Lesson_4_source_code01

actor {
    public type Message = {
        id: Text;
        time: Int;
    };
    type Time = Int;
    public type Microblog = actor {
        follow: shared(Principal) -> async (); // 增添关注对象
        follows: shared query() -> async [Principal]; // 返回关注列表
        post: shared(Text) -> async (); // 发布新消息
        posts: shared query(Time.Time) -> async [Message]; // 返回所有发布的消息
        timeline: shared () -> async [Message]; // 返回所有关注对象发布的消息
    };

    stable var followed : List.List<Principal> = List.nil();

    public shared func follow(id: Principal) : async (){
        followed := List.push(id, followed);
    };

    public shared query func follows() : async [Principal]{
        List.toArray(followed);
    };

    stable var messages : List.List<Message> = List.nil();

    public shared(msg) func post(text: Text) : async (){
        assert(Principal.toText(msg.caller) == "xyhhn-v72fd-5zdqy-ka3ek-52ugn-cglgb-g4dya-b7yqk-miwo2-o33y4-gae");
        let data = {
            id = text;
            time = Time.now();
        };
        messages := List.push(data, messages);
    };