Closes #8. Added DM support for buttons and slash commands. Added SlashCommandBuilder

src/Discord.Net.Core/Entities/Interactions/ApplicationCommandOption.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 
 namespace Discord
@@ -22,8 +23,15 @@ namespace Discord
             get => _name;
             set
             {
-                if (value?.Length > 32)
-                    throw new ArgumentException("Name length must be less than or equal to 32");
+                if (value == null)
+                    throw new ArgumentNullException($"{nameof(Name)} cannot be null!");
+
+                if (value.Length > 32)
+                    throw new ArgumentException($"{nameof(Name)} length must be less than or equal to 32");
+
+                if (!Regex.IsMatch(value, @"^[\w-]{1,32}$"))
+                    throw new ArgumentException($"{nameof(Name)} must match the regex ^[\\w-]{{1,32}}$");
+
                 _name = value;
             }
         }

src/Discord.Net.Core/Entities/Interactions/SlashCommandBuilder.cs

@@ -0,0 +1,489 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    /// <summary>
+    ///     A class used to build slash commands.
+    /// </summary>
+    public class SlashCommandBuilder
+    {
+        /// <summary> 
+        ///     Returns the maximun length a commands name allowed by Discord
+        /// </summary>
+        public const int MaxNameLength = 32;
+        /// <summary> 
+        ///     Returns the maximum length of a commands description allowed by Discord. 
+        /// </summary>
+        public const int MaxDescriptionLength = 100;
+        /// <summary> 
+        ///     Returns the maximum count of command options allowed by Discord
+        /// </summary>
+        public const int MaxOptionsCount = 10;
+
+        /// <summary>
+        ///     The name of this slash command.
+        /// </summary>
+        public string Name
+        {
+            get
+            {
+                return _name;
+            }
+            set
+            {
+                Preconditions.NotNullOrEmpty(value, nameof(Name));
+                Preconditions.AtLeast(value.Length, 3, nameof(Name));
+                Preconditions.AtMost(value.Length, MaxNameLength, nameof(Name));
+
+                // Discord updated the docs, this regex prevents special characters like @!$%(... etc,
+                // https://discord.com/developers/docs/interactions/slash-commands#applicationcommand
+                if (!Regex.IsMatch(value, @"^[\w-]{3,32}$"))
+                    throw new ArgumentException("Command name cannot contian any special characters or whitespaces!");
+
+                _name = value;
+            }
+        }
+
+        /// <summary>
+        ///    A 1-100 length description of this slash command
+        /// </summary>
+        public string Description
+        {
+            get
+            {
+                return _description;
+            }
+            set
+            {
+                Preconditions.AtLeast(value.Length, 1, nameof(Description));
+                Preconditions.AtMost(value.Length, MaxDescriptionLength, nameof(Description));
+
+                _description = value;
+            }
+        }
+
+        /// <summary>
+        ///     Gets or sets the options for this command.
+        /// </summary>
+        public List<SlashCommandOptionBuilder> Options
+        {
+            get => _options;
+            set
+            {
+                if (value != null)
+                    if (value.Count > MaxOptionsCount)
+                        throw new ArgumentException(message: $"Option count must be less than or equal to {MaxOptionsCount}.", paramName: nameof(Options));
+
+                _options = value;
+            }
+        }
+        private string _name { get; set; }
+        private string _description { get; set; }
+        private List<SlashCommandOptionBuilder> _options { get; set; }
+
+        public SlashCommandCreationProperties Build()
+        {
+            SlashCommandCreationProperties props = new SlashCommandCreationProperties()
+            {
+                Name = this.Name,
+                Description = this.Description,
+            };
+
+            if (this.Options != null && this.Options.Any())
+            {
+                var options = new List<ApplicationCommandOptionProperties>();
+
+                this.Options.ForEach(x => options.Add(x.Build()));
+
+                props.Options = options;
+            }
+
+            return props;
+
+        }
+
+        public SlashCommandBuilder WithName(string Name)
+        {
+            this.Name = Name;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the description of the current command.
+        /// </summary>
+        /// <param name="Description">The description of this command.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder WithDescription(string Description)
+        {
+            this.Description = Description;
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds an option to the current slash command.
+        /// </summary>
+        /// <param name="Name">The name of the option to add.</param>
+        /// <param name="Type">The type of this option.</param>
+        /// <param name="Description">The description of this option.</param>
+        /// <param name="Required">If this option is required for this command.</param>
+        /// <param name="Default">If this option is the default option.</param>
+        /// <param name="Options">The options of the option to add.</param>
+        /// <param name="Choices">The choices of this option.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder AddOption(string Name, ApplicationCommandOptionType Type,
+           string Description, bool Required = true, bool Default = false, List<SlashCommandOptionBuilder> Options = null, params ApplicationCommandOptionChoiceProperties[] Choices)
+        {
+            // Make sure the name matches the requirements from discord
+            Preconditions.NotNullOrEmpty(Name, nameof(Name));
+            Preconditions.AtLeast(Name.Length, 3, nameof(Name));
+            Preconditions.AtMost(Name.Length, MaxNameLength, nameof(Name));
+
+            // Discord updated the docs, this regex prevents special characters like @!$%( and s p a c e s.. etc,
+            // https://discord.com/developers/docs/interactions/slash-commands#applicationcommand
+            if (!Regex.IsMatch(Name, @"^[\w-]{3,32}$"))
+                throw new ArgumentException("Command name cannot contian any special characters or whitespaces!", nameof(Name));
+
+            // same with description
+            Preconditions.NotNullOrEmpty(Description, nameof(Description));
+            Preconditions.AtLeast(Description.Length, 3, nameof(Description));
+            Preconditions.AtMost(Description.Length, MaxDescriptionLength, nameof(Description));
+
+            // make sure theres only one option with default set to true
+            if (Default)
+            {
+                if (this.Options != null)
+                    if (this.Options.Any(x => x.Default))
+                        throw new ArgumentException("There can only be one command option with default set to true!", nameof(Default));
+            }
+
+            SlashCommandOptionBuilder option = new SlashCommandOptionBuilder();
+            option.Name = Name;
+            option.Description = Description;
+            option.Required = Required;
+            option.Default = Default;
+            option.Options = Options;
+            option.Choices = Choices != null ? new List<ApplicationCommandOptionChoiceProperties>(Choices) : null;
+
+            return AddOption(option);
+        }
+
+        /// <summary>
+        ///     Adds an option to the current slash command.
+        /// </summary>
+        /// <param name="Name">The name of the option to add.</param>
+        /// <param name="Type">The type of this option.</param>
+        /// <param name="Description">The description of this option.</param>
+        /// <param name="Required">If this option is required for this command.</param>
+        /// <param name="Default">If this option is the default option.</param>
+        /// <param name="Choices">The choices of this option.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder AddOption(string Name, ApplicationCommandOptionType Type,
+            string Description, bool Required = true, bool Default = false, params ApplicationCommandOptionChoiceProperties[] Choices)
+            => AddOption(Name, Type, Description, Required, Default, null, Choices);
+
+        /// <summary>
+        ///     Adds an option to the current slash command.
+        /// </summary>
+        /// <param name="Name">The name of the option to add.</param>
+        /// <param name="Type">The type of this option.</param>
+        /// <param name="Description">The sescription of this option.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder AddOption(string Name, ApplicationCommandOptionType Type, string Description)
+            => AddOption(Name, Type, Description, Options: null, Choices: null);
+
+        /// <summary>
+        ///     Adds an option to this slash command.
+        /// </summary>
+        /// <param name="Parameter">The option to add.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder AddOption(SlashCommandOptionBuilder Option)
+        {
+            if (this.Options == null)
+                this.Options = new List<SlashCommandOptionBuilder>();
+
+            if (this.Options.Count >= MaxOptionsCount)
+                throw new ArgumentOutOfRangeException(nameof(Options), $"Cannot have more than {MaxOptionsCount} options!");
+
+            if (Option == null)
+                throw new ArgumentNullException(nameof(Option), "Option cannot be null");
+
+            this.Options.Add(Option);
+            return this;
+        }
+        /// <summary>
+        ///     Adds a collection of options to the current slash command.
+        /// </summary>
+        /// <param name="Parameter">The collection of options to add.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandBuilder AddOptions(params SlashCommandOptionBuilder[] Options)
+        {
+            if (Options == null)
+                throw new ArgumentNullException(nameof(Options), "Options cannot be null!");
+
+            if (Options.Length == 0)
+                throw new ArgumentException(nameof(Options), "Options cannot be empty!");
+
+            if (this.Options == null)
+                this.Options = new List<SlashCommandOptionBuilder>();
+
+            if (this.Options.Count + Options.Length > MaxOptionsCount)
+                throw new ArgumentOutOfRangeException(nameof(Options), $"Cannot have more than {MaxOptionsCount} options!");
+
+            this.Options.AddRange(Options);
+            return this;
+        }
+    }
+
+    /// <summary>
+    ///     Represents a class used to build options for the <see cref="SlashCommandBuilder"/>.
+    /// </summary>
+    public class SlashCommandOptionBuilder
+    {
+        /// <summary>
+        ///     The max length of a choice's name allowed by Discord.
+        /// </summary>
+        public const int ChoiceNameMaxLength = 100;
+
+        /// <summary>
+        ///     The maximum number of choices allowed by Discord.
+        /// </summary>
+        public const int MaxChoiceCount = 10;
+
+        private string _name;
+        private string _description;
+
+        /// <summary>
+        ///     The name of this option.
+        /// </summary>
+        public string Name
+        {
+            get => _name;
+            set
+            {
+                if (value?.Length > SlashCommandBuilder.MaxNameLength)
+                    throw new ArgumentException("Name length must be less than or equal to 32");
+                if (value?.Length < 1)
+                    throw new ArgumentException("Name length must at least 1 characters in length");
+
+                if (value != null)
+                    if (!Regex.IsMatch(value, @"^[\w-]{3,32}$"))
+                        throw new ArgumentException("Option name cannot contian any special characters or whitespaces!");
+
+                _name = value;
+            }
+        }
+
+        /// <summary>
+        ///     The description of this option.
+        /// </summary>
+        public string Description
+        {
+            get => _description;
+            set
+            {
+                if (value?.Length > SlashCommandBuilder.MaxDescriptionLength)
+                    throw new ArgumentException("Description length must be less than or equal to 100");
+                if (value?.Length < 1)
+                    throw new ArgumentException("Name length must at least 1 character in length");
+
+                _description = value;
+            }
+        }
+
+        /// <summary>
+        ///     The type of this option.
+        /// </summary>
+        public ApplicationCommandOptionType Type { get; set; }
+
+        /// <summary>
+        ///     The first required option for the user to complete. only one option can be default.
+        /// </summary>
+        public bool Default { get; set; }
+
+        /// <summary>
+        ///     <see langword="true"/> if this option is required for this command, otherwise <see langword="false"/>.
+        /// </summary>
+        public bool Required { get; set; }
+
+        /// <summary>
+        ///     choices for string and int types for the user to pick from.
+        /// </summary>
+        public List<ApplicationCommandOptionChoiceProperties> Choices { get; set; }
+
+        /// <summary>
+        ///     If the option is a subcommand or subcommand group type, this nested options will be the parameters.
+        /// </summary>
+        public List<SlashCommandOptionBuilder> Options { get; set; }
+
+        /// <summary>
+        ///     Builds the current option.
+        /// </summary>
+        /// <returns>The built version of this option.</returns>
+        public ApplicationCommandOptionProperties Build()
+        {
+            bool isSubType = this.Type == ApplicationCommandOptionType.SubCommand || this.Type == ApplicationCommandOptionType.SubCommandGroup;
+
+            if (isSubType && (Options == null || !Options.Any()))
+                throw new ArgumentException(nameof(Options), "SubCommands/SubCommandGroups must have at least one option");
+
+            if (!isSubType && (Options != null && Options.Any()))
+                throw new ArgumentException(nameof(Options), $"Cannot have options on {Type} type");
+
+            return new ApplicationCommandOptionProperties()
+            {
+                Name = this.Name,
+                Description = this.Description,
+                Default = this.Default,
+                Required = this.Required,
+                Type = this.Type,
+                Options = new List<ApplicationCommandOptionProperties>(this.Options.Select(x => x.Build())),
+                Choices = this.Choices
+            };
+        }
+
+        /// <summary>
+        ///     Adds a sub option to the current option.
+        /// </summary>
+        /// <param name="option">The sub option to add.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder AddOption(SlashCommandOptionBuilder option)
+        {
+            if (this.Options == null)
+                this.Options = new List<SlashCommandOptionBuilder>();
+
+            if (this.Options.Count >= SlashCommandBuilder.MaxOptionsCount)
+                throw new ArgumentOutOfRangeException(nameof(Choices), $"There can only be {SlashCommandBuilder.MaxOptionsCount} options per sub command group!");
+
+            if (option == null)
+                throw new ArgumentNullException(nameof(option), "Option cannot be null");
+
+            Options.Add(option);
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds a choice to the current option.
+        /// </summary>
+        /// <param name="Name">The name of the choice.</param>
+        /// <param name="Value">The value of the choice.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder AddChoice(string Name, int Value)
+        {
+            if (Choices == null)
+                Choices = new List<ApplicationCommandOptionChoiceProperties>();
+
+            if (Choices.Count >= MaxChoiceCount)
+                throw new ArgumentOutOfRangeException(nameof(Choices), $"Cannot add more than {MaxChoiceCount} choices!");
+
+            if (Name == null)
+                throw new ArgumentNullException($"{nameof(Name)} cannot be null!");
+
+            Preconditions.AtLeast(Name.Length, 1, nameof(Name));
+            Preconditions.AtMost(Name.Length, 100, nameof(Name));
+
+            Choices.Add(new ApplicationCommandOptionChoiceProperties()
+            {
+                Name = Name,
+                Value = Value
+            });
+
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds a choice to the current option.
+        /// </summary>
+        /// <param name="Name">The name of the choice.</param>
+        /// <param name="Value">The value of the choice.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder AddChoice(string Name, string Value)
+        {
+            if (Choices == null)
+                Choices = new List<ApplicationCommandOptionChoiceProperties>();
+
+            if (Choices.Count >= MaxChoiceCount)
+                throw new ArgumentOutOfRangeException(nameof(Choices), $"Cannot add more than {MaxChoiceCount} choices!");
+
+            if (Name == null)
+                throw new ArgumentNullException($"{nameof(Name)} cannot be null!");
+
+            if (Value == null)
+                throw new ArgumentNullException($"{nameof(Value)} cannot be null!");
+
+            Preconditions.AtLeast(Name.Length, 1, nameof(Name));
+            Preconditions.AtMost(Name.Length, 100, nameof(Name));
+
+            Preconditions.AtLeast(Value.Length, 1, nameof(Value));
+            Preconditions.AtMost(Value.Length, 100, nameof(Value));
+
+            Choices.Add(new ApplicationCommandOptionChoiceProperties()
+            {
+                Name = Name,
+                Value = Value
+            });
+
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the current builders name.
+        /// </summary>
+        /// <param name="Name">The name to set the current option builder.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder WithName(string Name)
+        {
+            this.Name = Name;
+
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the current builders description.
+        /// </summary>
+        /// <param name="Description">The description to set.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder WithDescription(string Description)
+        {
+            this.Description = Description;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the current builders required field.
+        /// </summary>
+        /// <param name="value">The value to set.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder WithRequired(bool value)
+        {
+            this.Required = value;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the current builders default field.
+        /// </summary>
+        /// <param name="value">The value to set.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder WithDefault(bool value)
+        {
+            this.Default = value;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the current type of this builder.
+        /// </summary>
+        /// <param name="Type">The type to set.</param>
+        /// <returns>The current builder.</returns>
+        public SlashCommandOptionBuilder WithType(ApplicationCommandOptionType Type)
+        {
+            this.Type = Type;
+            return this;
+        }
+    }
+}

src/Discord.Net.WebSocket/Entities/Interaction/Slash Commands/SocketSlashCommand.cs

@@ -8,6 +8,9 @@ using Model = Discord.API.Gateway.InteractionCreated;
 
 namespace Discord.WebSocket
 {
+    /// <summary>
+    ///     Represents a Websocket-based slash command received over the gateway.
+    /// </summary>
     public class SocketSlashCommand : SocketInteraction
     {
         /// <summary>

src/Discord.Net.WebSocket/Entities/Interaction/Slash Commands/SocketSlashCommandData.cs

@@ -5,6 +5,9 @@ using Model = Discord.API.ApplicationCommandInteractionData;
 
 namespace Discord.WebSocket
 {
+    /// <summary>
+    ///     Represents the data tied with the <see cref="SocketSlashCommand"/> interaction.
+    /// </summary>
     public class SocketSlashCommandData : SocketEntity<ulong>, IApplicationCommandInteractionData
     {
         /// <inheritdoc/>