package services

import (
	"fmt"
	"log"
	"time"

	"attune-heart-therapy/internal/models"
	"attune-heart-therapy/internal/repositories"
)

// adminService implements the AdminService interface
type adminService struct {
	userRepo     repositories.UserRepository
	bookingRepo  repositories.BookingRepository
	scheduleRepo repositories.ScheduleRepository
}

// NewAdminService creates a new instance of AdminService
func NewAdminService(
	userRepo repositories.UserRepository,
	bookingRepo repositories.BookingRepository,
	scheduleRepo repositories.ScheduleRepository,
) AdminService {
	return &adminService{
		userRepo:     userRepo,
		bookingRepo:  bookingRepo,
		scheduleRepo: scheduleRepo,
	}
}

// GetDashboardStats retrieves dashboard statistics for admin overview
func (s *adminService) GetDashboardStats() (*DashboardStats, error) {
	var stats DashboardStats

	// Get user statistics
	totalUsers, err := s.userRepo.GetActiveUsersCount()
	if err != nil {
		log.Printf("Failed to get total users count: %v", err)
		return nil, fmt.Errorf("failed to get user statistics: %w", err)
	}
	stats.TotalUsers = totalUsers
	stats.ActiveUsers = totalUsers // For now, all users are considered active

	// Get booking statistics
	bookingStats, err := s.bookingRepo.GetBookingStats()
	if err != nil {
		log.Printf("Failed to get booking statistics: %v", err)
		return nil, fmt.Errorf("failed to get booking statistics: %w", err)
	}
	stats.TotalBookings = bookingStats.TotalBookings
	stats.UpcomingBookings = bookingStats.UpcomingBookings
	stats.CompletedBookings = bookingStats.CompletedBookings
	stats.CancelledBookings = bookingStats.CancelledBookings

	// Get financial statistics (all time)
	allTimeStart := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
	allTimeEnd := time.Now()

	financialStats, err := s.bookingRepo.GetFinancialStats(allTimeStart, allTimeEnd)
	if err != nil {
		log.Printf("Failed to get financial statistics: %v", err)
		return nil, fmt.Errorf("failed to get financial statistics: %w", err)
	}
	stats.TotalRevenue = financialStats.TotalRevenue

	// Get monthly revenue (current month)
	now := time.Now()
	monthStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
	monthEnd := monthStart.AddDate(0, 1, 0)

	monthlyStats, err := s.bookingRepo.GetFinancialStats(monthStart, monthEnd)
	if err != nil {
		log.Printf("Failed to get monthly financial statistics: %v", err)
		return nil, fmt.Errorf("failed to get monthly financial statistics: %w", err)
	}
	stats.MonthlyRevenue = monthlyStats.TotalRevenue

	return &stats, nil
}

// GetFinancialReports generates financial reports for a given date range
func (s *adminService) GetFinancialReports(startDate, endDate time.Time) (*FinancialReport, error) {
	// Validate date range
	if endDate.Before(startDate) {
		return nil, fmt.Errorf("end date cannot be before start date")
	}

	// Get overall financial statistics
	financialStats, err := s.bookingRepo.GetFinancialStats(startDate, endDate)
	if err != nil {
		log.Printf("Failed to get financial statistics for date range %v to %v: %v", startDate, endDate, err)
		return nil, fmt.Errorf("failed to get financial statistics: %w", err)
	}

	report := &FinancialReport{
		StartDate:      startDate,
		EndDate:        endDate,
		TotalRevenue:   financialStats.TotalRevenue,
		TotalBookings:  financialStats.TotalBookings,
		AverageBooking: financialStats.AverageBooking,
	}

	// Generate daily breakdown
	dailyBreakdown, err := s.generateDailyBreakdown(startDate, endDate)
	if err != nil {
		log.Printf("Failed to generate daily breakdown: %v", err)
		return nil, fmt.Errorf("failed to generate daily breakdown: %w", err)
	}
	report.DailyBreakdown = dailyBreakdown

	// Generate monthly breakdown
	monthlyBreakdown, err := s.generateMonthlyBreakdown(startDate, endDate)
	if err != nil {
		log.Printf("Failed to generate monthly breakdown: %v", err)
		return nil, fmt.Errorf("failed to generate monthly breakdown: %w", err)
	}
	report.MonthlyBreakdown = monthlyBreakdown

	return report, nil
}

// CreateSchedule creates a new schedule slot
func (s *adminService) CreateSchedule(req CreateScheduleRequest) (*models.Schedule, error) {
	// Validate the request
	if req.EndTime.Before(req.StartTime) || req.EndTime.Equal(req.StartTime) {
		return nil, fmt.Errorf("end time must be after start time")
	}

	if req.StartTime.Before(time.Now()) {
		return nil, fmt.Errorf("cannot create schedule slots in the past")
	}

	if req.MaxBookings < 1 {
		return nil, fmt.Errorf("max bookings must be at least 1")
	}

	// Create the schedule
	schedule := &models.Schedule{
		StartTime:   req.StartTime,
		EndTime:     req.EndTime,
		MaxBookings: req.MaxBookings,
		IsAvailable: true,
		BookedCount: 0,
	}

	if err := s.scheduleRepo.Create(schedule); err != nil {
		log.Printf("Failed to create schedule: %v", err)
		return nil, fmt.Errorf("failed to create schedule: %w", err)
	}

	log.Printf("Successfully created schedule slot from %v to %v with max bookings %d",
		schedule.StartTime, schedule.EndTime, schedule.MaxBookings)

	return schedule, nil
}

// UpdateSchedule updates an existing schedule slot
func (s *adminService) UpdateSchedule(scheduleID uint, req UpdateScheduleRequest) (*models.Schedule, error) {
	// Get the existing schedule
	schedule, err := s.scheduleRepo.GetByID(scheduleID)
	if err != nil {
		log.Printf("Failed to get schedule %d: %v", scheduleID, err)
		return nil, fmt.Errorf("schedule not found: %w", err)
	}

	// Update fields if provided
	if req.StartTime != nil {
		schedule.StartTime = *req.StartTime
	}
	if req.EndTime != nil {
		schedule.EndTime = *req.EndTime
	}
	if req.MaxBookings != nil {
		if *req.MaxBookings < 1 {
			return nil, fmt.Errorf("max bookings must be at least 1")
		}
		if *req.MaxBookings < schedule.BookedCount {
			return nil, fmt.Errorf("max bookings cannot be less than current booked count (%d)", schedule.BookedCount)
		}
		schedule.MaxBookings = *req.MaxBookings
	}
	if req.IsAvailable != nil {
		schedule.IsAvailable = *req.IsAvailable
	}

	// Validate time range if updated
	if !schedule.EndTime.After(schedule.StartTime) {
		return nil, fmt.Errorf("end time must be after start time")
	}

	// Update the schedule
	if err := s.scheduleRepo.Update(schedule); err != nil {
		log.Printf("Failed to update schedule %d: %v", scheduleID, err)
		return nil, fmt.Errorf("failed to update schedule: %w", err)
	}

	log.Printf("Successfully updated schedule %d", scheduleID)

	return schedule, nil
}

// GetAllUsers retrieves all users with pagination
func (s *adminService) GetAllUsers(limit, offset int) ([]models.User, int64, error) {
	if limit <= 0 {
		limit = 50 // Default limit
	}
	if limit > 100 {
		limit = 100 // Maximum limit
	}
	if offset < 0 {
		offset = 0
	}

	users, total, err := s.userRepo.GetAllUsers(limit, offset)
	if err != nil {
		log.Printf("Failed to get users with limit %d, offset %d: %v", limit, offset, err)
		return nil, 0, fmt.Errorf("failed to get users: %w", err)
	}

	return users, total, nil
}

// GetAllBookings retrieves all bookings with pagination
func (s *adminService) GetAllBookings(limit, offset int) ([]models.Booking, int64, error) {
	if limit <= 0 {
		limit = 50 // Default limit
	}
	if limit > 100 {
		limit = 100 // Maximum limit
	}
	if offset < 0 {
		offset = 0
	}

	bookings, total, err := s.bookingRepo.GetAllBookings(limit, offset)
	if err != nil {
		log.Printf("Failed to get bookings with limit %d, offset %d: %v", limit, offset, err)
		return nil, 0, fmt.Errorf("failed to get bookings: %w", err)
	}

	return bookings, total, nil
}

// generateDailyBreakdown generates daily financial breakdown for the given date range
func (s *adminService) generateDailyBreakdown(startDate, endDate time.Time) ([]DailyFinancialSummary, error) {
	var breakdown []DailyFinancialSummary

	// Iterate through each day in the range
	for d := startDate; !d.After(endDate); d = d.AddDate(0, 0, 1) {
		dayStart := time.Date(d.Year(), d.Month(), d.Day(), 0, 0, 0, 0, d.Location())
		dayEnd := dayStart.AddDate(0, 0, 1)

		stats, err := s.bookingRepo.GetFinancialStats(dayStart, dayEnd)
		if err != nil {
			return nil, fmt.Errorf("failed to get daily stats for %v: %w", d, err)
		}

		breakdown = append(breakdown, DailyFinancialSummary{
			Date:     dayStart,
			Revenue:  stats.TotalRevenue,
			Bookings: stats.TotalBookings,
		})
	}

	return breakdown, nil
}

// generateMonthlyBreakdown generates monthly financial breakdown for the given date range
func (s *adminService) generateMonthlyBreakdown(startDate, endDate time.Time) ([]MonthlyFinancialSummary, error) {
	var breakdown []MonthlyFinancialSummary

	// Start from the beginning of the start month
	current := time.Date(startDate.Year(), startDate.Month(), 1, 0, 0, 0, 0, startDate.Location())
	endMonth := time.Date(endDate.Year(), endDate.Month(), 1, 0, 0, 0, 0, endDate.Location())

	for !current.After(endMonth) {
		monthStart := current
		monthEnd := monthStart.AddDate(0, 1, 0)

		// Adjust for the actual date range
		if monthStart.Before(startDate) {
			monthStart = startDate
		}
		if monthEnd.After(endDate) {
			monthEnd = endDate
		}

		stats, err := s.bookingRepo.GetFinancialStats(monthStart, monthEnd)
		if err != nil {
			return nil, fmt.Errorf("failed to get monthly stats for %v: %w", current, err)
		}

		breakdown = append(breakdown, MonthlyFinancialSummary{
			Month:    current.Format("2006-01"),
			Revenue:  stats.TotalRevenue,
			Bookings: stats.TotalBookings,
		})

		current = current.AddDate(0, 1, 0)
	}

	return breakdown, nil
}