package service

import (
	"context"
	"fmt"
	"log"
	"time"

	"bugulma/backend/internal/domain"
	"bugulma/backend/internal/matching"
	"bugulma/backend/internal/matching/engine"
)

// EventDrivenMatchingService provides real-time match updates via event-driven architecture
type EventDrivenMatchingService struct {
	eventBus         domain.EventBus
	matchingService  *matching.Service
	resourceFlowRepo domain.ResourceFlowRepository
	matchRepo        domain.MatchRepository
	websocketHub     *WebSocketHub
	incrementalCalc  *IncrementalMatchCalculator
}

// NewEventDrivenMatchingService creates a new event-driven matching service
func NewEventDrivenMatchingService(
	eventBus domain.EventBus,
	matchingService *matching.Service,
	resourceFlowRepo domain.ResourceFlowRepository,
	matchRepo domain.MatchRepository,
	websocketHub *WebSocketHub,
	economicService *EconomicService,
) *EventDrivenMatchingService {

	return &EventDrivenMatchingService{
		eventBus:         eventBus,
		matchingService:  matchingService,
		resourceFlowRepo: resourceFlowRepo,
		matchRepo:        matchRepo,
		websocketHub:     websocketHub,
		incrementalCalc: NewIncrementalMatchCalculator(
			matchingService,
			matchRepo,
			economicService,
		),
	}
}

// StartEventProcessing begins listening for events that affect matches
func (edms *EventDrivenMatchingService) StartEventProcessing(ctx context.Context) error {
	if edms.eventBus == nil {
		log.Println("Event bus not available, skipping event processing")
		return nil
	}

	// Subscribe to resource flow events
	if err := edms.eventBus.Subscribe("resource_flow.*", func(event domain.Event) error {
		return edms.handleResourceFlowEvent(ctx, event)
	}); err != nil {
		return fmt.Errorf("failed to subscribe to resource flow events: %w", err)
	}

	// Subscribe to organization events
	if err := edms.eventBus.Subscribe("organization.*", func(event domain.Event) error {
		return edms.handleOrganizationEvent(ctx, event)
	}); err != nil {
		return fmt.Errorf("failed to subscribe to organization events: %w", err)
	}

	// Subscribe to match events
	if err := edms.eventBus.Subscribe("match.*", edms.handleMatchEvent); err != nil {
		return fmt.Errorf("failed to subscribe to match events: %w", err)
	}

	log.Println("Event-driven matching service started")
	return nil
}

// handleResourceFlowEvent processes resource flow changes
func (edms *EventDrivenMatchingService) handleResourceFlowEvent(ctx context.Context, event domain.Event) error {
	log.Printf("Processing resource flow event: %s for entity %s", event.Type, event.EntityID)

	switch event.Type {
	case domain.EventTypeResourceFlowCreated:
		return edms.handleResourceFlowCreated(ctx, event)
	case domain.EventTypeResourceFlowUpdated:
		return edms.handleResourceFlowUpdated(ctx, event)
	case domain.EventTypeResourceFlowDeleted:
		return edms.handleResourceFlowDeleted(ctx, event)
	default:
		log.Printf("Unhandled resource flow event type: %s", event.Type)
		return nil
	}
}

// handleOrganizationEvent processes organization changes
func (edms *EventDrivenMatchingService) handleOrganizationEvent(ctx context.Context, event domain.Event) error {
	log.Printf("Processing organization event: %s for entity %s", event.Type, event.EntityID)

	// Organization changes can affect matches for that organization
	// Invalidate cache and trigger recalculation
	affectedMatches, err := edms.findMatchesByOrganization(ctx, event.EntityID)
	if err != nil {
		return fmt.Errorf("failed to find matches for organization: %w", err)
	}

	return edms.processAffectedMatches(affectedMatches, event)
}

// handleMatchEvent processes match-related events
func (edms *EventDrivenMatchingService) handleMatchEvent(event domain.Event) error {
	log.Printf("Processing match event: %s for entity %s", event.Type, event.EntityID)

	// Notify WebSocket clients about match changes
	edms.notifyMatchUpdate(event)

	return nil
}

// handleResourceFlowCreated processes new resource flow creation
func (edms *EventDrivenMatchingService) handleResourceFlowCreated(ctx context.Context, event domain.Event) error {
	// Find potential matches for the new resource flow
	flow, err := edms.resourceFlowRepo.GetByID(ctx, event.EntityID)
	if err != nil {
		return fmt.Errorf("failed to get resource flow: %w", err)
	}

	// Run matching algorithm for this flow
	candidates, err := edms.findPotentialMatchesForFlow(ctx, flow)
	if err != nil {
		return fmt.Errorf("failed to find matches for new flow: %w", err)
	}

	// Create matches for high-confidence candidates
	for _, candidate := range candidates {
		if candidate.OverallScore > 0.7 { // High confidence threshold
			// Convert to engine.Candidate
			engineCandidate := &engine.Candidate{
				SourceFlow:         candidate.SourceFlow,
				TargetFlow:         candidate.TargetFlow,
				DistanceKm:         candidate.DistanceKm,
				CompatibilityScore: candidate.CompatibilityScore,
				EconomicScore:      candidate.EconomicScore,
				TemporalScore:      candidate.TemporalScore,
				QualityScore:       candidate.QualityScore,
				OverallScore:       candidate.OverallScore,
				Priority:           candidate.Priority,
				RiskLevel:          candidate.RiskLevel,
			}
			_, err := edms.matchingService.CreateMatch(context.Background(), engineCandidate, "system")
			if err != nil {
				log.Printf("Failed to create match for candidate: %v", err)
				continue
			}

			// Notify via WebSocket
			edms.notifyNewMatch(candidate, event.OrgID)
		}
	}

	return nil
}

// handleResourceFlowUpdated processes resource flow updates
func (edms *EventDrivenMatchingService) handleResourceFlowUpdated(ctx context.Context, event domain.Event) error {
	// Find and invalidate affected matches
	affectedMatches, err := edms.findMatchesByResourceFlow(ctx, event.EntityID)
	if err != nil {
		return fmt.Errorf("failed to find affected matches: %w", err)
	}

	return edms.processAffectedMatches(affectedMatches, event)
}

// handleResourceFlowDeleted processes resource flow deletion
func (edms *EventDrivenMatchingService) handleResourceFlowDeleted(ctx context.Context, event domain.Event) error {
	// Find matches that depend on this resource flow and mark them as affected
	affectedMatches, err := edms.findMatchesByResourceFlow(ctx, event.EntityID)
	if err != nil {
		return fmt.Errorf("failed to find affected matches: %w", err)
	}

	// Cancel matches that depend on deleted resource flows
	for _, matchID := range affectedMatches {
		err := edms.matchingService.UpdateMatchStatus(
			context.Background(),
			matchID,
			domain.MatchStatusCancelled,
			"system",
			"Resource flow was deleted",
		)
		if err != nil {
			log.Printf("Failed to cancel match %s: %v", matchID, err)
		}
	}

	return nil
}

// processAffectedMatches handles matches affected by data changes
func (edms *EventDrivenMatchingService) processAffectedMatches(matchIDs []string, event domain.Event) error {
	for _, matchID := range matchIDs {
		// Notify clients about the change
		edms.notifyMatchUpdate(event)

		// Optionally trigger incremental recalculation
		// This could be expensive, so we might want to batch or delay
		go func(id string) {
			if err := edms.incrementalCalc.RecalculateMatch(context.Background(), id); err != nil {
				log.Printf("Failed to recalculate match %s: %v", id, err)
			}
		}(matchID)
	}

	return nil
}

// findPotentialMatchesForFlow finds potential matches for a resource flow
func (edms *EventDrivenMatchingService) findPotentialMatchesForFlow(ctx context.Context, flow *domain.ResourceFlow) ([]*engine.Candidate, error) {
	// Use the existing matching criteria logic
	criteria := matching.Criteria{
		ResourceType:     flow.Type,
		MaxDistanceKm:    50.0, // Default distance
		MinCompatibility: 0.3,
		MinEconomicScore: 0.2,
		MinTemporalScore: 0.4,
		MinQualityScore:  0.4,
	}

	return edms.matchingService.FindMatches(ctx, criteria)
}

// findMatchesByResourceFlow finds matches that involve a specific resource flow
func (edms *EventDrivenMatchingService) findMatchesByResourceFlow(ctx context.Context, flowID string) ([]string, error) {
	matches, err := edms.matchRepo.GetByResourceID(ctx, flowID)
	if err != nil {
		return nil, err
	}

	matchIDs := make([]string, len(matches))
	for i, match := range matches {
		matchIDs[i] = match.ID
	}

	return matchIDs, nil
}

// findMatchesByOrganization finds matches for a specific organization
func (edms *EventDrivenMatchingService) findMatchesByOrganization(ctx context.Context, orgID string) ([]string, error) {
	matches, err := edms.matchRepo.GetByOrganizationID(ctx, orgID)
	if err != nil {
		return nil, err
	}

	matchIDs := make([]string, len(matches))
	for i, match := range matches {
		matchIDs[i] = match.ID
	}

	return matchIDs, nil
}

// notifyMatchUpdate sends WebSocket notification about match changes
func (edms *EventDrivenMatchingService) notifyMatchUpdate(event domain.Event) {
	if edms.websocketHub != nil {
		message := domain.WebSocketMessage{
			Type: "match_updated",
			Payload: map[string]interface{}{
				"match_id":  event.EntityID,
				"event":     event.Type,
				"timestamp": event.Timestamp,
			},
			Timestamp: time.Now(),
		}

		edms.websocketHub.BroadcastToOrganization(event.OrgID, message)
	}
}

// notifyNewMatch sends WebSocket notification about new matches
func (edms *EventDrivenMatchingService) notifyNewMatch(candidate *engine.Candidate, orgID string) {
	if edms.websocketHub != nil {
		message := domain.WebSocketMessage{
			Type: "new_match",
			Payload: map[string]interface{}{
				"compatibility_score": candidate.CompatibilityScore,
				"economic_score":      candidate.EconomicScore,
				"overall_score":       candidate.OverallScore,
				"distance_km":         candidate.DistanceKm,
			},
			Timestamp: time.Now(),
		}

		edms.websocketHub.BroadcastToOrganization(orgID, message)
	}
}

// PublishEvent publishes an event to the event bus
func (edms *EventDrivenMatchingService) PublishEvent(eventType domain.EventType, entityID, orgID, userID string, payload map[string]interface{}) error {
	event := domain.Event{
		ID:        fmt.Sprintf("%s-%d", entityID, time.Now().UnixNano()),
		Type:      eventType,
		EntityID:  entityID,
		OrgID:     orgID,
		UserID:    userID,
		Timestamp: time.Now(),
		Payload:   payload,
	}

	return edms.eventBus.Publish(event)
}