package service

import (
	"context"
	"strings"
	"time"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	"gorm.io/gorm"
)

func reportingServiceDB(eventRepo *repository.ReportingEventRepo, rollupRepo *repository.ReportingEventsRollupRepo) *gorm.DB {
	if rollupRepo != nil && rollupRepo.DB() != nil {
		return rollupRepo.DB()
	}
	if eventRepo != nil {
		return eventRepo.DB()
	}
	return nil
}

func accountReportingLocation(ctx context.Context, db *gorm.DB, accountID uint) (*time.Location, bool, error) {
	if db == nil {
		return nil, false, nil
	}
	var account model.Account
	if err := db.WithContext(ctx).First(&account, accountID).Error; err != nil {
		return nil, false, err
	}
	tz := strings.TrimSpace(account.ReportingTimezone)
	if tz == "" {
		return nil, false, nil
	}
	loc, err := time.LoadLocation(tz)
	if err != nil {
		return nil, false, nil
	}
	return loc, true, nil
}

func utcBoundariesForReportingDate(date time.Time, loc *time.Location) (time.Time, time.Time, time.Time) {
	localDate := time.Date(date.Year(), date.Month(), date.Day(), 0, 0, 0, 0, loc)
	startUTC := localDate.UTC()
	endUTC := localDate.AddDate(0, 0, 1).UTC()
	rollupDate := time.Date(localDate.Year(), localDate.Month(), localDate.Day(), 0, 0, 0, 0, time.UTC)
	return startUTC, endUTC, rollupDate
}

func rollupDateForReportingTime(value time.Time, loc *time.Location) time.Time {
	localTime := value.In(loc)
	return time.Date(localTime.Year(), localTime.Month(), localTime.Day(), 0, 0, 0, 0, time.UTC)
}

func dimensionIDForEvent(accountID uint, event model.ReportingEvent, dim DimensionSpec) (uint, bool) {
	switch dim.GroupColumn {
	case "":
		return accountID, true
	case "user_id":
		if event.UserID == nil {
			return 0, false
		}
		return *event.UserID, true
	case "inbox_id":
		if event.InboxID == nil {
			return 0, false
		}
		return *event.InboxID, true
	default:
		return 0, false
	}
}

func isDistinctCountEvent(name string) bool {
	for _, eventName := range DistinctCountEvents {
		if name == eventName {
			return true
		}
	}
	return false
}

func aggregateReportingEvents(accountID uint, events []model.ReportingEvent) []RollupAggregate {
	type groupKey struct {
		dimType model.DimensionType
		dimID   uint
		metric  model.RollupMetric
	}

	groups := map[groupKey]*RollupAggregate{}
	seenDistinct := map[groupKey]map[uint]struct{}{}

	for _, event := range events {
		for _, dim := range BackfillDimensions {
			dimID, ok := dimensionIDForEvent(accountID, event, dim)
			if !ok {
				continue
			}
			key := groupKey{dimType: dim.Type, dimID: dimID, metric: model.RollupMetric(event.Name)}
			agg, ok := groups[key]
			if !ok {
				agg = &RollupAggregate{DimensionType: dim.Type, DimensionID: dimID, Metric: model.RollupMetric(event.Name)}
				groups[key] = agg
			}

			if isDistinctCountEvent(event.Name) {
				if event.ConversationID == nil {
					continue
				}
				if seenDistinct[key] == nil {
					seenDistinct[key] = map[uint]struct{}{}
				}
				if _, exists := seenDistinct[key][*event.ConversationID]; exists {
					continue
				}
				seenDistinct[key][*event.ConversationID] = struct{}{}
				agg.Count++
				continue
			}

			agg.Count++
			agg.SumValue += event.Value
			agg.SumBizHours += event.ValueInBusinessHours
		}
	}

	aggregates := make([]RollupAggregate, 0, len(groups))
	for _, agg := range groups {
		if agg.Count == 0 {
			continue
		}
		aggregates = append(aggregates, *agg)
	}
	return aggregates
}

func rollupRowsFromAggregates(accountID uint, date time.Time, aggregates []RollupAggregate) []model.ReportingEventsRollup {
	var rollupRows []model.ReportingEventsRollup
	for _, agg := range aggregates {
		rollupMetrics := ExpandEventToRollupMetrics(agg.Metric, agg.Count, agg.SumValue, agg.SumBizHours)
		for rm, data := range rollupMetrics {
			rollupRows = append(rollupRows, model.ReportingEventsRollup{
				AccountID:             accountID,
				Date:                  date,
				DimensionType:         agg.DimensionType,
				DimensionID:           agg.DimensionID,
				Metric:                rm,
				Count:                 data.Count,
				SumValue:              data.SumValue,
				SumValueBusinessHours: data.SumBizHours,
			})
		}
	}
	return rollupRows
}