discord: Modal interaction support (#310)

* Support modal interactions along with the TextInput component

* Replace ModalInteraction with Modal to prevent confusion

* Fix the required field from not being used correctly

* PR Fixes

api/interaction.go

@@ -25,6 +25,7 @@ const (
 	DeferredMessageUpdate
 	UpdateMessage
 	AutocompleteResult
+	ModalResponse
 )
 
 // InteractionResponseFlags implements flags for an
@@ -78,6 +79,11 @@ type InteractionResponseData struct {
 	//
 	// During all other events, this should not be provided.
 	Choices *[]AutocompleteChoice `json:"choices"`
+
+	// CustomID used with the modal
+	CustomID option.NullableString `json:"custom_id,omitempty"`
+	// Title is the heading of the modal window
+	Title option.NullableString `json:"title,omitempty"`
 }
 
 // NeedsMultipart returns true if the InteractionResponseData has files.

discord/component.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/diamondburned/arikawa/v3/utils/json"
+	"github.com/diamondburned/arikawa/v3/utils/json/option"
 	"github.com/pkg/errors"
 )
 
@@ -15,6 +16,7 @@ const (
 	ActionRowComponentType
 	ButtonComponentType
 	SelectComponentType
+	TextInputComponentType
 )
 
 // String formats Type's name as a string.
@@ -26,6 +28,8 @@ func (t ComponentType) String() string {
 		return "Button"
 	case SelectComponentType:
 		return "Select"
+	case TextInputComponentType:
+		return "TextInput"
 	default:
 		return fmt.Sprintf("ComponentType(%d)", int(t))
 	}
@@ -126,6 +130,8 @@ func ParseComponent(b []byte) (Component, error) {
 		c = &ButtonComponent{}
 	case SelectComponentType:
 		c = &SelectComponent{}
+	case TextInputComponentType:
+		c = &TextInputComponent{}
 	default:
 		c = &UnknownComponent{typ: t.Type}
 	}
@@ -448,6 +454,69 @@ func (s *SelectComponent) MarshalJSON() ([]byte, error) {
 	return json.Marshal(msg)
 }
 
+type TextInputStyle uint8
+
+const (
+	_ TextInputStyle = iota
+	TextInputShortStyle
+	TextInputParagraphStyle
+)
+
+// TextInputComponents provide a user-facing text box to be filled out. They can only
+// be used with modals.
+type TextInputComponent struct {
+	// CustomID provides a developer-defined ID for the input (max 100 chars)
+	CustomID ComponentID `json:"custom_id"`
+	// Style determines if the component should use the short or paragraph style
+	Style TextInputStyle `json:"style"`
+	// Label is the title of this component, describing its use
+	Label string `json:"label"`
+	// ValueLimits is the minimum and maximum length for the input
+	ValueLimits [2]int `json:"-"`
+	// Required dictates whether or not the user must fill out the component
+	Required bool `json:"required"`
+	// Value is the pre-filled value of this component (max 4000 chars)
+	Value option.NullableString `json:"value,omitempty"`
+	// Placeholder is the text that appears when the input is empty (max 100 chars)
+	Placeholder option.NullableString `json:"placeholder,omitempty"`
+}
+
+func (s *TextInputComponent) _cmp() {}
+func (s *TextInputComponent) _icp() {}
+
+func (i *TextInputComponent) ID() ComponentID {
+	return i.CustomID
+}
+
+func (i *TextInputComponent) Type() ComponentType {
+	return TextInputComponentType
+}
+
+func (i *TextInputComponent) MarshalJSON() ([]byte, error) {
+	type text TextInputComponent
+
+	type Msg struct {
+		Type ComponentType `json:"type"`
+		*text
+		MinValues *int `json:"max_values,omitempty"`
+		MaxValues *int `json:"min_values,omitempty"`
+	}
+
+	m := Msg{
+		Type: i.Type(),
+		text: (*text)(i),
+	}
+
+	if i.ValueLimits != [2]int{0, 0} {
+		m.MinValues = new(int)
+		m.MaxValues = new(int)
+
+		*m.MinValues = i.ValueLimits[0]
+		*m.MaxValues = i.ValueLimits[1]
+	}
+	return json.Marshal(m)
+}
+
 // Unknown is reserved for components with unknown or not yet implemented
 // components types. It can also be used in place of a ComponentInteraction.
 type UnknownComponent struct {

discord/interaction.go

@@ -86,6 +86,8 @@ func (e *InteractionEvent) UnmarshalJSON(b []byte) error {
 		return nil
 	case AutocompleteInteractionType:
 		e.Data = &AutocompleteInteraction{}
+	case ModalInteractionType:
+		e.Data = &ModalInteraction{}
 	default:
 		e.Data = &UnknownInteractionData{
 			Raw: target.Data,
@@ -131,6 +133,7 @@ const (
 	CommandInteractionType
 	ComponentInteractionType
 	AutocompleteInteractionType
+	ModalInteractionType
 )
 
 // InteractionData holds the respose data of an interaction, or more
@@ -365,6 +368,19 @@ func (o CommandInteractionOption) FloatValue() (float64, error) {
 	return f, err
 }
 
+// ModalInteraction is the submitted modal form
+type ModalInteraction struct {
+	CustomID   ComponentID         `json:"custom_id"`
+	Components ContainerComponents `json:"components"`
+}
+
+// InteractionType implements InteractionData.
+func (m *ModalInteraction) InteractionType() InteractionDataType {
+	return ModalInteractionType
+}
+
+func (m *ModalInteraction) data() {}
+
 // UnknownInteractionData describes an Interaction response with an unknown
 // type.
 type UnknownInteractionData struct {