package com.gcsc.guide.auth;

import com.gcsc.guide.dto.AuthResponse;
import com.gcsc.guide.dto.GoogleLoginRequest;
import com.gcsc.guide.dto.UserResponse;
import com.gcsc.guide.entity.User;
import com.gcsc.guide.repository.UserRepository;
import com.gcsc.guide.service.ActivityService;
import com.google.api.client.googleapis.auth.oauth2.GoogleIdToken;
import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.media.Content;
import io.swagger.v3.oas.annotations.media.Schema;
import io.swagger.v3.oas.annotations.responses.ApiResponse;
import io.swagger.v3.oas.annotations.responses.ApiResponses;
import io.swagger.v3.oas.annotations.security.SecurityRequirement;
import io.swagger.v3.oas.annotations.tags.Tag;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.validation.Valid;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.security.core.Authentication;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.server.ResponseStatusException;

@Slf4j
@RestController
@RequestMapping("/api/auth")
@RequiredArgsConstructor
@Tag(name = "01. 인증", description = "Google OAuth2 로그인 및 JWT 토큰 관리")
public class AuthController {

    private static final String AUTO_ADMIN_EMAIL = "htlee@gcsc.co.kr";

    private final GoogleTokenVerifier googleTokenVerifier;
    private final JwtTokenProvider jwtTokenProvider;
    private final UserRepository userRepository;
    private final ActivityService activityService;

    @Operation(summary = "Google 로그인",
        description = "Google ID Token을 검증하고 JWT를 발급합니다. "
            + "신규 사용자는 PENDING 상태로 생성되며, htlee@gcsc.co.kr은 자동 ACTIVE + 관리자 부여됩니다.",
        security = {})
    @ApiResponses({
        @ApiResponse(responseCode = "200", description = "로그인 성공, JWT 토큰 발급",
            content = @Content(schema = @Schema(implementation = AuthResponse.class))),
        @ApiResponse(responseCode = "401", description = "유효하지 않은 Google 토큰 또는 허용되지 않은 이메일 도메인",
            content = @Content)
    })
    @PostMapping("/google")
    public ResponseEntity<AuthResponse> googleLogin(
            @Valid @RequestBody GoogleLoginRequest request,
            HttpServletRequest httpRequest) {
        GoogleIdToken.Payload payload = googleTokenVerifier.verify(request.idToken());
        if (payload == null) {
            throw new ResponseStatusException(HttpStatus.UNAUTHORIZED, "유효하지 않은 Google 토큰입니다");
        }

        String email = payload.getEmail();
        String name = (String) payload.get("name");
        String avatarUrl = (String) payload.get("picture");

        userRepository.findByEmail(email)
            .ifPresentOrElse(
                existingUser -> {
                    existingUser.updateProfile(name, avatarUrl);
                    existingUser.updateLastLogin();
                    userRepository.save(existingUser);
                },
                () -> createNewUser(email, name, avatarUrl)
            );

        User userWithRoles = userRepository.findByEmailWithRoles(email)
            .orElseThrow();

        activityService.recordLogin(
            userWithRoles.getId(),
            httpRequest.getRemoteAddr(),
            httpRequest.getHeader("User-Agent"));

        String token = jwtTokenProvider.generateToken(
            userWithRoles.getId(), userWithRoles.getEmail(), userWithRoles.isAdmin());

        return ResponseEntity.ok(new AuthResponse(token, UserResponse.from(userWithRoles)));
    }

    @Operation(summary = "현재 사용자 정보 조회",
        description = "JWT 토큰으로 인증된 현재 사용자의 상세 정보와 롤 목록을 반환합니다.")
    @ApiResponses({
        @ApiResponse(responseCode = "200", description = "사용자 정보 조회 성공"),
        @ApiResponse(responseCode = "401", description = "인증 실패 (토큰 없음/만료)", content = @Content),
        @ApiResponse(responseCode = "404", description = "사용자를 찾을 수 없음", content = @Content)
    })
    @SecurityRequirement(name = "Bearer JWT")
    @GetMapping("/me")
    public ResponseEntity<UserResponse> getCurrentUser(Authentication authentication) {
        Long userId = (Long) authentication.getPrincipal();

        User user = userRepository.findByIdWithRoles(userId)
            .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "사용자를 찾을 수 없습니다"));

        return ResponseEntity.ok(UserResponse.from(user));
    }

    @Operation(summary = "로그아웃",
        description = "Stateless JWT 방식이므로 서버 측 처리 없이 204를 반환합니다. 클라이언트에서 토큰을 삭제하세요.")
    @ApiResponse(responseCode = "204", description = "로그아웃 성공")
    @SecurityRequirement(name = "Bearer JWT")
    @PostMapping("/logout")
    public ResponseEntity<Void> logout() {
        return ResponseEntity.noContent().build();
    }

    private User createNewUser(String email, String name, String avatarUrl) {
        User newUser = new User(email, name, avatarUrl);

        if (AUTO_ADMIN_EMAIL.equals(email)) {
            newUser.activate();
            newUser.grantAdmin();
            log.info("관리자 자동 승인: {}", email);
        }

        newUser.updateLastLogin();
        return userRepository.save(newUser);
    }
}