// Global state
let isModelLoaded = false;

// DOM Elements
const els = {
    chat: document.getElementById("chat"),
    promptForm: document.getElementById("prompt-form"),
    promptInput: document.getElementById("prompt"),
    loadBtn: document.getElementById("btn-load"),
    testStreamBtn: document.getElementById("btn-test-stream"),
    status: document.getElementById("load-status"),
    sidebar: document.getElementById("sidebar"),
    sidebarToggle: document.getElementById("btn-toggle-sidebar"),
    chatList: document.getElementById("chat-list"),
    newChatBtn: document.getElementById("new-chat"),
    sendBtn: document.getElementById("btn-send"),
    steps: document.getElementById("steps"),
    block_size: document.getElementById("block_size"),
    max_new_tokens: document.getElementById("max_new_tokens"),
    parallel_blocks: document.getElementById("parallel_blocks"),
    stepsValue: document.getElementById("steps-value"),
    block_sizeValue: document.getElementById("block_size-value"),
    max_new_tokensValue: document.getElementById("max_new_tokens-value"),
    parallel_blocksValue: document.getElementById("parallel_blocks-value"),
};

// Update slider values
els.steps.addEventListener("input", () => {
    els.stepsValue.textContent = els.steps.value;
});
els.block_size.addEventListener("input", () => {
    els.block_sizeValue.textContent = els.block_size.value;
});
els.max_new_tokens.addEventListener("input", () => {
    els.max_new_tokensValue.textContent = els.max_new_tokens.value;
});
els.parallel_blocks.addEventListener("input", () => {
    els.parallel_blocksValue.textContent = els.parallel_blocks.value;
});

// --- Logic ---

async function checkLoadStatus() {
    try {
        const res = await fetch("/api/load", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ check_only: true }),
        });

        if (res.ok) {
            const data = await res.json();
            if (data.loaded) {
                isModelLoaded = true;
                els.status.textContent = "Ready";
                els.status.className = "text-sm text-green-600 font-medium";
                els.loadBtn.style.display = 'none';
            }
        }
    } catch (e) {
        console.log("Model check failed:", e);
    }
}

els.loadBtn.addEventListener("click", async () => {
    els.loadBtn.disabled = true;
    els.status.textContent = "Loading Model (this may take time)...";
    els.status.className = "text-sm text-yellow-600 font-medium";

    try {
        const res = await fetch("/api/load", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ check_only: false }),
        });
        const data = await res.json();

        if (res.ok) {
            isModelLoaded = true;
            els.status.textContent = "Model Loaded";
            els.status.className = "text-sm text-green-600 font-medium";
            els.loadBtn.style.display = 'none';
        } else {
            throw new Error(data.message || "Load failed");
        }
    } catch (e) {
        els.status.textContent = "Error Loading";
        els.status.className = "text-sm text-red-500";
        alert("Error: " + e.message);
    } finally {
        els.loadBtn.disabled = false;
    }
});

els.promptForm.addEventListener("submit", async (e) => {
    e.preventDefault();

    const text = els.promptInput.value.trim();
    if (!text) return;

    // UI Updates
    addMessage("user", text);
    els.promptInput.value = "";

    // Create Assistant Bubble
    const assistantBubble = addMessage("assistant", "");
    const contentPre = assistantBubble.querySelector(".content");
    const textContent = contentPre.querySelector(".text-content");

    const visualizationDiv = document.createElement("div");
    visualizationDiv.className = "visualization mb-2 font-mono text-xs";

    // Loading spinner (SVG)
    const spinner = document.createElement("div");
    spinner.className = "flex items-center gap-2 text-slate-400";
    spinner.innerHTML = `
        <svg class="animate-spin h-4 w-4" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
            <circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle>
            <path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8v4a4 4 0 00-4 4H4z"></path>
        </svg>
        <span class="text-xs">Generating...</span>
    `;
    visualizationDiv.appendChild(spinner);

    contentPre.insertBefore(visualizationDiv, textContent);

    // Disable send button
    els.sendBtn.disabled = true;
    els.sendBtn.textContent = "Generating...";
    els.promptInput.disabled = true;

    // Generate Request with Streaming
    try {
        const res = await fetch("/api/generate-stream", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({
                instruction: text,
                steps: parseInt(els.steps.value),
                block_size: parseInt(els.block_size.value),
                max_new_tokens: parseInt(els.max_new_tokens.value),
                parallel_blocks: parseInt(els.parallel_blocks.value),
            }),
        });

        if (!res.ok) {
            throw new Error(`Server Error ${res.status}`);
        }

        const reader = res.body.getReader();
        const decoder = new TextDecoder();
        let buffer = "";

        while (true) {
            const { done, value } = await reader.read();

            if (done) break;

            buffer += decoder.decode(value, { stream: true });
            const lines = buffer.split("\n");
            buffer = lines.pop(); // Keep incomplete line in buffer

            for (const line of lines) {
                if (line.startsWith("data: ")) {
                    const jsonStr = line.slice(6);
                    if (jsonStr.trim()) {
                        try {
                            const data = JSON.parse(jsonStr);
                            handleStreamEvent(data, visualizationDiv, textContent);
                        } catch (e) {
                            console.error("Failed to parse SSE data:", e);
                        }
                    }
                }
            }
        }
    } catch (error) {
        if (textContent) textContent.textContent = `Error: ${error.message}`;
    } finally {
        els.sendBtn.disabled = false;
        els.sendBtn.textContent = "Send";
        els.promptInput.disabled = false;
    }
});

function handleStreamEvent(data, visualizationDiv, textContent) {
    if (data.type === "start") {
        textContent.textContent = "";
    } else if (data.type === "update") {
        // Render visualization
        renderVisualization(data.data, visualizationDiv);
        scrollToBottom();
    } else if (data.type === "complete") {
        // Clear visualization and show final response
        visualizationDiv.innerHTML = "";
        textContent.textContent = data.response || "No response";
        scrollToBottom();
    } else if (data.type === "error") {
        textContent.textContent = `Error: ${data.error}`;
    }
}

function renderVisualization(vizData, container) {
    // Clear previous content
    container.innerHTML = "";

    // Show context
    const contextDiv = document.createElement("div");
    contextDiv.className = "text-slate-600 mb-1";
    contextDiv.textContent = vizData.context;
    container.appendChild(contextDiv);

    // Show blocks
    const blocksDiv = document.createElement("div");
    blocksDiv.classList.add("flex", "flex-wrap", "gap-0");

    const blockColors = ["text-green-600", "text-cyan-600", "text-yellow-600", "text-purple-600"];

    vizData.blocks.forEach((block, blockIdx) => {
        const blockSpan = document.createElement("span");
        blockSpan.className = blockColors[blockIdx % blockColors.length];

        block.tokens.forEach((token) => {
            if (token.type === "masked") {
                const maskedSpan = document.createElement("span");
                maskedSpan.className = blockColors[blockIdx % blockColors.length];
                maskedSpan.innerText = token.text + " ";
                blockSpan.appendChild(maskedSpan);
            } else {
                const textNode = document.createTextNode(token.text);
                blockSpan.appendChild(textNode);
            }
        });

        blocksDiv.appendChild(blockSpan);
    });

    container.appendChild(blocksDiv);

    // Add legend if multiple blocks
    if (vizData.num_blocks > 1) {
        const legendDiv = document.createElement("div");
        legendDiv.className = "text-xs text-slate-500 mt-1";
        const legends = [];
        for (let i = 0; i < vizData.num_blocks; i++) {
            legends.push(`Block ${i + 1}`);
        }
        legendDiv.textContent = `Generating: ${legends.join(" | ")}`;
        container.appendChild(legendDiv);
    }
}

// --- UI Helpers ---

function addMessage(role, text) {
    const wrapper = document.createElement("div");
    wrapper.className = "mb-6 max-w-[100%] flex flex-col";

    const bubble = document.createElement("div");
    const isUser = role === "user";

    bubble.className = isUser ? "self-end bg-slate-900 text-white p-4 rounded-2xl rounded-tr-sm max-w-[85%]" : "self-start bg-white border border-gray-200 text-slate-800 p-4 rounded-2xl rounded-tl-sm max-w-[65%] whitespace-pre-wrap overflow-x-auto shadow-sm flex flex-wrap";

    // Main Content container that holds the response text
    const pre = document.createElement("div");
    pre.className = "content whitespace-pre-wrap font-sans text-sm leading-relaxed";

    // The actual text content
    const textSpan = document.createElement("span");
    textSpan.className = "text-content";
    textSpan.textContent = text;

    pre.appendChild(textSpan);
    bubble.appendChild(pre);
    wrapper.appendChild(bubble);
    els.chat.appendChild(wrapper);
    scrollToBottom();

    // Hide welcome screen
    const welcome = document.getElementById("welcome");
    if (welcome) {
        welcome.classList.add("hidden");
    }
    els.chat.classList.remove("hidden");

    return bubble;
}

function scrollToBottom() {
    els.chat.scrollTop = els.chat.scrollHeight;
}

// Sidebar Toggle
els.sidebarToggle.addEventListener("click", () => {
    els.sidebar.classList.toggle("-translate-x-full");
});

// New Chat Button
els.newChatBtn.addEventListener("click", () => {
    // Clear chat
    els.chat.innerHTML = "";
    els.chat.classList.add("hidden");

    // Show welcome screen
    const welcome = document.getElementById("welcome");
    if (welcome) {
        welcome.classList.remove("hidden");
    }

    // Clear input
    els.promptInput.value = "";
});

// Initialize
(async () => {
    await checkLoadStatus();
    if (!isModelLoaded) {
        els.loadBtn.disabled = true;
        els.status.textContent = "Loading Model (this may take time)...";
        els.status.className = "text-sm text-yellow-600 font-medium";

        try {
            const res = await fetch("/api/load", {
                method: "POST",
                headers: { "Content-Type": "application/json" },
                body: JSON.stringify({ check_only: false }),
            });
            const data = await res.json();

            if (res.ok) {
                isModelLoaded = true;
                els.status.textContent = "Model Loaded";
                els.status.className = "text-sm text-green-600 font-medium";
                els.loadBtn.style.display = 'none';
            } else {
                throw new Error(data.message || "Load failed");
            }
        } catch (e) {
            els.status.textContent = "Error Loading";
            els.status.className = "text-sm text-red-500";
        } finally {
            els.loadBtn.disabled = false;
        }
    }
})();
els.chat.classList.add("hidden");