using Fitness_core_BE.Interfaces;
using Fitness_core_BE.Models;
using Microsoft.EntityFrameworkCore;

namespace Fitness_core_BE.Repos
{
    public class FacilityClassRepository : IFacilityClassRepository
    {
        private readonly TenantDbContext _context;

        public FacilityClassRepository(TenantDbContext context)
        {
            _context = context;
        }

        public async Task<FacilityClass> CreateFacilityClass(FacilityClass facilityClass)
        {
            facilityClass.FacilityClassId = Guid.NewGuid();
            facilityClass.CreatedAt = DateTime.UtcNow;
            facilityClass.IsActive = true;

            _context.FacilityClasses.Add(facilityClass);
            return facilityClass;
        }

        public async Task<List<FacilityClass>> GetFacilityClasses(Guid clientId, bool includeInactive = false)
        {
            var query = _context.FacilityClasses
                .Include(fc => fc.Facility)
                .Where(fc => fc.FKClientId == clientId);
            if (!includeInactive)
                query = query.Where(fc => fc.IsActive);

            return await query.OrderBy(fc => fc.Name).ToListAsync();
        }

        public Task<FacilityClass?> GetFacilityClassById(Guid facilityClassId)
            => _context.FacilityClasses
                .Include(fc => fc.Facility)
                .FirstOrDefaultAsync(fc => fc.FacilityClassId == facilityClassId);

        public async Task<FacilityClass> UpdateFacilityClass(FacilityClass facilityClass)
        {
            var existing = await _context.FacilityClasses.FindAsync(facilityClass.FacilityClassId)
                ?? throw new KeyNotFoundException("Class not found");

            existing.Name = facilityClass.Name;
            existing.Description = facilityClass.Description;
            existing.RecurrenceType = facilityClass.RecurrenceType;
            existing.StartTimeOfDay = facilityClass.StartTimeOfDay;
            existing.DurationMinutes = facilityClass.DurationMinutes;
            existing.WeekDaysMask = facilityClass.WeekDaysMask;
            existing.MonthDays = facilityClass.MonthDays;
            existing.SeriesStartDate = facilityClass.SeriesStartDate;
            existing.SeriesEndDate = facilityClass.SeriesEndDate;
            existing.Capacity = facilityClass.Capacity;
            existing.IsUnlimitedCapacity = facilityClass.IsUnlimitedCapacity;
            existing.IsActive = facilityClass.IsActive;
            existing.OccurrencesGeneratedThrough = facilityClass.OccurrencesGeneratedThrough;

            return existing;
        }

        public Task<List<FacilityClass>> GetClassesNeedingGenerationAsync(Guid clientId, DateTime horizon)
            => _context.FacilityClasses
                .Where(fc => fc.FKClientId == clientId && fc.IsActive && fc.RecurrenceType != "Custom"
                    && fc.OccurrencesGeneratedThrough < horizon)
                .ToListAsync();

        public async Task<HashSet<DateTime>> GetExistingOccurrenceStartTimesAsync(Guid facilityClassId, DateTime from, DateTime to)
        {
            var times = await _context.FacilitySessions
                .Where(s => s.FKFacilityClassId == facilityClassId && s.StartTime >= from && s.StartTime < to)
                .Select(s => s.StartTime)
                .ToListAsync();
            return times.ToHashSet();
        }

        public async Task AddOccurrencesAsync(IEnumerable<FacilitySession> occurrences)
        {
            var list = occurrences.ToList();
            foreach (var occurrence in list)
            {
                occurrence.FacilitySessionId = Guid.NewGuid();
                occurrence.CreatedAt = DateTime.UtcNow;
                occurrence.IsCancelled = false;
            }
            await _context.FacilitySessions.AddRangeAsync(list);
        }

        public Task<List<FacilitySession>> GetOccurrencesForClassAsync(Guid facilityClassId, bool includeCancelled)
        {
            var query = _context.FacilitySessions.Where(s => s.FKFacilityClassId == facilityClassId);
            if (!includeCancelled)
                query = query.Where(s => !s.IsCancelled);

            return query.OrderByDescending(s => s.StartTime).ToListAsync();
        }

        public async Task<int> DeleteFutureUnbookedOccurrencesAsync(Guid facilityClassId, DateTime nowUtc)
        {
            var candidates = await _context.FacilitySessions
                .Where(s => s.FKFacilityClassId == facilityClassId && s.StartTime > nowUtc)
                .Where(s => !_context.Bookings.Any(b => b.FKFacilitySessionId == s.FacilitySessionId))
                .ToListAsync();

            _context.FacilitySessions.RemoveRange(candidates);
            return candidates.Count;
        }

        public async Task LinkPlanToClassAsync(Guid customerPlanId, Guid facilityClassId)
        {
            _context.CustomerPlanClasses.Add(new CustomerPlanClass
            {
                CustomerPlanClassId = Guid.NewGuid(),
                FKCustomerPlanId = customerPlanId,
                FKFacilityClassId = facilityClassId
            });
        }

        public Task<List<Booking>> GetSchedulingConflictsAsync(Guid clientId)
        {
            return _context.Bookings
                .Include(b => b.Facility)
                .Where(b => b.FKClientId == clientId && b.FKFacilitySessionId == null && b.Status == "Confirmed")
                .Where(b => _context.FacilitySessions.Any(s =>
                    s.FKFacilityId == b.FKFacilityId && s.FKFacilityClassId != null && !s.IsCancelled &&
                    s.StartTime < b.EndTime && s.EndTime > b.StartTime))
                .ToListAsync();
        }
    }
}