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

namespace Domain.Entities.Store;

/// <summary>
/// 상점 주문 헤더. 단일 결제 = 단일 Order.
/// 결제 시점에 수익 배분 (PlatformFee/GameRevenue/ChannelReward) 동결.
/// 채널 미선택 주문은 ChannelRewardAmount=0, ChannelID=null. ChannelReward 만큼 PlatformFee 가 증가 (antooza 100%).
/// </summary>
public class Order
{
    [ForeignKey(nameof(MemberID))]
    public virtual Member? Member { get; private set; }

    [ForeignKey(nameof(ChannelID))]
    public virtual Channel? Channel { get; private set; }

    private readonly List<OrderItem> _items = [];
    public IReadOnlyCollection<OrderItem> Items => _items;

    private readonly List<OrderRefund> _refunds = [];
    public IReadOnlyCollection<OrderRefund> Refunds => _refunds;

    [Key]
    public int ID { get; private set; }

    /// <summary>주문 번호 (예: "20260522-A1B2C3"). UNIQUE. 사용자 표시용.</summary>
    public string OrderNumber { get; private set; } = default!;

    public int MemberID { get; private set; }

    /// <summary>선물 수신자 회원 ID (선택). null 이면 본인 구매. 값이 있으면 발급 대상은 수신자, 결제자는 MemberID.</summary>
    public int? GiftToMemberID { get; private set; }

    /// <summary>선물 메시지 (선택, 최대 200자).</summary>
    public string? GiftMessage { get; private set; }

    /// <summary>후원 채널 (선택). null 이면 antooza 100% 수익.</summary>
    public int? ChannelID { get; private set; }

    public int TotalAmount { get; private set; }

    /// <summary>antooza 몫 (= TotalAmount - GameRevenueAmount - ChannelRewardAmount).</summary>
    public int PlatformFeeAmount { get; private set; }

    /// <summary>게임사 정산 큐 적재 금액 (= TotalAmount × Game.CommissionRate / 100).</summary>
    public int GameRevenueAmount { get; private set; }

    /// <summary>[비활성] 채널 보상 입금 금액 — 채널 보상 적립 제거됨(2026-07-03), 과거 주문 호환용 유지. 신규 주문은 항상 0.</summary>
    public int ChannelRewardAmount { get; private set; }

    public OrderStatus Status { get; private set; } = OrderStatus.Pending;

    public string? CancelReason { get; private set; }

    public string? RefundReason { get; private set; }

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

    public DateTime? PaidAt { get; private set; }

    [Timestamp]
    public byte[] RowVersion { get; private set; } = default!;

    private Order() { }

    public static Order Create(
        string orderNumber,
        int memberID,
        int totalAmount,
        int? channelID,
        int platformFeeAmount,
        int gameRevenueAmount,
        int channelRewardAmount,
        int? giftToMemberID = null,
        string? giftMessage = null
    ) {
        if (string.IsNullOrWhiteSpace(orderNumber))
        {
            throw new ArgumentException("OrderNumber is required.", nameof(orderNumber));
        }

        if (orderNumber.Length > 20)
        {
            throw new ArgumentOutOfRangeException(nameof(orderNumber));
        }

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

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

        if (giftToMemberID == memberID)
        {
            throw new ArgumentException("본인에게는 선물할 수 없습니다.", nameof(giftToMemberID));
        }

        var trimmedGiftMessage = string.IsNullOrWhiteSpace(giftMessage) ? null : giftMessage.Trim();

        if (trimmedGiftMessage is { Length: > 200 })
        {
            throw new ArgumentOutOfRangeException(nameof(giftMessage), "선물 메시지는 200자 이하여야 합니다.");
        }

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

        if (platformFeeAmount < 0 || gameRevenueAmount < 0 || channelRewardAmount < 0)
        {
            throw new ArgumentOutOfRangeException(null, "수익 배분 금액은 음수 불가.");
        }

        if (platformFeeAmount + gameRevenueAmount + channelRewardAmount != totalAmount)
        {
            throw new ArgumentException("PlatformFee + GameRevenue + ChannelReward 의 합이 TotalAmount 와 일치해야 합니다.");
        }

        if (channelID is null && channelRewardAmount > 0)
        {
            throw new ArgumentException("채널 미선택 주문은 ChannelRewardAmount=0 이어야 합니다.");
        }

        return new Order
        {
            OrderNumber = orderNumber,
            MemberID = memberID,
            GiftToMemberID = giftToMemberID,
            GiftMessage = trimmedGiftMessage,
            ChannelID = channelID,
            TotalAmount = totalAmount,
            PlatformFeeAmount = platformFeeAmount,
            GameRevenueAmount = gameRevenueAmount,
            ChannelRewardAmount = channelRewardAmount
        };
    }

    /// <summary>선물 주문 여부.</summary>
    public bool IsGift => GiftToMemberID is not null;

    /// <summary>아이템 발급 대상 회원 ID (선물이면 수신자, 아니면 구매자).</summary>
    public int RecipientMemberID => GiftToMemberID ?? MemberID;

    public void AddItem(OrderItem item)
    {
        ArgumentNullException.ThrowIfNull(item);
        _items.Add(item);
    }

    public void MarkPaid()
    {
        if (Status != OrderStatus.Pending)
        {
            throw new InvalidOperationException($"Cannot mark paid from status {Status}.");
        }

        Status = OrderStatus.Paid;
        PaidAt = DateTime.UtcNow;
    }

    /// <summary>Digital 상품 단독 주문 시 Paid → Delivered 점프.</summary>
    public void MarkDelivered()
    {
        if (Status is not OrderStatus.Paid and not OrderStatus.Shipped)
        {
            throw new InvalidOperationException($"Cannot mark delivered from status {Status}.");
        }

        Status = OrderStatus.Delivered;
    }

    public void MarkPreparing()
    {
        if (Status != OrderStatus.Paid)
        {
            throw new InvalidOperationException($"Cannot mark preparing from status {Status}.");
        }

        Status = OrderStatus.Preparing;
    }

    public void MarkShipped()
    {
        if (Status is not OrderStatus.Paid and not OrderStatus.Preparing)
        {
            throw new InvalidOperationException($"Cannot mark shipped from status {Status}.");
        }

        Status = OrderStatus.Shipped;
    }

    public void Cancel(string reason)
    {
        if (Status is not OrderStatus.Pending and not OrderStatus.Paid)
        {
            throw new InvalidOperationException($"Cannot cancel from status {Status}.");
        }

        if (string.IsNullOrWhiteSpace(reason))
        {
            throw new ArgumentException("Cancel reason is required.", nameof(reason));
        }

        Status = OrderStatus.Cancelled;
        CancelReason = reason;
    }

    public void MarkRefunded(string reason)
    {
        if (string.IsNullOrWhiteSpace(reason))
        {
            throw new ArgumentException("Refund reason is required.", nameof(reason));
        }

        Status = OrderStatus.Refunded;
        RefundReason = reason;
    }

    public void MarkExchanged()
    {
        Status = OrderStatus.Exchanged;
    }
}