package services

import (
	"database/sql"

	"github.com/rede5/gohorsejobs/backend/internal/models"
)

// MetricsService handles job analytics
type MetricsService struct {
	DB *sql.DB
}

// NewMetricsService creates a new metrics service
func NewMetricsService(db *sql.DB) *MetricsService {
	return &MetricsService{DB: db}
}

// RecordView records a job view and increments the counter
func (s *MetricsService) RecordView(jobID int, userID *int, ip *string, userAgent *string) error {
	tx, err := s.DB.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	// Insert view record
	_, err = tx.Exec(`
		INSERT INTO job_views (job_id, user_id, ip_address, user_agent)
		VALUES ($1, $2, $3, $4)
	`, jobID, userID, ip, userAgent)
	if err != nil {
		return err
	}

	// Increment cached view count
	_, err = tx.Exec(`
		UPDATE jobs SET view_count = view_count + 1 WHERE id = $1
	`, jobID)
	if err != nil {
		return err
	}

	return tx.Commit()
}

// GetJobMetrics returns analytics data for a job
func (s *MetricsService) GetJobMetrics(jobID int) (*models.JobMetrics, error) {
	metrics := &models.JobMetrics{JobID: jobID}

	// Get view count from jobs table
	err := s.DB.QueryRow(`
		SELECT COALESCE(view_count, 0) FROM jobs WHERE id = $1
	`, jobID).Scan(&metrics.ViewCount)
	if err != nil {
		return nil, err
	}

	// Get unique viewers
	err = s.DB.QueryRow(`
		SELECT COUNT(DISTINCT COALESCE(user_id::text, ip_address))
		FROM job_views WHERE job_id = $1
	`, jobID).Scan(&metrics.UniqueViewers)
	if err != nil {
		metrics.UniqueViewers = 0 // Don't fail if table doesn't exist yet
	}

	// Get application count
	err = s.DB.QueryRow(`
		SELECT COUNT(*) FROM applications WHERE job_id = $1
	`, jobID).Scan(&metrics.ApplicationCount)
	if err != nil {
		metrics.ApplicationCount = 0
	}

	// Calculate conversion rate
	if metrics.ViewCount > 0 {
		metrics.ConversionRate = float64(metrics.ApplicationCount) / float64(metrics.ViewCount) * 100
	}

	// Get views last 7 days
	err = s.DB.QueryRow(`
		SELECT COUNT(*) FROM job_views 
		WHERE job_id = $1 AND viewed_at > NOW() - INTERVAL '7 days'
	`, jobID).Scan(&metrics.ViewsLast7Days)
	if err != nil {
		metrics.ViewsLast7Days = 0
	}

	// Get views last 30 days
	err = s.DB.QueryRow(`
		SELECT COUNT(*) FROM job_views 
		WHERE job_id = $1 AND viewed_at > NOW() - INTERVAL '30 days'
	`, jobID).Scan(&metrics.ViewsLast30Days)
	if err != nil {
		metrics.ViewsLast30Days = 0
	}

	return metrics, nil
}