import { useState } from "react";
import { Link, useNavigate } from "react-router-dom";
import { registerUser, loginUser, getMe, setClientTokens } from "../api/client";
import { useAuthStore } from "../stores/auth";

interface FormState {
  full_name: string;
  email: string;
  password: string;
}

interface Errors {
  full_name?: string;
  email?: string;
  password?: string;
  global?: string;
}

export default function RegisterPage() {
  const navigate = useNavigate();
  const login = useAuthStore((s) => s.login);
  const isAuthenticated = useAuthStore((s) => s.isAuthenticated);

  const [form, setForm] = useState<FormState>({
    full_name: "",
    email: "",
    password: "",
  });
  const [errors, setErrors] = useState<Errors>({});
  const [isLoading, setIsLoading] = useState(false);

  if (isAuthenticated) {
    navigate("/", { replace: true });
    return null;
  }

  function validate(): boolean {
    const errs: Errors = {};
    if (!form.full_name.trim() || form.full_name.trim().length < 2)
      errs.full_name = "Nom complet requis (2 caractères minimum)";
    if (!form.email) errs.email = "Email requis";
    else if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(form.email))
      errs.email = "Email invalide";
    if (!form.password || form.password.length < 8)
      errs.password = "Mot de passe requis (8 caractères minimum)";
    setErrors(errs);
    return Object.keys(errs).length === 0;
  }

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    if (!validate()) return;

    setIsLoading(true);
    setErrors({});
    try {
      await registerUser(form.email, form.password, form.full_name.trim());
      // Auto-login after registration
      const tokens = await loginUser(form.email, form.password);
      setClientTokens(tokens.access_token, tokens.refresh_token);
      const user = await getMe();
      login(user, tokens.access_token, tokens.refresh_token);
      navigate("/", { replace: true });
    } catch (err) {
      const isConflict =
        err instanceof Error && err.message.toLowerCase().includes("409");
      setErrors({
        global: isConflict
          ? "Cet email est déjà utilisé"
          : "Erreur lors de l'inscription, veuillez réessayer",
      });
    } finally {
      setIsLoading(false);
    }
  }

  return (
    <div className="flex min-h-screen items-center justify-center bg-gray-50 p-4">
      <div className="w-full max-w-sm">
        <div className="mb-8 text-center">
          <h1 className="text-2xl font-bold text-slate-800">Budget Tracker</h1>
          <p className="mt-1 text-sm text-slate-500">Créez votre compte</p>
        </div>

        <div className="rounded-xl bg-white p-6 shadow-sm ring-1 ring-slate-200">
          {errors.global && (
            <div className="mb-4 rounded-lg bg-red-50 px-3 py-2 text-sm text-red-600">
              {errors.global}
            </div>
          )}

          <form onSubmit={handleSubmit} className="space-y-4" noValidate>
            <div>
              <label
                htmlFor="full_name"
                className="mb-1.5 block text-sm font-medium text-slate-700"
              >
                Nom complet
              </label>
              <input
                id="full_name"
                type="text"
                autoComplete="name"
                value={form.full_name}
                onChange={(e) =>
                  setForm((f) => ({ ...f, full_name: e.target.value }))
                }
                className={`w-full rounded-lg border px-3 py-2 text-sm outline-none focus:ring-2 focus:ring-primary/30 ${
                  errors.full_name ? "border-red-400" : "border-slate-200"
                }`}
                placeholder="Jean Dupont"
              />
              {errors.full_name && (
                <p className="mt-1 text-xs text-red-500">{errors.full_name}</p>
              )}
            </div>

            <div>
              <label
                htmlFor="email"
                className="mb-1.5 block text-sm font-medium text-slate-700"
              >
                Email
              </label>
              <input
                id="email"
                type="email"
                autoComplete="email"
                value={form.email}
                onChange={(e) =>
                  setForm((f) => ({ ...f, email: e.target.value }))
                }
                className={`w-full rounded-lg border px-3 py-2 text-sm outline-none focus:ring-2 focus:ring-primary/30 ${
                  errors.email ? "border-red-400" : "border-slate-200"
                }`}
                placeholder="vous@exemple.com"
              />
              {errors.email && (
                <p className="mt-1 text-xs text-red-500">{errors.email}</p>
              )}
            </div>

            <div>
              <label
                htmlFor="password"
                className="mb-1.5 block text-sm font-medium text-slate-700"
              >
                Mot de passe
              </label>
              <input
                id="password"
                type="password"
                autoComplete="new-password"
                value={form.password}
                onChange={(e) =>
                  setForm((f) => ({ ...f, password: e.target.value }))
                }
                className={`w-full rounded-lg border px-3 py-2 text-sm outline-none focus:ring-2 focus:ring-primary/30 ${
                  errors.password ? "border-red-400" : "border-slate-200"
                }`}
                placeholder="8 caractères minimum"
              />
              {errors.password && (
                <p className="mt-1 text-xs text-red-500">{errors.password}</p>
              )}
            </div>

            <button
              type="submit"
              disabled={isLoading}
              className="w-full rounded-lg bg-primary py-2 text-sm font-medium text-white hover:bg-primary/90 disabled:opacity-50"
            >
              {isLoading ? "Inscription…" : "Créer mon compte"}
            </button>
          </form>
        </div>

        <p className="mt-4 text-center text-sm text-slate-500">
          Déjà un compte ?{" "}
          <Link to="/login" className="font-medium text-primary hover:underline">
            Se connecter
          </Link>
        </p>
      </div>
    </div>
  );
}