package com.mydreamjob.profileimage;

import com.mydreamjob.auth.*;
import com.mydreamjob.company.*;
import com.mydreamjob.common.exception.*;
import com.mydreamjob.messaging.*;
import com.mydreamjob.security.*;
import lombok.RequiredArgsConstructor;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.multipart.MultipartFile;
import java.util.*;

@Service @RequiredArgsConstructor
public class ProfileImageService {
    private final ProfileImageRepository images;
    private final ProfileImageValidator validator;
    private final UserRepository users;
    private final CompanyRepository companies;
    private final UserRoleGuard roles;
    private final CurrentUserAccessor currentUser;
    private final ConversationMemberRepository members;
    private final ConversationRepository conversations;
    private final MessagingService messaging;

    @Value("#{environment.getProperty('server.servlet.context-path', '/api/v1')}")
    private String contextPath;

    public record ImageView(String url, String version, String contentType, long size) {}

    @Transactional
    public ImageView upload(Long actor, boolean logo, MultipartFile file) {
        User user = lockActor(actor, logo);
        Company company = logo ? lockCompany(actor) : null;
        byte[] content = validator.validate(file);
        // 先 flush 删除以释放唯一键；事务失败会完整恢复旧二进制与引用。
        String kind = logo ? "LOGO" : "AVATAR";
        images.findByOwnerUserIdAndKind(actor, kind).ifPresent(images::delete);
        images.flush();
        ProfileImage image = new ProfileImage();
        image.setId(UUID.randomUUID().toString());
        image.setOwnerUserId(actor);
        image.setCompanyId(company == null ? null : company.getId());
        image.setKind(kind);
        image.setContent(content);
        images.saveAndFlush(image);
        if (logo) company.setLogoUrl(url(image.getId()));
        else user.setAvatarUrl(url(image.getId()));
        return new ImageView(url(image.getId()), image.getId(), "image/jpeg", content.length);
    }

    @Transactional
    public void delete(Long actor, boolean logo) {
        User user = lockActor(actor, logo);
        Company company = logo ? lockCompany(actor) : null;
        images.findByOwnerUserIdAndKind(actor, logo ? "LOGO" : "AVATAR").ifPresent(images::delete);
        if (logo) company.setLogoUrl(null);
        else user.setAvatarUrl(null);
    }

    @Transactional(readOnly = true)
    public byte[] read(String id) {
        if (id == null || !id.matches("[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}"))
            throw notFound();
        ProfileImage image = images.findById(id).orElseThrow(ProfileImageService::notFound);
        User owner = users.findById(image.getOwnerUserId()).orElseThrow(ProfileImageService::notFound);
        if (!Boolean.TRUE.equals(owner.getActive())) throw notFound();
        if ("LOGO".equals(image.getKind())) {
            Company company = companies.findById(image.getCompanyId()).orElseThrow(ProfileImageService::notFound);
            if (!Objects.equals(company.getOwnerUserId(), owner.getId()) || !url(id).equals(company.getLogoUrl()))
                throw notFound();
        } else {
            Long actor = currentUser.requireUserId();
            roles.requireAny(actor, User.Role.STUDENT, User.Role.COMPANY, User.Role.ADMIN);
            if (!url(id).equals(owner.getAvatarUrl())) throw notFound();
            if (!actor.equals(owner.getId()) && !canReadPeer(actor, owner.getId()))
                throw new BusinessException(ErrorCode.FORBIDDEN);
        }
        return image.getContent().clone();
    }

    private boolean canReadPeer(Long actor, Long owner) {
        for (ConversationMember member : members.findByUserId(actor)) {
            Long id = member.getConversationId();
            var conversation = conversations.findById(id).orElse(null);
            if (conversation == null || !("DIRECT".equals(conversation.getType()) || "TALENT_INVITATION".equals(conversation.getType()))
                    || !members.existsByConversationIdAndUserId(id, owner)) continue;
            try {
                // 非匿名邀约同样展示头像，但不能绕过成员、拉黑、撤回或企业接收门禁。
                messaging.assertProfileImageAccess(id, actor);
                return true;
            } catch (BusinessException denied) {
                // 另一条会话可能仍有合法授权；数据库/系统异常不会在此吞掉。
            }
        }
        return false;
    }

    private User lockActor(Long actor, boolean logo) {
        User user = users.findByIdForUpdate(actor).orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));
        if (logo) roles.requireCompany(user);
        else roles.requireAny(user, User.Role.STUDENT, User.Role.COMPANY, User.Role.ADMIN);
        return user;
    }

    private Company lockCompany(Long actor) {
        return companies.findByOwnerUserIdForUpdate(actor).orElseThrow(() -> new BusinessException(ErrorCode.COMPANY_NOT_FOUND));
    }

    private String url(String id) { return contextPath + "/profile-images/" + id; }
    private static BusinessException notFound() { return new BusinessException(ErrorCode.PROFILE_NOT_FOUND, "image not found"); }
}