/**
 * Group node parser — handles grouped shapes (p:grpSp).
 */

import { SafeXmlNode } from '../../parser/XmlParser';
import { BaseNodeData, Position, Size, parseBaseProps } from './BaseNode';
import { emuToPx } from '../../parser/units';

export interface GroupNodeData extends BaseNodeData {
  nodeType: 'group';
  childOffset: Position;
  childExtent: Size;
  /** @internal Raw XML nodes — opaque to consumers. Use serializePresentation() for JSON-safe data. */
  children: SafeXmlNode[];
}

/** Tag names of elements that can be children in a group's spTree.
 *  `AlternateContent` is included so inline formulas/labels inside a grouped
 *  diagram (e.g. 神经元图里的 x₁/σ/b/wᵢ 标注与 y=σ(…) 公式) aren't dropped —
 *  parseChildNode routes them to the math/text parser. */
const GROUP_CHILD_TAGS = new Set([
  'sp',
  'pic',
  'grpSp',
  'graphicFrame',
  'cxnSp',
  'AlternateContent',
]);

/**
 * Parse a group shape XML node (`p:grpSp`) into GroupNodeData.
 */
export function parseGroupNode(grpNode: SafeXmlNode): GroupNodeData {
  const base = parseBaseProps(grpNode);

  // --- Child coordinate space from grpSpPr > a:xfrm ---
  // OOXML: when chOff/chExt omitted, child box equals group box (chOff=0,0, chExt=ext).
  const grpSpPr = grpNode.child('grpSpPr');
  const xfrm = grpSpPr.child('xfrm');
  const chOff = xfrm.child('chOff');
  const chExt = xfrm.child('chExt');

  const childOffset: Position = chOff.exists()
    ? { x: emuToPx(chOff.numAttr('x') ?? 0), y: emuToPx(chOff.numAttr('y') ?? 0) }
    : { x: 0, y: 0 };

  const childExtent: Size = (() => {
    if (!chExt.exists()) return { w: base.size.w, h: base.size.h };
    const cx = chExt.numAttr('cx');
    const cy = chExt.numAttr('cy');
    return {
      w: cx !== undefined && cx > 0 ? emuToPx(cx) : base.size.w,
      h: cy !== undefined && cy > 0 ? emuToPx(cy) : base.size.h,
    };
  })();

  // --- Collect direct child shape nodes ---
  const children: SafeXmlNode[] = [];
  for (const child of grpNode.allChildren()) {
    if (GROUP_CHILD_TAGS.has(child.localName)) {
      children.push(child);
    }
  }

  return {
    ...base,
    nodeType: 'group',
    childOffset,
    childExtent,
    children,
  };
}