Add various property validation in EmbedBuilder

src/Discord.Net.Rest/Entities/Messages/EmbedBuilder.cs

@@ -8,14 +8,36 @@ namespace Discord
     {
         private readonly Embed _embed;
 
+        public const int MaxFieldCount = 25;
+        public const int MaxTitleLength = 256;
+        public const int MaxDescriptionLength = 2048;
+
         public EmbedBuilder()
         {
             _embed = new Embed("rich");
             Fields = new List<EmbedFieldBuilder>();
         }
 
-        public string Title { get { return _embed.Title; } set { _embed.Title = value; } }
-        public string Description { get { return _embed.Description; } set { _embed.Description = value; } }
+        public string Title
+        {
+            get => _embed.Title;
+            set
+            {
+                if (value?.Length > MaxTitleLength) throw new ArgumentException($"Title length must be less than or equal to {MaxTitleLength}.");
+                _embed.Title = value;
+            }
+        }
+
+        public string Description
+        {
+            get => _embed.Description;
+            set
+            {
+                if (value?.Length > MaxDescriptionLength) throw new ArgumentException($"Description length must be less than or equal to {MaxDescriptionLength}.");
+                _embed.Description = value;
+            }
+        }
+
         public string Url { get { return _embed.Url; } set { _embed.Url = value; } }
         public string ThumbnailUrl { get { return _embed.Thumbnail?.Url; } set { _embed.Thumbnail = new EmbedThumbnail(value, null, null, null); } }
         public string ImageUrl { get { return _embed.Image?.Url; } set { _embed.Image = new EmbedImage(value, null, null, null); } }
@@ -30,8 +52,10 @@ namespace Discord
             get => _fields;
             set
             {
-                if (value != null) _fields = value;
-                else throw new ArgumentNullException("Cannot set an embed builder's fields collection to null", nameof(value));
+
+                if (value == null) throw new ArgumentNullException("Cannot set an embed builder's fields collection to null", nameof(value));
+                if (value.Count > MaxFieldCount) throw new ArgumentException($"Field count must be less than or equal to {MaxFieldCount}.");
+                _fields = value;
             }
         }
 
@@ -107,7 +131,7 @@ namespace Discord
                 .WithIsInline(false)
                 .WithName(name)
                 .WithValue(value);
-            Fields.Add(field);
+            AddField(field);
             return this;
         }
         public EmbedBuilder AddInlineField(string name, object value)
@@ -116,11 +140,16 @@ namespace Discord
                 .WithIsInline(true)
                 .WithName(name)
                 .WithValue(value);
-            Fields.Add(field);
+            AddField(field);
             return this;
         }
         public EmbedBuilder AddField(EmbedFieldBuilder field)
         {
+            if (Fields.Count >= MaxFieldCount)
+            {
+                throw new ArgumentException($"Field count must be less than or equal to {MaxFieldCount}.");
+            }
+
             Fields.Add(field);
             return this;
         }
@@ -128,7 +157,7 @@ namespace Discord
         {
             var field = new EmbedFieldBuilder();
             action(field);
-            Fields.Add(field);
+            this.AddField(field);
             return this;
         }
 
@@ -149,8 +178,29 @@ namespace Discord
     {
         private EmbedField _field;
 
-        public string Name { get { return _field.Name; } set { _field.Name = value; } }
-        public object Value { get { return _field.Value; } set { _field.Value = value.ToString(); } }
+        public const int MaxFieldNameLength = 256;
+        public const int MaxFieldValueLength = 1024;
+
+        public string Name
+        {
+            get => _field.Name;
+            set
+            {
+                if (value?.Length > MaxFieldNameLength) throw new ArgumentException($"Field name length must be less than or equal to {MaxFieldNameLength}.");
+                _field.Name = value;
+            }
+        }
+
+        public object Value
+        {
+            get => _field.Value;
+            set
+            {
+                var stringValue = value.ToString();
+                if (stringValue.Length > MaxFieldValueLength) throw new ArgumentException($"Field value length must be less than or equal to {MaxFieldValueLength}.");
+                _field.Value = stringValue;
+            }
+        }
         public bool IsInline { get { return _field.Inline; } set { _field.Inline = value; } }
 
         public EmbedFieldBuilder()
@@ -182,7 +232,17 @@ namespace Discord
     {
         private EmbedAuthor _author;
 
-        public string Name { get { return _author.Name; } set { _author.Name = value; } }
+        public const int MaxAuthorNameLength = 256;
+
+        public string Name
+        {
+            get => _author.Name;
+            set
+            {
+                if (value?.Length > MaxAuthorNameLength) throw new ArgumentException($"Author name length must be less than or equal to {MaxAuthorNameLength}.");
+                _author.Name = value;
+            }
+        }
         public string Url { get { return _author.Url; } set { _author.Url = value; } }
         public string IconUrl { get { return _author.IconUrl; } set { _author.IconUrl = value; } }
 
@@ -215,7 +275,17 @@ namespace Discord
     {
         private EmbedFooter _footer;
 
-        public string Text { get { return _footer.Text; } set { _footer.Text = value; } }
+        public const int MaxFooterTextLength = 2048;
+
+        public string Text
+        {
+            get => _footer.Text;
+            set
+            {
+                if (value?.Length > MaxFooterTextLength) throw new ArgumentException($"Footer text length must be less than or equal to {MaxFooterTextLength}.");
+                _footer.Text = value;
+            }
+        }
         public string IconUrl { get { return _footer.IconUrl; } set { _footer.IconUrl = value; } }
 
         public EmbedFooterBuilder()