// ── Chat UI controller ────────────────────────────────────────────────────────

const $ = (sel) => document.querySelector(sel);

export class Chat {
  constructor() {
    this._container = $('#messages');
    this._emptyState = $('#empty-state');
  }

  clear() {
    this._container.innerHTML = '';
    this._emptyState?.classList.remove('hidden');
  }

  renderHistory(messages) {
    this._container.innerHTML = '';
    this._emptyState?.classList.add('hidden');
    messages.forEach((m) => this._appendBubble(m.role, m.content));
    this._scrollBottom();
  }

  async send(sessionId, message, contextIds = []) {
    // Immediately render user bubble
    this._appendBubble('user', message);
    this._emptyState?.classList.add('hidden');

    // Typing indicator
    const typingId = this._appendTyping();

    try {
      const res = await fetch(`/api/chat/sessions/${sessionId}/ask`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ message, context_ids: contextIds }),
      });

      this._removeTyping(typingId);

      let data;
      try {
        data = await res.json();
      } catch {
        this._appendBubble('assistant', 'Server error — could not parse response.', true);
        this._scrollBottom();
        return;
      }

      if (!res.ok) {
        this._appendBubble('assistant', `Error: ${data.error || 'Unknown error'}`, true);
      } else {
        this._appendBubble('assistant', data.reply);
      }
    } catch (err) {
      this._removeTyping(typingId);
      this._appendBubble('assistant', `Network error: ${err.message}`, true);
    }

    this._scrollBottom();
  }

  _appendBubble(role, content, isError = false) {
    const wrap = document.createElement('div');
    wrap.className = `flex ${role === 'user' ? 'justify-end' : 'justify-start'} gap-3`;

    if (role === 'assistant') {
      wrap.innerHTML = `
        <div class="w-7 h-7 rounded-full bg-copilot-accent flex items-center justify-center shrink-0 mt-0.5">
          <svg class="w-4 h-4 text-copilot-bg" fill="currentColor" viewBox="0 0 24 24">
            <path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2z"/>
          </svg>
        </div>
        <div class="max-w-[75%] rounded-2xl rounded-tl-sm px-4 py-3 text-sm leading-relaxed
          ${isError ? 'bg-copilot-danger text-copilot-bg' : 'bg-copilot-panel text-copilot-text'}
          shadow-sm whitespace-pre-wrap">${escapeHtml(content)}</div>`;
    } else {
      wrap.innerHTML = `
        <div class="max-w-[75%] rounded-2xl rounded-tr-sm px-4 py-3 text-sm leading-relaxed
          bg-copilot-user text-copilot-text shadow-sm whitespace-pre-wrap">
          ${escapeHtml(content)}
        </div>
        <div class="w-7 h-7 rounded-full bg-copilot-muted flex items-center justify-center shrink-0 mt-0.5 text-xs font-bold text-copilot-bg">
          U
        </div>`;
    }

    this._container.appendChild(wrap);
    return wrap;
  }

  _appendTyping() {
    const id = `typing-${Date.now()}`;
    const div = document.createElement('div');
    div.id = id;
    div.className = 'flex justify-start gap-3';
    div.innerHTML = `
      <div class="w-7 h-7 rounded-full bg-copilot-accent flex items-center justify-center shrink-0 mt-0.5">
        <svg class="w-4 h-4 text-copilot-bg" fill="currentColor" viewBox="0 0 24 24">
          <path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2z"/>
        </svg>
      </div>
      <div class="bg-copilot-panel rounded-2xl rounded-tl-sm px-4 py-3 shadow-sm flex gap-1 items-center">
        <span class="w-2 h-2 rounded-full bg-copilot-muted animate-bounce" style="animation-delay:0ms"></span>
        <span class="w-2 h-2 rounded-full bg-copilot-muted animate-bounce" style="animation-delay:150ms"></span>
        <span class="w-2 h-2 rounded-full bg-copilot-muted animate-bounce" style="animation-delay:300ms"></span>
      </div>`;
    this._container.appendChild(div);
    this._scrollBottom();
    return id;
  }

  _removeTyping(id) {
    document.getElementById(id)?.remove();
  }

  _scrollBottom() {
    this._container.scrollTop = this._container.scrollHeight;
  }
}

function escapeHtml(str = '') {
  return String(str)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;');
}