// hive-side-panel.js — <hive-side-panel>, the generic slide-in drawer
// shadow-DOM custom element behind the dashboard's and the per-agent UI's
// side panel (file previews, diffs, logs, inbox/todo lists — anything too
// long to expand inline). One singleton instance per page, created once,
// eagerly, by each package's own module (dashboard/src/common.js's
// `sidePanel`, agent/src/app.js's `sidePanel`) and used directly — no
// wrapper object, no per-call lazy-init guard.
//
// Builds all structural chrome itself in `connectedCallback` (backdrop,
// drawer, resize handle, header, title, close button) — shadow-owned,
// zero `::slotted()` needed. Only the panel *content* is opaque
// caller-built DOM, appended as a light-DOM child and picked up by the
// shadow tree's single default `<slot>`, exactly like `<hive-menu>`'s
// `content` (see that file's header for why). Each package's own global
// stylesheet reaches that content via the element's own tag name as the
// selector root (`hive-side-panel .md`, `hive-side-panel .agent-inbox`)
// — no compatibility class needed.
//
// Public API is instance methods: `open(title, content)`,
// `openNamed(name, title, content)`, `refresh(name, title, content)`,
// `close()`, `currentOwner()`. `open` is exactly `openNamed(null, title,
// content)` — untyped opens clear the owner, matching the dashboard's
// original semantics.
//
// Drag-to-resize + localStorage width persistence is ported from the
// dashboard's original `Panel` (the only one of the two originals that
// had it) — making it available to every consumer (the agent UI didn't
// have it before) is a deliberate behavior widening, not incidental.

import { el } from '../dom.js';
import { attachShadowCss } from '../shadow-css.js';
import sidePanelCss from './hive-side-panel.css';

// See docs/web-ui.md::Side panel for the hit-strip + pointer-capture +
// localStorage persistence model; CSS clamps the stored value to min
// 320px / max 96vw and out-of-range stored values are dropped silently.
// Shared by both packages deliberately — see module header.
const WIDTH_KEY = 'hyperhive:side-panel-width';
const WIDTH_MIN = 320;

class HiveSidePanel extends HTMLElement {
  connectedCallback() {
    const root = attachShadowCss(this, sidePanelCss);
    this.setAttribute('aria-hidden', 'true');
    this._owner = null;

    this._titleEl = el('span', { class: 'side-panel-title', id: 'side-panel-title' });
    this._closeBtn = el('button', {
      type: 'button', class: 'side-panel-close', title: 'close (esc)',
    }, '✕');
    const head = el('header', { class: 'side-panel-head' }, this._titleEl, this._closeBtn);

    this._resizeHandle = el('div', {
      class: 'side-panel-resize',
      role: 'separator',
      'aria-orientation': 'vertical',
      'aria-label': 'drag to resize side panel',
      title: 'drag to resize',
    });

    this._bodyEl = el('div', { class: 'side-panel-body' }, el('slot'));

    this._drawer = el('aside', {
      class: 'side-panel-drawer',
      role: 'dialog',
      'aria-modal': 'true',
      'aria-labelledby': 'side-panel-title',
    }, this._resizeHandle, head, this._bodyEl);

    this._backdrop = el('div', { class: 'side-panel-backdrop' });

    root.append(this._backdrop, this._drawer);

    this._closeBtn.addEventListener('click', () => this.close());
    this._backdrop.addEventListener('click', () => this.close());
    document.addEventListener('keydown', (e) => {
      if (e.key === 'Escape' && this.classList.contains('open')) this.close();
    });

    this._applyStoredWidth();
    this._bindResize();
  }

  open(title, content) {
    this.openNamed(null, title, content);
  }

  openNamed(name, title, content) {
    this._owner = name;
    this._titleEl.textContent = title;
    this.replaceChildren(...(content ? [content] : []));
    this.classList.add('open');
    this.setAttribute('aria-hidden', 'false');
  }

  refresh(name, title, content) {
    if (this._owner !== name) return;
    this._titleEl.textContent = title;
    this.replaceChildren(...(content ? [content] : []));
  }

  close() {
    this._owner = null;
    this.classList.remove('open');
    this.setAttribute('aria-hidden', 'true');
  }

  currentOwner() {
    return this._owner;
  }

  _clampWidth(w) {
    // Use document.documentElement.clientWidth rather than window.innerWidth:
    // clientWidth gives the actual CSS layout viewport width and is not
    // altered by Firefox's Fingerprinting Protection (which rounds
    // window.innerWidth/outerWidth to the nearest 200px).
    const max = Math.floor(document.documentElement.clientWidth * 0.96);
    return Math.max(WIDTH_MIN, Math.min(max, w));
  }

  _applyStoredWidth() {
    const raw = (() => {
      try { return localStorage.getItem(WIDTH_KEY); }
      catch { return null; }
    })();
    if (!raw) return;
    const parsed = parseInt(raw, 10);
    if (!Number.isFinite(parsed) || parsed <= 0) return;
    this._drawer.style.setProperty('--side-panel-w', this._clampWidth(parsed) + 'px');
  }

  _bindResize() {
    const handle = this._resizeHandle;
    const drawer = this._drawer;
    let dragging = false;
    handle.addEventListener('pointerdown', (e) => {
      e.preventDefault();
      dragging = true;
      document.body.classList.add('side-panel-resizing');
      // Shadow-scoped counterpart of the global `body.side-panel-resizing`
      // class below — the resize handle's own hover/drag appearance lives
      // inside this element's shadow tree, which the global class (a
      // light-DOM-only escape hatch for the page-wide cursor override)
      // can't reach.
      this.classList.add('resizing');
      // Capture so we keep getting pointermove even when the cursor
      // outpaces the handle band (drag-fast-then-pause loses the
      // handle's :hover state otherwise).
      try { handle.setPointerCapture(e.pointerId); } catch { /* legacy */ }
    });
    document.addEventListener('pointermove', (e) => {
      if (!dragging) return;
      // Drawer is anchored to the right edge — width = viewport - pointer X.
      const w = this._clampWidth(document.documentElement.clientWidth - e.clientX);
      drawer.style.setProperty('--side-panel-w', w + 'px');
    });
    const stopDrag = () => {
      if (!dragging) return;
      dragging = false;
      document.body.classList.remove('side-panel-resizing');
      this.classList.remove('resizing');
      // Persist the final width. Read the actual rendered width
      // rather than re-deriving so the stored value matches what
      // the operator saw at mouseup.
      const w = drawer.getBoundingClientRect().width;
      try { localStorage.setItem(WIDTH_KEY, String(Math.round(w))); }
      catch { /* localStorage unavailable — width is session-only */ }
    };
    document.addEventListener('pointerup', stopDrag);
    document.addEventListener('pointercancel', stopDrag);
    // Re-clamp on viewport resize so a persisted width that exceeds
    // 96vw doesn't push the drawer off-screen after a window shrink.
    window.addEventListener('resize', () => {
      if (dragging) return;
      const cur = drawer.getBoundingClientRect().width;
      const clamped = this._clampWidth(cur);
      if (clamped !== Math.round(cur)) {
        drawer.style.setProperty('--side-panel-w', clamped + 'px');
      }
    });
  }
}
customElements.define('hive-side-panel', HiveSidePanel);