// KI-Chat client: renders messages (markdown for assistant), sends messages,
// streams assistant tokens over SSE, and handles "new chat" reset.
// Tailwind CDN is loaded via the head partial; this file only handles logic.
(function () {
  const boot = window.__CHAT_BOOT__ || {};
  let activeId = boot.activeId || null;
  const log = document.getElementById('chatLog');
  const form = document.getElementById('chatForm');
  const input = document.getElementById('chatInput');
  const sendBtn = document.getElementById('sendBtn');
  const newThreadBtn = document.getElementById('newThreadBtn');
  const threadList = document.getElementById('threadList');
  let sending = false;

  // ----- helpers -----
  function escapeHtml(s) {
    const d = document.createElement('div');
    d.textContent = s == null ? '' : String(s);
    return d.innerHTML;
  }

  function scrollBottom() {
    if (log) log.scrollTop = log.scrollHeight;
  }

  // Minimal markdown → HTML. HTML is escaped first, so model output can never
  // inject markup; only the markdown tokens below are turned into tags.
  function inlineFmt(t) {
    return t
      .replace(/`([^`]+)`/g, '<code>$1</code>')
      .replace(/\*\*([^*]+)\*\*/g, '<strong>$1</strong>')
      .replace(/(^|[^*])\*([^*]+)\*/g, '$1<em>$2</em>')
      .replace(/\[([^\]]+)\]\(([^)\s]+)\)/g, '<a href="$2" target="_blank" rel="noopener">$1</a>');
  }

  function renderMarkdown(src) {
    const esc = escapeHtml(src == null ? '' : String(src)).replace(/\r\n/g, '\n');
    const lines = esc.split('\n');
    let html = '';
    let i = 0;
    let para = [];
    const flushPara = () => {
      if (para.length) html += '<p>' + inlineFmt(para.join(' ')) + '</p>';
      para = [];
    };
    while (i < lines.length) {
      const line = lines[i];
      if (/^```/.test(line)) { // fenced code block
        flushPara();
        const code = [];
        i++;
        while (i < lines.length && !/^```/.test(lines[i])) { code.push(lines[i]); i++; }
        i++; // closing fence
        html += '<pre><code>' + code.join('\n') + '</code></pre>';
        continue;
      }
      const hm = line.match(/^(#{1,6})\s+(.*)$/);
      if (hm) {
        flushPara();
        const lvl = Math.min(hm[1].length, 3);
        html += '<h' + lvl + '>' + inlineFmt(hm[2].trim()) + '</h' + lvl + '>';
        i++; continue;
      }
      if (/^\s*[-*]\s+/.test(line)) { // bullet list
        flushPara();
        const items = [];
        while (i < lines.length && /^\s*[-*]\s+/.test(lines[i])) {
          items.push('<li>' + inlineFmt(lines[i].replace(/^\s*[-*]\s+/, '')) + '</li>');
          i++;
        }
        html += '<ul>' + items.join('') + '</ul>';
        continue;
      }
      if (/^\s*\d+\.\s+/.test(line)) { // numbered list
        flushPara();
        const items = [];
        while (i < lines.length && /^\s*\d+\.\s+/.test(lines[i])) {
          items.push('<li>' + inlineFmt(lines[i].replace(/^\s*\d+\.\s+/, '')) + '</li>');
          i++;
        }
        html += '<ol>' + items.join('') + '</ol>';
        continue;
      }
      if (/^\s*$/.test(line)) { flushPara(); i++; continue; }
      para.push(line.trim());
      i++;
    }
    flushPara();
    return html;
  }

  function clearLogToEmpty(msg) {
    if (!log) return;
    log.innerHTML =
      '<div class="h-full flex items-center justify-center text-gray-400 text-sm px-6">' +
      escapeHtml(msg) + '</div>';
  }

  // Build a message row. Assistant content is markdown-rendered + left aligned;
  // user content is escaped plain text with preserved line breaks.
  function buildRow(role, contentHtml) {
    const wrap = document.createElement('div');
    wrap.className = 'flex ' + (role === 'user' ? 'justify-end' : 'justify-start');
    const bubble = document.createElement('div');
    bubble.className = 'max-w-[85%] rounded-lg px-3 py-2 text-sm text-left ' +
      (role === 'user'
        ? 'bg-blue-600 text-white whitespace-pre-wrap break-words'
        : 'bg-gray-100 dark:bg-gray-700 text-gray-800 dark:text-gray-100 chat-md');
    bubble.innerHTML = contentHtml;
    wrap.appendChild(bubble);
    return { wrap, bubble };
  }

  function addMessage(role, content) {
    if (log && log.querySelector('.h-full')) log.innerHTML = '';
    const html = role === 'user' ? escapeHtml(content) : renderMarkdown(content);
    const { wrap, bubble } = buildRow(role, html);
    log.appendChild(wrap);
    scrollBottom();
    return bubble;
  }

  function typingIndicator() {
    if (log && log.querySelector('.h-full')) log.innerHTML = '';
    const wrap = document.createElement('div');
    wrap.className = 'flex justify-start';
    wrap.id = 'typing';
    wrap.innerHTML = '<div class="rounded-lg px-3 py-2 bg-gray-100 dark:bg-gray-700 text-gray-500 flex gap-1">' +
      '<span class="typing-dot"></span><span class="typing-dot"></span><span class="typing-dot"></span></div>';
    log.appendChild(wrap);
    scrollBottom();
    return wrap;
  }

  function prependThread(id, titel) {
    if (!threadList) return;
    const empty = threadList.querySelector('li.text-center');
    if (empty) empty.remove();
    const li = document.createElement('li');
    li.setAttribute('data-thread-li', id);
    li.innerHTML =
      '<div class="flex items-center group">' +
        '<a href="/chat?thread=' + encodeURIComponent(id) + '" data-thread="' + id +
          '" class="threadLink flex-1 min-w-0 px-3 py-2 text-sm text-gray-700 dark:text-gray-200 hover:bg-gray-50 dark:hover:bg-gray-700/40">' +
          '<div class="truncate font-medium">' + escapeHtml(titel || '(neuer Chat)') + '</div>' +
          '<div class="text-[11px] text-gray-400">gerade</div>' +
        '</a>' +
        '<button type="button" data-delete-thread="' + id +
          '" class="threadDelete shrink-0 mr-2 p-1.5 rounded text-gray-400 hover:text-red-600 hover:bg-red-50 dark:hover:bg-red-900/30 opacity-0 group-hover:opacity-100 focus:opacity-100" title="Verlauf löschen" aria-label="Verlauf löschen">' +
          '<svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">' +
            '<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6M1 7h22M9 7V4a1 1 0 011-1h4a1 1 0 011 1v3"></path>' +
          '</svg>' +
        '</button>' +
      '</div>';
    threadList.insertBefore(li, threadList.firstChild);
  }

  // ----- "Neuer Chat": reset client-side to a fresh empty conversation -----
  function resetToNewChat() {
    activeId = null;
    document.getElementById('activeThread').value = '';
    clearLogToEmpty('Stelle eine Frage zu deinen Bewerbungen.');
    if (input) { input.value = ''; input.disabled = false; input.style.height = 'auto'; input.focus(); }
    if (sendBtn) sendBtn.disabled = false;
    // deselect sidebar rows
    threadList && threadList.querySelectorAll('.bg-blue-50, .dark\\:bg-gray-700').forEach((el) => {
      el.classList.remove('bg-blue-50', 'dark:bg-gray-700');
    });
    history.replaceState(null, '', '/chat');
  }

  async function createThread() {
    const res = await fetch('/chat/api/threads', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ titel: '' }),
    });
    if (!res.ok) throw new Error('Thread konnte nicht angelegt werden.');
    const data = await res.json();
    activeId = data.id;
    document.getElementById('activeThread').value = activeId;
    prependThread(activeId, data.titel);
    history.replaceState(null, '', '/chat?thread=' + activeId);
    return activeId;
  }

  // Parse the SSE response body stream; call onEvent with each parsed data object.
  async function consumeSSE(res, onEvent) {
    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 });
      let sep;
      while ((sep = buffer.indexOf('\n\n')) >= 0) {
        const block = buffer.slice(0, sep);
        buffer = buffer.slice(sep + 2);
        for (const line of block.split('\n')) {
          if (!line.startsWith('data:')) continue;
          const payload = line.slice(5).trim();
          if (!payload) continue;
          try { onEvent(JSON.parse(payload)); } catch (e) { /* ignore */ }
        }
      }
    }
  }

  async function sendMessage(text) {
    if (sending || !text.trim()) return;
    sending = true;
    sendBtn.disabled = true;

    if (!activeId) {
      try { await createThread(); }
      catch (e) { sending = false; sendBtn.disabled = false; alert(e.message); return; }
    }

    addMessage('user', text);
    input.value = '';
    input.style.height = 'auto';
    const typing = typingIndicator();
    let assistantBubble = null;
    let assistantText = '';

    try {
      const res = await fetch('/chat/api/threads/' + activeId + '/messages', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ content: text }),
      });
      if (!res.ok || !res.body) {
        let msg = 'Senden fehlgeschlagen (' + res.status + ')';
        try { const j = await res.json(); msg = j.error || msg; } catch (e) {}
        throw new Error(msg);
      }

      await consumeSSE(res, (ev) => {
        if (ev.type === 'token') {
          if (!assistantBubble) {
            if (typing) typing.remove();
            assistantBubble = addMessage('assistant', '');
          }
          assistantText += ev.content;
          assistantBubble.innerHTML = renderMarkdown(assistantText);
          scrollBottom();
        } else if (ev.type === 'done') {
          if (assistantBubble && ev.content) {
            assistantBubble.innerHTML = renderMarkdown(ev.content);
          } else if (!assistantBubble) {
            if (typing) typing.remove();
            addMessage('assistant', ev.content || '(keine Antwort)');
          }
          scrollBottom();
        } else if (ev.type === 'error') {
          if (typing) typing.remove();
          if (!assistantBubble) addMessage('assistant', 'Fehler: ' + ev.message);
          else assistantBubble.innerHTML = renderMarkdown(assistantText + '\n\n_Fehler: ' + ev.message + '_');
        }
      });
    } catch (err) {
      if (typing) typing.remove();
      addMessage('assistant', 'Fehler: ' + (err.message || 'unbekannt'));
    } finally {
      if (typing && typing.parentNode) typing.remove();
      sending = false;
      sendBtn.disabled = false;
      input.focus();
    }
  }

  // ----- wiring -----
  if (input) {
    input.addEventListener('input', () => {
      input.style.height = 'auto';
      input.style.height = Math.min(input.scrollHeight, 160) + 'px';
    });
    input.addEventListener('keydown', (e) => {
      if (e.key === 'Enter' && !e.shiftKey) {
        e.preventDefault();
        sendMessage(input.value);
      }
    });
  }

  if (form) {
    form.addEventListener('submit', (e) => {
      e.preventDefault();
      sendMessage(input.value);
    });
  }

  if (newThreadBtn) {
    newThreadBtn.addEventListener('click', resetToNewChat);
  }

  // Delete a thread from the sidebar. Event delegation: works for server-rendered
  // rows and ones added client-side (prependThread).
  if (threadList) {
    threadList.addEventListener('click', async (e) => {
      const btn = e.target.closest('[data-delete-thread]');
      if (!btn) return;
      e.preventDefault();
      e.stopPropagation();
      const id = Number(btn.getAttribute('data-delete-thread'));
      if (!id || !confirm('Diesen Chat-Verlauf wirklich löschen?')) return;
      try {
        const res = await fetch('/chat/api/threads/' + id, { method: 'DELETE' });
        if (!res.ok) throw new Error('Löschen fehlgeschlagen (' + res.status + ')');
      } catch (err) {
        alert(err.message);
        return;
      }
      const li = threadList.querySelector('li[data-thread-li="' + id + '"]');
      if (li) li.remove();
      // If the deleted thread was active, start a fresh chat.
      if (activeId === id) resetToNewChat();
      // If no threads remain, show the empty placeholder.
      if (!threadList.querySelector('li[data-thread-li]')) {
        const empty = document.createElement('li');
        empty.className = 'px-3 py-4 text-sm text-gray-400 text-center';
        empty.textContent = 'Noch keine Verläufe.';
        threadList.appendChild(empty);
      }
    });
  }

  // Render any pre-loaded messages (existing thread) with the same renderer.
  function renderInitial() {
    const blob = document.getElementById('initialMessages');
    if (!blob) return;
    let msgs = [];
    try { msgs = JSON.parse(blob.textContent); } catch (e) { return; }
    if (!Array.isArray(msgs) || !msgs.length) return;
    if (log.querySelector('.h-full')) log.innerHTML = '';
    msgs.forEach((m) => addMessage(m.role, m.content));
    scrollBottom();
  }

  renderInitial();
  scrollBottom();
  if (input && !input.disabled) input.focus();
})();