document.addEventListener('DOMContentLoaded', () => {
    const chatEl   = document.getElementById('chat');
    const promptEl = document.getElementById('prompt');
    const sendBtn  = document.getElementById('send');
    const abortBtn = document.getElementById('abort');
    const clearBtn = document.getElementById('clear');

    let abort = false;

    marked.setOptions({ breaks: true });

    function renderMarkdown(text) {
        return DOMPurify.sanitize(marked.parse(text));
    }

    function addMessage(role, html = '', extra = '') {
        const msg = document.createElement('div');
        msg.className = 'message ' + role;

        const bubble = document.createElement('div');
        bubble.className = 'bubble ' + extra;
        bubble.innerHTML = html;

        msg.appendChild(bubble);
        chatEl.appendChild(msg);
        chatEl.scrollTop = chatEl.scrollHeight;

        return bubble;
    }

    function addLoader() {
        return addMessage('assistant', 'AI is thinking…', 'loader');
    }

    async function loadHistory() {
        try {
            const res = await fetch('/history');
            if (!res.ok) return;
            const messages = await res.json();
            messages.forEach(m =>
                addMessage(m.role, renderMarkdown(m.text))
            );
        } catch {}
    }

    loadHistory();

    sendBtn.addEventListener('click', async () => {
        const prompt = promptEl.value.trim();
        if (!prompt) return;

        addMessage('user', renderMarkdown(prompt));
        promptEl.value = '';

        const bubble = addLoader();
        let raw = '';
        let firstChunk = true;
        let renderTimer = null;

        // 🔥 LÖSUNG: Throttled Rendering - maximal alle 100ms
        function scheduleRender() {
            if (renderTimer) return;

            renderTimer = setTimeout(() => {
                // Der StreamChunker sendet bereits korrekt strukturierte Chunks
                bubble.innerHTML = renderMarkdown(raw);
                chatEl.scrollTop = chatEl.scrollHeight;
                renderTimer = null;
            }, 100);
        }

        abort = false;
        sendBtn.disabled = true;
        abortBtn.disabled = false;
        clearBtn.disabled = true;

        try {
            document.getElementById('ai-cloud')?.classList.remove('d-none');

            const res = await fetch('/ask-sse', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ prompt })
            });

            const reader = res.body.getReader();
            const decoder = new TextDecoder();
            let sseBuffer = '';

            while (!abort) {
                const { value, done } = await reader.read();
                if (done) break;

                const chunk = decoder.decode(value, { stream: true });
                sseBuffer += chunk;

                // Parse SSE Events (können mehrere data:-Zeilen haben)
                const events = sseBuffer.split('\n\n');
                sseBuffer = events.pop() || ''; // Letzten unvollständigen Event behalten

                events.forEach(event => {
                    if (!event.trim()) return;

                    // Sammle alle "data:"-Zeilen und füge \n wieder ein
                    const dataLines = event
                        .split('\n')
                        .filter(line => line.startsWith('data: '))
                        .map(line => line.slice(6));

                    if (dataLines.length === 0) return;

                    // Verbinde mit \n (so wie es vom Backend kam)
                    const text = dataLines.join('\n');

                    if (text === '[DONE]') {

                        // 🔥 Final render flush
                        if (renderTimer) {
                            clearTimeout(renderTimer);
                            renderTimer = null;
                        }

                        bubble.innerHTML = renderMarkdown(raw);
                        chatEl.scrollTop = chatEl.scrollHeight;

                        abort = true;
                        return;
                    }

                    if (firstChunk) {
                        bubble.classList.remove('loader');
                        bubble.innerHTML = '';
                        firstChunk = false;
                        document.getElementById('ai-cloud')?.classList.add('d-none');
                    }

                    // Text sammeln und verzögert rendern
                    raw += text;
                    scheduleRender();
                });
            }

        } catch {
            bubble.innerHTML += '<br><em>Error occurred.</em>';
        } finally {
            if (renderTimer) clearTimeout(renderTimer);
            sendBtn.disabled = false;
            abortBtn.disabled = true;
            clearBtn.disabled = false;
        }
    });

    abortBtn.addEventListener('click', () => {
        abort = true;
        addMessage('assistant', '<em>[aborted]</em>');
    });

    clearBtn.addEventListener('click', async () => {
        await fetch('/history/delete', { method: 'POST' });
        chatEl.innerHTML = '';
        addMessage('assistant', '<em>History cleared.</em>');
    });
});