/**
 * @typedef {import('nlcst').Paragraph} Paragraph
 */

import {toString} from 'nlcst-to-string'
import {visitChildren} from 'unist-util-visit-children'
// Full stop characters that should not be treated as terminal sentence markers:
// A case-insensitive abbreviation.
import {terminalMarker} from '../expressions.js'

// Merge non-terminal-marker full stops into the previous word (if available),
// or the next word (if available).
export const mergeRemainingFullStops = visitChildren(
  /**
   * @type {import('unist-util-visit-children').Visitor<Paragraph>}
   */
  // eslint-disable-next-line complexity
  function (child, _, _parent) {
    if ('children' in child) {
      let position = child.children.length
      let hasFoundDelimiter = false

      while (child.children[--position]) {
        const grandchild = child.children[position]

        if (
          grandchild.type !== 'SymbolNode' &&
          grandchild.type !== 'PunctuationNode'
        ) {
          // This is a sentence without terminal marker, so we 'fool' the code to
          // make it think we have found one.
          if (grandchild.type === 'WordNode') {
            hasFoundDelimiter = true
          }

          continue
        }

        // Exit when this token is not a terminal marker.
        if (!terminalMarker.test(toString(grandchild))) {
          continue
        }

        // Ignore the first terminal marker found (starting at the end), as it
        // should not be merged.
        if (!hasFoundDelimiter) {
          hasFoundDelimiter = true
          continue
        }

        // Only merge a single full stop.
        if (toString(grandchild) !== '.') {
          continue
        }

        const previous = child.children[position - 1]
        const next = child.children[position + 1]

        if (previous && previous.type === 'WordNode') {
          const nextNext = child.children[position + 2]

          // Continue when the full stop is followed by a space and another full
          // stop, such as: `{.} .`
          if (
            next &&
            nextNext &&
            next.type === 'WhiteSpaceNode' &&
            toString(nextNext) === '.'
          ) {
            continue
          }

          // Remove `child` from parent.
          child.children.splice(position, 1)

          // Add the punctuation mark at the end of the previous node.
          previous.children.push(grandchild)

          // Update position.
          if (grandchild.position && previous.position) {
            previous.position.end = grandchild.position.end
          }

          position--
        } else if (next && next.type === 'WordNode') {
          // Remove `child` from parent.
          child.children.splice(position, 1)

          // Add the punctuation mark at the start of the next node.
          next.children.unshift(grandchild)

          if (grandchild.position && next.position) {
            next.position.start = grandchild.position.start
          }
        }
      }
    }
  }
)