/**
 * Rich text content helpers for editor max-length and validation.
 */

export function stripRichTextToPlainText(html: string): string {
  if (!html) {
    return ''
  }

  if (typeof document !== 'undefined') {
    const template = document.createElement('template')
    template.innerHTML = html
    return (template.content.textContent || '').trim()
  }

  return html
    .replace(/<[^>]*>/g, ' ')
    .replace(/\s+/g, ' ')
    .trim()
}

export function getRichTextPlainTextLength(html: string): number {
  if (!html) {
    return 0
  }
  return Array.from(stripRichTextToPlainText(html)).length
}

/**
 * Trim HTML to a maximum plain-text character count (images are kept, not counted).
 */
export function truncateRichTextToMaxPlainTextLength(html: string, maxLength: number): string {
  if (!html || maxLength <= 0) {
    return ''
  }

  if (getRichTextPlainTextLength(html) <= maxLength) {
    return html
  }

  if (typeof document === 'undefined') {
    const truncated = Array.from(stripRichTextToPlainText(html)).slice(0, maxLength).join('')
    return truncated ? `<p>${truncated}</p>` : ''
  }

  const template = document.createElement('template')
  template.innerHTML = html
  let remaining = maxLength

  const truncateNode = (node: Node): void => {
    const children = Array.from(node.childNodes)
    for (const child of children) {
      if (remaining <= 0) {
        if (
          child.nodeType === Node.ELEMENT_NODE &&
          (child as Element).tagName.toLowerCase() === 'img'
        ) {
          continue
        }
        child.remove()
        continue
      }

      if (child.nodeType === Node.TEXT_NODE) {
        const chars = Array.from(child.textContent || '')
        if (chars.length <= remaining) {
          remaining -= chars.length
          continue
        }
        child.textContent = chars.slice(0, remaining).join('')
        remaining = 0
        continue
      }

      if (child.nodeType === Node.ELEMENT_NODE) {
        const element = child as Element
        if (element.tagName.toLowerCase() === 'img') {
          continue
        }
        truncateNode(child)
        if (!element.textContent?.trim() && !element.querySelector('img')) {
          element.remove()
        }
      }
    }
  }

  truncateNode(template.content)
  return template.innerHTML
}