/**
 * @typedef {import('unist').Node} Node
 * @typedef {import('unist').Parent} Parent
 * @typedef {import('unist-util-is').Test} Test
 * @typedef {import('./complex-types').Action} Action
 * @typedef {import('./complex-types').Index} Index
 * @typedef {import('./complex-types').ActionTuple} ActionTuple
 * @typedef {import('./complex-types').VisitorResult} VisitorResult
 * @typedef {import('./complex-types').Visitor} Visitor
 */

import {convert} from 'unist-util-is'
import {color} from './color.js'

/**
 * Continue traversing as normal
 */
export const CONTINUE = true
/**
 * Do not traverse this node’s children
 */
export const SKIP = 'skip'
/**
 * Stop traversing immediately
 */
export const EXIT = false

/**
 * Visit children of tree which pass a test
 *
 * @param tree Abstract syntax tree to walk
 * @param test Test node, optional
 * @param visitor Function to run for each node
 * @param reverse Visit the tree in reverse order, defaults to false
 */
export const visitParents =
  /**
   * @type {(
   *   (<Tree extends Node, Check extends Test>(tree: Tree, test: Check, visitor: import('./complex-types').BuildVisitor<Tree, Check>, reverse?: boolean) => void) &
   *   (<Tree extends Node>(tree: Tree, visitor: import('./complex-types').BuildVisitor<Tree>, reverse?: boolean) => void)
   * )}
   */
  (
    /**
     * @param {Node} tree
     * @param {Test} test
     * @param {import('./complex-types').Visitor<Node>} visitor
     * @param {boolean} [reverse]
     */
    function (tree, test, visitor, reverse) {
      if (typeof test === 'function' && typeof visitor !== 'function') {
        reverse = visitor
        // @ts-expect-error no visitor given, so `visitor` is test.
        visitor = test
        test = null
      }

      const is = convert(test)
      const step = reverse ? -1 : 1

      factory(tree, null, [])()

      /**
       * @param {Node} node
       * @param {number?} index
       * @param {Array.<Parent>} parents
       */
      function factory(node, index, parents) {
        /** @type {Object.<string, unknown>} */
        // @ts-expect-error: hush
        const value = typeof node === 'object' && node !== null ? node : {}
        /** @type {string|undefined} */
        let name

        if (typeof value.type === 'string') {
          name =
            typeof value.tagName === 'string'
              ? value.tagName
              : typeof value.name === 'string'
              ? value.name
              : undefined

          Object.defineProperty(visit, 'name', {
            value:
              'node (' +
              color(value.type + (name ? '<' + name + '>' : '')) +
              ')'
          })
        }

        return visit

        function visit() {
          /** @type {ActionTuple} */
          let result = []
          /** @type {ActionTuple} */
          let subresult
          /** @type {number} */
          let offset
          /** @type {Array.<Parent>} */
          let grandparents

          if (!test || is(node, index, parents[parents.length - 1] || null)) {
            result = toResult(visitor(node, parents))

            if (result[0] === EXIT) {
              return result
            }
          }

          // @ts-expect-error looks like a parent.
          if (node.children && result[0] !== SKIP) {
            // @ts-expect-error looks like a parent.
            offset = (reverse ? node.children.length : -1) + step
            // @ts-expect-error looks like a parent.
            grandparents = parents.concat(node)

            // @ts-expect-error looks like a parent.
            while (offset > -1 && offset < node.children.length) {
              // @ts-expect-error looks like a parent.
              subresult = factory(node.children[offset], offset, grandparents)()

              if (subresult[0] === EXIT) {
                return subresult
              }

              offset =
                typeof subresult[1] === 'number' ? subresult[1] : offset + step
            }
          }

          return result
        }
      }
    }
  )

/**
 * @param {VisitorResult} value
 * @returns {ActionTuple}
 */
function toResult(value) {
  if (Array.isArray(value)) {
    return value
  }

  if (typeof value === 'number') {
    return [CONTINUE, value]
  }

  return [value]
}