ANTOOZA-BACKEND/Application/Abstractions/Chat/ChatRoomKeys.cs

namespace Application.Abstractions.Chat;

/// <summary>
/// 채팅 룸 키 규약 (개미투자 D2) — roomKey = main | stock:{code}.
/// channel:{sid} 는 기존 채널 채팅(비활성) 호환용 레거시 키 — JoinRoom 공개 계약에는 포함하지 않는다.
/// </summary>
public static class ChatRoomKeys
{
    public const string Main = "main";
    public const string StockPrefix = "stock:";
    public const string ChannelPrefix = "channel:";
    public const int MaxLength = 20;

    public static bool IsStockRoom(string roomKey) => roomKey.StartsWith(StockPrefix, StringComparison.Ordinal);

    public static bool IsChannelRoom(string roomKey) => roomKey.StartsWith(ChannelPrefix, StringComparison.Ordinal);

    /// <summary>공개 계약 유효성 — main 또는 stock:{6자리 숫자} 만 허용</summary>
    public static bool IsValid(string? roomKey)
    {
        if (string.IsNullOrWhiteSpace(roomKey) || roomKey.Length > MaxLength)
        {
            return false;
        }

        if (roomKey == Main)
        {
            return true;
        }

        if (IsStockRoom(roomKey))
        {
            var code = roomKey[StockPrefix.Length..];
            return code is { Length: 6 } && code.All(char.IsAsciiDigit);
        }

        return false;
    }

    public static string ForStock(string code) => $"{StockPrefix}{code}";

    public static string ForChannel(string channelSID) => $"{ChannelPrefix}{channelSID}";
}