package service

import (
	"context"
	"encoding/json"
	"fmt"
	"math"

	"bugulma/backend/internal/domain"
	"bugulma/backend/internal/geospatial"
)

// SpatialResourceMatcher enhances resource matching with geographical intelligence
type SpatialResourceMatcher struct {
	geoRepo          domain.GeographicalFeatureRepository
	siteRepo         domain.SiteRepository
	resourceFlowRepo domain.ResourceFlowRepository
	geospatialSvc    *GeospatialService
	transportSvc     *TransportationService
	geoCalc          geospatial.Calculator
}

// NewSpatialResourceMatcher creates a new spatial resource matcher
func NewSpatialResourceMatcher(
	geoRepo domain.GeographicalFeatureRepository,
	siteRepo domain.SiteRepository,
	resourceFlowRepo domain.ResourceFlowRepository,
	geospatialSvc *GeospatialService,
	transportSvc *TransportationService,
	geoCalc geospatial.Calculator,
) *SpatialResourceMatcher {
	return &SpatialResourceMatcher{
		geoRepo:          geoRepo,
		siteRepo:         siteRepo,
		resourceFlowRepo: resourceFlowRepo,
		geospatialSvc:    geospatialSvc,
		transportSvc:     transportSvc,
		geoCalc:          geoCalc,
	}
}

// SpatialMatchResult represents a resource match with spatial metadata
type SpatialMatchResult struct {
	ResourceFlow   *domain.ResourceFlow `json:"resource_flow"`
	ProviderSite   *domain.Site         `json:"provider_site"`
	RequesterSite  *domain.Site         `json:"requester_site"`
	SpatialMetrics *SpatialMetrics      `json:"spatial_metrics"`
	MatchScore     float64              `json:"match_score"`
}

// SpatialMetrics contains geographical analysis for a match
type SpatialMetrics struct {
	StraightLineDistance float64 `json:"straight_line_distance_km"`
	RoadDistance         float64 `json:"road_distance_km,omitempty"`
	TransportCost        float64 `json:"transport_cost_eur_month"`
	EnvironmentalScore   float64 `json:"environmental_score"`
	InfrastructureScore  float64 `json:"infrastructure_score"`
	TimeToDeliver        float64 `json:"time_to_deliver_hours,omitempty"`
}

// FindNearbyResourceProviders finds resource providers within geographical constraints
func (m *SpatialResourceMatcher) FindNearbyResourceProviders(
	ctx context.Context,
	resourceType domain.ResourceType,
	requesterLat, requesterLng float64,
	maxDistanceKm float64,
	preferredTransport domain.TransportMode,
) ([]*SpatialMatchResult, error) {

	// Find sites within radius that offer the requested resource
	nearbySites, err := m.siteRepo.GetWithinRadius(ctx, requesterLat, requesterLng, maxDistanceKm)
	if err != nil {
		return nil, fmt.Errorf("failed to find nearby sites: %w", err)
	}

	var results []*SpatialMatchResult

	// Process each site and check for matching resource flows
	for _, site := range nearbySites {
		if site == nil {
			continue
		}
		// Get resource flows for this site
		allFlows, err := m.resourceFlowRepo.GetBySiteID(ctx, site.ID)
		if err != nil {
			continue // Skip if no flows found or error
		}

		// Filter for output flows of the requested resource type
		var flows []*domain.ResourceFlow
		for _, flow := range allFlows {
			if flow.Direction == domain.DirectionOutput && flow.Type == resourceType {
				flows = append(flows, flow)
			}
		}

		// Skip sites that don't have matching flows
		if len(flows) == 0 {
			continue
		}

		// Calculate spatial metrics once per site (reused for all flows)
		metrics, err := m.calculateSpatialMetrics(ctx, requesterLat, requesterLng, site, preferredTransport)
		if err != nil {
			continue // Skip sites where we can't calculate metrics
		}

		// Create match results for each matching flow
		for _, flow := range flows {
			matchScore := m.calculateMatchScore(metrics, flow)
			result := &SpatialMatchResult{
				ResourceFlow:   flow,
				ProviderSite:   site,
				SpatialMetrics: metrics,
				MatchScore:     matchScore,
			}
			results = append(results, result)
		}
	}

	return results, nil
}

// siteProvidesResource checks if a site provides a specific resource type
// This method is deprecated - resource flow checking is now done directly in FindNearbyResourceProviders
// for better efficiency. Kept for backward compatibility if needed elsewhere.
func (m *SpatialResourceMatcher) siteProvidesResource(ctx context.Context, site *domain.Site, resourceType domain.ResourceType) (bool, error) {
	// Check if site has output flows of the requested resource type
	flows, err := m.resourceFlowRepo.GetBySiteID(ctx, site.ID)
	if err != nil {
		return false, err
	}

	for _, flow := range flows {
		if flow.Direction == domain.DirectionOutput && flow.Type == resourceType {
			return true, nil
		}
	}

	return false, nil
}

// calculateSpatialMetrics calculates spatial metrics between requester and provider
func (m *SpatialResourceMatcher) calculateSpatialMetrics(
	ctx context.Context,
	fromLat, fromLng float64,
	toSite *domain.Site,
	preferredTransport domain.TransportMode,
) (*SpatialMetrics, error) {
	if toSite == nil {
		return nil, fmt.Errorf("toSite cannot be nil")
	}

	metrics := &SpatialMetrics{}

	// Calculate straight-line distance
	result, err := m.geoCalc.CalculateDistance(
		geospatial.Point{Latitude: fromLat, Longitude: fromLng},
		geospatial.Point{Latitude: toSite.Latitude, Longitude: toSite.Longitude},
	)
	if err != nil {
		return nil, fmt.Errorf("failed to calculate distance: %w", err)
	}

	metrics.StraightLineDistance = result.DistanceKm

	// Estimate road distance (simplified approximation)
	metrics.RoadDistance = metrics.StraightLineDistance * 1.3 // 30% longer due to roads

	// Calculate transportation cost using dedicated service
	transportCost, err := m.transportSvc.CalculateTransportCost(
		fromLat, fromLng, toSite.Latitude, toSite.Longitude,
		preferredTransport, 10.0, // Assume 10 tons for cost calculation
	)
	if err != nil {
		// Use fallback calculation if transport service fails
		metrics.TransportCost = metrics.RoadDistance * 0.1  // €0.10 per km fallback
		metrics.TimeToDeliver = metrics.RoadDistance / 50.0 // 50 km/h fallback
	} else {
		metrics.TransportCost = transportCost.CostEur
		metrics.TimeToDeliver = transportCost.TimeHours
	}

	// Environmental score for the destination
	envScore, err := m.geospatialSvc.CalculateSiteEnvironmentalScore(ctx, toSite.Latitude, toSite.Longitude)
	if err != nil {
		metrics.EnvironmentalScore = 5.0 // Default neutral score
	} else {
		metrics.EnvironmentalScore = envScore
	}

	// Infrastructure score (simplified)
	metrics.InfrastructureScore = m.calculateInfrastructureScore(toSite)

	return metrics, nil
}

// calculateMatchScore calculates an overall match score
func (m *SpatialResourceMatcher) calculateMatchScore(metrics *SpatialMetrics, flow *domain.ResourceFlow) float64 {
	// Multi-criteria scoring
	distanceScore := math.Max(0, 10.0-(metrics.StraightLineDistance/10.0)) // Better closer, max 10km
	costScore := math.Max(0, 10.0-(metrics.TransportCost/100.0))           // Better cheaper, max €100
	envScore := metrics.EnvironmentalScore                                 // 0-10 scale
	infraScore := metrics.InfrastructureScore                              // 0-10 scale

	// Weighted average
	return (distanceScore*0.3 + costScore*0.3 + envScore*0.2 + infraScore*0.2)
}

// calculateInfrastructureScore calculates infrastructure quality score
func (m *SpatialResourceMatcher) calculateInfrastructureScore(site *domain.Site) float64 {
	score := 5.0 // Base score

	// Check available utilities
	if len(site.AvailableUtilities) > 0 {
		var utilities []string
		if err := json.Unmarshal(site.AvailableUtilities, &utilities); err == nil {
			score += float64(len(utilities)) * 0.5 // +0.5 per utility
		}
	}

	// Check parking spaces
	if site.ParkingSpaces > 0 {
		score += 1.0
	}

	// Check loading docks
	if site.LoadingDocks > 0 {
		score += 1.0
	}

	return math.Min(10.0, score) // Cap at 10
}