using System.ComponentModel.DataAnnotations.Schema;
using Domain.Entities.Members;

namespace Domain.Entities.Donations;

/// <summary>
/// 후원자별 × 채널별 누적 후원 금액 (칭호 획득 판정용).
/// 복합 PK: (DonorMemberID, ChannelID)
/// </summary>
public sealed class DonorChannelStats
{
    [ForeignKey(nameof(DonorMemberID))]
    public Member Donor { get; private set; } = null!;

    [ForeignKey(nameof(ChannelID))]
    public Channel Channel { get; private set; } = null!;

    public int DonorMemberID { get; private set; }

    public int ChannelID { get; private set; }

    public long CumulativeAmount { get; private set; }

    public int DonationCount { get; private set; }

    public DateTime? FirstDonatedAt { get; private set; }

    public DateTime? LastDonatedAt { get; private set; }

    public DateTime? UpdatedAt { get; private set; }

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

    private DonorChannelStats() { }

    private DonorChannelStats(int donorMemberID, int channelID)
    {
        if (donorMemberID <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(donorMemberID));
        }

        if (channelID <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(channelID));
        }

        DonorMemberID = donorMemberID;
        ChannelID = channelID;
    }

    public static DonorChannelStats Create(int donorMemberID, int channelID)
    {
        return new(donorMemberID, channelID);
    }

    public void AddDonation(long amount, DateTime when)
    {
        if (amount <= 0)
        {
            return;
        }

        CumulativeAmount += amount;
        DonationCount++;
        FirstDonatedAt ??= when;
        LastDonatedAt = when;
        UpdatedAt = DateTime.UtcNow;
    }
}