package com.snp.batch.service;

import com.snp.batch.global.dto.JobExecutionDetailDto;
import com.snp.batch.global.model.BatchCollectionPeriod;
import com.snp.batch.global.model.BatchLastExecution;
import com.snp.batch.global.model.BatchRecollectionHistory;
import com.snp.batch.global.repository.BatchApiLogRepository;
import com.snp.batch.global.repository.BatchCollectionPeriodRepository;
import com.snp.batch.global.repository.BatchLastExecutionRepository;
import com.snp.batch.global.repository.BatchRecollectionHistoryRepository;
import jakarta.persistence.criteria.Predicate;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.StepExecution;
import org.springframework.batch.core.explore.JobExplorer;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.snp.batch.global.model.BatchApiLog;

import java.time.Duration;
import java.time.LocalDateTime;
import java.util.*;
import java.util.stream.Collectors;

@Slf4j
@Service
@RequiredArgsConstructor
public class RecollectionHistoryService {

    private final BatchRecollectionHistoryRepository historyRepository;
    private final BatchCollectionPeriodRepository periodRepository;
    private final BatchLastExecutionRepository lastExecutionRepository;
    private final BatchApiLogRepository apiLogRepository;
    private final JobExplorer jobExplorer;

    /**
     * 재수집 실행 시작 기록
     * REQUIRES_NEW: Job 실패해도 이력은 보존
     */
    @Transactional(propagation = Propagation.REQUIRES_NEW)
    public BatchRecollectionHistory recordStart(
            String jobName,
            Long jobExecutionId,
            String apiKey,
            String executor,
            String reason) {

        Optional<BatchCollectionPeriod> period = periodRepository.findById(apiKey);
        if (period.isEmpty()) {
            log.warn("[RecollectionHistory] apiKey {} 에 대한 수집기간 없음, 이력 미생성", apiKey);
            return null;
        }

        BatchCollectionPeriod cp = period.get();
        LocalDateTime rangeFrom = cp.getRangeFromDate();
        LocalDateTime rangeTo = cp.getRangeToDate();

        // 기간 중복 검출
        List<BatchRecollectionHistory> overlaps = historyRepository
                .findOverlappingHistories(apiKey, rangeFrom, rangeTo, -1L);
        boolean hasOverlap = !overlaps.isEmpty();
        String overlapIds = overlaps.stream()
                .map(h -> String.valueOf(h.getHistoryId()))
                .collect(Collectors.joining(","));

        LocalDateTime now = LocalDateTime.now();
        BatchRecollectionHistory history = BatchRecollectionHistory.builder()
                .apiKey(apiKey)
                .apiKeyName(cp.getApiKeyName())
                .jobName(jobName)
                .jobExecutionId(jobExecutionId)
                .rangeFromDate(rangeFrom)
                .rangeToDate(rangeTo)
                .executionStatus("STARTED")
                .executionStartTime(now)
                .executor(executor != null ? executor : "SYSTEM")
                .recollectionReason(reason)
                .hasOverlap(hasOverlap)
                .overlappingHistoryIds(hasOverlap ? overlapIds : null)
                .createdAt(now)
                .updatedAt(now)
                .build();

        BatchRecollectionHistory saved = historyRepository.save(history);
        log.info("[RecollectionHistory] 재수집 이력 생성: historyId={}, apiKey={}, jobExecutionId={}, range={}~{}",
                saved.getHistoryId(), apiKey, jobExecutionId, rangeFrom, rangeTo);
        return saved;
    }

    /**
     * 재수집 실행 완료 기록
     */
    @Transactional(propagation = Propagation.REQUIRES_NEW)
    public void recordCompletion(
            Long jobExecutionId,
            String status,
            Long readCount,
            Long writeCount,
            Long skipCount,
            Integer apiCallCount,
            Long totalResponseTimeMs,
            String failureReason) {

        Optional<BatchRecollectionHistory> opt =
                historyRepository.findByJobExecutionId(jobExecutionId);

        if (opt.isEmpty()) {
            log.warn("[RecollectionHistory] jobExecutionId {} 에 해당하는 이력 없음", jobExecutionId);
            return;
        }

        BatchRecollectionHistory history = opt.get();
        LocalDateTime now = LocalDateTime.now();

        history.setExecutionStatus(status);
        history.setExecutionEndTime(now);
        history.setReadCount(readCount);
        history.setWriteCount(writeCount);
        history.setSkipCount(skipCount);
        history.setApiCallCount(apiCallCount);
        history.setTotalResponseTimeMs(totalResponseTimeMs);
        history.setFailureReason(failureReason);
        history.setUpdatedAt(now);

        if (history.getExecutionStartTime() != null) {
            history.setDurationMs(Duration.between(history.getExecutionStartTime(), now).toMillis());
        }

        historyRepository.save(history);
        log.info("[RecollectionHistory] 재수집 완료 기록: jobExecutionId={}, status={}, read={}, write={}",
                jobExecutionId, status, readCount, writeCount);
    }

    /**
     * 동적 필터링 + 페이징 목록 조회
     */
    @Transactional(readOnly = true)
    public Page<BatchRecollectionHistory> getHistories(
            String apiKey, String jobName, String status,
            LocalDateTime from, LocalDateTime to,
            Pageable pageable) {

        Specification<BatchRecollectionHistory> spec = (root, query, cb) -> {
            List<Predicate> predicates = new ArrayList<>();

            if (apiKey != null && !apiKey.isEmpty()) {
                predicates.add(cb.equal(root.get("apiKey"), apiKey));
            }
            if (jobName != null && !jobName.isEmpty()) {
                predicates.add(cb.equal(root.get("jobName"), jobName));
            }
            if (status != null && !status.isEmpty()) {
                predicates.add(cb.equal(root.get("executionStatus"), status));
            }
            if (from != null) {
                predicates.add(cb.greaterThanOrEqualTo(root.get("executionStartTime"), from));
            }
            if (to != null) {
                predicates.add(cb.lessThanOrEqualTo(root.get("executionStartTime"), to));
            }

            query.orderBy(cb.desc(root.get("createdAt")));
            return cb.and(predicates.toArray(new Predicate[0]));
        };

        return historyRepository.findAll(spec, pageable);
    }

    /**
     * 상세 조회 (중복 이력 실시간 재검사 포함)
     */
    @Transactional(readOnly = true)
    public Map<String, Object> getHistoryDetail(Long historyId) {
        BatchRecollectionHistory history = historyRepository.findById(historyId)
                .orElseThrow(() -> new IllegalArgumentException("이력을 찾을 수 없습니다: " + historyId));

        // 중복 이력 실시간 재검사
        List<BatchRecollectionHistory> currentOverlaps = historyRepository
                .findOverlappingHistories(history.getApiKey(),
                        history.getRangeFromDate(), history.getRangeToDate(),
                        history.getHistoryId());

        // API 응답시간 통계
        Map<String, Object> apiStats = null;
        if (history.getJobExecutionId() != null) {
            apiStats = getApiStats(history.getJobExecutionId());
        }

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("history", history);
        result.put("overlappingHistories", currentOverlaps);
        result.put("apiStats", apiStats);
        return result;
    }

    /**
     * 상세 조회 + Step Execution + Collection Period 포함
     * job_execution_id로 batch_step_execution, batch_collection_period를 조인
     */
    @Transactional(readOnly = true)
    public Map<String, Object> getHistoryDetailWithSteps(Long historyId) {
        BatchRecollectionHistory history = historyRepository.findById(historyId)
                .orElseThrow(() -> new IllegalArgumentException("이력을 찾을 수 없습니다: " + historyId));

        // 중복 이력 실시간 재검사
        List<BatchRecollectionHistory> currentOverlaps = historyRepository
                .findOverlappingHistories(history.getApiKey(),
                        history.getRangeFromDate(), history.getRangeToDate(),
                        history.getHistoryId());

        // API 응답시간 통계
        Map<String, Object> apiStats = null;
        if (history.getJobExecutionId() != null) {
            apiStats = getApiStats(history.getJobExecutionId());
        }

        // Collection Period 조회
        BatchCollectionPeriod collectionPeriod = periodRepository
                .findById(history.getApiKey()).orElse(null);

        // Step Execution 조회 (job_execution_id 기반)
        List<JobExecutionDetailDto.StepExecutionDto> stepExecutions = new ArrayList<>();
        if (history.getJobExecutionId() != null) {
            JobExecution jobExecution = jobExplorer.getJobExecution(history.getJobExecutionId());
            if (jobExecution != null) {
                stepExecutions = jobExecution.getStepExecutions().stream()
                        .map(this::convertStepToDto)
                        .collect(Collectors.toList());
            }
        }

        Map<String, Object> result = new LinkedHashMap<>();
        result.put("history", history);
        result.put("overlappingHistories", currentOverlaps);
        result.put("apiStats", apiStats);
        result.put("collectionPeriod", collectionPeriod);
        result.put("stepExecutions", stepExecutions);
        return result;
    }

    private JobExecutionDetailDto.StepExecutionDto convertStepToDto(StepExecution stepExecution) {
        Long duration = null;
        if (stepExecution.getStartTime() != null && stepExecution.getEndTime() != null) {
            duration = Duration.between(stepExecution.getStartTime(), stepExecution.getEndTime()).toMillis();
        }

        // StepExecutionContext에서 API 정보 추출 (ExecutionDetail 호환)
        JobExecutionDetailDto.ApiCallInfo apiCallInfo = null;
        var context = stepExecution.getExecutionContext();
        if (context.containsKey("apiUrl")) {
            apiCallInfo = JobExecutionDetailDto.ApiCallInfo.builder()
                    .apiUrl(context.getString("apiUrl", ""))
                    .method(context.getString("apiMethod", ""))
                    .totalCalls(context.containsKey("totalApiCalls") ? context.getInt("totalApiCalls", 0) : null)
                    .completedCalls(context.containsKey("completedApiCalls") ? context.getInt("completedApiCalls", 0) : null)
                    .lastCallTime(context.containsKey("lastCallTime") ? context.getString("lastCallTime", "") : null)
                    .build();
        }

        // batch_api_log 테이블에서 Step별 API 로그 집계 + 개별 로그 조회
        JobExecutionDetailDto.StepApiLogSummary apiLogSummary =
                buildStepApiLogSummary(stepExecution.getId());

        return JobExecutionDetailDto.StepExecutionDto.builder()
                .stepExecutionId(stepExecution.getId())
                .stepName(stepExecution.getStepName())
                .status(stepExecution.getStatus().name())
                .startTime(stepExecution.getStartTime())
                .endTime(stepExecution.getEndTime())
                .readCount((int) stepExecution.getReadCount())
                .writeCount((int) stepExecution.getWriteCount())
                .commitCount((int) stepExecution.getCommitCount())
                .rollbackCount((int) stepExecution.getRollbackCount())
                .readSkipCount((int) stepExecution.getReadSkipCount())
                .processSkipCount((int) stepExecution.getProcessSkipCount())
                .writeSkipCount((int) stepExecution.getWriteSkipCount())
                .filterCount((int) stepExecution.getFilterCount())
                .exitCode(stepExecution.getExitStatus().getExitCode())
                .exitMessage(stepExecution.getExitStatus().getExitDescription())
                .duration(duration)
                .apiCallInfo(apiCallInfo)
                .apiLogSummary(apiLogSummary)
                .build();
    }

    /**
     * Step별 batch_api_log 통계 집계 (개별 로그는 별도 API로 페이징 조회)
     */
    private JobExecutionDetailDto.StepApiLogSummary buildStepApiLogSummary(Long stepExecutionId) {
        List<Object[]> stats = apiLogRepository.getApiStatsByStepExecutionId(stepExecutionId);
        if (stats.isEmpty() || stats.get(0) == null || ((Number) stats.get(0)[0]).longValue() == 0L) {
            return null;
        }

        Object[] row = stats.get(0);

        return JobExecutionDetailDto.StepApiLogSummary.builder()
                .totalCalls(((Number) row[0]).longValue())
                .successCount(((Number) row[1]).longValue())
                .errorCount(((Number) row[2]).longValue())
                .avgResponseMs(((Number) row[3]).doubleValue())
                .maxResponseMs(((Number) row[4]).longValue())
                .minResponseMs(((Number) row[5]).longValue())
                .totalResponseMs(((Number) row[6]).longValue())
                .totalRecordCount(((Number) row[7]).longValue())
                .build();
    }

    /**
     * 대시보드용 최근 10건
     */
    @Transactional(readOnly = true)
    public List<BatchRecollectionHistory> getRecentHistories() {
        return historyRepository.findTop10ByOrderByCreatedAtDesc();
    }

    /**
     * 통계 조회
     */
    @Transactional(readOnly = true)
    public Map<String, Object> getHistoryStats() {
        Map<String, Object> stats = new LinkedHashMap<>();
        stats.put("totalCount", historyRepository.count());
        stats.put("completedCount", historyRepository.countByExecutionStatus("COMPLETED"));
        stats.put("failedCount", historyRepository.countByExecutionStatus("FAILED"));
        stats.put("runningCount", historyRepository.countByExecutionStatus("STARTED"));
        stats.put("overlapCount", historyRepository.countByHasOverlapTrue());
        return stats;
    }

    /**
     * API 응답시간 통계 (BatchApiLog 집계)
     */
    @Transactional(readOnly = true)
    public Map<String, Object> getApiStats(Long jobExecutionId) {
        List<Object[]> results = apiLogRepository.getApiStatsByJobExecutionId(jobExecutionId);
        if (results.isEmpty() || results.get(0) == null) {
            return null;
        }

        Object[] row = results.get(0);
        Map<String, Object> stats = new LinkedHashMap<>();
        stats.put("callCount", row[0]);
        stats.put("totalMs", row[1]);
        stats.put("avgMs", row[2]);
        stats.put("maxMs", row[3]);
        stats.put("minMs", row[4]);
        return stats;
    }

    /**
     * 재수집 실행 전: 현재 last_success_date 조회 (복원용)
     */
    @Transactional(readOnly = true)
    public LocalDateTime getLastSuccessDate(String apiKey) {
        return lastExecutionRepository.findById(apiKey)
                .map(BatchLastExecution::getLastSuccessDate)
                .orElse(null);
    }

    /**
     * 재수집 실행 후: Tasklet이 업데이트한 last_success_date를 원래 값으로 복원
     * 재수집은 과거 데이터 재처리이므로 last_success_date를 변경하면 안 됨
     */
    @Transactional(propagation = Propagation.REQUIRES_NEW)
    public void restoreLastSuccessDate(String apiKey, LocalDateTime originalDate) {
        if (originalDate == null) return;
        lastExecutionRepository.findById(apiKey).ifPresent(lastExec -> {
            LocalDateTime beforeDate = lastExec.getLastSuccessDate();
            lastExec.setLastSuccessDate(originalDate);
            lastExec.setUpdatedAt(LocalDateTime.now());
            lastExecutionRepository.save(lastExec);
            log.info("[RecollectionHistory] last_success_date 복원: apiKey={}, before={}, after={}",
                    apiKey, beforeDate, originalDate);
        });
    }

    /**
     * 수집 기간 전체 조회
     */
    @Transactional(readOnly = true)
    public List<BatchCollectionPeriod> getAllCollectionPeriods() {
        return periodRepository.findAllByOrderByOrderSeqAsc();
    }

    /**
     * 수집 기간 수정
     */
    @Transactional
    public BatchCollectionPeriod updateCollectionPeriod(String apiKey,
                                                        LocalDateTime rangeFromDate,
                                                        LocalDateTime rangeToDate) {
        BatchCollectionPeriod period = periodRepository.findById(apiKey)
                .orElseGet(() -> new BatchCollectionPeriod(apiKey, rangeFromDate, rangeToDate));

        period.setRangeFromDate(rangeFromDate);
        period.setRangeToDate(rangeToDate);
        return periodRepository.save(period);
    }

    /**
     * 수집 기간 초기화 (rangeFromDate, rangeToDate를 null로)
     */
    @Transactional
    public void resetCollectionPeriod(String apiKey) {
        periodRepository.findById(apiKey).ifPresent(period -> {
            period.setRangeFromDate(null);
            period.setRangeToDate(null);
            periodRepository.save(period);
            log.info("[RecollectionHistory] 수집 기간 초기화: apiKey={}", apiKey);
        });
    }
}