package repositories

import (
	"errors"
	"fmt"
	"time"

	"attune-heart-therapy/internal/models"

	"gorm.io/gorm"
)

// bookingRepository implements the BookingRepository interface
type bookingRepository struct {
	db *gorm.DB
}

// NewBookingRepository creates a new instance of BookingRepository
func NewBookingRepository(db *gorm.DB) BookingRepository {
	return &bookingRepository{
		db: db,
	}
}

// Create creates a new booking in the database
func (r *bookingRepository) Create(booking *models.Booking) error {
	if booking == nil {
		return errors.New("booking cannot be nil")
	}

	if err := r.db.Create(booking).Error; err != nil {
		return fmt.Errorf("failed to create booking: %w", err)
	}

	return nil
}

// GetByID retrieves a booking by its ID with user preloaded
func (r *bookingRepository) GetByID(id uint) (*models.Booking, error) {
	if id == 0 {
		return nil, errors.New("invalid booking ID")
	}

	var booking models.Booking
	if err := r.db.Preload("User").First(&booking, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, fmt.Errorf("booking with ID %d not found", id)
		}
		return nil, fmt.Errorf("failed to get booking by ID: %w", err)
	}

	return &booking, nil
}

// GetByUserID retrieves all bookings for a specific user with user preloaded
func (r *bookingRepository) GetByUserID(userID uint) ([]models.Booking, error) {
	if userID == 0 {
		return nil, errors.New("invalid user ID")
	}

	var bookings []models.Booking
	if err := r.db.Preload("User").Where("user_id = ?", userID).
		Order("scheduled_at DESC").Find(&bookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get bookings for user %d: %w", userID, err)
	}

	return bookings, nil
}

// Update updates an existing booking in the database
func (r *bookingRepository) Update(booking *models.Booking) error {
	if booking == nil {
		return errors.New("booking cannot be nil")
	}

	if booking.ID == 0 {
		return errors.New("booking ID is required for update")
	}

	// Check if booking exists
	var existingBooking models.Booking
	if err := r.db.First(&existingBooking, booking.ID).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return fmt.Errorf("booking with ID %d not found", booking.ID)
		}
		return fmt.Errorf("failed to check booking existence: %w", err)
	}

	// Update the booking
	if err := r.db.Save(booking).Error; err != nil {
		return fmt.Errorf("failed to update booking: %w", err)
	}

	return nil
}

// Delete soft deletes a booking by its ID
func (r *bookingRepository) Delete(id uint) error {
	if id == 0 {
		return errors.New("invalid booking ID")
	}

	// Check if booking exists
	var booking models.Booking
	if err := r.db.First(&booking, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return fmt.Errorf("booking with ID %d not found", id)
		}
		return fmt.Errorf("failed to check booking existence: %w", err)
	}

	// Soft delete the booking
	if err := r.db.Delete(&booking).Error; err != nil {
		return fmt.Errorf("failed to delete booking: %w", err)
	}

	return nil
}

// GetUpcomingBookings retrieves all upcoming bookings for notification scheduling
func (r *bookingRepository) GetUpcomingBookings() ([]models.Booking, error) {
	var bookings []models.Booking

	// Get bookings that are scheduled and in the future
	if err := r.db.Preload("User").
		Where("status = ? AND scheduled_at > ?", models.BookingStatusScheduled, time.Now()).
		Order("scheduled_at ASC").
		Find(&bookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get upcoming bookings: %w", err)
	}

	return bookings, nil
}

// GetByPaymentID retrieves a booking by its payment ID with user preloaded
func (r *bookingRepository) GetByPaymentID(paymentID string) (*models.Booking, error) {
	if paymentID == "" {
		return nil, errors.New("payment ID cannot be empty")
	}

	var booking models.Booking
	if err := r.db.Preload("User").Where("payment_id = ?", paymentID).First(&booking).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, fmt.Errorf("booking with payment ID %s not found", paymentID)
		}
		return nil, fmt.Errorf("failed to get booking by payment ID: %w", err)
	}

	return &booking, nil
}

// GetAllBookings retrieves all bookings with pagination
func (r *bookingRepository) GetAllBookings(limit, offset int) ([]models.Booking, int64, error) {
	var bookings []models.Booking
	var total int64

	// Get total count
	if err := r.db.Model(&models.Booking{}).Count(&total).Error; err != nil {
		return nil, 0, fmt.Errorf("failed to get bookings count: %w", err)
	}

	// Get bookings with pagination and user preloaded
	if err := r.db.Preload("User").Limit(limit).Offset(offset).
		Order("created_at DESC").Find(&bookings).Error; err != nil {
		return nil, 0, fmt.Errorf("failed to get bookings: %w", err)
	}

	// Clear password hashes for security
	for i := range bookings {
		bookings[i].User.PasswordHash = ""
	}

	return bookings, total, nil
}

// GetBookingStats retrieves booking statistics for admin dashboard
func (r *bookingRepository) GetBookingStats() (*BookingStats, error) {
	var stats BookingStats

	// Get total bookings
	if err := r.db.Model(&models.Booking{}).Count(&stats.TotalBookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get total bookings count: %w", err)
	}

	// Get upcoming bookings
	if err := r.db.Model(&models.Booking{}).
		Where("status = ? AND scheduled_at > ?", models.BookingStatusScheduled, time.Now()).
		Count(&stats.UpcomingBookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get upcoming bookings count: %w", err)
	}

	// Get completed bookings
	if err := r.db.Model(&models.Booking{}).
		Where("status = ?", models.BookingStatusCompleted).
		Count(&stats.CompletedBookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get completed bookings count: %w", err)
	}

	// Get cancelled bookings
	if err := r.db.Model(&models.Booking{}).
		Where("status = ?", models.BookingStatusCancelled).
		Count(&stats.CancelledBookings).Error; err != nil {
		return nil, fmt.Errorf("failed to get cancelled bookings count: %w", err)
	}

	return &stats, nil
}

// GetFinancialStats retrieves financial statistics for admin reports
func (r *bookingRepository) GetFinancialStats(startDate, endDate time.Time) (*FinancialStats, error) {
	var stats FinancialStats

	// Get total revenue and booking count for the date range
	var result struct {
		TotalRevenue  float64 `json:"total_revenue"`
		TotalBookings int64   `json:"total_bookings"`
	}

	if err := r.db.Model(&models.Booking{}).
		Select("COALESCE(SUM(amount), 0) as total_revenue, COUNT(*) as total_bookings").
		Where("payment_status = ? AND created_at >= ? AND created_at <= ?",
			models.PaymentStatusSucceeded, startDate, endDate).
		Scan(&result).Error; err != nil {
		return nil, fmt.Errorf("failed to get financial stats: %w", err)
	}

	stats.TotalRevenue = result.TotalRevenue
	stats.TotalBookings = result.TotalBookings

	// Calculate average booking value
	if stats.TotalBookings > 0 {
		stats.AverageBooking = stats.TotalRevenue / float64(stats.TotalBookings)
	}

	return &stats, nil
}