Added emoji validation

src/Discord.Net.Core/Discord.Net.Core.csproj

@@ -11,4 +11,20 @@
     <PackageReference Include="System.Collections.Immutable" Version="1.3.1" />
     <PackageReference Include="System.Interactive.Async" Version="3.1.1" />
   </ItemGroup>
+  <ItemGroup>
+    <None Update="Entities\Emotes\Emoji.Codepoints.tt">
+      <Generator>TextTemplatingFileGenerator</Generator>
+      <LastGenOutput>Emoji.Codepoints.cs</LastGenOutput>
+    </None>
+  </ItemGroup>
+  <ItemGroup>
+    <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Update="Entities\Emotes\Emoji.Codepoints.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Emoji.Codepoints.tt</DependentUpon>
+    </Compile>
+  </ItemGroup>
 </Project>

src/Discord.Net.Core/Entities/Emotes/Emoji.Codepoints.tt

@@ -0,0 +1,59 @@
+<#@ output extension=".cs" #>
+<#@ template language="C#" #>
+<#@ assembly name="System.Net.Http.dll" #>
+<#@ import namespace="System.Net.Http" #>
+<#@ assembly name="System.Core.dll" #>
+<#@ import namespace="System.Collections.Generic" #>
+<#@ import namespace="System.Linq" #>
+<#
+	const string DataUrl = "http://www.unicode.org/Public/emoji/6.0/emoji-data.txt";
+
+	List<int> codepoints = new List<int>();
+
+	void FetchData()
+	{
+		var client = new HttpClient();
+		try
+		{
+			var response = client.GetAsync(DataUrl).GetAwaiter().GetResult();
+			response.EnsureSuccessStatusCode();
+			string body = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
+
+			foreach (var line in body.Split('\n'))
+			{
+				if (line.StartsWith("#")) continue;
+				var split = line.Split(';');
+				if (split.Length < 1) continue;
+				var code = split[0].Trim();
+				if (string.IsNullOrEmpty(code)) continue;
+				var ranges = code.Split("..".ToCharArray());
+				if (ranges.Length == 3)
+				{
+					var lower = Convert.ToInt32(ranges[0], 16);
+					var upper = Convert.ToInt32(ranges[2], 16);
+					codepoints.AddRange(Enumerable.Range(lower, (upper-lower)+1));
+				}
+				else
+				{
+					var point = Convert.ToInt32(code, 16);
+					codepoints.Add(point);
+				}
+			}
+		}
+		catch
+		{
+		}
+	}
+
+	FetchData();
+#>
+namespace Discord
+{
+    public partial class Emoji
+    {
+		internal readonly int[] Codepoints = new int[]
+		{
+<# foreach (var codepoint in codepoints) { #><#= codepoint #>, <# } #>
+		};
+    }
+}

src/Discord.Net.Core/Entities/Emotes/Emoji.cs

@@ -1,9 +1,12 @@
-namespace Discord
+using System;
+using System.Text;
+
+namespace Discord
 {
     /// <summary>
     /// A unicode emoji
     /// </summary>
-    public class Emoji : IEmote
+    public partial class Emoji : IEmote
     {
         // TODO: need to constrain this to unicode-only emojis somehow
 
@@ -20,6 +23,31 @@
         /// <param name="unicode">The pure UTF-8 encoding of an emoji</param>
         public Emoji(string unicode)
         {
+            byte[] utf32 = Encoding.Unicode.GetBytes(unicode);
+            bool safe = false, any = false;
+            int codepoint = 0;
+            for (var i = 0; i < utf32.Length; i += 4)
+            {
+                codepoint = BitConverter.ToInt32(utf32, i);
+                any = false;
+                for (var j = 0; j < Codepoints.Length; j++)
+                {
+                    if (Codepoints[j] == codepoint)
+                    {
+                        any = true;
+                        break;
+                    }
+                }
+                if (any)
+                    safe = true;
+                else
+                {
+                    safe = false;
+                    break;
+                }
+            }
+            if (!safe)
+                throw new ArgumentException("One or more characters was not a valid Emoji", nameof(unicode));
             Name = unicode;
         }
 

test/Discord.Net.Tests/Discord.Net.Tests.csproj

@@ -10,6 +10,9 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
   </ItemGroup>
+  <ItemGroup>
+    <None Include="Tests.Emotes.cs" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../../src/Discord.Net.Commands/Discord.Net.Commands.csproj" />
     <ProjectReference Include="../../src/Discord.Net.Core/Discord.Net.Core.csproj" />

test/Discord.Net.Tests/Tests.Emotes.cs

@@ -0,0 +1,33 @@
+using System;
+using Xunit;
+
+namespace Discord
+{
+    public class EmoteTests
+    {
+		[Fact]
+		public void Emoji()
+        {
+			// Future: Validate emoji parsing
+            Assert.Equal("🦅", new Emoji("🦅").Name);
+        }
+
+		[Fact]
+		public void Emote()
+        {
+            Assert.Equal(true, Discord.Emote.TryParse("<:foxDab:280494667093508096>", out var emote));
+            Assert.NotNull(emote);
+            Assert.Equal("foxDab", emote.Name);
+            Assert.Equal(280494667093508096UL, emote.Id);
+            Assert.Equal(DateTimeOffset.FromUnixTimeMilliseconds(1486945539974), emote.CreatedAt);
+        }
+		[Fact]
+		public void Emote_Parse_Fail()
+        {
+            Assert.Equal(false, Discord.Emote.TryParse("", out _));
+            Assert.Equal(false, Discord.Emote.TryParse(":foxDab", out _));
+            Assert.Equal(false, Discord.Emote.TryParse(":foxDab:", out _));
+            Assert.Throws<ArgumentException>(() => Discord.Emote.Parse(":foxDab:"));
+        }
+    }
+}