/**
 * activity-feed.js — Real-time agent activity feed overlay (Issue #2)
 *
 * Polls the Gitea API every 30 s and renders a scrolling list of recent
 * events (PR opens, PR merges, issue opens, issue closes) in a side panel.
 *
 * Configuration (URL params take priority, then env vars, then defaults):
 *   ?gitea=http://host:3000   — Gitea base URL
 *   ?repo=owner/name          — repository slug
 *   VITE_GITEA_URL            — Gitea base URL env var
 *   VITE_GITEA_REPO           — repository slug env var
 */

const params       = new URLSearchParams(window.location.search);
const GITEA_URL    = params.get('gitea')
  ?? (import.meta.env.VITE_GITEA_URL  || 'http://143.198.27.163:3000');
const GITEA_REPO   = params.get('repo')
  ?? (import.meta.env.VITE_GITEA_REPO || 'rockachopa/the-matrix');
const REFRESH_MS   = 30_000;
const MAX_ITEMS    = 40;   // DOM items to keep in the list
const SHOWN_ITEMS  = 12;   // items visible without scrolling

/* ── escape helpers (no DOMParser dep) ───────────────────────── */
function escapeHtml(str) {
  return String(str)
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

/* ── time formatting ──────────────────────────────────────────── */
function relativeTime(isoString) {
  const delta = Math.floor((Date.now() - new Date(isoString).getTime()) / 1000);
  if (delta <   60) return `${delta}s ago`;
  if (delta < 3600) return `${Math.floor(delta / 60)}m ago`;
  if (delta < 86400) return `${Math.floor(delta / 3600)}h ago`;
  return `${Math.floor(delta / 86400)}d ago`;
}

/* ── build a single feed row ──────────────────────────────────── */
function buildRow(event) {
  /*
   * event = { kind, number, title, actor, when }
   * kind:  'pr_merged' | 'pr_opened' | 'issue_opened' | 'issue_closed'
   */
  const { kind, number, title, actor, when } = event;
  const icons = {
    pr_merged:     '⟳',
    pr_opened:     '↑',
    issue_opened:  '+',
    issue_closed:  '✓',
  };
  const colors = {
    pr_merged:    '#00ff88',
    pr_opened:    '#00aaff',
    issue_opened: '#00ff41',
    issue_closed: '#007722',
  };
  const labels = {
    pr_merged:    'PR MERGED',
    pr_opened:    'PR OPENED',
    issue_opened: 'ISSUE OPENED',
    issue_closed: 'ISSUE CLOSED',
  };

  const icon    = icons[kind]  ?? '·';
  const color   = escapeHtml(colors[kind] ?? '#00ff41');
  const label   = escapeHtml(labels[kind] ?? kind.toUpperCase());
  const safeNum  = escapeHtml(String(number));
  const safeTitle = escapeHtml(title.length > 40 ? title.slice(0, 38) + '…' : title);
  const safeActor = escapeHtml(actor);
  const safeWhen  = escapeHtml(when);

  const row = document.createElement('div');
  row.className = 'feed-row';
  row.innerHTML =
    `<span class="feed-icon" style="color:${color}">${icon}</span>` +
    `<span class="feed-body">` +
      `<span class="feed-label" style="color:${color}">${label}</span>` +
      ` <span class="feed-num">#${safeNum}</span>` +
      `<span class="feed-title">${safeTitle}</span>` +
      `<span class="feed-meta">${safeActor} · ${safeWhen}</span>` +
    `</span>`;
  return row;
}

/* ── normalise API responses → feed events ────────────────────── */
function pullsToEvents(pulls) {
  const events = [];
  for (const p of pulls) {
    if (p.merged) {
      events.push({
        kind:   'pr_merged',
        number: p.number,
        title:  p.title,
        actor:  p.merged_by?.login ?? p.user?.login ?? '?',
        when:   relativeTime(p.merged_at),
        ts:     new Date(p.merged_at).getTime(),
      });
    } else if (p.state === 'open') {
      events.push({
        kind:   'pr_opened',
        number: p.number,
        title:  p.title,
        actor:  p.user?.login ?? '?',
        when:   relativeTime(p.created_at),
        ts:     new Date(p.created_at).getTime(),
      });
    }
  }
  return events;
}

function issuesToEvents(issues) {
  const events = [];
  for (const i of issues) {
    if (i.state === 'closed') {
      events.push({
        kind:   'issue_closed',
        number: i.number,
        title:  i.title,
        actor:  i.assignee?.login ?? i.user?.login ?? '?',
        when:   relativeTime(i.updated_at),
        ts:     new Date(i.updated_at).getTime(),
      });
    } else {
      events.push({
        kind:   'issue_opened',
        number: i.number,
        title:  i.title,
        actor:  i.assignee?.login ?? i.user?.login ?? '?',
        when:   relativeTime(i.created_at),
        ts:     new Date(i.created_at).getTime(),
      });
    }
  }
  return events;
}

/* ── Gitea API fetch ──────────────────────────────────────────── */
async function fetchEvents() {
  const base    = `${GITEA_URL}/api/v1/repos/${GITEA_REPO}`;
  const headers = { Accept: 'application/json' };

  const [pullsRes, issuesRes] = await Promise.all([
    fetch(`${base}/pulls?state=all&limit=20`, { headers }),
    fetch(`${base}/issues?state=all&limit=20&type=issues`, { headers }),
  ]);

  if (!pullsRes.ok || !issuesRes.ok) throw new Error('Gitea API error');

  const [pulls, issues] = await Promise.all([pullsRes.json(), issuesRes.json()]);

  const events = [
    ...pullsToEvents(Array.isArray(pulls)  ? pulls  : []),
    ...issuesToEvents(Array.isArray(issues) ? issues : []),
  ];
  events.sort((a, b) => b.ts - a.ts);
  return events.slice(0, MAX_ITEMS);
}

/* ── DOM management ───────────────────────────────────────────── */
let $feed   = null;
let $status = null;
let rowsInDom = [];

function renderEvents(events) {
  if (!$feed) return;

  // Clear
  while ($feed.firstChild) $feed.removeChild($feed.firstChild);
  rowsInDom = [];

  for (const ev of events.slice(0, MAX_ITEMS)) {
    const row = buildRow(ev);
    $feed.appendChild(row);
    rowsInDom.push(row);
  }

  // Scroll to top (newest first)
  $feed.scrollTop = 0;
}

function setFeedStatus(text) {
  if ($status) $status.textContent = text;
}

/* ── poll loop ────────────────────────────────────────────────── */
let _pollTimer = null;

async function poll() {
  setFeedStatus('SYNCING...');
  try {
    const events = await fetchEvents();
    renderEvents(events);
    setFeedStatus(`LIVE · ${events.length} events`);
  } catch (err) {
    setFeedStatus('ERR · retrying');
    console.warn('[activity-feed] fetch error:', err);
  }
}

/* ── public init ──────────────────────────────────────────────── */
export function initActivityFeed() {
  $feed   = document.getElementById('activity-feed-list');
  $status = document.getElementById('activity-feed-status');

  if (!$feed) return; // element not in DOM

  poll();
  _pollTimer = setInterval(poll, REFRESH_MS);
}

export function disposeActivityFeed() {
  if (_pollTimer) { clearInterval(_pollTimer); _pollTimer = null; }
}