package com.xuqm.log.service;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.xuqm.log.dto.*;
import com.xuqm.log.entity.*;
import com.xuqm.log.repository.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.stream.Collectors;

@Service
public class LogService {

    private static final Logger log = LoggerFactory.getLogger(LogService.class);

    private final LogIssueRepository issueRepository;
    private final LogIssueEventRepository issueEventRepository;
    private final LogEventRepository eventRepository;
    private final LogWebhookRepository webhookRepository;
    private final WebhookService webhookService;
    private final ObjectMapper objectMapper;

    public LogService(LogIssueRepository issueRepository,
                      LogIssueEventRepository issueEventRepository,
                      LogEventRepository eventRepository,
                      LogWebhookRepository webhookRepository,
                      WebhookService webhookService,
                      ObjectMapper objectMapper) {
        this.issueRepository = issueRepository;
        this.issueEventRepository = issueEventRepository;
        this.eventRepository = eventRepository;
        this.webhookRepository = webhookRepository;
        this.webhookService = webhookService;
        this.objectMapper = objectMapper;
    }

    @Transactional
    public void processIssueBatch(IssueBatchRequest request) {
        for (IssueBatchRequest.IssueEventItem item : request.events()) {
            try {
                processSingleIssue(item);
            } catch (Exception e) {
                log.error("Failed to process issue event: fingerprint={}", item.fingerprint(), e);
            }
        }
    }

    private void processSingleIssue(IssueBatchRequest.IssueEventItem item) {
        LocalDateTime now = LocalDateTime.now();
        LocalDateTime eventTime = Instant.ofEpochMilli(item.timestamp()).atZone(ZoneOffset.UTC).toLocalDateTime();

        Optional<LogIssueEntity> existing = issueRepository.findByAppKeyAndFingerprint(item.appKey(), item.fingerprint());

        LogIssueEntity issue;
        if (existing.isPresent()) {
            issue = existing.get();
            issueRepository.incrementCount(item.appKey(), item.fingerprint(), now);
            issue.setLastSeenAt(now);
            issue.setCount(issue.getCount() + 1);
        } else {
            issue = new LogIssueEntity();
            issue.setAppKey(item.appKey());
            issue.setFingerprint(item.fingerprint());
            issue.setType(item.type());
            issue.setTitle(truncate(item.message(), 500));
            issue.setFirstSeenAt(eventTime);
            issue.setLastSeenAt(now);
            issue.setCount(1);
            issue.setPlatform(item.platform());
            issue.setAppVersion(item.appVersion());
            issue = issueRepository.save(issue);
        }

        LogIssueEventEntity eventEntity = new LogIssueEventEntity();
        eventEntity.setIssueId(issue.getId());
        eventEntity.setAppKey(item.appKey());
        eventEntity.setUserId(item.userId());
        eventEntity.setSessionId(item.sessionId());
        eventEntity.setMessage(item.message());
        eventEntity.setStack(item.stack());
        eventEntity.setPlatform(item.platform());
        eventEntity.setAppVersion(item.appVersion());
        eventEntity.setCreatedAt(eventTime);
        issueEventRepository.save(eventEntity);

        triggerWebhookAsync(issue);
        triggerSymbolicationAsync(issue.getId(), item.appKey(), item.platform(), item.appVersion());
    }

    @Async
    void triggerWebhookAsync(LogIssueEntity issue) {
        try {
            webhookService.checkAndNotify(issue);
        } catch (Exception e) {
            log.error("Webhook trigger failed for issue={}", issue.getId(), e);
        }
    }

    @Async
    void triggerSymbolicationAsync(Long issueId, String appKey, String platform, String appVersion) {
        // Symbolication is triggered asynchronously; actual implementation depends on SourceMap availability
        log.debug("Symbolication triggered for issueId={}, appKey={}, platform={}, version={}", issueId, appKey, platform, appVersion);
    }

    @Transactional
    public void processEventBatch(EventBatchRequest request) {
        for (EventBatchRequest.EventItem item : request.events()) {
            try {
                LogEventEntity entity = new LogEventEntity();
                entity.setAppKey(item.appKey());
                entity.setName(item.name());
                entity.setUserId(item.userId());
                entity.setSessionId(item.sessionId());
                entity.setProperties(item.properties());
                entity.setPlatform(item.platform());
                entity.setAppVersion(item.appVersion());
                entity.setCreatedAt(
                    item.timestamp() > 0
                        ? Instant.ofEpochMilli(item.timestamp()).atZone(ZoneOffset.UTC).toLocalDateTime()
                        : LocalDateTime.now()
                );
                eventRepository.save(entity);
            } catch (Exception e) {
                log.error("Failed to process event: name={}", item.name(), e);
            }
        }
    }

    @Transactional(readOnly = true)
    public Page<IssueResponse> queryIssues(String appKey, String type, String platform,
                                           String from, String to, int page, int size) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);
        Pageable pageable = PageRequest.of(page, size, Sort.by(Sort.Direction.DESC, "lastSeenAt"));

        Page<LogIssueEntity> result;
        if (fromDate != null && toDate != null) {
            result = issueRepository.findByAppKeyAndTypeAndPlatformAndLastSeenAtBetween(
                    appKey, type, platform, fromDate, toDate, pageable);
        } else {
            result = issueRepository.findByAppKey(appKey, pageable);
        }

        return result.map(this::toIssueResponse);
    }

    @Transactional(readOnly = true)
    public IssueResponse getIssueDetail(Long id) {
        LogIssueEntity issue = issueRepository.findById(id)
                .orElseThrow(() -> new IllegalArgumentException("Issue not found: " + id));

        List<LogIssueEventEntity> events = issueEventRepository.findTop20ByIssueIdOrderByCreatedAtDesc(id);
        List<IssueEventResponse> eventResponses = events.stream()
                .map(this::toIssueEventResponse)
                .toList();

        return new IssueResponse(
                issue.getId(), issue.getAppKey(), issue.getFingerprint(),
                issue.getType(), issue.getTitle(),
                issue.getFirstSeenAt(), issue.getLastSeenAt(),
                issue.getCount(), issue.isResolved(),
                issue.getPlatform(), issue.getAppVersion(),
                eventResponses
        );
    }

    @Transactional(readOnly = true)
    public List<IssueResponse> getFrequencyRankings(String appKey, String from, String to, int limit) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);
        Pageable pageable = PageRequest.of(0, limit);

        List<LogIssueEntity> issues = issueRepository.findTopByFrequency(appKey, fromDate, toDate, pageable);
        return issues.stream().map(this::toIssueResponse).toList();
    }

    @Transactional(readOnly = true)
    public List<IssueResponse> getRiskRankings(String appKey, String from, String to, int limit) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);
        Pageable pageable = PageRequest.of(0, limit);

        List<LogIssueEntity> issues = issueRepository.findTopByRisk(appKey, fromDate, toDate, pageable);
        return issues.stream().map(this::toIssueResponse).toList();
    }

    @Transactional(readOnly = true)
    public Page<IssueEventResponse> queryEvents(String appKey, String name, String userId,
                                                String from, String to, int page, int size) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);
        Pageable pageable = PageRequest.of(page, size, Sort.by(Sort.Direction.DESC, "createdAt"));

        Page<LogEventEntity> result;
        if (fromDate != null && toDate != null) {
            if (name != null && userId != null) {
                result = eventRepository.findByAppKeyAndNameAndUserIdAndCreatedAtBetween(
                        appKey, name, userId, fromDate, toDate, pageable);
            } else if (name != null) {
                result = eventRepository.findByAppKeyAndNameAndCreatedAtBetween(
                        appKey, name, fromDate, toDate, pageable);
            } else {
                result = eventRepository.findByAppKeyAndCreatedAtBetween(appKey, fromDate, toDate, pageable);
            }
        } else {
            result = eventRepository.findByAppKeyAndCreatedAtBetween(appKey, fromDate, toDate, pageable);
        }

        return result.map(e -> new IssueEventResponse(
                e.getId(), null, e.getAppKey(), e.getUserId(), e.getSessionId(),
                e.getName(), null, null, e.getProperties(),
                e.getPlatform(), e.getAppVersion(), e.getCreatedAt()
        ));
    }

    @Transactional(readOnly = true)
    public FunnelResponse queryFunnel(String appKey, List<String> steps, String from, String to) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);

        List<Object[]> rawData = eventRepository.findFunnelData(appKey, steps, fromDate, toDate);

        // Count unique sessions per step
        Map<String, Set<String>> sessionsPerStep = new LinkedHashMap<>();
        for (String step : steps) {
            sessionsPerStep.put(step, new HashSet<>());
        }

        for (Object[] row : rawData) {
            String sessionId = (String) row[0];
            String name = (String) row[1];
            if (sessionsPerStep.containsKey(name) && sessionId != null) {
                sessionsPerStep.get(name).add(sessionId);
            }
        }

        List<Long> counts = steps.stream()
                .map(step -> (long) sessionsPerStep.get(step).size())
                .toList();

        long firstCount = counts.isEmpty() ? 1 : Math.max(counts.getFirst(), 1);
        List<Double> rates = counts.stream()
                .map(c -> Math.round((double) c / firstCount * 1000.0) / 10.0)
                .toList();

        return new FunnelResponse(steps, counts, rates);
    }

    @Transactional(readOnly = true)
    public OverviewResponse getOverview(String appKey, String from, String to) {
        LocalDateTime fromDate = parseDate(from);
        LocalDateTime toDate = parseDate(to);

        long totalIssues = issueRepository.countByAppKeyAndFirstSeenAtBetween(appKey, fromDate, toDate);

        LocalDateTime todayStart = LocalDate.now().atStartOfDay();
        long todayNewIssues = issueRepository.countByAppKeyAndFirstSeenAtAfter(appKey, todayStart);

        // Build daily crash trend
        List<OverviewResponse.DailyCrashRate> trend = new ArrayList<>();
        if (fromDate != null && toDate != null) {
            LocalDate current = fromDate.toLocalDate();
            LocalDate end = toDate.toLocalDate();
            while (!current.isAfter(end)) {
                LocalDateTime dayStart = current.atStartOfDay();
                LocalDateTime dayEnd = current.plusDays(1).atStartOfDay();
                long dayCount = issueRepository.countByAppKeyAndFirstSeenAtBetween(appKey, dayStart, dayEnd);
                trend.add(new OverviewResponse.DailyCrashRate(
                        current.toString(),
                        dayCount,
                        0.0  // crash rate requires total session data, placeholder for now
                ));
                current = current.plusDays(1);
            }
        }

        return new OverviewResponse(totalIssues, todayNewIssues, 0, trend);
    }

    @Transactional
    public void deleteIssueAndEvents(Long issueId) {
        issueEventRepository.deleteByIssueId(issueId);
        issueRepository.deleteById(issueId);
    }

    private IssueResponse toIssueResponse(LogIssueEntity issue) {
        return new IssueResponse(
                issue.getId(), issue.getAppKey(), issue.getFingerprint(),
                issue.getType(), issue.getTitle(),
                issue.getFirstSeenAt(), issue.getLastSeenAt(),
                issue.getCount(), issue.isResolved(),
                issue.getPlatform(), issue.getAppVersion(),
                null
        );
    }

    private IssueEventResponse toIssueEventResponse(LogIssueEventEntity e) {
        return new IssueEventResponse(
                e.getId(), e.getIssueId(), e.getAppKey(), e.getUserId(), e.getSessionId(),
                e.getMessage(), e.getStack(), e.getStackSymbolicated(), e.getMetadata(),
                e.getPlatform(), e.getAppVersion(), e.getCreatedAt()
        );
    }

    private String truncate(String s, int maxLen) {
        if (s == null) return "";
        return s.length() <= maxLen ? s : s.substring(0, maxLen);
    }

    private LocalDateTime parseDate(String dateStr) {
        if (dateStr == null || dateStr.isBlank()) return null;
        try {
            return LocalDate.parse(dateStr).atStartOfDay();
        } catch (Exception e) {
            return null;
        }
    }
}