export function checkTagOpen()

in src/language/providers/utils.ts [234:325]
82 lines of code
28 McCabe index (conditional complexity)

export function checkTagOpen(
  document: vscode.TextDocument,
  position: vscode.Position,
  nsPrefix: string,
  tag: string
): [boolean, boolean] {
  let triggerLine = position.line
  let triggerText = document.lineAt(triggerLine).text
  let itemsOnLine = getItemsOnLineCount(triggerText)
  let isMultiLineTag = false
  let isDfdlPrefix = false
  let origTriggerLine = triggerLine
  let compareText = triggerText
  let compareLine = triggerLine
  const triggerPos = position.character
  const textBeforeTrigger = triggerText.substring(0, triggerPos)

  while (itemsOnLine < 2 && !triggerText.trim().startsWith('<')) {
    triggerText = document.lineAt(--triggerLine).text
  }

  if (!(triggerText.endsWith('>') && triggerText.includes('<'))) {
    isMultiLineTag = true
  }

  let tagPos = textBeforeTrigger.lastIndexOf('<' + nsPrefix + tag)
  if (tagPos < 0) {
    tagPos = textBeforeTrigger.lastIndexOf('<dfdl:' + tag)
    if (tagPos > 0) {
      isDfdlPrefix = true
      nsPrefix = 'dfdl:'
    }
  }
  const nextTagPos = triggerText.indexOf('<', tagPos + 1)
  let tagEndPos = triggerText.indexOf('>', tagPos)

  if (tagPos > -1 && itemsOnLine > 1) {
    if (
      triggerPos > tagPos &&
      ((triggerPos <= tagEndPos &&
        (nextTagPos > tagEndPos || nextTagPos === -1)) ||
        tagEndPos === -1)
    ) {
      return [true, isDfdlPrefix]
    }
  }

  while (compareText.trim() === '') {
    compareText = document.lineAt(--compareLine).text
  }
  tagPos = triggerText.indexOf('<' + nsPrefix + tag)
  if (tagPos < 0) {
    tagPos = textBeforeTrigger.lastIndexOf('<dfdl:' + tag)
    if (tagPos > 0) {
      isDfdlPrefix = true
      nsPrefix = 'dfdl:'
    }
  }

  if (itemsOnLine < 2 && tagPos > -1) {
    if (triggerText !== compareText) {
      tagEndPos = compareText.indexOf('>')
    }

    if (
      (triggerPos > tagPos &&
        triggerPos <= tagEndPos &&
        triggerLine === position.line) ||
      (compareLine == position.line &&
        triggerPos <= tagEndPos &&
        triggerPos > tagPos) ||
      position.line < origTriggerLine
    ) {
      return [true, isDfdlPrefix]
    }
  }

  if (!isMultiLineTag || tagPos === -1) {
    return [false, isDfdlPrefix]
  }
  //if this tag is part of a multi line set of annotations return true
  //else this tag is not open return false
  return checkMultiLineTag(
    document,
    position,
    itemsOnLine,
    nsPrefix,
    tagPos,
    triggerLine,
    tag
  )
}