LinkedList.rb

require "./Node"
require 'pry'
class LinkedList
  attr_accessor :head, :next_node

  def initialize
    @head = nil
  end

  def append(data)
    if invalid_word?(data)
      nil
    elsif @head.nil?
      @head = Node.new(data)
    else
      find_tail.next_node = Node.new(data)
    end
    data
  end

  def insert(position, data)
    if invalid_word?(data)
      nil
    else
      @head = Node.new(data) if empty?
      if position == 0
        prepend(data)
      else position > 0
        current = @head
        count = 0
        until position - 1 == count
          count += 1
          current = current.next_node
        end
          reattach_node = current.next_node
          current.next_node = Node.new(data)
          current.next_node.next_node = reattach_node
        end
      end
  end

  def prepend(data)
    if invalid_word?(data)
      nil
    else
      head = Node.new(data)
      head.next_node = @head
      @head = head
      data
    end
  end

  def empty?
    if head.nil?
      true
    end
  end

  def count
    if empty?
      counter = 0
    else
      current = @head
      counter = 1
      until current.next_node.nil?
        counter += 1
        current = current.next_node
      end
    end
    counter
  end

  def to_string
    string = "#{@head.data} "
    current = @head
    until current.next_node == nil
      current = current.next_node
      string << current.data + " "
    end
    string.strip
  end

  def find_tail
    current = @head
    until current.next_node.nil?
      current = current.next_node
    end
    current
  end

  def includes?(chunk)
    false if empty?
    current = @head
    until current.data == chunk
      current = current.next_node
      break if find_tail.data != chunk
    end
      current.data == chunk
  end

  def find(position, length)
      current = @head
      count = 1
      until position == count
        count += 1
        current = current.next_node
      end
      string = ""
      length.times do
        string << current.data + " "
        current = current.next_node
      end
      string.strip
  end

  def pop
    tail_return = find_tail.data
    current = @head
    counter = 1
    if current.next_node == nil
      current.data = nil
    else
      until counter + 1 == count
        counter += 1
        current = current.next_node
      end
      if counter + 1 == count
        current.next_node = nil
      end
    end
    tail_return
  end

  def invalid_word?(data)
    invalid_words = ["Charlie", "Mississippi", "Patagonia", "Junngle", "Beats", "Turing"]
    invalid_words.include?(data.to_s)
  end

end