package com.labelsys.backend.service;

import java.nio.charset.StandardCharsets;
import java.util.List;

import org.springframework.stereotype.Service;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.labelsys.backend.common.ResultCode;
import com.labelsys.backend.common.exception.BusinessException;
import com.labelsys.backend.context.LoginUser;
import com.labelsys.backend.dto.common.PageResult;
import com.labelsys.backend.dto.request.AnnotationResultPageQuery;
import com.labelsys.backend.dto.response.AnnotationResultCompareResponse;
import com.labelsys.backend.dto.response.AnnotationResultResponse;
import com.labelsys.backend.entity.AnnotationResult;
import com.labelsys.backend.entity.SourceResource;
import com.labelsys.backend.enums.AnnotationResultStatus;
import com.labelsys.backend.enums.QaContentStorageMode;
import com.labelsys.backend.mapper.AnnotationResultMapper;
import com.labelsys.backend.mapper.SourceResourceMapper;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;

@Slf4j
@Service
@RequiredArgsConstructor
public class AnnotationResultService {

    private final AnnotationResultMapper annotationResultMapper;
    private final SourceResourceMapper sourceResourceMapper;
    private final DataPermissionService dataPermissionService;
    private final ObjectStorageService objectStorageService;

    public PageResult<AnnotationResultResponse> pageResults(LoginUser currentUser, AnnotationResultPageQuery query) {
        List<String> allowedRoles = dataPermissionService.getAllowedRoles(currentUser);
        boolean shouldFilterByUserId = dataPermissionService.shouldFilterByUserId(currentUser);

        LambdaQueryWrapper<AnnotationResult> wrapper = new LambdaQueryWrapper<AnnotationResult>()
                .eq(AnnotationResult::getCompanyId, currentUser.companyId())
                .eq(query.taskId() != null, AnnotationResult::getTaskId, query.taskId())
                .eq(query.resourceId() != null, AnnotationResult::getResourceId, query.resourceId())
                .eq(query.requiresManualReview() != null, AnnotationResult::getRequiresManualReview,
                        query.requiresManualReview());

        if (shouldFilterByUserId) {
            wrapper.eq(AnnotationResult::getCreatorId, currentUser.userId());
        } else if (!allowedRoles.isEmpty()) {
            wrapper.in(AnnotationResult::getCreatorRole, allowedRoles);
        }

        wrapper.orderByDesc(AnnotationResult::getCreatedAt);

        Page<AnnotationResult> page = new Page<>(query.pageNo(), query.pageSize());
        Page<AnnotationResult> resultPage = annotationResultMapper.selectPage(page, wrapper);

        List<AnnotationResultResponse> records = resultPage.getRecords().stream().map(this::toResponse)
                .filter(response -> query.runtimeStatus() == null
                        || query.runtimeStatus().equals(response.runtimeStatus()))
                .toList();

        return new PageResult<>(records, resultPage.getTotal(), (int) resultPage.getCurrent(),
                (int) resultPage.getSize());
    }

    public AnnotationResultResponse getResult(LoginUser currentUser, Long resultId) {
        AnnotationResult result = annotationResultMapper.findActiveByIdAndCompanyId(resultId, currentUser.companyId());
        if (result == null) {
            log.warn("Result not found or cross-tenant access attempt: resultId={}, companyId={}, userId={}", resultId,
                    currentUser.companyId(), currentUser.userId());
            throw new BusinessException(ResultCode.NOT_FOUND, "结果不存在");
        }
        return toResponse(result);
    }

    private AnnotationResultResponse toResponse(AnnotationResult result) {
        return new AnnotationResultResponse(result.getId(), result.getTaskId(), result.getResourceId(),
                deriveStatus(result), result.getRequiresManualReview(), result.getIsDeleted(),
                result.getQaContentStorageMode(), result.getReviewComment(), result.getReviewedAt(),
                result.getCreatedAt());
    }

    private AnnotationResultStatus deriveStatus(AnnotationResult result) {
        if (Boolean.TRUE.equals(result.getIsDeleted())) {
            return AnnotationResultStatus.ARCHIVED;
        }
        if (Boolean.TRUE.equals(result.getRequiresManualReview())) {
            return AnnotationResultStatus.MANUAL_REVIEW_PENDING;
        }
        return AnnotationResultStatus.AUTO_ARCHIVE_PENDING;
    }

    public AnnotationResultCompareResponse compareResult(LoginUser currentUser, Long resultId) {
        AnnotationResult result = annotationResultMapper.findActiveByIdAndCompanyId(resultId, currentUser.companyId());
        if (result == null) {
            log.warn("Result not found or cross-tenant access attempt: resultId={}, companyId={}, userId={}", resultId,
                    currentUser.companyId(), currentUser.userId());
            throw new BusinessException(ResultCode.NOT_FOUND, "结果不存在");
        }

        String qaContentJson = resolveQaContent(result);

        SourceResource resource = sourceResourceMapper.selectById(result.getResourceId());
        return new AnnotationResultCompareResponse(
                result.getId(),
                result.getTaskId(),
                result.getResourceId(),
                qaContentJson,
                result.getDiffSummary(),
                result.getQaContentStorageMode(),
                result.getQaContentFilePath(),
                resource == null ? null : resource.getFilePath());
    }

    private String resolveQaContent(AnnotationResult result) {
        if (QaContentStorageMode.EXTERNAL.name().equals(result.getQaContentStorageMode())) {
            if (result.getQaContentFilePath() == null || result.getQaContentFilePath().isBlank()) {
                log.warn("External storage mode but file path is empty, resultId={}", result.getId());
                return "{}";
            }
            try {
                String filePath = result.getQaContentFilePath();
                String bucketName = extractBucketName(filePath);
                String objectKey = extractObjectKey(filePath);
                byte[] content = objectStorageService.download(bucketName, objectKey);
                return new String(content, StandardCharsets.UTF_8);
            } catch (Exception e) {
                log.error("Failed to download external qa content, resultId={}, filePath={}",
                        result.getId(), result.getQaContentFilePath(), e);
                throw new BusinessException(ResultCode.ERROR, "下载问答内容失败");
            }
        } else {
            return result.getQaContentJson() != null ? result.getQaContentJson() : "{}";
        }
    }

    private String extractBucketName(String filePath) {
        if (filePath.startsWith("/")) {
            filePath = filePath.substring(1);
        }
        int firstSlash = filePath.indexOf("/");
        if (firstSlash > 0) {
            return filePath.substring(0, firstSlash);
        }
        throw new BusinessException(ResultCode.BAD_REQUEST, "无效的文件路径格式");
    }

    private String extractObjectKey(String filePath) {
        if (filePath.startsWith("/")) {
            filePath = filePath.substring(1);
        }
        int firstSlash = filePath.indexOf("/");
        if (firstSlash > 0 && firstSlash < filePath.length() - 1) {
            return filePath.substring(firstSlash + 1);
        }
        throw new BusinessException(ResultCode.BAD_REQUEST, "无效的文件路径格式");
    }
}