"use client";

import { authClient, resolveApiBaseUrl, signIn } from "@/lib/auth-client";
import { useRouter } from "next/navigation";
import { useEffect, useState } from "react";

const OTP_STEP_STORAGE_KEY = "hellthhub_login_step_otp";
const OTP_STEP_TTL_MS = 5 * 60 * 1000;

function hasActiveOtpStep(): boolean {
  try {
    const raw = window.localStorage.getItem(OTP_STEP_STORAGE_KEY);
    if (!raw) return false;
    const parsed = JSON.parse(raw) as { expiresAt?: number };
    if (!parsed?.expiresAt || Date.now() > parsed.expiresAt) {
      window.localStorage.removeItem(OTP_STEP_STORAGE_KEY);
      return false;
    }
    return true;
  } catch {
    return false;
  }
}

function setOtpStepActive() {
  try {
    window.localStorage.setItem(
      OTP_STEP_STORAGE_KEY,
      JSON.stringify({ expiresAt: Date.now() + OTP_STEP_TTL_MS }),
    );
  } catch {
    // ignore storage access issues
  }
}

function clearOtpStep() {
  try {
    window.localStorage.removeItem(OTP_STEP_STORAGE_KEY);
  } catch {
    // ignore storage access issues
  }
}

async function assertAuthApiReachable() {
  const controller = new AbortController();
  const timeout = window.setTimeout(() => controller.abort(), 3000);
  try {
    const response = await fetch(`${resolveApiBaseUrl().replace(/\/$/, "")}/api/health`, {
      cache: "no-store",
      signal: controller.signal,
    });
    if (!response.ok) {
      throw new Error(`HTTP ${response.status}`);
    }
  } finally {
    window.clearTimeout(timeout);
  }
}

export default function LoginPage() {
  const router = useRouter();
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [loading, setLoading] = useState(false);
  const [otpStepChecked, setOtpStepChecked] = useState(false);
  const [passkeyAutofillTried, setPasskeyAutofillTried] = useState(false);

  useEffect(() => {
    if (hasActiveOtpStep()) {
      router.replace("/login/otp");
      return;
    }
    setOtpStepChecked(true);
  }, [router]);

  useEffect(() => {
    if (!otpStepChecked || passkeyAutofillTried) return;

    async function tryPasskeyAutofill() {
      setPasskeyAutofillTried(true);
      if (typeof window === "undefined" || !("PublicKeyCredential" in window)) {
        return;
      }

      const pk = window.PublicKeyCredential as typeof PublicKeyCredential & {
        isConditionalMediationAvailable?: () => Promise<boolean>;
      };
      if (typeof pk.isConditionalMediationAvailable !== "function") {
        return;
      }

      try {
        const available = await pk.isConditionalMediationAvailable();
        if (!available) return;

        const result = await authClient.signIn.passkey({ autoFill: true });
        const hasTwoFactorChallenge =
          Boolean(result.data && "twoFactorRedirect" in result.data) ||
          Boolean((result as { twoFactorRedirect?: boolean }).twoFactorRedirect);

        if (result.error) return;
        if (hasTwoFactorChallenge) {
          setOtpStepActive();
          router.push("/login/otp");
          return;
        }
        clearOtpStep();
        router.push("/");
      } catch {
        // Best-effort only; manual login remains available.
      }
    }

    void tryPasskeyAutofill();
  }, [otpStepChecked, passkeyAutofillTried, router]);

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    setError(null);
    setLoading(true);

    try {
      await assertAuthApiReachable();
      const result = await signIn.email({ email, password });
      const hasTwoFactorChallenge =
        Boolean(result.data && "twoFactorRedirect" in result.data) ||
        Boolean((result as { twoFactorRedirect?: boolean }).twoFactorRedirect);

      if (result.error) {
        setError("E-Mail oder Passwort ungültig.");
        return;
      }

      if (hasTwoFactorChallenge) {
        setOtpStepActive();
        router.push("/login/otp");
        return;
      }

      clearOtpStep();

      router.push("/");
    } catch {
      setError(
        "Login derzeit nicht möglich. Bitte prüfe, ob API/Auth auf Port 3002 läuft.",
      );
    } finally {
      setLoading(false);
    }
  }

  async function handlePasskeyLogin() {
    setError(null);
    setLoading(true);
    try {
      const result = await authClient.signIn.passkey();
      const hasTwoFactorChallenge =
        Boolean(result.data && "twoFactorRedirect" in result.data) ||
        Boolean((result as { twoFactorRedirect?: boolean }).twoFactorRedirect);

      if (result.error) {
        const message = (result.error.message ?? "").toLowerCase();
        if (message.includes("cancel")) {
          setError("Passkey-Vorgang abgebrochen.");
          return;
        }
        if (
          window.location.hostname !== "localhost" &&
          (message.includes("origin") || message.includes("rp") || message.includes("domain"))
        ) {
          setError(
            "Passkey auf lokaler Entwicklung bitte unter http://localhost:3001 nutzen (nicht 127.0.0.1 oder ::1).",
          );
          return;
        }
        setError(result.error.message ?? "Passkey-Anmeldung fehlgeschlagen. Bitte erneut versuchen.");
        return;
      }

      if (hasTwoFactorChallenge) {
        setOtpStepActive();
        router.push("/login/otp");
        return;
      }

      clearOtpStep();
      router.push("/");
    } catch {
      setError("Passkey-Anmeldung derzeit nicht möglich.");
    } finally {
      setLoading(false);
    }
  }

  return (
    <div className="relative min-h-screen overflow-hidden bg-gradient-to-br from-[#F5F9F8] via-[#F9FAFB] to-[#ECFDF5]">
      <div
        aria-hidden="true"
        className="pointer-events-none absolute -top-32 -left-32 h-96 w-96 rounded-full bg-[#0F766E]/15 blur-3xl"
      />
      <div
        aria-hidden="true"
        className="pointer-events-none absolute -bottom-40 -right-32 h-[28rem] w-[28rem] rounded-full bg-emerald-200/40 blur-3xl"
      />

      <div className="relative flex min-h-screen items-center justify-center px-4 py-12 sm:px-6">
        {!otpStepChecked ? (
          <div className="h-10 w-10 animate-spin rounded-full border-2 border-[#0F766E] border-t-transparent" />
        ) : (
          <div className="w-full max-w-sm">
            <div className="mb-8 flex flex-col items-center text-center">
              <div className="mb-5 flex h-16 w-16 items-center justify-center rounded-2xl bg-gradient-to-br from-[#0F766E] to-[#0d9488] text-xl font-bold text-white shadow-lg shadow-[#0F766E]/25 ring-1 ring-white/40">
                HH
              </div>
              <h1 className="text-2xl font-bold tracking-tight text-gray-900">Hellth Hub</h1>
              <p className="mt-1.5 text-sm text-gray-500">
                Health-Tracking fuer dein Home-Lab
              </p>
            </div>

            <div className="rounded-2xl border border-gray-100 bg-white/90 p-6 shadow-xl shadow-gray-900/5 backdrop-blur sm:p-7">
              <form onSubmit={handleSubmit} className="space-y-4">
                {error && (
                  <div
                    role="alert"
                    className="flex items-start gap-2 rounded-lg border border-red-100 bg-red-50 px-3 py-2.5 text-sm text-red-700"
                  >
                    <span aria-hidden="true" className="mt-0.5 font-bold text-red-500">
                      !
                    </span>
                    <span>{error}</span>
                  </div>
                )}

                <div>
                  <label htmlFor="login-email" className="mb-1.5 block text-sm font-medium text-gray-700">
                    E-Mail
                  </label>
                  <input
                    id="login-email"
                    type="email"
                    required
                    autoComplete="username webauthn"
                    value={email}
                    onChange={(e) => setEmail(e.target.value)}
                    placeholder="du@example.com"
                    className="w-full rounded-lg border border-gray-200 bg-white px-3.5 py-2.5 text-sm text-gray-900 placeholder-gray-400 transition-shadow focus:border-[#0F766E] focus:outline-none focus:ring-2 focus:ring-[#0F766E]/20"
                  />
                </div>

                <div>
                  <label htmlFor="login-password" className="mb-1.5 block text-sm font-medium text-gray-700">
                    Passwort
                  </label>
                  <input
                    id="login-password"
                    type="password"
                    required
                    autoComplete="current-password"
                    value={password}
                    onChange={(e) => setPassword(e.target.value)}
                    placeholder="••••••••••••"
                    className="w-full rounded-lg border border-gray-200 bg-white px-3.5 py-2.5 text-sm text-gray-900 placeholder-gray-400 transition-shadow focus:border-[#0F766E] focus:outline-none focus:ring-2 focus:ring-[#0F766E]/20"
                  />
                </div>

                <button
                  type="submit"
                  disabled={loading}
                  className="mt-1 inline-flex w-full items-center justify-center gap-2 rounded-lg bg-[#0F766E] py-2.5 text-sm font-semibold text-white shadow-sm transition-colors hover:bg-[#115E59] disabled:cursor-not-allowed disabled:opacity-50"
                >
                  {loading ? (
                    <span className="inline-block h-4 w-4 animate-spin rounded-full border-2 border-white/40 border-t-white" />
                  ) : null}
                  {loading ? "Anmelden..." : "Anmelden"}
                </button>

                <div className="relative pt-1">
                  <div aria-hidden="true" className="absolute inset-0 flex items-center">
                    <div className="w-full border-t border-gray-200" />
                  </div>
                  <div className="relative flex justify-center">
                    <span className="bg-white px-3 text-xs uppercase tracking-wider text-gray-400">
                      oder
                    </span>
                  </div>
                </div>

                <button
                  type="button"
                  onClick={handlePasskeyLogin}
                  disabled={loading}
                  className="inline-flex w-full items-center justify-center gap-2 rounded-lg border border-gray-200 bg-white py-2.5 text-sm font-semibold text-gray-800 transition-colors hover:bg-gray-50 disabled:cursor-not-allowed disabled:opacity-50"
                >
                  <svg
                    aria-hidden="true"
                    viewBox="0 0 24 24"
                    fill="none"
                    stroke="currentColor"
                    strokeWidth="1.8"
                    className="h-4 w-4 text-[#0F766E]"
                  >
                    <path
                      strokeLinecap="round"
                      strokeLinejoin="round"
                      d="M15.75 5.25a3 3 0 11-6 0 3 3 0 016 0zM4.5 19.5l4.5-7.5h6l4.5 7.5"
                    />
                  </svg>
                  Mit Passkey anmelden
                </button>
              </form>
            </div>

            <p className="mt-6 text-center text-xs text-gray-400">
              Geschuetzt durch 2FA, Passkeys und verschluesselte Verbindungen.
            </p>
          </div>
        )}
      </div>
    </div>
  );
}