import type { DetailScreen } from './types'
const combiningMark = new RegExp('\\p{Mark}', 'u')

/** Conservative grapheme wrapping matches the fixed font and Fabric splitByGrapheme layout. */
export function estimateDetailTextHeight(text: string, width: number, fontSize: number, lineHeight: number): number {
  if (!text) return Math.ceil(fontSize * 1.13)
  let lines = 0
  for (const paragraph of text.split('\n')) {
    let occupied = 0; let paragraphLines = 1
    for (const character of Array.from(paragraph)) {
      if (combiningMark.test(character)) continue
      const factor = /[MW@%]/.test(character) ? 1 : /[\x20-\x7e]/.test(character) ? 0.65 : 1.05
      const next = fontSize * factor
      if (occupied > 0 && occupied + next > width) { paragraphLines++; occupied = 0 }
      occupied += next
    }
    lines += paragraphLines
  }
  return Math.ceil(lines * fontSize * 1.13 * lineHeight)
}

/** v1 preserves the template while letting copy grow without covering the product image. */
export function reflowDetailScreen(screen: DetailScreen): DetailScreen {
  const [title, body] = screen.texts
  if (!title || !body || !title.id.endsWith('-title') || !body.id.endsWith('-body')) return screen
  const titleY = screen.logo ? Math.max(58, screen.logo.y + screen.logo.height + 24) : 58
  const titleHeight = estimateDetailTextHeight(screen.title, title.width, title.fontSize, title.lineHeight)
  const bodyY = titleY + titleHeight + 24
  const bodyHeight = estimateDetailTextHeight(screen.body, body.width, body.fontSize, body.lineHeight)
  const imageArea = { x: 0, y: bodyY + bodyHeight + 32, width: 750, height: 750 }
  const height = Math.max(1200, imageArea.y + imageArea.height + 48)
  if (height > 2400) throw new Error('文案过长，请精简后确认；每屏高度最多 2400px')
  return {
    ...screen, height, imageArea,
    ...(screen.image ? { image: { assetId: screen.image.assetId, ...imageArea } } : {}),
    texts: [{ ...title, text: screen.title, y: titleY }, { ...body, text: screen.body, y: bodyY }, ...screen.texts.slice(2)],
  }
}