/**
 * Event Log — real-time SSE events with filtering
 */

const EVENT_CATEGORIES = {
  'session.created': 'lifecycle',
  'execution.started': 'lifecycle',
  'execution.completed': 'lifecycle',
  'agent.delta': 'content',
  'tool.started': 'tool',
  'tool.completed': 'tool',
  'subagent.assigned': 'orchestration',
  'error': 'error',
  'keepalive': 'keepalive',
};

const CATEGORY_LABELS = ['lifecycle', 'content', 'tool', 'orchestration', 'error'];

let entriesEl;
let activeFilters = new Set(CATEGORY_LABELS);
let stickToBottom = true;
let events = [];

export function initEventLog() {
  const panel = document.getElementById('event-log-panel');

  panel.innerHTML = `
    <div class="event-log-header" id="event-log-toggle">
      <span class="chevron">&#9660;</span>
      <span>Event Log</span>
      <span class="toolbar-spacer"></span>
      <span class="text-muted text-sm" id="event-count">0 events</span>
      <button class="btn btn-sm" id="btn-clear-events" style="margin-left:8px">Clear</button>
      <button class="btn btn-sm" id="btn-export-events">Export</button>
    </div>
    <div class="event-log-filters" id="event-filters"></div>
    <div class="event-log-entries" id="event-entries"></div>
  `;

  entriesEl = document.getElementById('event-entries');

  // Toggle panel
  document.getElementById('event-log-toggle').addEventListener('click', () => {
    panel.classList.toggle('open');
  });

  // Filters
  const filtersEl = document.getElementById('event-filters');
  for (const cat of CATEGORY_LABELS) {
    const btn = document.createElement('button');
    btn.className = `event-filter-btn active`;
    btn.textContent = cat;
    btn.dataset.category = cat;
    btn.addEventListener('click', () => {
      if (activeFilters.has(cat)) {
        activeFilters.delete(cat);
        btn.classList.remove('active');
      } else {
        activeFilters.add(cat);
        btn.classList.add('active');
      }
      renderEvents();
    });
    filtersEl.appendChild(btn);
  }

  // Auto-scroll detection
  entriesEl.addEventListener('scroll', () => {
    const { scrollTop, scrollHeight, clientHeight } = entriesEl;
    stickToBottom = scrollHeight - scrollTop - clientHeight < 20;
  });

  // Clear
  document.getElementById('btn-clear-events').addEventListener('click', (e) => {
    e.stopPropagation();
    clearEvents();
  });

  // Export
  document.getElementById('btn-export-events').addEventListener('click', (e) => {
    e.stopPropagation();
    const blob = new Blob([JSON.stringify(events, null, 2)], { type: 'application/json' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = `events-${Date.now()}.json`;
    a.click();
    URL.revokeObjectURL(url);
  });
}

export function addEvent(event) {
  events.push(event);
  document.getElementById('event-count').textContent = `${events.length} events`;

  const type = event.type || '';
  const category = EVENT_CATEGORIES[type] || 'lifecycle';

  if (!activeFilters.has(category)) return;
  if (category === 'keepalive') return; // Hide keepalives by default

  const entry = createEventEntry(event, type, category);
  entriesEl.appendChild(entry);

  if (stickToBottom) {
    entriesEl.scrollTop = entriesEl.scrollHeight;
  }
}

function createEventEntry(event, type, category) {
  const el = document.createElement('div');
  el.className = 'event-entry';

  const time = event.timestamp
    ? new Date(event.timestamp).toLocaleTimeString('en-US', { hour12: false, fractionalSecondDigits: 3 })
    : '--:--:--';

  const data = event.data || {};
  const summary = summarizeEventData(type, data);

  el.innerHTML = `
    <span class="event-time">${time}</span>
    <span class="event-type-badge ${category}">${type.split('.').pop()}</span>
    <span class="event-data" title="Click to expand">${summary}</span>
  `;

  // Toggle expand
  const dataEl = el.querySelector('.event-data');
  dataEl.addEventListener('click', () => {
    if (dataEl.classList.contains('expanded')) {
      dataEl.classList.remove('expanded');
      dataEl.textContent = summary;
    } else {
      dataEl.classList.add('expanded');
      dataEl.textContent = JSON.stringify(data, null, 2);
    }
  });

  return el;
}

function summarizeEventData(type, data) {
  switch (type) {
    case 'agent.delta': return `[${data.agent || '?'}] "${(data.delta || '').substring(0, 60)}..."`;
    case 'tool.started': return `Tool: ${data.tool}`;
    case 'tool.completed': return `Tool: ${data.tool} → ${data.status}`;
    case 'subagent.assigned': return `Step ${data.step}/${data.total_steps}: ${data.agent} — ${(data.description || '').substring(0, 50)}`;
    case 'execution.started': return `Session: ${(data.session_id || '').substring(0, 12)}`;
    case 'execution.completed': return `Steps: ${data.steps_completed} — ${data.status}`;
    case 'error': return JSON.stringify(data);
    default: return JSON.stringify(data).substring(0, 80);
  }
}

function renderEvents() {
  entriesEl.innerHTML = '';
  for (const event of events) {
    const type = event.type || '';
    const category = EVENT_CATEGORIES[type] || 'lifecycle';
    if (!activeFilters.has(category)) continue;
    if (category === 'keepalive') continue;
    entriesEl.appendChild(createEventEntry(event, type, category));
  }
}

export function clearEvents() {
  events = [];
  if (entriesEl) entriesEl.innerHTML = '';
  const countEl = document.getElementById('event-count');
  if (countEl) countEl.textContent = '0 events';
}