package com.mydreamjob.preference;

import com.mydreamjob.auth.User;
import com.mydreamjob.auth.UserRepository;
import com.mydreamjob.common.exception.BusinessException;
import com.mydreamjob.common.exception.ErrorCode;
import com.mydreamjob.candidatescore.refresh.CandidateScoringRefreshRequestService;
import com.mydreamjob.preference.dto.StudentPreferenceRequest;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mydreamjob.security.UserRoleGuard;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Slf4j
@Service
@RequiredArgsConstructor
public class PreferenceService {

    private final com.mydreamjob.security.UserRoleGuard userRoleGuard;
    private final StudentPreferenceRepository preferenceRepository;
    private final UserRepository userRepository;
    /** R01-D4-1：求职偏好更新后登记评分快照刷新（COMPLIANCE 维度）。 */
    private final CandidateScoringRefreshRequestService scoringRefreshRequestService;
    private static final ObjectMapper mapper = new ObjectMapper();

    // ── 角色校验 ──────────────────────────────────────────────

    public void assertStudentRole(Long userId) {
        userRoleGuard.requireStudent(userId);
    }

    // ── 查询 ──────────────────────────────────────────────────

    public Map<String, Object> getPreferences(Long studentUserId) {
        assertStudentRole(studentUserId);
        return preferenceRepository.findByStudentUserId(studentUserId)
                .map(this::toView)
                .orElse(emptyView());
    }

    // ── 保存/更新 ────────────────────────────────────────────

    @Transactional
    public Map<String, Object> savePreferences(Long studentUserId, StudentPreferenceRequest req) {
        assertStudentRole(studentUserId);

        StudentPreference pref = preferenceRepository.findByStudentUserId(studentUserId)
                .orElse(StudentPreference.builder()
                        .studentUserId(studentUserId)
                        .remoteAllowed(false)
                        .build());

        if (req.getExpectedSalaryMin() != null) pref.setExpectedSalaryMin(req.getExpectedSalaryMin());
        if (req.getExpectedSalaryMax() != null) pref.setExpectedSalaryMax(req.getExpectedSalaryMax());
        if (req.getPreferredCities() != null) pref.setPreferredCities(toJson(req.getPreferredCities()));
        if (req.getEmploymentTypes() != null) pref.setEmploymentTypes(toJson(req.getEmploymentTypes()));
        if (req.getPreferredIndustries() != null) pref.setPreferredIndustries(toJson(req.getPreferredIndustries()));
        if (req.getPreferredJobTypes() != null) pref.setPreferredJobTypes(toJson(req.getPreferredJobTypes()));
        if (req.getRemoteAllowed() != null) pref.setRemoteAllowed(req.getRemoteAllowed());

        StudentPreference saved = preferenceRepository.save(pref);
        // R01-D4-1：偏好更新影响 COMPLIANCE 维度 → 登记当前周期刷新。
        scoringRefreshRequestService.requestRefresh(studentUserId, LocalDateTime.now());
        return toView(saved);
    }

    // ── 视图 ──────────────────────────────────────────────────

    private Map<String, Object> toView(StudentPreference pref) {
        Map<String, Object> view = new HashMap<>();
        view.put("id", pref.getId());
        view.put("studentUserId", pref.getStudentUserId());
        view.put("expectedSalaryMin", pref.getExpectedSalaryMin());
        view.put("expectedSalaryMax", pref.getExpectedSalaryMax());
        view.put("preferredCities", fromJson(pref.getPreferredCities()));
        view.put("employmentTypes", fromJson(pref.getEmploymentTypes()));
        view.put("preferredIndustries", fromJson(pref.getPreferredIndustries()));
        view.put("preferredJobTypes", fromJson(pref.getPreferredJobTypes()));
        view.put("remoteAllowed", pref.getRemoteAllowed());
        view.put("createdAt", pref.getCreatedAt());
        view.put("updatedAt", pref.getUpdatedAt());
        return view;
    }

    private Map<String, Object> emptyView() {
        Map<String, Object> view = new HashMap<>();
        view.put("expectedSalaryMin", null);
        view.put("expectedSalaryMax", null);
        view.put("preferredCities", List.of());
        view.put("employmentTypes", List.of());
        view.put("preferredIndustries", List.of());
        view.put("preferredJobTypes", List.of());
        view.put("remoteAllowed", false);
        return view;
    }

    private String toJson(List<String> list) {
        try {
            return mapper.writeValueAsString(list);
        } catch (JsonProcessingException e) {
            throw new RuntimeException("Failed to serialize", e);
        }
    }

    private List<String> fromJson(String json) {
        if (json == null || json.isBlank()) return List.of();
        try {
            return mapper.readValue(json, new TypeReference<List<String>>() {});
        } catch (JsonProcessingException e) {
            return List.of();
        }
    }
}