Implement default values for auto-populated selections (#108)

* Implement default values for selections

* Added validation for default selection values

* Fix check

* Update validation check

* Add case to handle warning

src/Disqord.Core/Entities/Core/Interactions/Components/IDefaultSelectionValue.cs

@@ -0,0 +1,12 @@
+namespace Disqord;
+
+/// <summary>
+///     Represents a default value of a selection message component.
+/// </summary>
+public interface IDefaultSelectionValue: IIdentifiableEntity
+{
+    /// <summary>
+    ///     Gets the type of this default value.
+    /// </summary>
+    DefaultSelectionValueType Type { get; }
+}

src/Disqord.Core/Entities/Core/Interactions/Components/ISelectionComponent.cs

@@ -26,6 +26,15 @@ public interface ISelectionComponent : IComponent, ICustomIdentifiableEntity
     /// </summary>
     string? Placeholder { get; }
 
+    /// <summary>
+    ///     Gets the default values that auto-populate this selection component.
+    /// </summary>
+    /// <remarks>
+    ///     This is only valid for <see cref="SelectionComponentType.User"/>,
+    ///     <see cref="SelectionComponentType.Role"/>, or <see cref="SelectionComponentType.Channel"/> selections.
+    /// </remarks>
+    IReadOnlyList<IDefaultSelectionValue> DefaultValues { get; }
+
     /// <summary>
     ///     Gets the minimum amount of options that must be selected at once of this selection component.
     /// </summary>

src/Disqord.Core/Entities/Local/Interaction/Components/LocalComponent.cs

@@ -113,6 +113,7 @@ public virtual ComponentJsonModel ToModel()
             model.Type = (ComponentType) selectionComponent.Type;
             model.ChannelTypes = Optional.Convert(selectionComponent.ChannelTypes, channelTypes => channelTypes?.ToArray())!;
             model.Placeholder = selectionComponent.Placeholder;
+            model.DefaultValues = Optional.Convert(selectionComponent.DefaultValues, defaultValues => defaultValues.Select(defaultValue => defaultValue.ToModel()).ToArray());
             model.MinValues = selectionComponent.MinimumSelectedOptions;
             model.MaxValues = selectionComponent.MaximumSelectedOptions;
             model.Disabled = selectionComponent.IsDisabled;

src/Disqord.Core/Entities/Local/Interaction/Components/Selection/Extensions/LocalSelectionComponentExtensions.cs

@@ -49,6 +49,32 @@ public static TComponent WithPlaceholder<TComponent>(this TComponent selection,
         return selection;
     }
 
+    public static TComponent AddDefaultValue<TComponent>(this TComponent selection, LocalDefaultSelectionValue defaultValue)
+        where TComponent : LocalSelectionComponent
+    {
+        if (selection.DefaultValues.Add(defaultValue, out var list))
+            selection.DefaultValues = new(list);
+
+        return selection;
+    }
+
+    public static TComponent WithDefaultValues<TComponent>(this TComponent selection, IEnumerable<LocalDefaultSelectionValue> defaultValues)
+        where TComponent : LocalSelectionComponent
+    {
+        Guard.IsNotNull(defaultValues);
+
+        if (selection.DefaultValues.With(defaultValues, out var list))
+            selection.DefaultValues = new(list);
+
+        return selection;
+    }
+
+    public static TComponent WithDefaultValues<TComponent>(this TComponent selection, params LocalDefaultSelectionValue[] defaultValues)
+        where TComponent : LocalSelectionComponent
+    {
+        return selection.WithDefaultValues(defaultValues as IEnumerable<LocalDefaultSelectionValue>);
+    }
+
     public static TComponent WithMinimumSelectedOptions<TComponent>(this TComponent selection, int minimumSelectedOptions)
         where TComponent : LocalSelectionComponent
     {

src/Disqord.Core/Entities/Local/Interaction/Components/Selection/LocalDefaultSelectionValue.cs

@@ -0,0 +1,69 @@
+using Disqord.Models;
+
+namespace Disqord;
+
+public class LocalDefaultSelectionValue : IDefaultSelectionValue, ILocalConstruct<LocalDefaultSelectionValue>, IJsonConvertible<DefaultValueJsonModel>
+{
+    public static LocalDefaultSelectionValue User(Snowflake id)
+    {
+        return new(id, DefaultSelectionValueType.User);
+    }
+
+    public static LocalDefaultSelectionValue Role(Snowflake id)
+    {
+        return new(id, DefaultSelectionValueType.Role);
+    }
+
+    public static LocalDefaultSelectionValue Channel(Snowflake id)
+    {
+        return new(id, DefaultSelectionValueType.Channel);
+    }
+
+    /// <inheritdoc/>
+    public Snowflake Id { get; set; }
+
+    /// <inheritdoc/>
+    public DefaultSelectionValueType Type { get; set; }
+
+    /// <summary>
+    ///     Instantiates a new <see cref="LocalDefaultSelectionValue"/>.
+    /// </summary>
+    public LocalDefaultSelectionValue()
+    { }
+
+    /// <summary>
+    ///     Instantiates a new <see cref="LocalDefaultSelectionValue"/>.
+    /// </summary>
+    /// <param name="id"> The id of the entity. </param>
+    /// <param name="type"> The type of the entity. </param>
+    public LocalDefaultSelectionValue(Snowflake id, DefaultSelectionValueType type)
+    {
+        Id = id;
+        Type = type;
+    }
+
+    /// <summary>
+    ///     Instantiates a new <see cref="LocalDefaultSelectionValue"/> with the properties copied from another instance.
+    /// </summary>
+    /// <param name="other"> The other instance to copy properties from. </param>
+    protected LocalDefaultSelectionValue(LocalDefaultSelectionValue other)
+    {
+        Id = other.Id;
+        Type = other.Type;
+    }
+
+    /// <inheritdoc/>
+    public LocalDefaultSelectionValue Clone()
+    {
+        return new(this);
+    }
+
+    public DefaultValueJsonModel ToModel()
+    {
+        return new DefaultValueJsonModel
+        {
+            Id = Id,
+            Type = Type
+        };
+    }
+}

src/Disqord.Core/Entities/Local/Interaction/Components/Selection/LocalSelectionComponent.cs

@@ -30,6 +30,15 @@ public class LocalSelectionComponent : LocalComponent, ILocalCustomIdentifiableE
     /// </summary>
     public Optional<string> Placeholder { get; set; }
 
+    /// <summary>
+    ///     Gets or sets the default values of this selection.
+    /// </summary>
+    /// <remarks>
+    ///     This is only valid for <see cref="SelectionComponentType.User"/>,
+    ///     <see cref="SelectionComponentType.Role"/>, or <see cref="SelectionComponentType.Channel"/> selections.
+    /// </remarks>
+    public Optional<IList<LocalDefaultSelectionValue>> DefaultValues { get; set; }
+
     /// <summary>
     ///     Gets or sets the minimum amount of options of this selection.
     /// </summary>
@@ -69,6 +78,7 @@ protected LocalSelectionComponent(LocalSelectionComponent other)
         Type = other.Type;
         ChannelTypes = other.ChannelTypes.Clone();
         Placeholder = other.Placeholder;
+        DefaultValues = other.DefaultValues.DeepClone();
         MinimumSelectedOptions = other.MinimumSelectedOptions;
         MaximumSelectedOptions = other.MaximumSelectedOptions;
         Options = other.Options.DeepClone();
@@ -112,6 +122,19 @@ public static LocalSelectionComponent CreateFrom(ISelectionComponent selectionCo
 
             selection.Options = localOptions;
         }
+        else
+        {
+            var defaultValues = selectionComponent.DefaultValues;
+            var defaultValueCount = defaultValues.Count;
+            var localDefaultValues = new List<LocalDefaultSelectionValue>(defaultValueCount);
+            for (var i = 0; i < defaultValueCount; i++)
+            {
+                var defaultValue = defaultValues[i];
+                localDefaultValues.Add(new(defaultValue.Id, defaultValue.Type));
+            }
+
+            selection.DefaultValues = localDefaultValues;
+        }
 
         return selection;
     }

src/Disqord.Core/Entities/Transient/Interactions/Components/TransientDefaultSelectionValue.cs

@@ -0,0 +1,17 @@
+using Disqord.Models;
+
+namespace Disqord;
+
+/// <inheritdoc cref="IDefaultSelectionValue"/>
+public class TransientDefaultSelectionValue : TransientClientEntity<DefaultValueJsonModel>, IDefaultSelectionValue
+{
+    /// <inheritdoc/>
+    public Snowflake Id => Model.Id;
+
+    /// <inheritdoc/>
+    public DefaultSelectionValueType Type => Model.Type;
+
+    public TransientDefaultSelectionValue(IClient client, DefaultValueJsonModel model)
+        : base(client, model)
+    { }
+}

src/Disqord.Core/Entities/Transient/Interactions/Components/TransientSelectionComponent.cs

@@ -29,6 +29,11 @@ public IReadOnlyList<ChannelType> ChannelTypes
     /// <inheritdoc/>
     public string? Placeholder => Model.Placeholder.GetValueOrDefault();
 
+    /// <inheritdoc/>
+    public IReadOnlyList<IDefaultSelectionValue> DefaultValues => _defaultValues ??= Model.DefaultValues.Value.ToReadOnlyList(Client, (model, client) => new TransientDefaultSelectionValue(client, model));
+
+    private IReadOnlyList<IDefaultSelectionValue>? _defaultValues;
+
     /// <inheritdoc/>
     public int MinimumSelectedOptions => Model.MinValues.Value;
 

src/Disqord.Core/Enums/Interactions/Components/DefaultSelectionValueType.cs

@@ -0,0 +1,20 @@
+using System.Runtime.Serialization;
+using Disqord.Serialization.Json;
+
+namespace Disqord;
+
+/// <summary>
+///     Represents the type of default selection value.
+/// </summary>
+[StringEnum]
+public enum DefaultSelectionValueType
+{
+    [EnumMember(Value = "user")]
+    User,
+
+    [EnumMember(Value = "role")]
+    Role,
+
+    [EnumMember(Value = "channel")]
+    Channel,
+}

src/Disqord.Core/Models/Interactions/Components/ComponentJsonModel.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using Disqord.Serialization.Json;
 using Qommon;
 
@@ -39,6 +40,9 @@ public class ComponentJsonModel : JsonModel
     [JsonProperty("placeholder")]
     public Optional<string> Placeholder;
 
+    [JsonProperty("default_values")]
+    public Optional<DefaultValueJsonModel[]> DefaultValues;
+
     [JsonProperty("min_values")]
     public Optional<int> MinValues;
 
@@ -137,6 +141,22 @@ protected override void OnValidate()
                 if (MinValues.HasValue && MaxValues.HasValue)
                     Guard.IsLessThanOrEqualTo(MinValues.Value, MaxValues.Value);
 
+                OptionalGuard.CheckValue(DefaultValues, defaultValues =>
+                {
+                    Guard.IsBetweenOrEqualTo(defaultValues.Length, MinValues.GetValueOrDefault(Discord.Limits.Component.Selection.MinMinimumSelectedOptions), MaxValues.GetValueOrDefault(Discord.Limits.Component.Selection.MaxMaximumSelectedOptions));
+
+                    Predicate<DefaultValueJsonModel> predicate = Type switch
+                    {
+                        ComponentType.UserSelection => value => value.Type is DefaultSelectionValueType.User,
+                        ComponentType.RoleSelection => value => value.Type is DefaultSelectionValueType.Role,
+                        ComponentType.MentionableSelection => value => value.Type is DefaultSelectionValueType.User or DefaultSelectionValueType.Role,
+                        ComponentType.ChannelSelection => value => value.Type is DefaultSelectionValueType.Channel,
+                        _ => value => true
+                    };
+
+                    Guard.IsTrue(Array.TrueForAll(defaultValues, predicate), message: "The types of default selection values must match the type of the component.");
+                });
+
                 break;
             }
             case ComponentType.TextInput:

src/Disqord.Core/Models/Interactions/Components/DefaultValueJsonModel.cs

@@ -0,0 +1,12 @@
+using Disqord.Serialization.Json;
+
+namespace Disqord.Models;
+
+public class DefaultValueJsonModel : JsonModel
+{
+    [JsonProperty("id")]
+    public Snowflake Id;
+
+    [JsonProperty("type")]
+    public DefaultSelectionValueType Type;
+}