"use client";

import { useEffect, useState } from "react";
import Link from "next/link";
import { signInWithEmailAndPassword, GoogleAuthProvider, signInWithPopup } from "firebase/auth";
import { auth } from "@/lib/firebase";
import { c2api } from "@/lib/c2api";
import { useRouter } from "next/navigation";
import { useAuth } from "@/components/AuthProvider";
import { describeAuthError } from "@/lib/authErrors";

export default function LoginPage() {
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [misconfigured, setMisconfigured] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const router = useRouter();
  const { user, loading: authLoading, orgId } = useAuth();

  // Do NOT navigate straight from the sign-in handlers below: signInWith*
  // resolves before AuthProvider's onAuthStateChanged listener has fetched
  // claims and set/cleared the drb_session cookie. Pushing to /dashboard
  // immediately races that — for a no-org account the cookie never gets
  // set, so middleware.ts bounces the very next request straight back to
  // /login, which is the ping-pong this screen used to cause. Instead,
  // react to AuthProvider's own settled state: this also covers a user who
  // arrives here already signed in (e.g. redirected from a protected route
  // by middleware while their Firebase session was still valid) — same
  // destination logic, no separate code path, no bounce.
  useEffect(() => {
    if (authLoading) return;
    if (!user) return;
    router.replace(orgId ? "/dashboard" : "/onboarding");
  }, [authLoading, user, orgId, router]);

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    setSubmitting(true);
    setError(null);
    setMisconfigured(false);
    try {
      await signInWithEmailAndPassword(auth, email, password);
      c2api.recordSession().catch(() => {});
      // Redirect happens via the effect above once claims are settled.
    } catch (err) {
      const info = describeAuthError(err, "Invalid email or password.");
      setError(info.message);
      setMisconfigured(info.misconfiguration);
      setSubmitting(false);
    }
  }

  async function handleGoogle() {
    setSubmitting(true);
    setError(null);
    setMisconfigured(false);
    try {
      await signInWithPopup(auth, new GoogleAuthProvider());
      c2api.recordSession().catch(() => {});
      // Redirect happens via the effect above once claims are settled.
    } catch (err) {
      const info = describeAuthError(err, "Google sign-in failed. Try again.");
      setError(info.message);
      setMisconfigured(info.misconfiguration);
      setSubmitting(false);
    }
  }

  const loading = submitting || !!user;

  return (
    <div className="max-w-sm mx-auto pt-16">
      <Link href="/" className="flex items-center justify-center gap-2 mb-6 font-mono font-bold text-white">
        <span className="inline-flex items-center justify-center w-8 h-8 rounded-lg bg-indigo-600 text-white">D</span>
        DRB
      </Link>
      <div className="bg-gray-900 border border-gray-700 rounded-xl p-8 space-y-5 font-mono">
        <h1 className="text-white text-lg font-bold">Sign in</h1>

        <form onSubmit={handleSubmit} className="space-y-4">
          <div>
            <label className="text-xs text-gray-400 block mb-1">Email</label>
            <input
              type="email"
              value={email}
              onChange={(e) => setEmail(e.target.value)}
              required
              autoComplete="email"
              className="w-full bg-gray-800 border border-gray-700 rounded-lg px-3 py-2 text-white text-sm focus:outline-none focus:border-indigo-500"
            />
          </div>
          <div>
            <label className="text-xs text-gray-400 block mb-1">Password</label>
            <input
              type="password"
              value={password}
              onChange={(e) => setPassword(e.target.value)}
              required
              autoComplete="current-password"
              className="w-full bg-gray-800 border border-gray-700 rounded-lg px-3 py-2 text-white text-sm focus:outline-none focus:border-indigo-500"
            />
          </div>
          {error && (
            <p className={`text-xs ${misconfigured ? "text-amber-400" : "text-red-400"}`}>{error}</p>
          )}
          <button
            type="submit"
            disabled={loading}
            className="w-full bg-indigo-600 hover:bg-indigo-500 disabled:opacity-50 text-white rounded-lg py-2 text-sm font-semibold transition-colors"
          >
            {loading ? "Signing in…" : "Sign in"}
          </button>
        </form>

        <div className="flex items-center gap-3">
          <div className="flex-1 h-px bg-gray-700" />
          <span className="text-xs text-gray-500">or</span>
          <div className="flex-1 h-px bg-gray-700" />
        </div>

        <button
          type="button"
          onClick={handleGoogle}
          disabled={loading}
          className="w-full flex items-center justify-center gap-3 bg-white hover:bg-gray-100 disabled:opacity-50 text-gray-900 rounded-lg py-2 text-sm font-semibold transition-colors"
        >
          <svg width="18" height="18" viewBox="0 0 18 18" xmlns="http://www.w3.org/2000/svg">
            <path d="M17.64 9.2c0-.637-.057-1.251-.164-1.84H9v3.481h4.844c-.209 1.125-.843 2.078-1.796 2.717v2.258h2.908c1.702-1.567 2.684-3.875 2.684-6.615z" fill="#4285F4"/>
            <path d="M9 18c2.43 0 4.467-.806 5.956-2.184l-2.908-2.258c-.806.54-1.837.859-3.048.859-2.344 0-4.328-1.584-5.036-3.711H.957v2.332C2.438 15.983 5.482 18 9 18z" fill="#34A853"/>
            <path d="M3.964 10.706A5.41 5.41 0 0 1 3.682 9c0-.593.102-1.17.282-1.706V4.962H.957A8.996 8.996 0 0 0 0 9c0 1.452.348 2.827.957 4.038l3.007-2.332z" fill="#FBBC05"/>
            <path d="M9 3.58c1.321 0 2.508.454 3.44 1.345l2.582-2.58C13.463.891 11.426 0 9 0 5.482 0 2.438 2.017.957 4.962L3.964 6.294C4.672 4.169 6.656 3.58 9 3.58z" fill="#EA4335"/>
          </svg>
          Continue with Google
        </button>

        <p className="text-center text-xs text-gray-500">
          Don&apos;t have an account?{" "}
          <Link href="/signup" className="text-indigo-400 hover:text-indigo-300 transition-colors">Sign up</Link>
        </p>
      </div>
    </div>
  );
}