/**
 * @typedef {import('mdast').Nodes} Nodes
 * @typedef {import('mdast').Paragraph} Paragraph
 *
 * @typedef {import('mdast-util-from-markdown').CompileContext} CompileContext
 * @typedef {import('mdast-util-from-markdown').Extension} FromMarkdownExtension
 * @typedef {import('mdast-util-from-markdown').Handle} FromMarkdownHandle
 * @typedef {import('mdast-util-from-markdown').Token} Token
 *
 * @typedef {import('mdast-util-to-markdown').ConstructName} ConstructName
 * @typedef {import('mdast-util-to-markdown').Handle} ToMarkdownHandle
 * @typedef {import('mdast-util-to-markdown').Options} ToMarkdownExtension
 * @typedef {import('mdast-util-to-markdown').State} State
 *
 * @typedef {import('../index.js').Directives} Directives
 * @typedef {import('../index.js').LeafDirective} LeafDirective
 * @typedef {import('../index.js').TextDirective} TextDirective
 */

import {ok as assert} from 'devlop'
import {parseEntities} from 'parse-entities'
import {stringifyEntitiesLight} from 'stringify-entities'
import {visitParents} from 'unist-util-visit-parents'

const own = {}.hasOwnProperty

const shortcut = /^[^\t\n\r "#'.<=>`}]+$/

handleDirective.peek = peekDirective

/**
 * Create an extension for `mdast-util-from-markdown` to enable directives in
 * markdown.
 *
 * @returns {FromMarkdownExtension}
 *   Extension for `mdast-util-from-markdown` to enable directives.
 */
export function directiveFromMarkdown() {
  return {
    canContainEols: ['textDirective'],
    enter: {
      directiveContainer: enterContainer,
      directiveContainerAttributes: enterAttributes,
      directiveContainerLabel: enterContainerLabel,

      directiveLeaf: enterLeaf,
      directiveLeafAttributes: enterAttributes,

      directiveText: enterText,
      directiveTextAttributes: enterAttributes
    },
    exit: {
      directiveContainer: exit,
      directiveContainerAttributeClassValue: exitAttributeClassValue,
      directiveContainerAttributeIdValue: exitAttributeIdValue,
      directiveContainerAttributeName: exitAttributeName,
      directiveContainerAttributeValue: exitAttributeValue,
      directiveContainerAttributes: exitAttributes,
      directiveContainerLabel: exitContainerLabel,
      directiveContainerName: exitName,

      directiveLeaf: exit,
      directiveLeafAttributeClassValue: exitAttributeClassValue,
      directiveLeafAttributeIdValue: exitAttributeIdValue,
      directiveLeafAttributeName: exitAttributeName,
      directiveLeafAttributeValue: exitAttributeValue,
      directiveLeafAttributes: exitAttributes,
      directiveLeafName: exitName,

      directiveText: exit,
      directiveTextAttributeClassValue: exitAttributeClassValue,
      directiveTextAttributeIdValue: exitAttributeIdValue,
      directiveTextAttributeName: exitAttributeName,
      directiveTextAttributeValue: exitAttributeValue,
      directiveTextAttributes: exitAttributes,
      directiveTextName: exitName
    }
  }
}

/**
 * Create an extension for `mdast-util-to-markdown` to enable directives in
 * markdown.
 *
 * @returns {ToMarkdownExtension}
 *   Extension for `mdast-util-to-markdown` to enable directives.
 */
export function directiveToMarkdown() {
  return {
    unsafe: [
      {
        character: '\r',
        inConstruct: ['leafDirectiveLabel', 'containerDirectiveLabel']
      },
      {
        character: '\n',
        inConstruct: ['leafDirectiveLabel', 'containerDirectiveLabel']
      },
      {
        before: '[^:]',
        character: ':',
        after: '[A-Za-z]',
        inConstruct: ['phrasing']
      },
      {atBreak: true, character: ':', after: ':'}
    ],
    handlers: {
      containerDirective: handleDirective,
      leafDirective: handleDirective,
      textDirective: handleDirective
    }
  }
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function enterContainer(token) {
  enter.call(this, 'containerDirective', token)
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function enterLeaf(token) {
  enter.call(this, 'leafDirective', token)
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function enterText(token) {
  enter.call(this, 'textDirective', token)
}

/**
 * @this {CompileContext}
 * @param {Directives['type']} type
 * @param {Token} token
 */
function enter(type, token) {
  this.enter({type, name: '', attributes: {}, children: []}, token)
}

/**
 * @this {CompileContext}
 * @param {Token} token
 */
function exitName(token) {
  const node = this.stack[this.stack.length - 1]
  assert(
    node.type === 'containerDirective' ||
      node.type === 'leafDirective' ||
      node.type === 'textDirective'
  )
  node.name = this.sliceSerialize(token)
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function enterContainerLabel(token) {
  this.enter(
    {type: 'paragraph', data: {directiveLabel: true}, children: []},
    token
  )
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitContainerLabel(token) {
  this.exit(token)
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function enterAttributes() {
  this.data.directiveAttributes = []
  this.buffer() // Capture EOLs
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitAttributeIdValue(token) {
  const list = this.data.directiveAttributes
  assert(list, 'expected `directiveAttributes`')
  list.push([
    'id',
    parseEntities(this.sliceSerialize(token), {
      attribute: true
    })
  ])
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitAttributeClassValue(token) {
  const list = this.data.directiveAttributes
  assert(list, 'expected `directiveAttributes`')
  list.push([
    'class',
    parseEntities(this.sliceSerialize(token), {
      attribute: true
    })
  ])
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitAttributeValue(token) {
  const list = this.data.directiveAttributes
  assert(list, 'expected `directiveAttributes`')
  list[list.length - 1][1] = parseEntities(this.sliceSerialize(token), {
    attribute: true
  })
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitAttributeName(token) {
  const list = this.data.directiveAttributes
  assert(list, 'expected `directiveAttributes`')

  // Attribute names in CommonMark are significantly limited, so character
  // references can’t exist.
  list.push([this.sliceSerialize(token), ''])
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exitAttributes() {
  const list = this.data.directiveAttributes
  assert(list, 'expected `directiveAttributes`')
  /** @type {Record<string, string>} */
  const cleaned = {}
  let index = -1

  while (++index < list.length) {
    const attribute = list[index]

    if (attribute[0] === 'class' && cleaned.class) {
      cleaned.class += ' ' + attribute[1]
    } else {
      cleaned[attribute[0]] = attribute[1]
    }
  }

  this.data.directiveAttributes = undefined
  this.resume() // Drop EOLs
  const node = this.stack[this.stack.length - 1]
  assert(
    node.type === 'containerDirective' ||
      node.type === 'leafDirective' ||
      node.type === 'textDirective'
  )
  node.attributes = cleaned
}

/**
 * @this {CompileContext}
 * @type {FromMarkdownHandle}
 */
function exit(token) {
  this.exit(token)
}

/**
 * @type {ToMarkdownHandle}
 * @param {Directives} node
 */
function handleDirective(node, _, state, info) {
  const tracker = state.createTracker(info)
  const sequence = fence(node)
  const exit = state.enter(node.type)
  let value = tracker.move(sequence + (node.name || ''))
  /** @type {LeafDirective | Paragraph | TextDirective | undefined} */
  let label

  if (node.type === 'containerDirective') {
    const head = (node.children || [])[0]
    label = inlineDirectiveLabel(head) ? head : undefined
  } else {
    label = node
  }

  if (label && label.children && label.children.length > 0) {
    const exit = state.enter('label')
    /** @type {ConstructName} */
    const labelType = `${node.type}Label`
    const subexit = state.enter(labelType)
    value += tracker.move('[')
    value += tracker.move(
      // @ts-expect-error: `containerPhrasing` is typed correctly, but TS
      // generates *hardcoded* types, which means that our dynamically added
      // directives are not present.
      // At some point, TS should fix that, and `from-markdown` should be fine.
      state.containerPhrasing(label, {
        ...tracker.current(),
        before: value,
        after: ']'
      })
    )
    value += tracker.move(']')
    subexit()
    exit()
  }

  value += tracker.move(attributes(node, state))

  if (node.type === 'containerDirective') {
    const head = (node.children || [])[0]
    let shallow = node

    if (inlineDirectiveLabel(head)) {
      shallow = Object.assign({}, node, {children: node.children.slice(1)})
    }

    if (shallow && shallow.children && shallow.children.length > 0) {
      value += tracker.move('\n')
      value += tracker.move(state.containerFlow(shallow, tracker.current()))
    }

    value += tracker.move('\n' + sequence)
  }

  exit()
  return value
}

/** @type {ToMarkdownHandle} */
function peekDirective() {
  return ':'
}

/**
 * @param {Directives} node
 * @param {State} state
 * @returns {string}
 */
function attributes(node, state) {
  const quote = state.options.quote || '"'
  const subset = node.type === 'textDirective' ? [quote] : [quote, '\n', '\r']
  const attrs = node.attributes || {}
  /** @type {Array<string>} */
  const values = []
  /** @type {string | undefined} */
  let classesFull
  /** @type {string | undefined} */
  let classes
  /** @type {string | undefined} */
  let id
  /** @type {string} */
  let key

  for (key in attrs) {
    if (
      own.call(attrs, key) &&
      attrs[key] !== undefined &&
      attrs[key] !== null
    ) {
      const value = String(attrs[key])

      if (key === 'id') {
        id = shortcut.test(value) ? '#' + value : quoted('id', value)
      } else if (key === 'class') {
        const list = value.split(/[\t\n\r ]+/g)
        /** @type {Array<string>} */
        const classesFullList = []
        /** @type {Array<string>} */
        const classesList = []
        let index = -1

        while (++index < list.length) {
          ;(shortcut.test(list[index]) ? classesList : classesFullList).push(
            list[index]
          )
        }

        classesFull =
          classesFullList.length > 0
            ? quoted('class', classesFullList.join(' '))
            : ''
        classes = classesList.length > 0 ? '.' + classesList.join('.') : ''
      } else {
        values.push(quoted(key, value))
      }
    }
  }

  if (classesFull) {
    values.unshift(classesFull)
  }

  if (classes) {
    values.unshift(classes)
  }

  if (id) {
    values.unshift(id)
  }

  return values.length > 0 ? '{' + values.join(' ') + '}' : ''

  /**
   * @param {string} key
   * @param {string} value
   * @returns {string}
   */
  function quoted(key, value) {
    return (
      key +
      (value
        ? '=' + quote + stringifyEntitiesLight(value, {subset}) + quote
        : '')
    )
  }
}

/**
 * @param {Nodes} node
 * @returns {node is Paragraph & {data: {directiveLabel: true}}}
 */
function inlineDirectiveLabel(node) {
  return Boolean(
    node && node.type === 'paragraph' && node.data && node.data.directiveLabel
  )
}

/**
 * @param {Directives} node
 * @returns {string}
 */
function fence(node) {
  let size = 0

  if (node.type === 'containerDirective') {
    visitParents(node, function (node, parents) {
      if (node.type === 'containerDirective') {
        let index = parents.length
        let nesting = 0

        while (index--) {
          if (parents[index].type === 'containerDirective') {
            nesting++
          }
        }

        if (nesting > size) size = nesting
      }
    })
    size += 3
  } else if (node.type === 'leafDirective') {
    size = 2
  } else {
    size = 1
  }

  return ':'.repeat(size)
}