add API constraints

src/rules.ts

@@ -1,12 +1,14 @@
-type SerializedRule = { group_id: string; target_role: TargetRole };
 export type TargetRole = { guild_id: string; role_id: string };
+type SerializedRule = { group_id: string; target_role: TargetRole };
+
 export class RuleSet {
-	rules;
-	constructor() {
+	private rules;
+
+	public constructor() {
 		this.rules = new Map<string, TargetRole[]>();
 	}
 
-	static async from_file(path: string) {
+	public static async from_file(path: string) {
 		const result = new RuleSet();
 		const file_content = await Deno.readTextFile(path);
 		const parsed = JSON.parse(file_content) as SerializedRule[];
@@ -14,6 +16,16 @@ export class RuleSet {
 		return result;
 	}
 
+	public roles_for_group(group_id: string) {
+		return this.rules.get(group_id) ?? [];
+	}
+
+	public size() {
+		let result = 0;
+		for (const roles of this.rules.values()) result += roles.length;
+		return result;
+	}
+
 	private append_rule(group_id: string, target_role: TargetRole) {
 		let roles = this.rules.get(group_id);
 		if (roles === undefined) {
@@ -22,8 +34,4 @@ export class RuleSet {
 		}
 		roles.push(target_role);
 	}
-
-	roles_for_group(group_id: string) {
-		return this.rules.get(group_id) ?? [];
-	}
 }