package service

import (
	"context"
	"time"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// SummaryReportService implements business logic for summary reports.
// Reference: Chatwoot SummaryReport controller — read-only collection GET endpoints for
// agent, team, inbox, and label summary metrics.
type SummaryReportService struct {
	rollupRepo *repository.ReportingEventsRollupRepo
}

// NewSummaryReportService creates a new SummaryReportService.
func NewSummaryReportService(rollupRepo *repository.ReportingEventsRollupRepo) *SummaryReportService {
	return &SummaryReportService{rollupRepo: rollupRepo}
}

// GetAgentSummary returns agent-level aggregated metrics for a date range.
func (s *SummaryReportService) GetAgentSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionAgent, since, until)
}

// GetTeamSummary returns team-level aggregated metrics for a date range.
func (s *SummaryReportService) GetTeamSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionTeam, since, until)
}

// GetInboxSummary returns inbox-level aggregated metrics for a date range.
func (s *SummaryReportService) GetInboxSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionInbox, since, until)
}

// GetLabelSummary returns label-level aggregated metrics for a date range.
func (s *SummaryReportService) GetLabelSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionLabel, since, until)
}

// GetAccountSummary returns account-level aggregated metrics for a date range.
func (s *SummaryReportService) GetAccountSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionAccount, since, until)
}

// GetConversationSummary returns conversation-level aggregated metrics for a date range.
func (s *SummaryReportService) GetConversationSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionConversation, since, until)
}

// GetChannelSummary returns channel-level aggregated metrics for a date range.
// Reference: Chatwoot summary_reports#channel — enforces max 6-month date range
func (s *SummaryReportService) GetChannelSummary(ctx context.Context, accountID uint, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	return s.getDimensionSummary(ctx, accountID, model.DimensionInbox, since, until)
}

// --- Response DTOs for summary reports ---

// SummaryReportDimensionMetrics holds metrics grouped by a dimension entity.
type SummaryReportDimensionMetrics struct {
	DimensionID   uint                    `json:"id"`
	DimensionType string                  `json:"dimension_type"`
	Metrics       []SummaryReportMetric   `json:"metrics"`
}

// SummaryReportMetric holds a single aggregated metric within a dimension group.
type SummaryReportMetric struct {
	Metric              string  `json:"metric"`
	Count               int64   `json:"count"`
	AverageValue        float64 `json:"average_value"`
	AverageBusinessHours float64 `json:"average_business_hours,omitempty"`
}

// getDimensionSummary queries rollups for a dimension type and groups results by dimension_id.
func (s *SummaryReportService) getDimensionSummary(ctx context.Context, accountID uint, dimType model.DimensionType, since, until time.Time) ([]SummaryReportDimensionMetrics, error) {
	rollups, err := s.rollupRepo.AggregateSummary(ctx, accountID, dimType, since, until)
	if err != nil {
		applogger.L().Errorf("SummaryReportService.getDimensionSummary(%s) query: %v", dimType, err)
		return nil, err
	}

	// Group by dimension_id
	grouped := map[uint]*SummaryReportDimensionMetrics{}
	for _, r := range rollups {
		dm, ok := grouped[r.DimensionID]
		if !ok {
			dm = &SummaryReportDimensionMetrics{
				DimensionID:   r.DimensionID,
				DimensionType: string(r.DimensionType),
			}
			grouped[r.DimensionID] = dm
		}
		dm.Metrics = append(dm.Metrics, SummaryReportMetric{
			Metric:               string(r.Metric),
			Count:                r.Count,
			AverageValue:         r.SumValue / float64(r.Count),
			AverageBusinessHours: r.SumValueBusinessHours / float64(r.Count),
		})
	}

	// Convert map to sorted slice
	result := make([]SummaryReportDimensionMetrics, 0, len(grouped))
	for _, dm := range grouped {
		result = append(result, *dm)
	}

	return result, nil
}