Add basic mailboxes command

This can be improved in the future, to show some additional information
about each mailbox like:

- "how many users are in that room"
- "which users are in that room"
- "who is the owner of the mailbox"

This can all be done later though.

bot/access.go

@@ -35,3 +35,7 @@ func (b *Bot) allowOwner(actorID id.UserID, targetRoomID id.RoomID) (bool, error
 
 	return owner == actorID.String(), nil
 }
+
+func (b *Bot) allowAdmin(actorID id.UserID, targetRoomID id.RoomID) (bool, error) {
+	return utils.Match(actorID.String(), b.allowedAdmins), nil
+}

bot/admin_command.go

@@ -0,0 +1,39 @@
+package bot
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"maunium.net/go/mautrix/id"
+)
+
+func (b *Bot) sendMailboxes(ctx context.Context) {
+	evt := eventFromContext(ctx)
+
+	mailboxes := map[string]id.RoomID{}
+
+	b.rooms.Range(func(mailbox any, roomID any) bool {
+		mailboxes[mailbox.(string)] = roomID.(id.RoomID)
+		return true
+	})
+
+	if len(mailboxes) == 0 {
+		b.Notice(ctx, evt.RoomID, "No mailboxes are managed by the bot so far, kupo!")
+		return
+	}
+
+	var msg strings.Builder
+	msg.WriteString("The following mailboxes are managed by the bot:\n")
+	for mailbox, roomID := range mailboxes {
+		email := fmt.Sprintf("%s@%s", mailbox, b.domain)
+		msg.WriteString("* `")
+		msg.WriteString(email)
+		msg.WriteString("` - `")
+		msg.WriteString(roomID.String())
+		msg.WriteString("`")
+		msg.WriteString("\n")
+	}
+
+	b.Notice(ctx, evt.RoomID, msg.String())
+}

bot/command.go

@@ -109,6 +109,12 @@ func (b *Bot) buildCommandList() commandList {
 			sanitizer:     utils.SanitizeBoolString,
 			accessChecker: b.allowOwner,
 		},
+		{}, // delimiter
+		{
+			key:           commandMailboxes,
+			description:   "Show the list of all mailboxes",
+			accessChecker: b.allowAdmin,
+		},
 	}
 }
 
@@ -138,6 +144,8 @@ func (b *Bot) handleCommand(ctx context.Context, evt *event.Event, commandSlice
 		b.sendHelp(ctx, evt.RoomID)
 	case commandStop:
 		b.runStop(ctx)
+	case commandMailboxes:
+		b.sendMailboxes(ctx)
 	default:
 		b.handleOption(ctx, commandSlice)
 	}