package com.mydreamjob.deletion;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.mydreamjob.common.api.ApiResponse;
import com.mydreamjob.common.exception.ErrorCode;
import com.mydreamjob.security.CurrentUserAccessor;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.RequiredArgsConstructor;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.http.MediaType;
import org.springframework.security.authentication.InsufficientAuthenticationException;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import java.util.Set;

/**
 * 注销守卫拦截器。
 *
 * <p>基于当前已认证用户的账号注销状态拦截业务请求：
 * <ul>
 *   <li>COMPLETED：除注销接口与 OPTIONS 外，所有普通业务接口一律返回 409/9303（旧 JWT 即使未过期也被拒绝）</li>
 *   <li>PENDING：拦截 POST/PUT/PATCH/DELETE 写操作返回 409/9302；GET 与 OPTIONS 放行</li>
 * </ul>
 * 注销接口（POST/GET /profile/me/deletion、POST /profile/me/deletion/cancel）始终放行，交由 Controller 决策。
 * 未认证、未注销用户不受影响。</p>
 *
 * <p><strong>身份解析复用唯一的 {@link CurrentUserAccessor}</strong>（R01-A）：本拦截器注册在
 * {@code /**}，先于所有 Controller 执行，因此绝不能自己解析主体。此前它用
 * {@code Character::isDigit} 判断后直接 {@code Long.valueOf(name)}，导致 Long 溢出主体
 * （如 {@code "99999999999999999999"}）抛出 {@code NumberFormatException}，在到达任何
 * Controller 之前就逃逸为全站 HTTP 500。现在非法主体一律视为未认证并放行，
 * 由 Controller 统一返回 401。</p>
 */
@Component
@RequiredArgsConstructor
public class DeletionGuardInterceptor implements HandlerInterceptor {

    private static final Set<String> DELETION_PATHS = Set.of(
            "/profile/me/deletion",
            "/profile/me/deletion/cancel");

    private static final Set<String> WRITE_METHODS = Set.of("POST", "PUT", "PATCH", "DELETE");

    private final ObjectProvider<AccountDeletionService> deletionServiceProvider;
    private final CurrentUserAccessor currentUserAccessor;
    private final ObjectMapper objectMapper;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        if ("OPTIONS".equalsIgnoreCase(request.getMethod())) {
            return true;
        }
        // 未认证 / 匿名 / 非法或溢出主体 → 一律放行，交由 Controller 按未登录处理（401）。
        Long userId = resolveUserIdOrNull(SecurityContextHolder.getContext().getAuthentication());
        if (userId == null) {
            return true;
        }
        // 切片测试（@WebMvcTest）等场景可能无此服务 Bean，此时不拦截
        AccountDeletionService deletionService = deletionServiceProvider.getIfAvailable();
        if (deletionService == null) {
            return true;
        }
        String path = resolvePath(request);
        if (DELETION_PATHS.contains(path)) {
            return true;
        }
        DeletionStatus status = deletionService.effectiveStatus(userId);
        if (status == DeletionStatus.COMPLETED) {
            return reject(response, ErrorCode.ACCOUNT_DELETED, request); // 409/9303
        }
        if (status == DeletionStatus.PENDING && WRITE_METHODS.contains(request.getMethod().toUpperCase())) {
            return reject(response, ErrorCode.ACCOUNT_DELETION_PENDING, request); // 409/9302
        }
        return true;
    }

    /**
     * 解析用户 ID；任何非法主体返回 {@code null}，绝不抛出。
     *
     * <p>该安全依赖由构造器强制注入；装配缺失时应用必须失败启动。</p>
     */
    private Long resolveUserIdOrNull(Authentication authentication) {
        try {
            return currentUserAccessor.requireUserId(authentication);
        } catch (InsufficientAuthenticationException e) {
            return null;
        }
    }

    private boolean reject(HttpServletResponse response, ErrorCode errorCode,
                           HttpServletRequest request) throws Exception {
        response.setStatus(409);
        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
        response.setCharacterEncoding("UTF-8");
        String requestId = request.getHeader("X-Request-Id");
        response.getWriter().write(
                objectMapper.writeValueAsString(ApiResponse.error(errorCode.getCode(), errorCode.getMessage(), requestId)));
        return false;
    }

    /** 解析去除 context-path 的请求路径，兼容真实服务器与 MockMvc。 */
    private String resolvePath(HttpServletRequest request) {
        String uri = request.getRequestURI();
        String ctx = request.getContextPath();
        if (ctx != null && !ctx.isEmpty() && uri.startsWith(ctx)) {
            return uri.substring(ctx.length());
        }
        return uri;
    }
}