function parseIRCMessage(line) {
  line = line.replace(/\r?\n$/, '');
  let tags = {};
  let prefix = null;
  let nick = null;
  let command = null;
  const params = [];

  // tags
  if (line[0] === '@') {
    const end = line.indexOf(' ');
    const rawTags = line.slice(1, end);
    for (const tag of rawTags.split(';')) {
      const [k, v = true] = tag.split('=');
      tags[k] = v === true ? true : v;
    }
    line = line.slice(end + 1);
  }

  // prefix
  if (line[0] === ':') {
    const end = line.indexOf(' ');
    prefix = line.slice(1, end);
    const bang = prefix.indexOf('!');
    if (bang !== -1) nick = prefix.slice(0, bang);
    line = line.slice(end + 1);
  }

  // command and params
  const parts = line.split(' ');
  command = parts.shift();
  for (let i = 0; i < parts.length; i++) {
    if (parts[i][0] === ':') {
      params.push(parts.slice(i).join(' ').slice(1));
      break;
    }
    if (parts[i].length) params.push(parts[i]);
  }

  return { tags, prefix, nick, command, params };
}

function addMessage(message) {
    const messages = document.getElementById("messages");
    if (!messages || message.command != "PRIVMSG") {
        return;
    }
    
    // msg base
    const elem = document.createElement("p");
    elem.classList.add("message");
    
    // badges
    if ("badges" in message.tags && message.tags["badges"].length > 0) {
        for (const b of message.tags["badges"].split(",")) {
            if (b in badges) {
                const badgeImg = document.createElement("img");
                badgeImg.src = badges[b];
                badgeImg.loading = 'lazy';
                badgeImg.classList.add("badge");
                elem.append(badgeImg);
            }
        }
    }
    
    // parsing twitch emotes
    if ("emotes" in message.tags && message.tags["emotes"].length > 0) {
        const parts = message.tags["emotes"].split("/");
        for (const part of parts) {
            const p = part.split(":");
            const id = p[0];
            const positions = p[1].split(",");
            
            for (const pos of positions) {
                const p = pos.split("-");
                const start = p[0];
                const end = p[1];
                const emotename = message.params[1].substring(parseInt(start), parseInt(end) + 1);
                emotes[emotename] = `https://static-cdn.jtvnw.net/emoticons/v2/${id}/default/dark/1.0`;
            }
        }
    }
    
    // username
    if (message.nick != null && message.nick.length > 0) {
        const usernameElem = document.createElement("span");
        elem.append(usernameElem);
        if ("color" in message.tags) {
            usernameElem.style.color = message.tags["color"];
        }
        usernameElem.classList.add("author");
        usernameElem.textContent = `${message.nick}:`;
    }
    
    // message text
    let msgWords = message.params[1].split(" ");
    for (let i = 0; i < msgWords.length; i++) {
        if (msgWords[i] in emotes) {
            msgWords[i] = `<img src="${emotes[msgWords[i]]}" loading="lazy" alt="${msgWords[i]}" class="emote" />`;
        }
    }
    
    elem.innerHTML += ' ' + msgWords.join(" ");
    
    messages.append(elem);
    
    window.scrollTo(0, document.body.scrollHeight);
    
    // remove old messages
    if (messages.childElementCount > 100) {
        for (let i = 0; i < messages.childElementCount - 100; i++) {
            messages.childNodes[i].remove();
        }
    }
}

function addSystemMessage(message, nick = "System") {
    addMessage({
        "params": ["#", message],
        "nick": nick,
        "prefix": "system",
        "tags": {},
        "command": "PRIVMSG",
    });
}

function connectToChat(host, nick, password, room) {
    const socket = new WebSocket(host);
    const membership = {
        "joined": [],
        "parted": []
    };
    
    const membershipInterval = setInterval(() => {
        if (membership.joined.length > 0) {
            addSystemMessage(`Users joined: ${membership.joined.join(", ")}`, null);
            membership.joined = [];
        }
        
        if (membership.parted.length > 0) {
            addSystemMessage(`Users parted: ${membership.parted.join(", ")}`, null);
            membership.parted = [];
        }
    }, 10000);
    
    socket.addEventListener("open", () => {
        socket.send(`NICK ${nick}`);
        socket.send(`PASS ${password}`);
        socket.send("CAP REQ :twitch.tv/tags");
        if (params["membership"] == "1") {
            socket.send("CAP REQ :twitch.tv/membership");
        }
        socket.send(`JOIN #${room}`);
        addSystemMessage("Connected to the chat!");
    });
    
    socket.addEventListener("message", (e) => {
        const lines = e.data.split("\r\n");
        
        for (const line of lines) {
            const l = line.trim();
            if (l.length == 0) {
                continue;
            }
            let m = parseIRCMessage(l);
            console.log(m);
            addMessage(m);
            
            if (m.command == "JOIN" && m.nick != "justinfan12345") {
                membership.joined.push(m.nick);
            } else if (m.command == "PART" && m.nick != "justinfan12345") {
                membership.parted.push(m.nick);
            } else if (m.command == "PING") {
                socket.send(`PONG :${m.params[0]}`);
            }
        }
    });
    
    socket.addEventListener("close", (e) => {
        addMessage("Chat", `Disconnected from the chat: ${e.reason}`);
        addMessage("Chat", "Reconnecting to the chat in 5 seconds...");
        clearInterval(membershipInterval);
        setTimeout(() => connectToChat(host, nick, password, room), 5000);
    });
}

function getRecentMessages(room) {
    fetch(`https://recent-messages.robotty.de/api/v2/recent-messages/${room}`)
        .then((r) => r.json())
        .then((json) => {
            if (json["error"] != null) {
                addSystemMessage(`${json["error"]} (Recent messages)`);
                return;
            }
            
            for (const message of json["messages"]) {
                addMessage(parseIRCMessage(message));
            }
        });
}