import { useEffect } from "react";
import { Form, Link, useNavigate, useNavigation, useSearchParams } from "react-router";
import { useTranslation } from "react-i18next";
import { FeatherArrowLeft, FeatherMail, FeatherRotateCw, FeatherWand2 } from "@subframe/core";
import { Button } from "~/ui/components/Button";
import { LinkButton } from "~/ui/components/LinkButton";
import { TextInput } from "~/ui/components/TextInput";
import { useRootData } from "~/utils/data/useRootData";
import { AuthShell, AuthStatus, AuthDivider } from "~/components/auth/AuthShell";
import type { LoginActionData } from "~/modules/users/components/LoginForm";

// Login-Screen nach Davids Subframe-Design ("Login"): Logo + Card (Anmelden/Willkommen zurueck) +
// E-Mail/Passwort + "Passwort vergessen?" + Anmelden + "oder" + Magic-Link + Footer "Registrieren".
// Voll an die bestehende Login-Action verdrahtet (action=login, csrf, redirectTo, Feldfehler, 2FA-Redirect).
// Reines ~/ui (TextInput/Button/LinkButton) + AuthShell. Wird vom Login-Route fuer den NICHT-Admin-Pfad
// gerendert; der Admin-/SSO-Pfad bleibt in login.tsx unveraendert.

export default function LoginScreen({
  actionData,
  redirectTo,
}: {
  actionData: LoginActionData | null | undefined;
  redirectTo?: string;
}) {
  const { t } = useTranslation();
  const { csrf } = useRootData();
  const navigation = useNavigation();
  const navigate = useNavigate();
  const [searchParams] = useSearchParams();
  const isSubmitting = navigation.state !== "idle";
  const mfaVerifyPath = actionData?.mfaVerifyPath ?? "/login-mfa";
  const emailError = actionData?.fieldErrors?.email;
  const passwordError = actionData?.fieldErrors?.password;

  // D1 — Passwort ok, aber 2FA noetig: Pending-Cookie ist gesetzt, jetzt zur Verify-Route.
  useEffect(() => {
    if (actionData?.requiresMfa) {
      navigate(mfaVerifyPath);
    }
  }, [actionData?.requiresMfa, mfaVerifyPath, navigate]);

  if (actionData?.requiresMfa) {
    return (
      <AuthShell title={t("account.loginMfa.title")} dataUiId="ui.auth.login.page">
        <div className="flex flex-col items-center gap-3 text-center" data-ui-id="ui.auth.login.mfaRedirect">
          <p className="text-body-small-regular-0 font-body-small-regular-0 text-text-neutral-tertiary">
            {t("account.loginMfa.redirecting")}
          </p>
          <Link to={mfaVerifyPath} className="no-underline" data-ui-id="ui.auth.login.mfaContinue">
            <LinkButton hideIcon>{t("account.loginMfa.continue")}</LinkButton>
          </Link>
        </div>
      </AuthShell>
    );
  }

  // D-D0a — Magic-Link ausgegeben -> Davids "Link gesendet"-Screen (AuthStatus).
  if (actionData?.magicLinkSent) {
    return (
      <AuthStatus
        icon={<FeatherMail />}
        tone="positive"
        title={t("account.login.magicLinkSentTitle")}
        message={t("account.login.magicLinkSentBody", { email: actionData.magicLinkEmail ?? "" })}
        hint={t("account.login.magicLinkSentHint")}
        dataUiId="ui.auth.login.magicLinkSent"
      >
        <Form method="post" className="contents">
          <input type="hidden" name="intent" value="magicLink" readOnly />
          <input type="hidden" name="csrf" value={csrf} readOnly />
          <input type="hidden" name="email" value={actionData.magicLinkEmail ?? ""} readOnly />
          <LinkButton type="submit" size="small" icon={<FeatherRotateCw />} disabled={isSubmitting} data-ui-id="ui.auth.login.magicLinkResend">
            {t("account.login.magicLinkResend")}
          </LinkButton>
        </Form>
        <LinkButton size="small" icon={<FeatherArrowLeft />} onClick={() => navigate("/login")} data-ui-id="ui.auth.login.backToLogin">
          {t("account.login.backToLogin")}
        </LinkButton>
      </AuthStatus>
    );
  }

  return (
    <AuthShell
      title={t("account.login.title")}
      subtitle={t("account.login.headline")}
      titleAlign="center"
      dataUiId="ui.auth.login.page"
      footer={
        <>
          <span className="text-body-small-regular-0 font-body-small-regular-0 text-text-neutral-tertiary">
            {t("account.login.noAccount")}
          </span>
          <Link to="/register" className="no-underline" data-ui-id="ui.auth.login.register">
            <LinkButton size="small" hideIcon>
              {t("account.login.register")}
            </LinkButton>
          </Link>
        </>
      }
    >
      <Form id="loginForm" method="post" noValidate className="flex w-full flex-col gap-4" data-ui-id="ui.auth.login.form">
        <input type="hidden" name="action" value="login" readOnly />
        <input type="hidden" name="csrf" value={csrf} readOnly />
        <input
          type="hidden"
          name="redirectTo"
          value={redirectTo ?? searchParams.get("redirect") ?? searchParams.get("redirectTo") ?? ""}
          readOnly
        />

        <TextInput
          className="h-auto w-full flex-none"
          showLabel
          label={t("account.shared.email")}
          helpText={emailError ?? ""}
          error={!!emailError}
          type="email"
        >
          <TextInput.Input
            name="email"
            type="email"
            required
            autoFocus
            autoComplete="email"
            placeholder={t("account.shared.emailPlaceholder")}
            defaultValue={actionData?.fields?.email}
            disabled={isSubmitting}
            data-ui-id="ui.auth.login.email"
          />
        </TextInput>

        <TextInput
          className="h-auto w-full flex-none"
          showLabel
          label={t("account.shared.password")}
          helpText={passwordError ?? ""}
          error={!!passwordError}
          type="password"
        >
          <TextInput.Input
            name="password"
            type="password"
            required
            autoComplete="current-password"
            placeholder=""
            defaultValue={actionData?.fields?.password}
            disabled={isSubmitting}
            data-ui-id="ui.auth.login.password"
          />
        </TextInput>

        <Link to="/forgot-password" className="no-underline" data-ui-id="ui.auth.login.forgot">
          <LinkButton size="small" hideIcon>
            {t("account.login.forgot")}
          </LinkButton>
        </Link>

        <Button type="submit" loading={isSubmitting} disabled={isSubmitting} data-ui-id="ui.auth.login.submit">
          {t("account.login.button")}
        </Button>

        {actionData?.error && navigation.state === "idle" ? (
          <p className="text-center text-body-small-regular-0 font-body-small-regular-0 text-text-feedback-negative" role="alert">
            {actionData.error}
          </p>
        ) : null}
      </Form>

      <AuthDivider label={t("account.login.divider")} />

      {/* Magic-Link-Login: submitet die Login-Form (via form="loginForm") mit intent=magicLink ->
          login-Action gibt den Login-Magic-Link aus -> "Link gesendet"-Screen. */}
      <Button
        type="submit"
        form="loginForm"
        name="intent"
        value="magicLink"
        variant="secondary"
        icon={<FeatherWand2 />}
        loading={isSubmitting}
        data-ui-id="ui.auth.login.magicLink"
      >
        {t("account.login.magicLink")}
      </Button>
    </AuthShell>
  );
}