'use client';

import './style.scss';
import Link from 'next/link';
import { Checkbox } from '@/components/ui/checkbox';
import { Field, FieldGroup, FieldLabel } from "@/components/ui/field";
import { useState, useEffect, useRef } from 'react';
import { useSearchParams } from 'next/navigation';
import { GoogleLogin } from '@react-oauth/google';
import { fetchApi } from '@/lib/utils/client';
import { LoginRequest } from '@/types/request/auth';
import { LoginResponse } from '@/types/response/auth';
import useAuth from '@/hooks/useAuth';
import { useConfigContext } from '@/contexts/configProvider';

export default function Page()
{
    const { login } = useAuth();
    const config = useConfigContext();
    // 소셜 로그인 on/off (Admin /Config/External) — 값이 없으면(구버전 config) 노출(fail-open), 백엔드가 최종 게이트
    const naverEnabled = config?.external?.naverLoginEnabled !== false;
    const kakaoEnabled = config?.external?.kakaoLoginEnabled !== false;
    const googleEnabled = config?.external?.googleLoginEnabled !== false;
    const searchParams = useSearchParams();
    const [error, setError] = useState<string>('');
    const [loading, setLoading] = useState<boolean>(false);
    const [email, setEmail] = useState<string>('');
    const [password, setPassword] = useState<string>('');
    const [rememberMe, setRememberMe] = useState<boolean>(false);
    const emailRef = useRef<HTMLInputElement>(null);
    const passwordRef = useRef<HTMLInputElement>(null);
    const googleBtnRef = useRef<HTMLDivElement>(null);
    const [googleBtnWidth, setGoogleBtnWidth] = useState<number>(0);

    useEffect(() => {
        if (error) {
            alert(error);
            setError('');
        }
    }, [error]);

    // URL ?error=... 처리 — Google OAuth callback 등 외부에서 리다이렉트된 에러 메시지 표시
    useEffect(() => {
        const urlError = searchParams.get('error');
        if (urlError) {
            setError(urlError);
            // 뒤로가기/새로고침 시 alert 중복 방지를 위해 query 정리
            const url = new URL(window.location.href);
            url.searchParams.delete('error');
            window.history.replaceState({}, '', url.toString());
        }
    }, [searchParams]);

    useEffect(() => {
        if (googleBtnRef.current) {
            const observer = new ResizeObserver(entries => {
                for (const entry of entries) {
                    setGoogleBtnWidth(Math.floor(entry.contentRect.width));
                }
            });
            observer.observe(googleBtnRef.current);
            return () => observer.disconnect();
        }
    }, []);

    // 로그인 검증
    const handleSubmit = async (e: React.FormEvent<HTMLFormElement>) => {
        e.preventDefault();

        try {

            if (email.length < 1) {
                emailRef.current?.focus();
                throw new Error('이메일을 입력하세요.');
            }

            if (password.length < 1) {
                passwordRef.current?.focus();
                throw new Error('비밀번호를 입력하세요.');
            }

            await fetchApi<LoginResponse>('/api/auth/login', {
                method: 'POST',
                body: { Email: email, Password: password } as LoginRequest
            });

            login(rememberMe);

        } catch (err) {
            if (err instanceof Error) {
                setError(err.message);
            }
        } finally {
            setLoading(false);
        }
    }

    // 구글 로그인
    const handleGoogleLogin = async (credentialResponse: { credential?: string }) => {
        try {

            await fetchApi<LoginResponse>('/api/auth/google-login', {
                method: 'POST',
                body: {
                    credential: credentialResponse.credential
                }
            });

            login(rememberMe);

        } catch (err) {
            if (err instanceof Error) {
                setError(err.message);
            }
        }
    };

    const handleGoogleLoginFailed = () => {
        setError('Google 로그인에 실패했습니다.');
    };

    return (
		<>
			<div id="loginForm" className="row-start-2 flex flex-col sm:flex-row gap-2">
				<fieldset className="grow min-w-0 sm:basis-1/2">
					<legend>로그인</legend>
					<form method="post" acceptCharset="utf-8" autoComplete="off" className="grid min-w-0 p-4" onSubmit={handleSubmit}>
						<label htmlFor="email">이메일</label>
						<input type="email" name="email" id="email" ref={emailRef} maxLength={30} onChange={e => setEmail(e.target.value)} autoComplete="off" autoFocus />

						<label htmlFor="password">비밀번호</label>
						<input type="password" name="password" id="password" ref={passwordRef} maxLength={20} onChange={e => setPassword(e.target.value)} />

						<button type="submit" className="btn btn-primary" disabled={loading}>
							{loading ? "로그인 중..." : "로그인"}
						</button>

                        {googleEnabled && (
                            <div ref={googleBtnRef} className='w-full mt-2 pb-1'>
                                {googleBtnWidth > 0 && (
                                    <GoogleLogin
                                        onSuccess={handleGoogleLogin}
                                        onError={handleGoogleLoginFailed}
                                        width={googleBtnWidth}
                                        size="large"
                                        shape="rectangular"
                                        context="signin"
                                        ux_mode="redirect"
                                        login_uri={`${window.location.origin}/login/google/callback`}
                                        logo_alignment="center"
                                    />
                                )}
                            </div>
                        )}

                        {/* Naver/Kakao 소셜 로그인 — start 라우트가 state 생성 후 각사 authorize 로 리다이렉트.
                            route handler 라 Link prefetch 시 OAuth 시작이 실행되므로 일반 <a> 사용.
                            노출 여부는 Admin /Config/External 의 사용 체크박스(config.external.*LoginEnabled)로 제어 */}
                        {(naverEnabled || kakaoEnabled) && (
                            <div className="social-login" role="group" aria-label="소셜 로그인">
                                {naverEnabled && (
                                    <a href="/login/naver/start" className="social-login__button social-login__button--naver">
                                        <span className="social-login__icon social-login__icon--naver" aria-hidden="true">N</span>
                                        <span>네이버 로그인</span>
                                    </a>
                                )}
                                {kakaoEnabled && (
                                    <a href="/login/kakao/start" className="social-login__button social-login__button--kakao">
                                        <svg className="social-login__icon social-login__icon--kakao" viewBox="0 0 24 24" aria-hidden="true">
                                            <path fill="currentColor" d="M12 3C6.48 3 2 6.54 2 10.9c0 2.8 1.86 5.25 4.64 6.65-.2.75-.74 2.72-.85 3.14-.13.53.2.52.41.38.17-.11 2.65-1.8 3.72-2.53.67.1 1.37.15 2.08.15 5.52 0 10-3.53 10-7.89S17.52 3 12 3z"/>
                                        </svg>
                                        <span>카카오 로그인</span>
                                    </a>
                                )}
                            </div>
                        )}
					</form>
                    <hr hidden/>
				</fieldset>
				<fieldset className="grow min-w-0 sm:basis-1/2">
					<dl>
						<dt>아직 회원이 아니신가요?</dt>
						<dd>회원가입 한번으로 커뮤니티에 참여하세요!</dd>
						<dd>
							<Link href="/register">
								<small>＞</small> 회원가입
							</Link>
						</dd>
					</dl>

					<hr />

					<dl>
						<dt>비밀번호를 잊으셨나요?</dt>
						<dd>비밀번호를 깜박했다면 다시 설정할 수 있어요!</dd>
						<dd>
							<Link href="/forgot-password">
								<small>＞</small> 비밀번호 재설정
							</Link>
						</dd>
					</dl>

                    <section className="mt-3">
                        <FieldGroup>
                            <Field orientation="horizontal">
                                <Checkbox name="remember_me" id="rememberMe" checked={rememberMe} onCheckedChange={(checked) => setRememberMe(checked === true)} />
                                <FieldLabel htmlFor="rememberMe">로그인 상태 유지</FieldLabel>
                            </Field>
                        </FieldGroup>
                    </section>
				</fieldset>
			</div>
		</>
    );
}