exports.tokenize = initializeFlow

var assert = require('assert')
var codes = require('../character/codes')
var markdownLineEnding = require('../character/markdown-line-ending')
var types = require('../constant/types')
var createSpace = require('../tokenize/factory-space')
var blank = require('../tokenize/partial-blank-line')
var content = require('../tokenize/content')

function initializeFlow(effects) {
  var self = this
  var initial = effects.attempt(
    // Try to parse a blank line.
    blank,
    atBlankEnding,
    // Try to parse initial flow (essentially, only code).
    effects.attempt(
      this.parser.constructs.flowInitial,
      afterConstruct,
      createSpace(
        effects,
        effects.attempt(
          this.parser.constructs.flow,
          afterConstruct,
          effects.attempt(content, afterConstruct)
        ),
        types.linePrefix
      )
    )
  )

  return initial

  function atBlankEnding(code) {
    assert(
      code === codes.eof || markdownLineEnding(code),
      'expected eol or eof'
    )

    if (code === codes.eof) {
      effects.consume(code)
      return
    }

    effects.enter(types.lineEndingBlank)
    effects.consume(code)
    effects.exit(types.lineEndingBlank)
    self.currentConstruct = undefined
    return initial
  }

  function afterConstruct(code) {
    assert(
      code === codes.eof || markdownLineEnding(code),
      'expected eol or eof'
    )

    if (code === codes.eof) {
      effects.consume(code)
      return
    }

    effects.enter(types.lineEnding)
    effects.consume(code)
    effects.exit(types.lineEnding)
    self.currentConstruct = undefined
    return initial
  }
}