/**
 * Parse OOXML custom geometry (a:custGeom) into SVG path strings.
 */

import type { SafeXmlNode } from '../parser/xml-parser'

function inferPathExtent(pathNode: SafeXmlNode): { w: number; h: number } {
  let maxX = 0
  let maxY = 0

  for (const cmd of pathNode.allChildren()) {
    if (cmd.localName === 'moveTo' || cmd.localName === 'lnTo') {
      const pt = cmd.child('pt')
      maxX = Math.max(maxX, pt.numAttr('x') ?? 0)
      maxY = Math.max(maxY, pt.numAttr('y') ?? 0)
      continue
    }
    if (cmd.localName === 'cubicBezTo' || cmd.localName === 'quadBezTo') {
      for (const pt of cmd.children('pt')) {
        maxX = Math.max(maxX, pt.numAttr('x') ?? 0)
        maxY = Math.max(maxY, pt.numAttr('y') ?? 0)
      }
      continue
    }
    if (cmd.localName === 'arcTo') {
      maxX = Math.max(maxX, cmd.numAttr('wR') ?? 0)
      maxY = Math.max(maxY, cmd.numAttr('hR') ?? 0)
    }
  }

  return {
    w: Math.max(1, maxX),
    h: Math.max(1, maxY),
  }
}

/**
 * Render a custom geometry element to an SVG path d-attribute string.
 *
 * @param custGeom - SafeXmlNode wrapping the `a:custGeom` element
 * @param width - Target width in pixels
 * @param height - Target height in pixels
 * @returns SVG path d-attribute string
 */
export function renderCustomGeometry(
  custGeom: SafeXmlNode,
  width: number,
  height: number,
  sourceExtent?: { w: number; h: number }
): string {
  const pathLst = custGeom.child('pathLst')
  if (!pathLst.exists()) return ''

  const paths = pathLst.children('path')
  const segments: string[] = []

  for (const pathNode of paths) {
    const fallbackExtent = inferPathExtent(pathNode)
    const pathW = pathNode.numAttr('w') ?? sourceExtent?.w ?? fallbackExtent.w
    const pathH = pathNode.numAttr('h') ?? sourceExtent?.h ?? fallbackExtent.h

    const scaleX = pathW > 0 ? width / pathW : 1
    const scaleY = pathH > 0 ? height / pathH : 1

    // Track current position for arcTo calculations
    let curX = 0
    let curY = 0

    const commands = pathNode.allChildren()
    for (const cmd of commands) {
      switch (cmd.localName) {
        case 'moveTo': {
          const pt = cmd.child('pt')
          const x = (pt.numAttr('x') ?? 0) * scaleX
          const y = (pt.numAttr('y') ?? 0) * scaleY
          segments.push(`M${x},${y}`)
          curX = x
          curY = y
          break
        }

        case 'lnTo': {
          const pt = cmd.child('pt')
          const x = (pt.numAttr('x') ?? 0) * scaleX
          const y = (pt.numAttr('y') ?? 0) * scaleY
          segments.push(`L${x},${y}`)
          curX = x
          curY = y
          break
        }

        case 'cubicBezTo': {
          const pts = cmd.children('pt')
          if (pts.length >= 3) {
            const x1 = (pts[0].numAttr('x') ?? 0) * scaleX
            const y1 = (pts[0].numAttr('y') ?? 0) * scaleY
            const x2 = (pts[1].numAttr('x') ?? 0) * scaleX
            const y2 = (pts[1].numAttr('y') ?? 0) * scaleY
            const x3 = (pts[2].numAttr('x') ?? 0) * scaleX
            const y3 = (pts[2].numAttr('y') ?? 0) * scaleY
            segments.push(`C${x1},${y1} ${x2},${y2} ${x3},${y3}`)
            curX = x3
            curY = y3
          }
          break
        }

        case 'quadBezTo': {
          const pts = cmd.children('pt')
          if (pts.length >= 2) {
            const x1 = (pts[0].numAttr('x') ?? 0) * scaleX
            const y1 = (pts[0].numAttr('y') ?? 0) * scaleY
            const x2 = (pts[1].numAttr('x') ?? 0) * scaleX
            const y2 = (pts[1].numAttr('y') ?? 0) * scaleY
            segments.push(`Q${x1},${y1} ${x2},${y2}`)
            curX = x2
            curY = y2
          }
          break
        }

        case 'arcTo': {
          const wRRaw = cmd.numAttr('wR') ?? 0
          const hRRaw = cmd.numAttr('hR') ?? 0
          const wR = wRRaw * scaleX
          const hR = hRRaw * scaleY
          const stAngRaw = cmd.numAttr('stAng') ?? 0
          const swAngRaw = cmd.numAttr('swAng') ?? 0

          // OOXML angles are in 60000ths of a degree
          const stAng = stAngRaw / 60000
          const swAng = swAngRaw / 60000

          if (wR === 0 || hR === 0 || swAng === 0) {
            // Degenerate arc, skip
            break
          }

          // OOXML arcTo angles are visual (geometric ray) angles in path coordinate space.
          // Convert to parametric using UNSCALED radii before computing positions.
          const stVisRad = (stAng * Math.PI) / 180
          const stAngRad = Math.atan2(wRRaw * Math.sin(stVisRad), hRRaw * Math.cos(stVisRad))

          const endVisRad = ((stAng + swAng) * Math.PI) / 180
          const endAngRad = Math.atan2(wRRaw * Math.sin(endVisRad), hRRaw * Math.cos(endVisRad))

          // Compute center and endpoint in unscaled path space, then scale
          const curXU = curX / scaleX
          const curYU = curY / scaleY
          const cx = curXU - wRRaw * Math.cos(stAngRad)
          const cy = curYU - hRRaw * Math.sin(stAngRad)
          const endX = (cx + wRRaw * Math.cos(endAngRad)) * scaleX
          const endY = (cy + hRRaw * Math.sin(endAngRad)) * scaleY

          // SVG arc flags
          const largeArc = Math.abs(swAng) > 180 ? 1 : 0
          const sweep = swAng > 0 ? 1 : 0

          segments.push(`A${wR},${hR} 0 ${largeArc},${sweep} ${endX},${endY}`)
          curX = endX
          curY = endY
          break
        }

        case 'close': {
          segments.push('Z')
          break
        }

        default:
          // Unknown command, skip
          break
      }
    }
  }

  return segments.join(' ')
}