let ws = null;

function uploadFile() {
    const file = document.getElementById("fileInput").files[0];
    if (!file) return alert("Choose a file!");

    const formData = new FormData();
    formData.append("file", file);

    // Show spinner
    document.getElementById("spinner").style.display = "block";

    fetch("/upload", { method: "POST", body: formData })
        .then(res => res.json())
        .then(data => {
            // Hide spinner
            document.getElementById("spinner").style.display = "none";

            if (data.status === "success") {
                document.getElementById("uploadStatus").innerText = "Uploaded!";
                startChat();
            } else {
                alert(data.message);
            }
        })
        .catch(err => {
            document.getElementById("spinner").style.display = "none";
            alert("Upload failed");
        });
}

function startChat() {
    ws = new WebSocket(`ws://${location.host}/ws`);

    // Show chat card
    document.getElementById("chatCard").style.display = "block";

    ws.onmessage = (e) => {
        appendMessage("Bot: " + e.data);
    };
}

function sendMessage() {
    const input = document.getElementById("msg");
    const text = input.value.trim();
    if (!text) return;

    appendMessage("You: " + text);
    input.value = "";

    // Show chat spinner
    document.getElementById("chatSpinner").style.display = "block";

    // Send message to WebSocket
    ws.send(text);

    // Wait for backend reply
    ws.onmessage = (e) => {
        // Hide spinner
        document.getElementById("chatSpinner").style.display = "none";

        appendMessage("Bot: " + e.data);

        // Keep WebSocket listener alive for next message
        ws.onmessage = (e) => {
            document.getElementById("chatSpinner").style.display = "none";
            appendMessage("Bot: " + e.data);
        };
    };
}

function appendMessage(msg) {
    const box = document.getElementById("messages");
    box.innerHTML += msg + "<br>";
    box.scrollTop = box.scrollHeight;
}