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

import { emuToPx } from '../../parser/units'
import type { SafeXmlNode } from '../../parser/xml-parser'
import { type BaseNodeData, type Position, parseBaseProps, type Size } from './base-node'

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. */
const GROUP_CHILD_TAGS = new Set(['sp', 'pic', 'grpSp', 'graphicFrame', 'cxnSp'])

/**
 * 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,
  }
}