Confessions module

This commit adds a confessions feature that allows users to mark a
"confessional" channel and also to post anonymously to it. The changes
that this comprises of are as follows:

- New discord "slash" commands for both marking a confessional and
  posting to it
- a bunch of stuff in the discord module to register and deregister
  "slash" commands
- New event type to track marked confessionals
- confession module that processes new confession channel links
  and also posts confessions to corresponding confessionals

Not included in this commit:
- a way to cleanup obsolete or reconfigured confession channel links
- access control for the confessional slash commands

Signed-off-by: Ava Affine <ava@sunnypup.io>

internal/state/state.go

@@ -183,6 +183,7 @@ const (
 	Restoration
 	UserActive
 	Test
+	ConfessionsChannelLink
 	// ...
 
 	// leave this last
@@ -202,6 +203,8 @@ func EventTypeFromString(doc string) EventType {
 		return UserActive
 	case "Test":
 		return Test
+	case "ConfessionsChannelLink":
+		return ConfessionsChannelLink
 	default:
 		// error case
 		return NumEventTypes
@@ -215,6 +218,7 @@ func (et EventType) String() string {
 		"Restoration",
 		"UserActive",
 		"Test",
+		"ConfessionsChannelLink",
 	}
 
 	if et < 0 || et >= NumEventTypes {
@@ -266,24 +270,28 @@ func (et EventType) MakeEvent(data map[string]string) (Event, error) {
 	switch et {
 	case Vote:
 		return VoteEvent(data), nil
+
 	case Challenge:
 		e, err := MakeUserEvent(data)
 		if err != nil {
 			return nil, errors.Join(errors.New(BadChallengeEvent), err)
 		}
 		return ChallengeEvent{*e}, nil
+
 	case Restoration:
 		e, err := MakeUserEvent(data)
 		if err != nil {
 			return nil, errors.Join(errors.New(BadRestorationEvent), err)
 		}
 		return RestorationEvent{*e}, nil
+
 	case UserActive:
 		e, err := MakeUserEvent(data)
 		if err != nil {
 			return nil, errors.Join(errors.New(BadUserActiveEvent), err)
 		}
 		return UserActiveEvent{*e}, nil
+
 	case Test:
 		disp := false
 		if v, ok := data[TestEventDisposeKey]; ok && v == "t" {
@@ -300,6 +308,33 @@ func (et EventType) MakeEvent(data map[string]string) (Event, error) {
 			Dispose: disp,
 			ID:      id,
 		}, nil
+
+	case ConfessionsChannelLink:
+		gid, ok := data[ConfessionsLinkEventGuildKey]
+		if !ok {
+			return nil, errors.New(BadConfessionsLinkEventError)
+		}
+
+		cid, ok := data[ConfessionsLinkEventChannelKey]
+		if !ok {
+			return nil, errors.New(BadConfessionsLinkEventError)
+		}
+
+		ti, ok := data[ConfessionsLinkEventCreatedKey]
+		if !ok {
+			return nil, errors.New(BadConfessionsLinkEventError)
+		}
+		t, err := time.Parse(time.RFC3339, ti)
+		if err != nil {
+			return nil, errors.Join(errors.New(BadConfessionsLinkEventError), err)
+		}
+
+		return ConfessionsChannelLinkEvent{
+			GuildID: gid,
+			ChannelID: cid,
+			Created: t,
+		}, nil
+
 	default:
 		return nil, errors.New(BadEventTypeError)
 	}