/* FluentGerman.ai — Chat interface logic */

// Configure marked for safe rendering
marked.setOptions({
    breaks: true,
    gfm: true,
});

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

function relativeTime(dateStr) {
    if (!dateStr) return null;
    const date = new Date(dateStr);
    const now = new Date();
    const diffMs = now - date;
    const diffMins = Math.floor(diffMs / 60000);
    const diffHours = Math.floor(diffMs / 3600000);
    const diffDays = Math.floor(diffMs / 86400000);

    if (diffMins < 1) return 'just now';
    if (diffMins < 60) return `${diffMins} minute${diffMins !== 1 ? 's' : ''} ago`;
    if (diffHours < 24) return `${diffHours} hour${diffHours !== 1 ? 's' : ''} ago`;
    if (diffDays === 1) return 'yesterday';
    if (diffDays < 30) return `${diffDays} days ago`;
    return date.toLocaleDateString('en-GB', { day: 'numeric', month: 'short', year: 'numeric' });
}



document.addEventListener('DOMContentLoaded', async () => {
    if (!requireAuth()) return;

    const user = getUser();
    const displayName = user?.username || 'User';
    document.getElementById('user-name').textContent = displayName;

    // Deterministic avatar based on username (tutor1.jpg - tutor5.jpg)
    const avatarImg = document.getElementById('avatar-img');

    // Simple hash function for username
    let hash = 0;
    for (let i = 0; i < displayName.length; i++) {
        hash = displayName.charCodeAt(i) + ((hash << 5) - hash);
    }

    // Map hash to index 1-5
    const avatarIndex = (Math.abs(hash) % 5) + 1;
    avatarImg.src = `/img/tutor${avatarIndex}.jpg`;

    const messagesEl = document.getElementById('chat-messages');
    const inputEl = document.getElementById('chat-input');
    const sendBtn = document.getElementById('send-btn');
    const micBtn = document.getElementById('mic-btn');
    const voiceToggle = document.getElementById('voice-toggle-input');

    let history = [];
    let voiceModeOn = false;

    // ── Personalised welcome ──────────────────────────────────────────
    const greetingEl = document.getElementById('welcome-greeting');
    const subtitleEl = document.getElementById('welcome-subtitle');
    const metaEl = document.getElementById('welcome-meta');

    greetingEl.textContent = `Hallo, ${displayName}! 👋`;

    try {
        const resp = await api('/chat/dashboard');
        if (resp?.ok) {
            const data = await resp.json();
            greetingEl.textContent = `Hallo, ${data.username}! 👋`;

            if (data.latest_instruction_at) {
                const ago = relativeTime(data.latest_instruction_at);
                metaEl.innerHTML = `<span class="meta-dot"></span> Lessons last updated <strong>${ago}</strong>`;
                metaEl.classList.add('visible');
            } else {
                metaEl.textContent = 'No custom lessons configured yet';
                metaEl.classList.add('visible');
            }
        }
    } catch (e) {
        console.warn('[Chat] Could not fetch dashboard:', e);
    }

    // ── Voice ─────────────────────────────────────────────────────────
    const voice = new VoiceManager();
    await voice.init();

    // Voice toggle handler
    voiceToggle.addEventListener('change', () => {
        voiceModeOn = voiceToggle.checked;

        if (voiceModeOn) {
            if (voice.isDisabled) {
                showToast('Voice requires Chrome or Edge (HTTPS).', 'error');
                voiceToggle.checked = false;
                voiceModeOn = false;
                return;
            }
            micBtn.classList.remove('hidden');
            inputEl.placeholder = 'Voice mode ON — click the mic to speak...';
        } else {
            micBtn.classList.add('hidden');
            inputEl.placeholder = 'Type your message...';
            // Stop any active recording
            if (voice.isRecording) voice.stopRecording();
        }
    });

    voice.onResult = (text) => {
        inputEl.value = text;
        voice.lastInputWasVoice = true;
        sendMessage();
    };

    voice.onStateChange = (recording) => {
        micBtn.classList.toggle('recording', recording);
    };

    // Show "Transcribing..." state
    voice.onProcessing = (processing) => {
        if (processing) {
            inputEl.placeholder = 'Transcribing...';
            inputEl.disabled = true;
        } else {
            inputEl.placeholder = voiceModeOn ? 'Voice mode ON — click the mic to speak...' : 'Type your message...';
            inputEl.disabled = false;
            inputEl.focus();
        }
    };

    micBtn.addEventListener('click', () => voice.toggleRecording());

    // ── Chat ──────────────────────────────────────────────────────────
    function appendMessage(role, content) {
        const div = document.createElement('div');
        div.className = `message message-${role}`;

        if (role === 'assistant') {
            // content might be empty initially for thinking state
            if (content === 'Thinking...') {
                div.innerHTML = '<span class="thinking-dots">Thinking<span>.</span><span>.</span><span>.</span></span>';
                div.classList.add('message-thinking');
            } else {
                div.innerHTML = renderMarkdown(content);
            }
        } else {
            div.textContent = content;
        }

        messagesEl.appendChild(div);
        messagesEl.scrollTop = messagesEl.scrollHeight;
        return div;
    }

    async function sendMessage() {
        const text = inputEl.value.trim();
        if (!text) return;

        voice.lastInputWasVoice = false;

        inputEl.value = '';
        sendBtn.disabled = true;

        appendMessage('user', text);
        history.push({ role: 'user', content: text });

        const assistantEl = appendMessage('assistant', voiceModeOn ? 'Thinking...' : '');
        let fullResponse = '';

        try {
            const response = await api('/chat/', {
                method: 'POST',
                body: JSON.stringify({ message: text, history: history.slice(-20) }),
            });

            if (!response?.ok) {
                const errData = await response?.json().catch(() => ({}));
                throw new Error(errData.detail || `Chat failed (${response?.status})`);
            }

            const reader = response.body.getReader();
            const decoder = new TextDecoder();

            // Special handling for Voice Mode: Buffer text, wait for TTS, then show & play
            if (voiceModeOn) {
                // "Thinking..." is already shown from appendMessage above

                while (true) {
                    const { done, value } = await reader.read();
                    if (done) break;
                    const chunk = decoder.decode(value);
                    const lines = chunk.split('\n');
                    for (const line of lines) {
                        if (line.startsWith('data: ')) {
                            const data = line.slice(6).trim();
                            if (data === '[DONE]') break;
                            try {
                                const parsed = JSON.parse(data);
                                if (parsed.token) fullResponse += parsed.token;
                                if (parsed.error) showToast(parsed.error, 'error');
                            } catch (e) { }
                        }
                    }
                }

                // Text complete. Now fetch audio.
                if (fullResponse) {
                    history.push({ role: 'assistant', content: fullResponse });

                    // Keep "Thinking..." until audio is ready or failed
                    const audioUrl = await voice.fetchAudio(fullResponse);

                    // Visual update: Remove thinking, show text
                    assistantEl.classList.remove('message-thinking');
                    assistantEl.innerHTML = renderMarkdown(fullResponse);
                    messagesEl.scrollTop = messagesEl.scrollHeight;

                    if (audioUrl) {
                        await voice.playAudio(audioUrl, assistantEl);
                    }
                }

            } else {
                // Normal Text Mode: Stream directly to UI
                while (true) {
                    const { done, value } = await reader.read();
                    if (done) break;

                    const chunk = decoder.decode(value);
                    const lines = chunk.split('\n');

                    for (const line of lines) {
                        if (line.startsWith('data: ')) {
                            const data = line.slice(6).trim();
                            if (data === '[DONE]') break;

                            try {
                                const parsed = JSON.parse(data);
                                if (parsed.token) {
                                    fullResponse += parsed.token;
                                    assistantEl.innerHTML = renderMarkdown(fullResponse);
                                    messagesEl.scrollTop = messagesEl.scrollHeight;
                                }
                                if (parsed.error) {
                                    showToast(parsed.error, 'error');
                                }
                            } catch (e) {
                                // skip unparseable chunks
                            }
                        }
                    }
                }

                if (fullResponse) {
                    history.push({ role: 'assistant', content: fullResponse });
                }
            }
        } catch (e) {
            assistantEl.textContent = 'Sorry, something went wrong. Please try again.';
            showToast(e.message, 'error');
            console.error('[Chat] Error:', e);
        }

        sendBtn.disabled = false;
        inputEl.focus();
    }

    sendBtn.addEventListener('click', sendMessage);
    inputEl.addEventListener('keydown', (e) => {
        if (e.key === 'Enter' && !e.shiftKey) {
            e.preventDefault();
            sendMessage();
        }
    });

    // Logout
    document.getElementById('logout-btn').addEventListener('click', logout);
});