        autoComplete={autoComplete}
        defaultValue={defaultValue}
        aria-invalid={!!error}
        aria-describedby={errorId ?? helperId}
      />
      {error ? (
        <p
          id={errorId}
          role="alert"
          aria-live="polite"
          className="text-xs text-destructive"
        >
          {error}
        </p>
      ) : helperText ? (
        <p id={helperId} className="text-xs text-muted-foreground">
          {helperText}
        </p>
      ) : null}
    </div>
  );
}