using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Fitness_core_BE.Models
{
    /// <summary>A recurring class definition (Zumba, Yoga) on a Facility that SupportsClasses --
    /// generates FacilitySession rows ("occurrences") on a schedule. Replaces manually creating
    /// one-off FacilitySession rows from the Bookings page for anything that recurs.</summary>
    public class FacilityClass
    {
        [Key]
        public Guid FacilityClassId { get; set; }

        public Guid FKClientId { get; set; }
        [ForeignKey(nameof(FKClientId))]
        public Client Client { get; set; }

        public Guid FKFacilityId { get; set; }
        [ForeignKey(nameof(FKFacilityId))]
        public Facility Facility { get; set; }

        [MaxLength(128)]
        public string Name { get; set; } = string.Empty;

        [MaxLength(500)]
        public string? Description { get; set; }

        /// <summary>"Daily" | "Weekly" | "Monthly" | "Custom". Custom skips every rule field
        /// below -- occurrences are written explicitly (as FacilitySession rows) at creation/
        /// edit time with their own dates, instead of being generated from a rule.</summary>
        [MaxLength(20)]
        public string RecurrenceType { get; set; } = "Weekly";

        /// <summary>The class's daily time window, in the facility's local time (not UTC) -- the
        /// generator converts to UTC per-occurrence using the club's timezone. Unused (0) for
        /// Custom, where each occurrence's own FacilitySession.StartTime/EndTime is explicit.</summary>
        public TimeSpan StartTimeOfDay { get; set; }
        public int DurationMinutes { get; set; } = 60;

        /// <summary>Weekly only. Bit flags, Sunday = 1 (bit 0) through Saturday = 64 (bit 6).</summary>
        public int WeekDaysMask { get; set; } = 0;

        /// <summary>Monthly only. Comma-separated day-of-month list, e.g. "1,15".</summary>
        [MaxLength(200)]
        public string? MonthDays { get; set; }

        /// <summary>Unused for Custom (occurrences are explicit, not generated from a range).</summary>
        public DateTime SeriesStartDate { get; set; } = DateTime.UtcNow.Date;
        /// <summary>Null = ongoing, no end date. Unused for Custom.</summary>
        public DateTime? SeriesEndDate { get; set; }

        /// <summary>Null = unlimited (see IsUnlimitedCapacity); otherwise the per-occurrence
        /// headcount cap, same meaning as Facility.DefaultCapacity/FacilitySession.Capacity.</summary>
        public int? Capacity { get; set; }

        /// <summary>When true, Capacity is ignored and every generated occurrence has no cap --
        /// a distinct flag rather than a sentinel value, since FacilitySession.Capacity == null
        /// already means "use the facility default," and int.MaxValue would overflow the
        /// checked Sum() in FacilityService.GetAvailability.</summary>
        public bool IsUnlimitedCapacity { get; set; } = false;

        public bool IsActive { get; set; } = true;

        /// <summary>Watermark: occurrences have been generated through this date already.
        /// Advanced by FacilityService.EnsureOccurrencesGeneratedAsync; never consulted for
        /// Custom classes (their occurrences are all written explicitly, never generated).</summary>
        public DateTime OccurrencesGeneratedThrough { get; set; } = DateTime.UtcNow.Date;

        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
    }
}