"use client";

import { useState, type FormEvent } from "react";

import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { parseAuthIdentity, type AuthIdentity } from "@/lib/auth/types";

type LoginScreenProps = {
  onAuthenticated: (token: string, user: AuthIdentity) => void;
};

type LoginResponse = {
  token: string;
  user: AuthIdentity;
};

export function LoginScreen({ onAuthenticated }: LoginScreenProps) {
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [isSubmitting, setIsSubmitting] = useState(false);
  const [error, setError] = useState("");

  async function handleSubmit(event: FormEvent<HTMLFormElement>) {
    event.preventDefault();

    if (!email.trim() || !password.trim() || isSubmitting) {
      return;
    }

    setIsSubmitting(true);
    setError("");

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

      if (!response.ok) {
        throw new Error("Login failed");
      }

      const payload = parseLoginResponse(await response.json());

      if (!payload) {
        throw new Error("Invalid login response");
      }

      onAuthenticated(payload.token, payload.user);
    } catch {
      setError("Не удалось войти. Проверьте логин и пароль.");
    } finally {
      setIsSubmitting(false);
    }
  }

  return (
    <main className="flex min-h-screen items-center justify-center bg-muted/30 p-6">
      <section className="w-full max-w-sm rounded-lg border bg-background p-8 shadow-sm">
        <p className="mb-6 text-sm font-medium text-muted-foreground">
          AI Control Center
        </p>
        <h1 className="text-2xl font-semibold">Вход</h1>
        <form className="mt-6 space-y-4" onSubmit={handleSubmit}>
          <div className="space-y-2">
            <label className="text-sm font-medium" htmlFor="email">
              Логин или почта
            </label>
            <Input
              autoComplete="username"
              id="email"
              onChange={(event) => setEmail(event.target.value)}
              type="text"
              value={email}
            />
          </div>
          <div className="space-y-2">
            <label className="text-sm font-medium" htmlFor="password">
              Пароль
            </label>
            <Input
              autoComplete="current-password"
              id="password"
              onChange={(event) => setPassword(event.target.value)}
              type="password"
              value={password}
            />
          </div>
          <p aria-live="polite" className="min-h-5 text-sm text-destructive">
            {error}
          </p>
          <Button
            className="w-full"
            disabled={!email.trim() || !password.trim() || isSubmitting}
            type="submit"
          >
            {isSubmitting ? "Выполняем вход…" : "Продолжить"}
          </Button>
        </form>
      </section>
    </main>
  );
}

function parseLoginResponse(value: unknown): LoginResponse | null {
  if (
    typeof value !== "object" ||
    value === null ||
    !("token" in value) ||
    typeof value.token !== "string" ||
    !value.token ||
    !("user" in value)
  ) {
    return null;
  }

  const user = parseAuthIdentity(value.user);
  return user ? { token: value.token, user } : null;
}