package service

import (
	"bugulma/backend/internal/domain"
	"context"
	"fmt"

	"gorm.io/gorm"
)

// AnalyticsService provides platform analytics and statistics
type AnalyticsService struct {
	db               *gorm.DB
	orgRepo          domain.OrganizationRepository
	siteRepo         domain.SiteRepository
	resourceFlowRepo domain.ResourceFlowRepository
	matchRepo        domain.MatchRepository
	sharedAssetRepo  domain.SharedAssetRepository
}

// NewAnalyticsService creates a new analytics service
func NewAnalyticsService(
	db *gorm.DB,
	orgRepo domain.OrganizationRepository,
	siteRepo domain.SiteRepository,
	resourceFlowRepo domain.ResourceFlowRepository,
	matchRepo domain.MatchRepository,
	sharedAssetRepo domain.SharedAssetRepository,
) *AnalyticsService {
	return &AnalyticsService{
		db:               db,
		orgRepo:          orgRepo,
		siteRepo:         siteRepo,
		resourceFlowRepo: resourceFlowRepo,
		matchRepo:        matchRepo,
		sharedAssetRepo:  sharedAssetRepo,
	}
}

// PlatformStatistics represents overall platform metrics
type PlatformStatistics struct {
	TotalOrganizations int     `json:"total_organizations"`
	TotalSites         int     `json:"total_sites"`
	TotalResourceFlows int     `json:"total_resource_flows"`
	TotalMatches       int     `json:"total_matches"`
	TotalSharedAssets  int     `json:"total_shared_assets"`
	ActiveMatches      int     `json:"active_matches"`
	CO2SavingsTonnes   float64 `json:"co2_savings_tonnes"`
	EconomicValueEUR   float64 `json:"economic_value_eur"`
}

// OrganizationStatistics represents statistics for a single organization
type OrganizationStatistics struct {
	OrganizationID     string  `json:"organization_id"`
	TotalSites         int     `json:"total_sites"`
	TotalResourceFlows int     `json:"total_resource_flows"`
	ActiveMatches      int     `json:"active_matches"`
	TotalMatches       int     `json:"total_matches"`
	CO2SavingsTonnes   float64 `json:"co2_savings_tonnes"`
	EconomicValueEUR   float64 `json:"economic_value_eur"`
}

// MatchingStatistics represents matching engine performance metrics
type MatchingStatistics struct {
	TotalMatches          int     `json:"total_matches"`
	ActiveMatches         int     `json:"active_matches"`
	CompletedMatches      int     `json:"completed_matches"`
	AvgCompatibilityScore float64 `json:"avg_compatibility_score"`
	AvgEconomicValue      float64 `json:"avg_economic_value"`
	AvgDistanceKm         float64 `json:"avg_distance_km"`
}

// ResourceFlowStatistics represents resource flow metrics
type ResourceFlowStatistics struct {
	TotalFlows       int            `json:"total_flows"`
	InputFlows       int            `json:"input_flows"`
	OutputFlows      int            `json:"output_flows"`
	FlowsByType      map[string]int `json:"flows_by_type"`
	FlowsByDirection map[string]int `json:"flows_by_direction"`
}

// ImpactMetrics represents environmental and economic impact
type ImpactMetrics struct {
	TotalCO2SavingsTonnes   float64 `json:"total_co2_savings_tonnes"`
	TotalEconomicValueEUR   float64 `json:"total_economic_value_eur"`
	MaterialsRecycledTonnes float64 `json:"materials_recycled_tonnes"`
	EnergySharedMWh         float64 `json:"energy_shared_mwh"`
	WaterReclaimedM3        float64 `json:"water_reclaimed_m3"`
}

// DashboardStatistics represents dashboard overview statistics
type DashboardStatistics struct {
	TotalOrganizations int            `json:"total_organizations"`
	TotalSites         int            `json:"total_sites"`
	TotalResourceFlows int            `json:"total_resource_flows"`
	TotalMatches       int            `json:"total_matches"`
	ActiveProposals    int            `json:"active_proposals"`
	RecentActivity     []ActivityItem `json:"recent_activity"`
}

// ActivityItem represents a recent activity entry
type ActivityItem struct {
	ID          string `json:"id"`
	Type        string `json:"type"`
	Description string `json:"description"`
	Timestamp   string `json:"timestamp"`
}

// ConnectionStatistics represents connection and relationship statistics
type ConnectionStatistics struct {
	TotalConnections     int `json:"total_connections"`
	ActiveConnections    int `json:"active_connections"`
	PotentialConnections int `json:"potential_connections"`
}

// SupplyDemandAnalysis represents supply and demand analysis
type SupplyDemandAnalysis struct {
	TopNeeds  []ItemCount `json:"top_needs"`
	TopOffers []ItemCount `json:"top_offers"`
}

// ItemCount represents an item with its count
type ItemCount struct {
	Item  string `json:"item"`
	Count int    `json:"count"`
}

// GetPlatformStatistics retrieves overall platform statistics
func (s *AnalyticsService) GetPlatformStatistics(ctx context.Context) (*PlatformStatistics, error) {
	stats := &PlatformStatistics{}

	// Count organizations
	var orgCount int64
	if err := s.db.Model(&domain.Organization{}).Count(&orgCount).Error; err != nil {
		return nil, err
	}
	stats.TotalOrganizations = int(orgCount)

	// Count sites
	var siteCount int64
	if err := s.db.Model(&domain.Site{}).Count(&siteCount).Error; err != nil {
		return nil, err
	}
	stats.TotalSites = int(siteCount)

	// Count resource flows
	var flowCount int64
	if err := s.db.Model(&domain.ResourceFlow{}).Count(&flowCount).Error; err != nil {
		return nil, err
	}
	stats.TotalResourceFlows = int(flowCount)

	// Count matches
	var matchCount int64
	if err := s.db.Model(&domain.Match{}).Count(&matchCount).Error; err != nil {
		return nil, err
	}
	stats.TotalMatches = int(matchCount)

	// Count active matches
	var activeMatchCount int64
	if err := s.db.Model(&domain.Match{}).
		Where("status IN ?", []string{"suggested", "negotiating", "reserved", "contracted", "live"}).
		Count(&activeMatchCount).Error; err != nil {
		return nil, err
	}
	stats.ActiveMatches = int(activeMatchCount)

	// Count shared assets
	var assetCount int64
	if err := s.db.Model(&domain.SharedAsset{}).Count(&assetCount).Error; err != nil {
		return nil, err
	}
	stats.TotalSharedAssets = int(assetCount)

	// Calculate aggregate impact metrics
	var aggregates struct {
		CO2Savings    float64
		EconomicValue float64
	}
	s.db.Model(&domain.Match{}).
		Select("COALESCE(SUM(environmental_impact->>'co2_savings_kg'), 0) as co2_savings, COALESCE(SUM(economic_value), 0) as economic_value").
		Where("status IN ?", []string{"contracted", "live"}).
		Scan(&aggregates)

	stats.CO2SavingsTonnes = aggregates.CO2Savings / 1000 // Convert kg to tonnes
	stats.EconomicValueEUR = aggregates.EconomicValue

	return stats, nil
}

// GetOrganizationStatistics retrieves statistics for a specific organization
func (s *AnalyticsService) GetOrganizationStatistics(ctx context.Context, orgID string) (*OrganizationStatistics, error) {
	stats := &OrganizationStatistics{
		OrganizationID: orgID,
	}

	// Count sites
	var siteCount int64
	if err := s.db.Model(&domain.Site{}).
		Where("owner_organization_id = ?", orgID).
		Count(&siteCount).Error; err != nil {
		return nil, err
	}
	stats.TotalSites = int(siteCount)

	// Count resource flows
	var flowCount int64
	if err := s.db.Model(&domain.ResourceFlow{}).
		Where("organization_id = ?", orgID).
		Count(&flowCount).Error; err != nil {
		return nil, err
	}
	stats.TotalResourceFlows = int(flowCount)

	// Count matches (source or target)
	var matchCount int64
	s.db.Model(&domain.Match{}).
		Joins("JOIN resource_flows rf ON matches.source_resource_id = rf.id OR matches.target_resource_id = rf.id").
		Where("rf.organization_id = ?", orgID).
		Count(&matchCount)
	stats.TotalMatches = int(matchCount)

	// Count active matches
	var activeMatchCount int64
	s.db.Model(&domain.Match{}).
		Joins("JOIN resource_flows rf ON matches.source_resource_id = rf.id OR matches.target_resource_id = rf.id").
		Where("rf.organization_id = ? AND matches.status IN ?", orgID, []string{"suggested", "negotiating", "reserved", "contracted", "live"}).
		Count(&activeMatchCount)
	stats.ActiveMatches = int(activeMatchCount)

	return stats, nil
}

// GetMatchingStatistics retrieves matching engine performance statistics
func (s *AnalyticsService) GetMatchingStatistics(ctx context.Context) (*MatchingStatistics, error) {
	stats := &MatchingStatistics{}

	// Total matches
	var matchCount int64
	if err := s.db.Model(&domain.Match{}).Count(&matchCount).Error; err != nil {
		return nil, err
	}
	stats.TotalMatches = int(matchCount)

	// Active matches
	var activeCount int64
	if err := s.db.Model(&domain.Match{}).
		Where("status IN ?", []string{"suggested", "negotiating", "reserved", "contracted", "live"}).
		Count(&activeCount).Error; err != nil {
		return nil, err
	}
	stats.ActiveMatches = int(activeCount)

	// Completed matches
	var completedCount int64
	if err := s.db.Model(&domain.Match{}).
		Where("status = ?", "completed").
		Count(&completedCount).Error; err != nil {
		return nil, err
	}
	stats.CompletedMatches = int(completedCount)

	// Average metrics
	var averages struct {
		AvgScore    float64
		AvgValue    float64
		AvgDistance float64
	}
	s.db.Model(&domain.Match{}).
		Select("AVG(compatibility_score) as avg_score, AVG(economic_value) as avg_value, AVG(distance_km) as avg_distance").
		Scan(&averages)

	stats.AvgCompatibilityScore = averages.AvgScore
	stats.AvgEconomicValue = averages.AvgValue
	stats.AvgDistanceKm = averages.AvgDistance

	return stats, nil
}

// GetResourceFlowStatistics retrieves resource flow statistics
func (s *AnalyticsService) GetResourceFlowStatistics(ctx context.Context) (*ResourceFlowStatistics, error) {
	stats := &ResourceFlowStatistics{
		FlowsByType:      make(map[string]int),
		FlowsByDirection: make(map[string]int),
	}

	// Total flows
	var flowCount int64
	if err := s.db.Model(&domain.ResourceFlow{}).Count(&flowCount).Error; err != nil {
		return nil, err
	}
	stats.TotalFlows = int(flowCount)

	// Count by direction
	var directionCounts []struct {
		Direction string
		Count     int
	}
	s.db.Model(&domain.ResourceFlow{}).
		Select("direction, COUNT(*) as count").
		Group("direction").
		Scan(&directionCounts)

	for _, dc := range directionCounts {
		stats.FlowsByDirection[dc.Direction] = dc.Count
		if dc.Direction == "input" {
			stats.InputFlows = dc.Count
		} else if dc.Direction == "output" {
			stats.OutputFlows = dc.Count
		}
	}

	// Count by type
	var typeCounts []struct {
		Type  string
		Count int
	}
	s.db.Model(&domain.ResourceFlow{}).
		Select("type, COUNT(*) as count").
		Group("type").
		Scan(&typeCounts)

	for _, tc := range typeCounts {
		stats.FlowsByType[tc.Type] = tc.Count
	}

	return stats, nil
}

// GetImpactMetrics retrieves environmental and economic impact metrics
func (s *AnalyticsService) GetImpactMetrics(ctx context.Context) (*ImpactMetrics, error) {
	metrics := &ImpactMetrics{}

	// Aggregate impact from active/completed matches
	var aggregates struct {
		CO2Savings float64
		EconValue  float64
	}
	s.db.Model(&domain.Match{}).
		Select("COALESCE(SUM(environmental_impact->>'co2_savings_kg'), 0) as co2_savings, COALESCE(SUM(economic_value), 0) as econ_value").
		Where("status IN ?", []string{"contracted", "live", "completed"}).
		Scan(&aggregates)

	metrics.TotalCO2SavingsTonnes = aggregates.CO2Savings / 1000
	metrics.TotalEconomicValueEUR = aggregates.EconValue

	// TODO: Calculate materials recycled, energy shared, water reclaimed from resource flows
	// This would require additional analysis of resource flow quantity data

	return metrics, nil
}

// GetDashboardStatistics retrieves dashboard overview statistics
func (s *AnalyticsService) GetDashboardStatistics(ctx context.Context) (*DashboardStatistics, error) {
	stats := &DashboardStatistics{}

	// Get basic counts
	var orgCount, siteCount, flowCount, matchCount, activeProposalCount int64

	s.db.Model(&domain.Organization{}).Count(&orgCount)
	s.db.Model(&domain.Site{}).Count(&siteCount)
	s.db.Model(&domain.ResourceFlow{}).Count(&flowCount)
	s.db.Model(&domain.Match{}).Count(&matchCount)

	// Active proposals (matches in early stages)
	s.db.Model(&domain.Match{}).
		Where("status IN ?", []string{"suggested", "negotiating"}).
		Count(&activeProposalCount)

	stats.TotalOrganizations = int(orgCount)
	stats.TotalSites = int(siteCount)
	stats.TotalResourceFlows = int(flowCount)
	stats.TotalMatches = int(matchCount)
	stats.ActiveProposals = int(activeProposalCount)

	// Recent activity (last 10 activities)
	var recentMatches []domain.Match
	s.db.Order("created_at DESC").
		Limit(10).
		Find(&recentMatches)

	stats.RecentActivity = make([]ActivityItem, 0, len(recentMatches))
	for _, match := range recentMatches {
		description := fmt.Sprintf("Match created with compatibility score %.2f", match.CompatibilityScore)

		stats.RecentActivity = append(stats.RecentActivity, ActivityItem{
			ID:          match.ID,
			Type:        "match",
			Description: description,
			Timestamp:   match.CreatedAt.Format("2006-01-02T15:04:05Z"),
		})
	}

	return stats, nil
}

// GetConnectionStatistics retrieves connection and relationship statistics
func (s *AnalyticsService) GetConnectionStatistics(ctx context.Context) (*ConnectionStatistics, error) {
	stats := &ConnectionStatistics{}

	// Total connections (active matches)
	var totalConnections int64
	s.db.Model(&domain.Match{}).
		Where("status IN ?", []string{"contracted", "live", "completed"}).
		Count(&totalConnections)
	stats.TotalConnections = int(totalConnections)

	// Active connections (live matches)
	var activeConnections int64
	s.db.Model(&domain.Match{}).
		Where("status = ?", "live").
		Count(&activeConnections)
	stats.ActiveConnections = int(activeConnections)

	// Potential connections (suggested matches)
	var potentialConnections int64
	s.db.Model(&domain.Match{}).
		Where("status IN ?", []string{"suggested", "negotiating"}).
		Count(&potentialConnections)
	stats.PotentialConnections = int(potentialConnections)

	return stats, nil
}

// GetSupplyDemandAnalysis retrieves supply and demand analysis
func (s *AnalyticsService) GetSupplyDemandAnalysis(ctx context.Context) (*SupplyDemandAnalysis, error) {
	analysis := &SupplyDemandAnalysis{
		TopNeeds:  []ItemCount{},
		TopOffers: []ItemCount{},
	}

	// Top needs (most requested resource types)
	var needCounts []struct {
		ResourceType string
		Count        int
	}
	s.db.Model(&domain.ResourceFlow{}).
		Select("resource_type, COUNT(*) as count").
		Where("direction = ?", "input").
		Group("resource_type").
		Order("count DESC").
		Limit(10).
		Scan(&needCounts)

	for _, nc := range needCounts {
		analysis.TopNeeds = append(analysis.TopNeeds, ItemCount{
			Item:  nc.ResourceType,
			Count: nc.Count,
		})
	}

	// Top offers (most offered resource types)
	var offerCounts []struct {
		ResourceType string
		Count        int
	}
	s.db.Model(&domain.ResourceFlow{}).
		Select("resource_type, COUNT(*) as count").
		Where("direction = ?", "output").
		Group("resource_type").
		Order("count DESC").
		Limit(10).
		Scan(&offerCounts)

	for _, oc := range offerCounts {
		analysis.TopOffers = append(analysis.TopOffers, ItemCount{
			Item:  oc.ResourceType,
			Count: oc.Count,
		})
	}

	return analysis, nil
}