From 807db7f365612386710da3d10c2f3a43747b46b8 Mon Sep 17 00:00:00 2001
From: Ryzhehvost <kotlyar.andrey@gmail.com>
Date: Wed, 30 Jun 2021 13:45:58 +0300
Subject: [PATCH] Implement splitting of steam messages on newlines (#2348)

* implement split on newlines

* replace test of splitting on newlines

* sugar-sugar syntax

* Revert "sugar-sugar syntax"

This reverts commit ee9b558faf4c94331d560bb5dd43daefad40dd33.

* add test to confirm that paragraph character size is less or equal to continuation character size
---
 ArchiSteamFarm.Tests/SteamChatMessage.cs      | 11 ++++++----
 .../Steam/Integration/SteamChatMessage.cs     | 22 +++++++++++++++++--
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/ArchiSteamFarm.Tests/SteamChatMessage.cs b/ArchiSteamFarm.Tests/SteamChatMessage.cs
index 3503cb978..8f7735a45 100644
--- a/ArchiSteamFarm.Tests/SteamChatMessage.cs
+++ b/ArchiSteamFarm.Tests/SteamChatMessage.cs
@@ -50,6 +50,9 @@ namespace ArchiSteamFarm.Tests {
 		[TestMethod]
 		public void ContinuationCharacterSizeIsProperlyCalculated() => Assert.AreEqual(ContinuationCharacterBytes, Encoding.UTF8.GetByteCount(ContinuationCharacter.ToString()));
 
+		[TestMethod]
+		public void ParagraphCharacterSizeIsLessOrEqualToContinuationCharacterSize() => Assert.IsTrue(ContinuationCharacterBytes >= Encoding.UTF8.GetByteCount(ParagraphCharacter.ToString()));
+
 		[TestMethod]
 		public async Task DoesntSkipEmptyNewlines() {
 			string message = "asdf" + Environment.NewLine + Environment.NewLine + "asdf";
@@ -277,7 +280,7 @@ namespace ArchiSteamFarm.Tests {
 		[DataRow(false)]
 		[DataRow(true)]
 		[DataTestMethod]
-		public async Task SplitsOnNewlinesWithoutContinuationCharacter(bool isAccountLimited) {
+		public async Task SplitsOnNewlinesWithParagraphCharacter(bool isAccountLimited) {
 			int maxMessageBytes = isAccountLimited ? MaxMessageBytesForLimitedAccounts : MaxMessageBytesForUnlimitedAccounts;
 
 			StringBuilder newlinePartBuilder = new();
@@ -299,9 +302,9 @@ namespace ArchiSteamFarm.Tests {
 
 			Assert.AreEqual(4, output.Count);
 
-			Assert.AreEqual(newlinePart, output[0]);
-			Assert.AreEqual(newlinePart, output[1]);
-			Assert.AreEqual(newlinePart, output[2]);
+			Assert.AreEqual(newlinePart + ParagraphCharacter, output[0]);
+			Assert.AreEqual(newlinePart + ParagraphCharacter, output[1]);
+			Assert.AreEqual(newlinePart + ParagraphCharacter, output[2]);
 			Assert.AreEqual(newlinePart, output[3]);
 		}
 
diff --git a/ArchiSteamFarm/Steam/Integration/SteamChatMessage.cs b/ArchiSteamFarm/Steam/Integration/SteamChatMessage.cs
index be6b65527..54a900984 100644
--- a/ArchiSteamFarm/Steam/Integration/SteamChatMessage.cs
+++ b/ArchiSteamFarm/Steam/Integration/SteamChatMessage.cs
@@ -33,6 +33,7 @@ namespace ArchiSteamFarm.Steam.Integration {
 	internal static class SteamChatMessage {
 		internal const char ContinuationCharacter = '…'; // A character used for indicating that the next newline part is a continuation of the previous line
 		internal const byte ContinuationCharacterBytes = 3; // The continuation character specified above uses 3 bytes in UTF-8
+		internal const char ParagraphCharacter = '¶'; // A character used for indicating that this is not the last part of message (2 bytes, so it fits in ContinuationCharacterBytes)
 		internal const ushort MaxMessageBytesForLimitedAccounts = 1945; // This is a limitation enforced by Steam
 		internal const ushort MaxMessageBytesForUnlimitedAccounts = 6340; // This is a limitation enforced by Steam
 		internal const ushort MaxMessagePrefixBytes = MaxMessageBytesForLimitedAccounts - ReservedContinuationMessageBytes - ReservedEscapeMessageBytes; // Simplified calculation, nobody should be using prefixes even close to that anyway
@@ -86,6 +87,10 @@ namespace ArchiSteamFarm.Steam.Integration {
 
 					// Check if we reached the limit for one message
 					if (messagePartBytes + NewlineWeight + ReservedEscapeMessageBytes > maxMessageBytes) {
+						if (stringReader.Peek() != -1) {
+							messagePart.Append(ParagraphCharacter);
+						}
+
 						yield return messagePart.ToString();
 
 						messagePartBytes = prefixBytes;
@@ -101,8 +106,17 @@ namespace ArchiSteamFarm.Steam.Integration {
 
 				for (int lineBytesRead = 0; lineBytesRead < lineBytes.Length;) {
 					if (messagePart.Length > prefixLength) {
-						messagePartBytes += NewlineWeight;
-						messagePart.AppendLine();
+						if (messagePartBytes + NewlineWeight + lineBytes.Length > maxMessageBytes) {
+							messagePart.Append(ParagraphCharacter);
+							yield return messagePart.ToString();
+
+							messagePartBytes = prefixBytes;
+							messagePart.Clear();
+							messagePart.Append(steamMessagePrefix);
+						} else {
+							messagePartBytes += NewlineWeight;
+							messagePart.AppendLine();
+						}
 					}
 
 					int bytesToTake = Math.Min(maxMessageBytes - messagePartBytes, lineBytes.Length - lineBytesRead);
@@ -152,6 +166,10 @@ namespace ArchiSteamFarm.Steam.Integration {
 						continue;
 					}
 
+					if (stringReader.Peek() != -1 && messagePart[messagePart.Length-1] != ContinuationCharacter) {
+						messagePart.Append(ParagraphCharacter);
+					}
+
 					yield return messagePart.ToString();
 
 					messagePartBytes = prefixBytes;