'use strict'

var toString = require('nlcst-to-string')
var modifyChildren = require('unist-util-modify-children')
var expressions = require('../expressions')

module.exports = modifyChildren(breakImplicitSentences)

// Two or more new line characters.
var multiNewLine = expressions.newLineMulti

// Break a sentence if a white space with more than one new-line is found.
function breakImplicitSentences(child, index, parent) {
  var children
  var position
  var length
  var tail
  var head
  var end
  var insertion
  var node

  if (child.type !== 'SentenceNode') {
    return
  }

  children = child.children

  // Ignore first and last child.
  length = children.length - 1
  position = 0

  while (++position < length) {
    node = children[position]

    if (node.type !== 'WhiteSpaceNode' || !multiNewLine.test(toString(node))) {
      continue
    }

    child.children = children.slice(0, position)

    insertion = {
      type: 'SentenceNode',
      children: children.slice(position + 1)
    }

    tail = children[position - 1]
    head = children[position + 1]

    parent.children.splice(index + 1, 0, node, insertion)

    if (child.position && tail.position && head.position) {
      end = child.position.end

      child.position.end = tail.position.end

      insertion.position = {
        start: head.position.start,
        end: end
      }
    }

    return index + 1
  }
}