package sql

import (
	"context"
	"fmt"
	"tercul/internal/app/analytics"
	"tercul/internal/domain"
	"tercul/internal/domain/work"
	"time"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/trace"
	"gorm.io/gorm"
)

type analyticsRepository struct {
	db     *gorm.DB
	tracer trace.Tracer
}

func NewAnalyticsRepository(db *gorm.DB) analytics.Repository {
	return &analyticsRepository{
		db:     db,
		tracer: otel.Tracer("analytics.repository"),
	}
}

var allowedWorkCounterFields = map[string]bool{
	"views":             true,
	"likes":             true,
	"comments":          true,
	"bookmarks":         true,
	"shares":            true,
	"translation_count": true,
}

var allowedTranslationCounterFields = map[string]bool{
	"views":    true,
	"likes":    true,
	"comments": true,
	"shares":   true,
}

func (r *analyticsRepository) IncrementWorkCounter(ctx context.Context, workID uint, field string, value int) error {
	ctx, span := r.tracer.Start(ctx, "IncrementWorkCounter")
	defer span.End()
	if !allowedWorkCounterFields[field] {
		return fmt.Errorf("invalid work counter field: %s", field)
	}

	// Using a transaction to ensure atomicity
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// First, try to update the existing record
		result := tx.Model(&work.WorkStats{}).Where("work_id = ?", workID).UpdateColumn(field, gorm.Expr(fmt.Sprintf("%s + ?", field), value))
		if result.Error != nil {
			return result.Error
		}

		// If no rows were affected, the record does not exist, so create it
		if result.RowsAffected == 0 {
			initialData := map[string]interface{}{"work_id": workID, field: value}
			return tx.Model(&work.WorkStats{}).Create(initialData).Error
		}

		return nil
	})
}

func (r *analyticsRepository) GetTrendingWorks(ctx context.Context, timePeriod string, limit int) ([]*work.Work, error) {
	ctx, span := r.tracer.Start(ctx, "GetTrendingWorks")
	defer span.End()
	var trendingWorks []*domain.Trending
	err := r.db.WithContext(ctx).
		Where("entity_type = ? AND time_period = ?", "Work", timePeriod).
		Order("rank ASC").
		Limit(limit).
		Find(&trendingWorks).Error
	if err != nil {
		return nil, err
	}

	if len(trendingWorks) == 0 {
		return []*work.Work{}, nil
	}

	workIDs := make([]uint, len(trendingWorks))
	for i, tw := range trendingWorks {
		workIDs[i] = tw.EntityID
	}

	var works []*work.Work
	err = r.db.WithContext(ctx).
		Where("id IN ?", workIDs).
		Find(&works).Error

	// This part is tricky because the order from the IN clause is not guaranteed.
	// We need to re-order the works based on the trending rank.
	workMap := make(map[uint]*work.Work)
	for _, w := range works {
		workMap[w.ID] = w
	}

	orderedWorks := make([]*work.Work, len(workIDs))
	for i, id := range workIDs {
		if w, ok := workMap[id]; ok {
			orderedWorks[i] = w
		}
	}

	return orderedWorks, err
}

func (r *analyticsRepository) IncrementTranslationCounter(ctx context.Context, translationID uint, field string, value int) error {
	ctx, span := r.tracer.Start(ctx, "IncrementTranslationCounter")
	defer span.End()
	if !allowedTranslationCounterFields[field] {
		return fmt.Errorf("invalid translation counter field: %s", field)
	}

	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		result := tx.Model(&domain.TranslationStats{}).Where("translation_id = ?", translationID).UpdateColumn(field, gorm.Expr(fmt.Sprintf("%s + ?", field), value))
		if result.Error != nil {
			return result.Error
		}

		if result.RowsAffected == 0 {
			initialData := map[string]interface{}{"translation_id": translationID, field: value}
			return tx.Model(&domain.TranslationStats{}).Create(initialData).Error
		}

		return nil
	})
}

func (r *analyticsRepository) UpdateWorkStats(ctx context.Context, workID uint, stats work.WorkStats) error {
	ctx, span := r.tracer.Start(ctx, "UpdateWorkStats")
	defer span.End()
	return r.db.WithContext(ctx).Model(&work.WorkStats{}).Where("work_id = ?", workID).Updates(stats).Error
}

func (r *analyticsRepository) UpdateTranslationStats(ctx context.Context, translationID uint, stats domain.TranslationStats) error {
	ctx, span := r.tracer.Start(ctx, "UpdateTranslationStats")
	defer span.End()
	return r.db.WithContext(ctx).Model(&domain.TranslationStats{}).Where("translation_id = ?", translationID).Updates(stats).Error
}

func (r *analyticsRepository) GetOrCreateWorkStats(ctx context.Context, workID uint) (*work.WorkStats, error) {
	ctx, span := r.tracer.Start(ctx, "GetOrCreateWorkStats")
	defer span.End()
	var stats work.WorkStats
	err := r.db.WithContext(ctx).Where(work.WorkStats{WorkID: workID}).FirstOrCreate(&stats).Error
	return &stats, err
}

func (r *analyticsRepository) GetOrCreateTranslationStats(ctx context.Context, translationID uint) (*domain.TranslationStats, error) {
	ctx, span := r.tracer.Start(ctx, "GetOrCreateTranslationStats")
	defer span.End()
	var stats domain.TranslationStats
	err := r.db.WithContext(ctx).Where(domain.TranslationStats{TranslationID: translationID}).FirstOrCreate(&stats).Error
	return &stats, err
}

func (r *analyticsRepository) GetOrCreateUserEngagement(ctx context.Context, userID uint, date time.Time) (*domain.UserEngagement, error) {
	ctx, span := r.tracer.Start(ctx, "GetOrCreateUserEngagement")
	defer span.End()
	var engagement domain.UserEngagement
	err := r.db.WithContext(ctx).Where(domain.UserEngagement{UserID: userID, Date: date}).FirstOrCreate(&engagement).Error
	return &engagement, err
}

func (r *analyticsRepository) UpdateUserEngagement(ctx context.Context, userEngagement *domain.UserEngagement) error {
	ctx, span := r.tracer.Start(ctx, "UpdateUserEngagement")
	defer span.End()
	return r.db.WithContext(ctx).Save(userEngagement).Error
}

func (r *analyticsRepository) UpdateTrendingWorks(ctx context.Context, timePeriod string, trending []*domain.Trending) error {
	ctx, span := r.tracer.Start(ctx, "UpdateTrendingWorks")
	defer span.End()
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// Clear old trending data for this time period
		if err := tx.Where("time_period = ?", timePeriod).Delete(&domain.Trending{}).Error; err != nil {
			return fmt.Errorf("failed to delete old trending data: %w", err)
		}

		if len(trending) == 0 {
			return nil
		}

		// Insert new trending data
		if err := tx.Create(trending).Error; err != nil {
			return fmt.Errorf("failed to insert new trending data: %w", err)
		}

		return nil
	})
}