/**
 * @import {Chunk, Event, Token} from 'micromark-util-types'
 */

import {ok as assert} from 'devlop'
import {splice} from 'micromark-util-chunked'
import {codes, types} from 'micromark-util-symbol'
import {SpliceBuffer} from './lib/splice-buffer.js'

// Hidden API exposed for testing.
export {SpliceBuffer} from './lib/splice-buffer.js'

/**
 * Tokenize subcontent.
 *
 * @param {Array<Event>} eventsArray
 *   List of events.
 * @returns {boolean}
 *   Whether subtokens were found.
 */
// eslint-disable-next-line complexity
export function subtokenize(eventsArray) {
  /** @type {Record<string, number>} */
  const jumps = {}
  let index = -1
  /** @type {Event} */
  let event
  /** @type {number | undefined} */
  let lineIndex
  /** @type {number} */
  let otherIndex
  /** @type {Event} */
  let otherEvent
  /** @type {Array<Event>} */
  let parameters
  /** @type {Array<Event>} */
  let subevents
  /** @type {boolean | undefined} */
  let more
  const events = new SpliceBuffer(eventsArray)

  while (++index < events.length) {
    while (index in jumps) {
      index = jumps[index]
    }

    event = events.get(index)

    // Add a hook for the GFM tasklist extension, which needs to know if text
    // is in the first content of a list item.
    if (
      index &&
      event[1].type === types.chunkFlow &&
      events.get(index - 1)[1].type === types.listItemPrefix
    ) {
      assert(event[1]._tokenizer, 'expected `_tokenizer` on subtokens')
      subevents = event[1]._tokenizer.events
      otherIndex = 0

      if (
        otherIndex < subevents.length &&
        subevents[otherIndex][1].type === types.lineEndingBlank
      ) {
        otherIndex += 2
      }

      if (
        otherIndex < subevents.length &&
        subevents[otherIndex][1].type === types.content
      ) {
        while (++otherIndex < subevents.length) {
          if (subevents[otherIndex][1].type === types.content) {
            break
          }

          if (subevents[otherIndex][1].type === types.chunkText) {
            subevents[otherIndex][1]._isInFirstContentOfListItem = true
            otherIndex++
          }
        }
      }
    }

    // Enter.
    if (event[0] === 'enter') {
      if (event[1].contentType) {
        Object.assign(jumps, subcontent(events, index))
        index = jumps[index]
        more = true
      }
    }
    // Exit.
    else if (event[1]._container) {
      otherIndex = index
      lineIndex = undefined

      while (otherIndex--) {
        otherEvent = events.get(otherIndex)

        if (
          otherEvent[1].type === types.lineEnding ||
          otherEvent[1].type === types.lineEndingBlank
        ) {
          if (otherEvent[0] === 'enter') {
            if (lineIndex) {
              events.get(lineIndex)[1].type = types.lineEndingBlank
            }

            otherEvent[1].type = types.lineEnding
            lineIndex = otherIndex
          }
        } else {
          break
        }
      }

      if (lineIndex) {
        // Fix position.
        event[1].end = {...events.get(lineIndex)[1].start}

        // Switch container exit w/ line endings.
        parameters = events.slice(lineIndex, index)
        parameters.unshift(event)
        events.splice(lineIndex, index - lineIndex + 1, parameters)
      }
    }
  }

  // The changes to the `events` buffer must be copied back into the eventsArray
  splice(eventsArray, 0, Number.POSITIVE_INFINITY, events.slice(0))
  return !more
}

/**
 * Tokenize embedded tokens.
 *
 * @param {SpliceBuffer<Event>} events
 *   Events.
 * @param {number} eventIndex
 *   Index.
 * @returns {Record<string, number>}
 *   Gaps.
 */
function subcontent(events, eventIndex) {
  const token = events.get(eventIndex)[1]
  const context = events.get(eventIndex)[2]
  let startPosition = eventIndex - 1
  /** @type {Array<number>} */
  const startPositions = []
  assert(token.contentType, 'expected `contentType` on subtokens')
  const tokenizer =
    token._tokenizer || context.parser[token.contentType](token.start)
  const childEvents = tokenizer.events
  /** @type {Array<[number, number]>} */
  const jumps = []
  /** @type {Record<string, number>} */
  const gaps = {}
  /** @type {Array<Chunk>} */
  let stream
  /** @type {Token | undefined} */
  let previous
  let index = -1
  /** @type {Token | undefined} */
  let current = token
  let adjust = 0
  let start = 0
  const breaks = [start]

  // Loop forward through the linked tokens to pass them in order to the
  // subtokenizer.
  while (current) {
    // Find the position of the event for this token.
    while (events.get(++startPosition)[1] !== current) {
      // Empty.
    }

    assert(
      !previous || current.previous === previous,
      'expected previous to match'
    )
    assert(!previous || previous.next === current, 'expected next to match')

    startPositions.push(startPosition)

    if (!current._tokenizer) {
      stream = context.sliceStream(current)

      if (!current.next) {
        stream.push(codes.eof)
      }

      if (previous) {
        tokenizer.defineSkip(current.start)
      }

      if (current._isInFirstContentOfListItem) {
        tokenizer._gfmTasklistFirstContentOfListItem = true
      }

      tokenizer.write(stream)

      if (current._isInFirstContentOfListItem) {
        tokenizer._gfmTasklistFirstContentOfListItem = undefined
      }
    }

    // Unravel the next token.
    previous = current
    current = current.next
  }

  // Now, loop back through all events (and linked tokens), to figure out which
  // parts belong where.
  current = token

  while (++index < childEvents.length) {
    if (
      // Find a void token that includes a break.
      childEvents[index][0] === 'exit' &&
      childEvents[index - 1][0] === 'enter' &&
      childEvents[index][1].type === childEvents[index - 1][1].type &&
      childEvents[index][1].start.line !== childEvents[index][1].end.line
    ) {
      assert(current, 'expected a current token')
      start = index + 1
      breaks.push(start)
      // Help GC.
      current._tokenizer = undefined
      current.previous = undefined
      current = current.next
    }
  }

  // Help GC.
  tokenizer.events = []

  // If there’s one more token (which is the cases for lines that end in an
  // EOF), that’s perfect: the last point we found starts it.
  // If there isn’t then make sure any remaining content is added to it.
  if (current) {
    // Help GC.
    current._tokenizer = undefined
    current.previous = undefined
    assert(!current.next, 'expected no next token')
  } else {
    breaks.pop()
  }

  // Now splice the events from the subtokenizer into the current events,
  // moving back to front so that splice indices aren’t affected.
  index = breaks.length

  while (index--) {
    const slice = childEvents.slice(breaks[index], breaks[index + 1])
    const start = startPositions.pop()
    assert(start !== undefined, 'expected a start position when splicing')
    jumps.push([start, start + slice.length - 1])
    events.splice(start, 2, slice)
  }

  jumps.reverse()
  index = -1

  while (++index < jumps.length) {
    gaps[adjust + jumps[index][0]] = adjust + jumps[index][1]
    adjust += jumps[index][1] - jumps[index][0] - 1
  }

  return gaps
}
