ChatMessage.cs

using DCL.FeatureFlags;
using System;
using System.Globalization;

namespace DCL.Chat.History
{
    public readonly struct ChatMessage : IEquatable<ChatMessage>
    {
        private const string DCL_SYSTEM_SENDER = "DCL System";

        public readonly string Message;
        public readonly string MessageId;
        public readonly string SenderValidatedName;
        public readonly string SenderWalletId;
        public readonly string SenderWalletAddress;
        public readonly bool IsSenderOfficial;
        public readonly bool IsSentByOwnUser;
        public readonly bool IsSystemMessage;
        public readonly bool IsMention;

        /// <summary>
        /// The instant when the message was sent (UTC), in OLE Automation Date format. Zero means null or unassigned.
        /// </summary>
        public readonly double SentTimestampRaw;

        public readonly DateTime? SentTimestamp;

        public ChatMessage(
            string message,
            string senderValidatedName,
            string senderWalletAddress,
            bool isSentByOwnUser,
            string senderWalletId,
            double sentTimestamp,
            bool isMention = false,
            bool isSystemMessage = false)
        {
            // NOTE: pseudo-unique ID generation for non-system messages
            MessageId = isSystemMessage
                ? Guid.NewGuid().ToString()
                : ChatUtils.GetId(senderWalletAddress, sentTimestamp);

            Message = message;
            SenderValidatedName = senderValidatedName;
            SenderWalletAddress = senderWalletAddress;
            IsSentByOwnUser = isSentByOwnUser;
            SenderWalletId = senderWalletId;
            IsMention = isMention;
            IsSenderOfficial = OfficialWalletsHelper.Instance.IsOfficialWallet(senderWalletAddress);
            IsSystemMessage = isSystemMessage;
            SentTimestampRaw = sentTimestamp;
            SentTimestamp = sentTimestamp != 0.0 ? DateTime.FromOADate(sentTimestamp) : null;
        }

        public static ChatMessage CopyWithNewMessage(string newMessage, ChatMessage chatMessage) =>
            new ( newMessage,
                chatMessage.SenderValidatedName,
                chatMessage.SenderWalletAddress,
                chatMessage.IsSentByOwnUser,
                chatMessage.SenderWalletId,
                chatMessage.SentTimestampRaw,
                chatMessage.IsMention,
                false);

        public static ChatMessage NewFromSystem(string message) =>
            new (message, DCL_SYSTEM_SENDER, string.Empty, true,
                string.Empty, DateTime.UtcNow.ToOADate(), false, true);

        public bool Equals(ChatMessage other) => MessageId == other.MessageId;
        public override bool Equals(object? obj) => obj is ChatMessage other && Equals(other);
        public override int GetHashCode() => (MessageId != null ? MessageId.GetHashCode() : 0);

        public override string ToString() =>
            IsSystemMessage ? $"[System] {Message}" :
            $"[{SenderValidatedName}] {Message}";
    }

    public static class ChatUtils
    {
        /// <summary>
        ///     Creates a composite, pseudo-unique identifier for a chat message.
        /// </summary>
        public static string GetId(string walletId, double timestampRaw) =>
            $"{walletId}:{timestampRaw.ToString(CultureInfo.InvariantCulture)}";

        /// <summary>
        ///     Recovers the sender wallet address from an id produced by <see cref="GetId" />.
        ///     Returns false for ids that don't follow the composite format (e.g. system-message GUIDs).
        /// </summary>
        public static bool TryGetSenderWalletAddress(string messageId, out string walletAddress)
        {
            int separator = messageId.IndexOf(':');

            if (separator <= 0)
            {
                walletAddress = string.Empty;
                return false;
            }

            walletAddress = messageId.Substring(0, separator);
            return true;
        }
    }
}