/**
 * @typedef {import('micromark-util-types').Construct} Construct
 * @typedef {import('micromark-util-types').State} State
 * @typedef {import('micromark-util-types').TokenizeContext} TokenizeContext
 * @typedef {import('micromark-util-types').Tokenizer} Tokenizer
 */

import {markdownLineEnding} from 'micromark-util-character'
import {codes, types} from 'micromark-util-symbol'
import {ok as assert} from 'devlop'

/** @type {Construct} */
export const hardBreakEscape = {
  name: 'hardBreakEscape',
  tokenize: tokenizeHardBreakEscape
}

/**
 * @this {TokenizeContext}
 * @type {Tokenizer}
 */
function tokenizeHardBreakEscape(effects, ok, nok) {
  return start

  /**
   * Start of a hard break (escape).
   *
   * ```markdown
   * > | a\
   *      ^
   *   | b
   * ```
   *
   * @type {State}
   */
  function start(code) {
    assert(code === codes.backslash, 'expected `\\`')
    effects.enter(types.hardBreakEscape)
    effects.consume(code)
    return after
  }

  /**
   * After `\`, at eol.
   *
   * ```markdown
   * > | a\
   *       ^
   *   | b
   * ```
   *
   *  @type {State}
   */
  function after(code) {
    if (markdownLineEnding(code)) {
      effects.exit(types.hardBreakEscape)
      return ok(code)
    }

    return nok(code)
  }
}