Feature: Implement modals (#2087)

* Implement Modals (#428)

* Socket Modal Support

* fix shareded client support

* Properly use `HasResponded` instead of `_hasResponded`

* `ModalBuilder` and `TextInputBuilder` validation.

* make orginisation more consistant.

* Rest Modals.

* Docs + add missing methods

* fix message signatures and missing abstract members

* modal changes

* um?????

* update modal docs

* update docs - again for some reason

* cleanup

* fix message signatures

* add modal commands support to interaction service

* Fix _hasResponded

* update to new unsupported standard.

* Sending modals with Interaction service.

* fix spelling in ComponentBuilder

* sending IModals when responding to interactions

* interaction service modals

* fix rest modals

* spelling and minor improvements.

* improve interaction service modal proformance

* use precompiled lambda for interaction service modals

* respect user compiled lambda choice

* changes to modals in the interaction service (more)

* support compiled lambdas in modal properties.

* modal interactions tweaks

* fix inline doc

* more modal docs

* configure responce to faild modal component

* init

* solve runtime errors

* solve build errors

* add default value parsing

* make modal info caching static

* make ModalUtils static

* add inline docs

* fix build errors

* code cleanup

* Introduce Required and Label properties as seperate attributes.

* replace internal dictionary of ModalInfo with a list

* change input building logic of modals

* update RespondWithModalAsync method

* add initial value parameter back to ModalTextInput and fix optional modal field

* add missing inline docs

* dispose the reference modal instance after building

* code cleanup on modalcommandbuilder

* Update docs/guides/int_basics/message-components/text-input.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/message-components/text-input.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/samples/intro/modal.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/MessageComponents/IComponentInteractionData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/MessageComponents/TextInputComponent.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/IModalInteraction.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/Attributes/Commands/ModalInteractionAttribute.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/Attributes/Modals/RequiredInputAttribute.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/InteractionServiceConfig.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.WebSocket/Entities/Interaction/MessageComponents/SocketMessageComponentData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.WebSocket/Entities/Interaction/Modals/SocketModalData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* update interaction service modal docs

* implements ExitOnMissingmModalField config option and adds Type field to modal info

* Add WithValue to text input builders

* Fix rare NRE on component enumeration

* Fix RequestOptions being required in some methods

* Use 'OfType' instead of 'Where'

* Remove android unsported warning

* Change publicity of properties in IInputComponeontBuilder.cs

Co-authored-by: Cenk Ergen <57065323+Cenngo@users.noreply.github.com>
Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Remove complex parameter ref

Co-authored-by: CottageDwellingCat <80918250+CottageDwellingCat@users.noreply.github.com>
Co-authored-by: Cenk Ergen <57065323+Cenngo@users.noreply.github.com>
Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

src/Discord.Net.Interactions/Builders/Commands/ModalCommandBuilder.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating a <see cref="ModalCommandInfo"/>.
+    /// </summary>
+    public class ModalCommandBuilder : CommandBuilder<ModalCommandInfo, ModalCommandBuilder, ModalCommandParameterBuilder>
+    {
+        protected override ModalCommandBuilder Instance => this;
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandBuilder"/>.
+        /// </summary>
+        /// <param name="module">Parent module of this modal.</param>
+        public ModalCommandBuilder(ModuleBuilder module) : base(module) { }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandBuilder"/>.
+        /// </summary>
+        /// <param name="module">Parent module of this modal.</param>
+        /// <param name="name">Name of this modal.</param>
+        /// <param name="callback">Execution callback of this modal.</param>
+        public ModalCommandBuilder(ModuleBuilder module, string name, ExecuteCallback callback) : base(module, name, callback) { }
+
+        /// <summary>
+        ///     Adds a modal parameter to the parameters collection.
+        /// </summary>
+        /// <param name="configure"><see cref="ModalCommandParameterBuilder"/> factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public override ModalCommandBuilder AddParameter(Action<ModalCommandParameterBuilder> configure)
+        {
+            var parameter = new ModalCommandParameterBuilder(this);
+            configure(parameter);
+            AddParameters(parameter);
+            return this;
+        }
+
+        internal override ModalCommandInfo Build(ModuleInfo module, InteractionService commandService) =>
+            new(this, module, commandService);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/IInputComponentBuilder.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represent a builder for creating <see cref="InputComponentInfo"/>.
+    /// </summary>
+    public interface IInputComponentBuilder
+    {
+        /// <summary>
+        ///     Gets the parent modal of this input component.
+        /// </summary>
+        ModalBuilder Modal { get; }
+
+        /// <summary>
+        ///     Gets the custom id of this input component.
+        /// </summary>
+        string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the label of this input component.
+        /// </summary>
+        string Label { get; }
+
+        /// <summary>
+        ///     Gets whether this input component is required.
+        /// </summary>
+        bool IsRequired { get; }
+
+        /// <summary>
+        ///     Gets the component type of this input component.
+        /// </summary>
+        ComponentType ComponentType { get; }
+
+        /// <summary>
+        ///     Get the reference type of this input component.
+        /// </summary>
+        Type Type { get; }
+
+        /// <summary>
+        ///     Gets the default value of this input component.
+        /// </summary>
+        object DefaultValue { get; }
+
+        /// <summary>
+        ///     Gets a collection of the attributes of this component.
+        /// </summary>
+        IReadOnlyCollection<Attribute> Attributes { get; }
+
+        /// <summary>
+        ///     Sets <see cref="CustomId"/>.
+        /// </summary>
+        /// <param name="customId">New value of the <see cref="CustomId"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithCustomId(string customId);
+
+        /// <summary>
+        ///     Sets <see cref="Label"/>.
+        /// </summary>
+        /// <param name="label">New value of the <see cref="Label"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithLabel(string label);
+
+        /// <summary>
+        ///     Sets <see cref="IsRequired"/>.
+        /// </summary>
+        /// <param name="isRequired">New value of the <see cref="IsRequired"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder SetIsRequired(bool isRequired);
+
+        /// <summary>
+        ///     Sets <see cref="Type"/>.
+        /// </summary>
+        /// <param name="type">New value of the <see cref="Type"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithType(Type type);
+
+        /// <summary>
+        ///     Sets <see cref="DefaultValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="DefaultValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder SetDefaultValue(object value);
+
+        /// <summary>
+        ///     Adds attributes to <see cref="Attributes"/>.
+        /// </summary>
+        /// <param name="attributes">New attributes to be added to <see cref="Attributes"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithAttributes(params Attribute[] attributes);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/InputComponentBuilder.cs

@@ -0,0 +1,164 @@
+using System;
+using System.Collections.Generic;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents the base builder class for creating <see cref="InputComponentInfo"/>.
+    /// </summary>
+    /// <typeparam name="TInfo">The <see cref="InputComponentInfo"/> this builder yields when built.</typeparam>
+    /// <typeparam name="TBuilder">Inherited <see cref="InputComponentBuilder{TInfo, TBuilder}"/> type.</typeparam>
+    public abstract class InputComponentBuilder<TInfo, TBuilder> : IInputComponentBuilder
+        where TInfo : InputComponentInfo
+        where TBuilder : InputComponentBuilder<TInfo, TBuilder>
+    {
+        private readonly List<Attribute> _attributes;
+        protected abstract TBuilder Instance { get; }
+
+        /// <inheritdoc/>
+        public ModalBuilder Modal { get; }
+
+        /// <inheritdoc/>
+        public string CustomId { get; set; }
+
+        /// <inheritdoc/>
+        public string Label { get; set; }
+
+        /// <inheritdoc/>
+        public bool IsRequired { get; set; } = true;
+
+        /// <inheritdoc/>
+        public ComponentType ComponentType { get; internal set; }
+
+        /// <inheritdoc/>
+        public Type Type { get; private set; }
+
+        /// <inheritdoc/>
+        public object DefaultValue { get; set; }
+
+        /// <inheritdoc/>
+        public IReadOnlyCollection<Attribute> Attributes => _attributes;
+
+        /// <summary>
+        ///     Creates an instance of <see cref="InputComponentBuilder{TInfo, TBuilder}"/>
+        /// </summary>
+        /// <param name="modal">Parent modal of this input component.</param>
+        public InputComponentBuilder(ModalBuilder modal)
+        {
+            Modal = modal;
+            _attributes = new();
+        }
+
+        /// <summary>
+        ///     Sets <see cref="CustomId"/>.
+        /// </summary>
+        /// <param name="customId">New value of the <see cref="CustomId"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithCustomId(string customId)
+        {
+            CustomId = customId;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Label"/>.
+        /// </summary>
+        /// <param name="label">New value of the <see cref="Label"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithLabel(string label)
+        {
+            Label = label;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="IsRequired"/>.
+        /// </summary>
+        /// <param name="isRequired">New value of the <see cref="IsRequired"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder SetIsRequired(bool isRequired)
+        {
+            IsRequired = isRequired;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="ComponentType"/>.
+        /// </summary>
+        /// <param name="componentType">New value of the <see cref="ComponentType"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithComponentType(ComponentType componentType)
+        {
+            ComponentType = componentType;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Type"/>.
+        /// </summary>
+        /// <param name="type">New value of the <see cref="Type"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithType(Type type)
+        {
+            Type = type;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="DefaultValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="DefaultValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder SetDefaultValue(object value)
+        {
+            DefaultValue = value;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Adds attributes to <see cref="Attributes"/>.
+        /// </summary>
+        /// <param name="attributes">New attributes to be added to <see cref="Attributes"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithAttributes(params Attribute[] attributes)
+        {
+            _attributes.AddRange(attributes);
+            return Instance;
+        }
+
+        internal abstract TInfo Build(ModalInfo modal);
+
+        //IInputComponentBuilder
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithCustomId(string customId) => WithCustomId(customId);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithLabel(string label) => WithCustomId(label);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithType(Type type) => WithType(type);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.SetDefaultValue(object value) => SetDefaultValue(value);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithAttributes(params Attribute[] attributes) => WithAttributes(attributes);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.SetIsRequired(bool isRequired) => SetIsRequired(isRequired);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/TextInputComponentBuilder.cs

@@ -0,0 +1,109 @@
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating <see cref="TextInputComponentInfo"/>.
+    /// </summary>
+    public class TextInputComponentBuilder : InputComponentBuilder<TextInputComponentInfo, TextInputComponentBuilder>
+    {
+        protected override TextInputComponentBuilder Instance => this;
+
+        /// <summary>
+        ///     Gets and sets the style of the text input.
+        /// </summary>
+        public TextInputStyle Style { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the placeholder of the text input.
+        /// </summary>
+        public string Placeholder { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the minimum length of the text input.
+        /// </summary>
+        public int MinLength { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the maximum length of the text input.
+        /// </summary>
+        public int MaxLength { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the initial value to be displayed by this input.
+        /// </summary>
+        public string InitialValue { get; set; }
+
+        /// <summary>
+        ///     Initializes a new <see cref="TextInputComponentBuilder"/>.
+        /// </summary>
+        /// <param name="modal">Parent modal of this component.</param>
+        public TextInputComponentBuilder(ModalBuilder modal) : base(modal) { }
+
+        /// <summary>
+        ///     Sets <see cref="Style"/>.
+        /// </summary>
+        /// <param name="style">New value of the <see cref="SetValue(string)"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithStyle(TextInputStyle style)
+        {
+            Style = style;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Placeholder"/>.
+        /// </summary>
+        /// <param name="placeholder">New value of the <see cref="Placeholder"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithPlaceholder(string placeholder)
+        {
+            Placeholder = placeholder;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="MinLength"/>.
+        /// </summary>
+        /// <param name="minLenght">New value of the <see cref="MinLength"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithMinLenght(int minLenght)
+        {
+            MinLength = minLenght;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="MaxLength"/>.
+        /// </summary>
+        /// <param name="maxLenght">New value of the <see cref="MaxLength"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithMaxLenght(int maxLenght)
+        {
+            MaxLength = maxLenght;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="InitialValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="InitialValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithInitialValue(string value)
+        {
+            InitialValue = value;
+            return this;
+        }
+
+        internal override TextInputComponentInfo Build(ModalInfo modal) =>
+            new(this, modal);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/ModalBuilder.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating <see cref="ModalInfo"/>.
+    /// </summary>
+    public class ModalBuilder
+    {
+        internal readonly List<IInputComponentBuilder> _components;
+
+        /// <summary>
+        ///     Gets the initialization delegate for this modal.
+        /// </summary>
+        public ModalInitializer ModalInitializer { get; internal set; }
+
+        /// <summary>
+        ///     Gets the title of this modal.
+        /// </summary>
+        public string Title { get; set; }
+
+        /// <summary>
+        ///     Gets the <see cref="IModal"/> implementation used to initialize this object.
+        /// </summary>
+        public Type Type { get; }
+
+        /// <summary>
+        ///     Gets a collection of the components of this modal.
+        /// </summary>
+        public IReadOnlyCollection<IInputComponentBuilder> Components => _components;
+
+        internal ModalBuilder(Type type)
+        {
+            if (!typeof(IModal).IsAssignableFrom(type))
+                throw new ArgumentException($"Must be an implementation of {nameof(IModal)}", nameof(type));
+
+            _components = new();
+        }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalBuilder"/>
+        /// </summary>
+        /// <param name="modalInitializer">The initialization delegate for this modal.</param>
+        public ModalBuilder(Type type, ModalInitializer modalInitializer) : this(type)
+        {
+            ModalInitializer = modalInitializer;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Title"/>.
+        /// </summary>
+        /// <param name="title">New value of the <see cref="Title"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModalBuilder WithTitle(string title)
+        {
+            Title = title;
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds text components to <see cref="TextComponents"/>.
+        /// </summary>
+        /// <param name="configure">Text Component builder factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModalBuilder AddTextComponent(Action<TextInputComponentBuilder> configure)
+        {
+            var builder = new TextInputComponentBuilder(this);
+            configure(builder);
+            _components.Add(builder);
+            return this;
+        }
+
+        internal ModalInfo Build() => new(this);
+    }
+}

src/Discord.Net.Interactions/Builders/ModuleBuilder.cs

@@ -16,6 +16,7 @@ namespace Discord.Interactions.Builders
         private readonly List<ContextCommandBuilder> _contextCommands;
         private readonly List<ComponentCommandBuilder> _componentCommands;
         private readonly List<AutocompleteCommandBuilder> _autocompleteCommands;
+        private readonly List<ModalCommandBuilder> _modalCommands;
 
         /// <summary>
         ///     Gets the underlying Interaction Service.
@@ -92,6 +93,11 @@ namespace Discord.Interactions.Builders
         /// </summary>
         public IReadOnlyList<AutocompleteCommandBuilder> AutocompleteCommands => _autocompleteCommands;
 
+        /// <summary>
+        ///     Gets a collection of the Modal Commands of this module.
+        /// </summary>
+        public IReadOnlyList<ModalCommandBuilder> ModalCommands => _modalCommands;
+
         internal TypeInfo TypeInfo { get; set; }
 
         internal ModuleBuilder (InteractionService interactionService, ModuleBuilder parent = null)
@@ -105,6 +111,7 @@ namespace Discord.Interactions.Builders
             _contextCommands = new List<ContextCommandBuilder>();
             _componentCommands = new List<ComponentCommandBuilder>();
             _autocompleteCommands = new List<AutocompleteCommandBuilder>();
+            _modalCommands = new List<ModalCommandBuilder> ();
             _preconditions = new List<PreconditionAttribute>();
         }
 
@@ -152,7 +159,7 @@ namespace Discord.Interactions.Builders
         /// <returns>
         ///     The builder instance.
         /// </returns>
-        public ModuleBuilder WithDefaultPermision (bool permission)
+        public ModuleBuilder WithDefaultPermission (bool permission)
         {
             DefaultPermission = permission;
             return this;
@@ -310,6 +317,21 @@ namespace Discord.Interactions.Builders
             configure(command);
             _autocompleteCommands.Add(command);
             return this;
+
+        }
+        
+        ///     Adds a modal command builder to <see cref="ModalCommands"/>.
+        /// </summary>
+        /// <param name="configure"><see cref="ModalCommands"/> factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModuleBuilder AddModalCommand(Action<ModalCommandBuilder> configure)
+        {
+            var command = new ModalCommandBuilder(this);
+            configure(command);
+            _modalCommands.Add(command);
+            return this;
         }
 
         /// <summary>

src/Discord.Net.Interactions/Builders/ModuleClassBuilder.cs

@@ -103,6 +103,7 @@ namespace Discord.Interactions.Builders
             var validContextCommands = methods.Where(IsValidContextCommandDefinition);
             var validInteractions = methods.Where(IsValidComponentCommandDefinition);
             var validAutocompleteCommands = methods.Where(IsValidAutocompleteCommandDefinition);
+            var validModalCommands = methods.Where(IsValidModalCommanDefinition);
 
             Func<IServiceProvider, IInteractionModuleBase> createInstance = commandService._useCompiledLambda ?
                 ReflectionUtils<IInteractionModuleBase>.CreateLambdaBuilder(typeInfo, commandService) : ReflectionUtils<IInteractionModuleBase>.CreateBuilder(typeInfo, commandService);
@@ -118,6 +119,9 @@ namespace Discord.Interactions.Builders
 
             foreach(var method in validAutocompleteCommands)
                 builder.AddAutocompleteCommand(x => BuildAutocompleteCommand(x, createInstance, method, commandService, services));
+
+            foreach(var method in validModalCommands)
+                builder.AddModalCommand(x => BuildModalCommand(x, createInstance, method, commandService, services));
         }
 
         private static void BuildSubModules (ModuleBuilder parent, IEnumerable<TypeInfo> subModules, IList<TypeInfo> builtTypes, InteractionService commandService,
@@ -298,6 +302,47 @@ namespace Discord.Interactions.Builders
             builder.Callback = CreateCallback(createInstance, methodInfo, commandService);
         }
 
+        private static void BuildModalCommand(ModalCommandBuilder builder, Func<IServiceProvider, IInteractionModuleBase> createInstance, MethodInfo methodInfo,
+            InteractionService commandService, IServiceProvider services)
+        {
+            var parameters = methodInfo.GetParameters();
+
+            if (parameters.Count(x => typeof(IModal).IsAssignableFrom(x.ParameterType)) > 1)
+                throw new InvalidOperationException($"A modal command can only have one {nameof(IModal)} parameter.");
+
+            if (!parameters.All(x => x.ParameterType == typeof(string) || typeof(IModal).IsAssignableFrom(x.ParameterType)))
+                throw new InvalidOperationException($"All parameters of a modal command must be either a string or an implementation of {nameof(IModal)}");
+
+            var attributes = methodInfo.GetCustomAttributes();
+
+            builder.MethodName = methodInfo.Name;
+
+            foreach (var attribute in attributes)
+            {
+                switch (attribute)
+                {
+                    case ModalInteractionAttribute modal:
+                        {
+                            builder.Name = modal.CustomId;
+                            builder.RunMode = modal.RunMode;
+                            builder.IgnoreGroupNames = modal.IgnoreGroupNames;
+                        }
+                        break;
+                    case PreconditionAttribute precondition:
+                        builder.WithPreconditions(precondition);
+                        break;
+                    default:
+                        builder.WithAttributes(attribute);
+                        break;
+                }
+            }
+
+            foreach (var parameter in parameters)
+                builder.AddParameter(x => BuildParameter(x, parameter));
+
+            builder.Callback = CreateCallback(createInstance, methodInfo, commandService);
+        }
+
         private static ExecuteCallback CreateCallback (Func<IServiceProvider, IInteractionModuleBase> createInstance,
             MethodInfo methodInfo, InteractionService commandService)
         {
@@ -400,7 +445,9 @@ namespace Discord.Interactions.Builders
             builder.Name = Regex.Replace(builder.Name, "(?<=[a-z])(?=[A-Z])", "-").ToLower();
         }
 
-        private static void BuildParameter (CommandParameterBuilder builder, ParameterInfo paramInfo)
+        private static void BuildParameter<TInfo, TBuilder> (ParameterBuilder<TInfo, TBuilder> builder, ParameterInfo paramInfo)
+            where TInfo : class, IParameterInfo
+            where TBuilder : ParameterBuilder<TInfo, TBuilder>
         {
             var attributes = paramInfo.GetCustomAttributes();
             var paramType = paramInfo.ParameterType;
@@ -428,6 +475,84 @@ namespace Discord.Interactions.Builders
         }
         #endregion
 
+        #region Modals
+        public static ModalInfo BuildModalInfo(Type modalType)
+        {
+            if (!typeof(IModal).IsAssignableFrom(modalType))
+                throw new InvalidOperationException($"{modalType.FullName} isn't an implementation of {typeof(IModal).FullName}");
+
+            var instance = Activator.CreateInstance(modalType, false) as IModal;
+
+            try
+            {
+                var builder = new ModalBuilder(modalType)
+                {
+                    Title = instance.Title
+                };
+
+                var inputs = modalType.GetProperties().Where(IsValidModalInputDefinition);
+
+                foreach (var prop in inputs)
+                {
+                    var componentType = prop.GetCustomAttribute<ModalInputAttribute>()?.ComponentType;
+
+                    switch (componentType)
+                    {
+                        case ComponentType.TextInput:
+                            builder.AddTextComponent(x => BuildTextInput(x, prop, prop.GetValue(instance)));
+                            break;
+                        case null:
+                            throw new InvalidOperationException($"{prop.Name} of {prop.DeclaringType.Name} isn't a valid modal input field.");
+                        default:
+                            throw new InvalidOperationException($"Component type {componentType} cannot be used in modals.");
+                    }
+                }
+
+                var memberInit = ReflectionUtils<IModal>.CreateLambdaMemberInit(modalType.GetTypeInfo(), modalType.GetConstructor(Type.EmptyTypes), x => x.IsDefined(typeof(ModalInputAttribute)));
+                builder.ModalInitializer = (args) => memberInit(Array.Empty<object>(), args);
+                return builder.Build();
+            }
+            finally
+            {
+                (instance as IDisposable)?.Dispose();
+            }
+        }
+
+        private static void BuildTextInput(TextInputComponentBuilder builder, PropertyInfo propertyInfo, object defaultValue)
+        {
+            var attributes = propertyInfo.GetCustomAttributes();
+
+            builder.Label = propertyInfo.Name;
+            builder.DefaultValue = defaultValue;
+            builder.WithType(propertyInfo.PropertyType);
+
+            foreach(var attribute in attributes)
+            {
+                switch (attribute)
+                {
+                    case ModalTextInputAttribute textInput:
+                        builder.CustomId = textInput.CustomId;
+                        builder.ComponentType = textInput.ComponentType;
+                        builder.Style = textInput.Style;
+                        builder.Placeholder = textInput.Placeholder;
+                        builder.MaxLength = textInput.MaxLength;
+                        builder.MinLength = textInput.MinLength;
+                        builder.InitialValue = textInput.InitialValue;
+                        break;
+                    case RequiredInputAttribute requiredInput:
+                        builder.IsRequired = requiredInput.IsRequired;
+                        break;
+                    case InputLabelAttribute inputLabel:
+                        builder.Label = inputLabel.Label;
+                        break;
+                    default:
+                        builder.WithAttributes(attribute);
+                        break;
+                }
+            }
+        }
+        #endregion
+
         internal static bool IsValidModuleDefinition (TypeInfo typeInfo)
         {
             return ModuleTypeInfo.IsAssignableFrom(typeInfo) &&
@@ -467,5 +592,21 @@ namespace Discord.Interactions.Builders
                 !methodInfo.IsGenericMethod &&
                 methodInfo.GetParameters().Length == 0;
         }
+
+        private static bool IsValidModalCommanDefinition(MethodInfo methodInfo)
+        {
+            return methodInfo.IsDefined(typeof(ModalInteractionAttribute)) &&
+                (methodInfo.ReturnType == typeof(Task) || methodInfo.ReturnType == typeof(Task<RuntimeResult>)) &&
+                !methodInfo.IsStatic &&
+                !methodInfo.IsGenericMethod &&
+                typeof(IModal).IsAssignableFrom(methodInfo.GetParameters().Last().ParameterType);
+        }
+
+        private static bool IsValidModalInputDefinition(PropertyInfo propertyInfo)
+        {
+            return propertyInfo.SetMethod?.IsPublic == true &&
+                propertyInfo.SetMethod?.IsStatic == false &&
+                propertyInfo.IsDefined(typeof(ModalInputAttribute));
+        }
     }
 }

src/Discord.Net.Interactions/Builders/Parameters/ModalCommandParameterBuilder.cs

@@ -0,0 +1,45 @@
+using System;
+
+namespace Discord.Interactions.Builders
+{
+
+    /// <summary>
+    ///     Represents a builder for creating <see cref="ModalCommandBuilder"/>.
+    /// </summary>
+    public class ModalCommandParameterBuilder : ParameterBuilder<ModalCommandParameterInfo, ModalCommandParameterBuilder>
+    {
+        protected override ModalCommandParameterBuilder Instance => this;
+
+        /// <summary>
+        ///     Gets the built <see cref="ModalInfo"/> class for this parameter, if <see cref="IsModalParameter"/> is <see langword="true"/>.
+        /// </summary>
+        public ModalInfo Modal { get; private set; }
+
+        /// <summary>
+        ///     Gets whether or not this parameter is an <see cref="IModal"/>.
+        /// </summary>
+        public bool IsModalParameter => Modal is not null;
+
+        internal ModalCommandParameterBuilder(ICommandBuilder command) : base(command) { }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandParameterBuilder"/>.
+        /// </summary>
+        /// <param name="command">Parent command of this parameter.</param>
+        /// <param name="name">Name of this command.</param>
+        /// <param name="type">Type of this parameter.</param>
+        public ModalCommandParameterBuilder(ICommandBuilder command, string name, Type type) : base(command, name, type) { }
+
+        /// <inheritdoc/>
+        public override ModalCommandParameterBuilder SetParameterType(Type type)
+        {
+            if (typeof(IModal).IsAssignableFrom(type))
+                Modal = ModalUtils.GetOrAdd(type);
+
+            return base.SetParameterType(type);
+        }
+
+        internal override ModalCommandParameterInfo Build(ICommandInfo command) =>
+            new(this, command);
+    }
+}