import { OListParser } from '../block';
import { Recursion } from '../context';
import { List, Node } from '../../combinator/parser';
import { union, inits, subsequence, some, recursion, block, line, validate, indent, focus, open, match, fallback, lazy, fmap } from '../../combinator';
import { ulist_, checkbox, fillFirstLine } from './ulist';
import { ilist_, ilistitem } from './ilist';
import { inline, indexee, indexer, dataindex } from '../inline';
import { invalid, unwrap } from '../util';
import { visualize, trimBlank } from '../visibility';
import { memoize } from 'spica/memoize';
import { html, define, defrag } from 'typed-dom/dom';

const openers = {
  '.': /([0-9]+|[a-z]+|[A-Z]+)(?:-(?=$|[0-9\r\n])[0-9]*)*(?:\.?(?=$|[\r\n])|\. )/y,
  '(': /\((?=$|[0-9a-z\r\n])([0-9]*|[a-z]*)(?=$|[)\r\n])\)?(?:-(?=$|[0-9\r\n])[0-9]*)*(?=$|[ \r\n])/y,
} as const;

export const olist: OListParser = lazy(() => block(validate(
  new RegExp([
    /(?:[0-9]+)(?:-[0-9]+)*\. /y.source,
    /\((?:[0-9]+)\)(?:-[0-9]+)* /y.source,
  ].join('|'), 'y'),
  olist_)));

export const olist_: OListParser = lazy(() => block(union([
  match(
    openers['.'],
    memoize(ms => list(type(ms[1]), '.'), ms => idx(ms[1]), [])),
  match(
    openers['('],
    memoize(ms => list(type(ms[1]), '('), ms => idx(ms[1]), [])),
])));

// TODO: リストマーカーの直書き
const list = (type: string, form: string): OListParser.ListParser => fmap(
  recursion(Recursion.block, some(union([
    indexee(fmap(fallback(
      inits([
        open(heads[form], subsequence([
          checkbox,
          line(visualize(trimBlank(some(union([indexer, inline])))))]), true),
        indent(union([ulist_, olist_, ilist_])),
      ]),
      ilistitem),
      ns => new List([
        new Node(html('li', {
          'data-index': dataindex(ns),
          'data-marker': ns.shift()?.value as string || undefined,
        }, defrag(unwrap(fillFirstLine(ns)))))
      ]))),
  ]))),
  ns => new List([new Node(format(html('ol', unwrap(ns)), type, form))]));

const heads = {
  '.': focus(
    openers['.'],
    ({ source }, output) => output.append(
      new Node(source.trimEnd().split('.', 1)[0] + '.'))),
  '(': focus(
    openers['('],
    ({ source }, output) => output.append(
      new Node(source.trimEnd().replace(/^\($/, '(1)').replace(/^\((\w+)$/, '($1)')))),
} as const;

function idx(value: string): number {
  switch (value) {
    case 'i':
      return 1;
    case 'a':
      return 2;
    case 'I':
      return 3;
    case 'A':
      return 4;
    default:
      return 0;
  }
}

function type(value: string): string {
  switch (value) {
    case 'i':
      return 'i';
    case 'a':
      return 'a';
    case 'I':
      return 'I';
    case 'A':
      return 'A';
    default:
      return '';
  }
}

function style(type: string): string {
  switch (type) {
    case 'i':
      return 'lower-roman';
    case 'a':
      return 'lower-alpha';
    case 'I':
      return 'upper-roman';
    case 'A':
      return 'upper-alpha';
    default:
      return '';
  }
}

function pattern(type: string): RegExp {
  switch (type) {
    case 'i':
      return /\(?i[).]?$/y;
    case 'a':
      return /\(?a[).]?$/y;
    case 'I':
      return /\(?I[).]?$/y;
    case 'A':
      return /\(?A[).]?$/y;
    default:
      return /\(?[01][).]?$/y;
  }
}

function format(list: HTMLOListElement, type: string, form: string): HTMLOListElement {
  if (list.firstElementChild?.firstElementChild?.classList.contains('checkbox')) {
    list.classList.add('checklist');
  }
  define(list, {
    type: type || undefined,
    'data-format': form === '.' ? undefined : 'paren',
    'data-type': style(type) || undefined,
  });
  const marker = list.firstElementChild?.getAttribute('data-marker') ?? '';
  // TODO: CSSカウンターをattr(start)でリセットできるようになればstart値からのオートインクリメントに対応させる。
  const start = marker.match(pattern(type))?.[0] ?? '';
  for (let es = list.children, len = es.length, i = 0; i < len; ++i) {
    const item = es[i];
    assert(item.getAttribute('data-marker') !== '');
    switch (item.getAttribute('data-marker')) {
      case null:
        continue;
      case start:
        item.removeAttribute('data-marker');
        continue;
      case marker:
        if (i === 0 || item.classList.contains('invalid')) continue;
        define(item, {
          class: 'invalid',
          ...invalid('list', 'index', 'Fix the duplicate index'),
        });
    }
    break;
  }
  return list;
}