"use client";

import { useState, useEffect } from "react";
import { Card, Button, Input } from "@/shared/components";
import { useRouter } from "next/navigation";
import Link from "next/link";

export default function LoginPage() {
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [resetHint, setResetHint] = useState("");
  const [retryAfter, setRetryAfter] = useState(0);
  const [loading, setLoading] = useState(false);
  const [hasPassword, setHasPassword] = useState(null);
  const [authMode, setAuthMode] = useState("password");
  const [oidcConfigured, setOidcConfigured] = useState(false);
  const [oidcLoginLabel, setOidcLoginLabel] = useState("Sign in with OIDC");
  const router = useRouter();

  // Countdown for rate-limit
  useEffect(() => {
    if (retryAfter <= 0) return;
    const id = setInterval(() => setRetryAfter((s) => (s > 0 ? s - 1 : 0)), 1000);
    return () => clearInterval(id);
  }, [retryAfter]);

  useEffect(() => {
    async function checkAuth() {
      const controller = new AbortController();
      const timeoutId = setTimeout(() => controller.abort(), 5000);
      const baseUrl = typeof window !== "undefined" ? window.location.origin : "";

      try {
        const res = await fetch(`${baseUrl}/api/auth/status`, {
          signal: controller.signal,
        });
        clearTimeout(timeoutId);

        if (res.ok) {
          const data = await res.json();
          if (data.requireLogin === false) {
            router.push("/dashboard");
            router.refresh();
            return;
          }
          setHasPassword(!!data.hasPassword);
          setAuthMode(data.authMode || "password");
          setOidcConfigured(data.oidcConfigured === true);
          setOidcLoginLabel(data.oidcLoginLabel || "Sign in with OIDC");
        } else {
          // Safe fallback on non-OK response to avoid infinite loading state.
          setHasPassword(true);
        }
      } catch (err) {
        clearTimeout(timeoutId);
        setHasPassword(true);
      }
    }
    checkAuth();
  }, [router]);

  const handleLogin = async (e) => {
    e.preventDefault();
    setLoading(true);
    setError("");
    setResetHint("");

    try {
      const res = await fetch("/api/auth/login", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ username: username.trim(), password }),
      });

      if (res.ok) {
        router.push("/dashboard");
        router.refresh();
      } else {
        const data = await res.json();
        setError(data.error || "Invalid credentials");
        if (data.resetHint) setResetHint(data.resetHint);
        if (data.retryAfter) setRetryAfter(Number(data.retryAfter));
      }
    } catch (err) {
      setError("An error occurred. Please try again.");
    } finally {
      setLoading(false);
    }
  };

  const handleOidcLogin = () => {
    window.location.href = "/api/auth/oidc/start";
  };

  const oidcAvailable = oidcConfigured && ["oidc", "both"].includes(authMode);
  const passwordAvailable = authMode !== "oidc" || !oidcConfigured;

  // Show loading state while checking password
  if (hasPassword === null) {
    return (
      <div className="min-h-screen flex items-center justify-center bg-bg p-4">
        <div className="text-center">
          <div className="inline-block animate-spin rounded-full h-8 w-8 border-b-2 border-primary"></div>
          <p className="text-text-muted mt-4">Loading...</p>
        </div>
      </div>
    );
  }

  return (
    <div className="min-h-screen flex items-center justify-center bg-bg p-4 relative overflow-hidden">
      {/* Faint grid background */}
      <div className="landing-grid absolute inset-0 pointer-events-none" aria-hidden="true" />
      <div className="relative z-10 w-full max-w-md">
        <div className="text-center mb-8">
          {/* eslint-disable-next-line @next/next/no-img-element */}
          <img src="/kentutai-icon.png" alt="KentutAI" className="w-16 h-16 mx-auto mb-4 object-contain" />
          <h1 className="text-3xl font-bold text-primary mb-2">KentutAI</h1>
          <p className="text-text-muted">
            {authMode === "oidc" && oidcConfigured
              ? "Sign in with your OIDC provider to access the dashboard"
              : "Enter your credentials to access the dashboard"}
          </p>
        </div>

        <Card>
          <div className="flex flex-col gap-4">
            {oidcAvailable && (
              <Button type="button" variant="primary" className="w-full" onClick={handleOidcLogin}>
                {oidcLoginLabel}
              </Button>
            )}

            {oidcAvailable && passwordAvailable && <div className="h-px bg-border/60" />}

            {passwordAvailable ? (
              <form onSubmit={handleLogin} className="flex flex-col gap-4">
                {((authMode === "oidc" && !oidcConfigured) || (authMode === "both" && !oidcConfigured)) && (
                  <p className="text-xs text-amber-600 dark:text-amber-400 text-center">
                    OIDC login is enabled, but the issuer/client fields are not configured yet. Password login is still available for recovery.
                  </p>
                )}

                {authMode === "both" && oidcConfigured && (
                  <p className="text-xs text-text-muted text-center">
                    Password and OIDC login are both enabled.
                  </p>
                )}

                <div className="flex flex-col gap-3">
                  <Input
                    label="Username"
                    type="text"
                    placeholder="Enter username"
                    value={username}
                    onChange={(e) => setUsername(e.target.value)}
                    required
                    autoFocus={!oidcAvailable}
                    data-testid="login-username"
                  />
                  <Input
                    label="Password"
                    type="password"
                    placeholder="Enter password"
                    value={password}
                    onChange={(e) => setPassword(e.target.value)}
                    required
                    data-testid="login-password"
                  />
                  {error && <p className="text-xs text-red-500">{error}</p>}
                  {retryAfter > 0 && (
                    <p className="text-xs text-amber-600 dark:text-amber-400">
                      Locked. Retry in <span className="font-mono">{retryAfter}s</span>.
                    </p>
                  )}
                  {resetHint && (
                    <p className="text-xs text-text-muted">
                      Forgot password? Open <code className="bg-sidebar px-1 rounded">kentutai</code> CLI on the host → <b>Settings</b> → <b>Reset Password to Default</b>.
                    </p>
                  )}
                </div>

                <Button
                  type="submit"
                  variant="primary"
                  className="w-full"
                  loading={loading}
                  disabled={retryAfter > 0}
                >
                  {retryAfter > 0 ? `Wait ${retryAfter}s` : "Login"}
                </Button>

                <p className="text-sm text-center text-text-muted mt-2">
                  Don't have an account?{" "}
                  <Link href="/register" className="text-primary hover:underline">
                    Register
                  </Link>
                </p>
                {hasPassword === false && (
                  <p className="text-xs text-center text-text-muted">
                    No custom password is set yet. The default password above will work until you change it.
                  </p>
                )}
              </form>
            ) : (
              error && <p className="text-xs text-red-500">{error}</p>
            )}
          </div>
        </Card>
      </div>
    </div>
  );
}
