/**
 * Hello World plugin — module entry point.
 *
 * The host calls mount(container, api) when the plugin tab is activated and
 * unmount(container) when it is torn down.
 *
 * api shape:
 *   api.context                          — current PluginContext snapshot
 *   api.onContextChange(cb) → unsubscribe — called whenever theme/project/session changes
 *   api.rpc(method, path, body?) → Promise — proxied to this plugin's server subprocess
 */

export function mount(container, api) {
  // ── Build DOM ──────────────────────────────────────────────────────────────
  container.innerHTML = `
    <div id="hw-root" style="
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      padding: 24px;
      height: 100%;
      box-sizing: border-box;
    ">
      <h1 style="font-size: 1.4rem; margin: 0 0 8px;">Hello from a plugin!</h1>
      <p style="font-size: 0.9rem; opacity: 0.7; margin: 0 0 20px;">
        This tab is rendered by a plain ES module — no iframe.
      </p>

      <h2 style="font-size: 1rem; margin: 0 0 6px; opacity: 0.8;">Context</h2>
      <dl style="font-size: 0.85rem; opacity: 0.7; margin: 0 0 24px;">
        <dt style="font-weight: 600; margin-top: 6px;">Theme</dt>
        <dd id="hw-theme" style="margin-left: 12px;">—</dd>
        <dt style="font-weight: 600; margin-top: 6px;">Project</dt>
        <dd id="hw-project" style="margin-left: 12px;">—</dd>
        <dt style="font-weight: 600; margin-top: 6px;">Session</dt>
        <dd id="hw-session" style="margin-left: 12px;">—</dd>
      </dl>

      <h2 style="font-size: 1rem; margin: 0 0 6px; opacity: 0.8;">Server RPC</h2>
      <p style="font-size: 0.85rem; opacity: 0.7; margin: 0 0 10px;">
        Calls this plugin's Node.js server subprocess via the RPC bridge.
      </p>
      <div style="display: flex; gap: 8px; flex-wrap: wrap;">
        <button id="hw-btn-hello">GET /hello</button>
        <button id="hw-btn-echo">POST /echo</button>
      </div>
      <pre id="hw-result" style="
        margin-top: 12px;
        padding: 12px;
        border-radius: 6px;
        font-size: 0.8rem;
        overflow-x: auto;
        white-space: pre-wrap;
      ">Click a button to make an RPC call…</pre>
    </div>
  `;

  // ── Theme helper ──────────────────────────────────────────────────────────
  function applyTheme(theme) {
    const root = container.querySelector('#hw-root');
    if (!root) return;
    const isDark = theme === 'dark';
    root.style.background = isDark ? '#1a1a2e' : '#ffffff';
    root.style.color = isDark ? '#e0e0e0' : '#1a1a2e';
    const pre = container.querySelector('#hw-result');
    if (pre) pre.style.background = isDark ? '#2a2a3e' : '#f0f0f4';
  }

  // ── Render context values ─────────────────────────────────────────────────
  function renderContext(ctx) {
    const t = container.querySelector('#hw-theme');
    const p = container.querySelector('#hw-project');
    const s = container.querySelector('#hw-session');
    if (t) t.textContent = ctx.theme || '—';
    if (p) p.textContent = ctx.project ? ctx.project.name : '(none)';
    if (s) s.textContent = ctx.session ? (ctx.session.title || ctx.session.id) : '(none)';
    applyTheme(ctx.theme);
  }

  // Apply initial context
  renderContext(api.context);

  // Subscribe to future changes
  const unsubscribe = api.onContextChange(renderContext);

  // ── Button styles ─────────────────────────────────────────────────────────
  container.querySelectorAll('button').forEach((btn) => {
    Object.assign(btn.style, {
      padding: '8px 16px',
      border: '1px solid currentColor',
      borderRadius: '6px',
      background: 'transparent',
      color: 'inherit',
      cursor: 'pointer',
      fontSize: '0.85rem',
      opacity: '0.8',
    });
    btn.addEventListener('mouseenter', () => { btn.style.opacity = '1'; });
    btn.addEventListener('mouseleave', () => { btn.style.opacity = '0.8'; });
  });

  // ── RPC buttons ───────────────────────────────────────────────────────────
  const resultEl = container.querySelector('#hw-result');

  container.querySelector('#hw-btn-hello').addEventListener('click', async () => {
    resultEl.textContent = 'Loading…';
    try {
      const data = await api.rpc('GET', '/hello');
      resultEl.textContent = JSON.stringify(data, null, 2);
    } catch (err) {
      resultEl.textContent = `Error: ${err.message}`;
    }
  });

  container.querySelector('#hw-btn-echo').addEventListener('click', async () => {
    resultEl.textContent = 'Loading…';
    try {
      const data = await api.rpc('POST', '/echo', { greeting: 'Hello from the plugin module!' });
      resultEl.textContent = JSON.stringify(data, null, 2);
    } catch (err) {
      resultEl.textContent = `Error: ${err.message}`;
    }
  });

  // Store unsubscribe so unmount can clean up
  container._hwUnsubscribe = unsubscribe;
}

export function unmount(container) {
  if (typeof container._hwUnsubscribe === 'function') {
    container._hwUnsubscribe();
    delete container._hwUnsubscribe;
  }
  container.innerHTML = '';
}