// source: https://www.youtube.com/watch?v=7XmS8McW_1U

let Node = function () {
  this.keys = new Map()

  this.end = false

  this.setEnd = function () {
    this.end = true
  }

  this.isEnd = function () {
    return this.end
  }
}

let Trie = function () {
  this.root = new Node()

  this.add = function (input, node = this.root) {
    if (input.length == 0) {
      node.setEnd()
      return
    } else if (!node.keys.has(input[0])) {
      node.keys.set(input[0], new Node())
      return this.add(input.substr(1), node.keys.get(input[0]))
    } else {
      return this.add(input.substr(1), node.keys.get(input[0]))
    }
  }

  this.isWord = function (word) {
    let node = this.root
    while (word.length > 1) {
      if (!node.keys.has(word[0])) {
        return false
      } else {
        node = node.keys.get(word[0])
        word = word.substr(1)
      }
    }

    return node.keys.has(word) && node.keys.get(word).isEnd() ? true : false
  }

  this.print = function () {
    let words = []
    let search = function (node, string) {
      if (node.keys.size != 0) {
        for (let letter of node.keys.keys()) {
          search(node.keys.get(letter), string.concat(letter))
        }
        if (node.isEnd()) {
          words.push(string)
        }
      } else {
        string.length > 0 ? words.push(string) : undefined
        return
      }
    }
    search(this.root, new String())

    return words.length > 0 ? words : mo
  }
}

module.exports = Trie
