const CollabChatAPI = (()=>{
    const version = 1;

    const onMessage = (()=>{
        const messageCallbacks = [];

        // chat omits a persons name if they send consecutive messages, so the
        // last person who sent a message is stored here so that every message
        // object has a "from".
        let lastFrom = null;

        const observer = new MutationObserver(mutations => {
            mutations.forEach(mutation => {
                if (mutation.type != "childList") return;
                mutation.addedNodes.forEach(node => {
                    if (node.tagName != "LI") return;

                    // extract information
                    lastFrom = $(".participant-name", node).text() || lastFrom;
                    const contents = $(".activity-body", node).text();

                    // construct message
                    const message = {
                        from: lastFrom,
                        contents,
                    };

                    // call callbacks
                    messageCallbacks.forEach(callback => callback(message));
                });
            })
        });

        // changing breakout group, minimizing the chat, etc, causes a new chat
        // element to be created, meaning the observer is now observing the old
        // chat. This loop lazily rebinds the observer to the current chat
        // every second.
        setInterval(()=>{
            observer.disconnect();
            const chatRoot = $("#chat-channel-history");
            if (chatRoot.length == 0) return;
            observer.observe(chatRoot[0], { childList: true });
        }, 1000);

        function onMessage(callback) {
            messageCallbacks.push(callback);
        }

        return onMessage;
    })();

    function sendMessage(message) {
        const messageInput = $("#message-input");
        if (messageInput.length == 0) {
            console.warn("CollabChatAPI attempted to sendMessage but no chat was open!");
            return false;
        }
        const pressEnter = $.Event("keypress");
        pressEnter.which = 13;
        messageInput.val(message);
        messageInput.trigger("change");
        messageInput.trigger(pressEnter);
        return true;
    }

    return {
        version,
        onMessage,
        sendMessage,
    };

})();

/*

// send a message from your account

CollabChatAPI.sendMessage("hello!");

// do something when a new message is received:

CollabChatAPI.onMessage(msg => {
    // do something with msg
});

// msg in onMessage is the following object
{
    from: "John Bobington",
    contents: "Hey there!"
}

// example !roll command
CollabChatAPI.onMessage(msg => {
    if (msg.contents.toLowerCase() == "!roll") {
        const roll = ~~(Math.random()*100);
        CollabChatAPI.sendMessage(`[bot] you rolled ${roll}!`);
    }
});

// example logging all messages
CollabChatAPI.onMessage(console.log);

*/