gistfile1.rb

require 'pry'

# Constants
INITIAL_MARKER = " "
PLAYER_MARKER = "X"
COMPUTER_MARKER = "O"
WINNING_LINES = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] + # rows
                [[1, 4, 7], [2, 5, 8], [3, 6, 9]] + # columns
                [[1, 5, 9], [3, 5, 7]]              # diagonals

# Variables
score_arr = [0, 0]
first = ''

# Methods
def prompt(msg)
  puts "=> #{msg}"
end

def joinor(arr, separator, word="or")
  arr[-1] = "#{word} #{arr.last}" if arr.size > 1
  arr.join(separator)
end

def display_board(brd, arr)
  system "clear"
  puts "You are #{PLAYER_MARKER}, the computer is #{COMPUTER_MARKER}"
  puts "Current score: Player #{arr[0]}, Computer #{arr[1]}"
  puts ""
  puts "     |     |"
  puts "  #{brd[1]}  |  #{brd[2]}  |  #{brd[3]}"
  puts "     |     |"
  puts "-----+-----+-----"
  puts "     |     |"
  puts "  #{brd[4]}  |  #{brd[5]}  |  #{brd[6]}"
  puts "     |     |"
  puts "-----+-----+-----"
  puts "     |     |"
  puts "  #{brd[7]}  |  #{brd[8]}  |  #{brd[9]}"
  puts "     |     |"
  puts ""
end

def initialize_game
  board = {}
  (1..9).each { |num| board[num] = INITIAL_MARKER }
  board
end

def empty_squares(brd)
  brd.keys.select { |num| brd[num] == INITIAL_MARKER }
end

def player_turn!(brd)
  choice = ''
  loop do
    prompt "Pick a square #{joinor(empty_squares(brd), ', ')}"
    choice = gets.chomp.to_i
    break if empty_squares(brd).include?(choice)
    prompt "This is not a valid choice."
  end

  brd[choice] = PLAYER_MARKER
end

def find_at_risk_squares(line, brd, marker)
  if brd.values_at(*line).count(marker) == 2
    brd.select{ |k,v| line.include?(k) && v == INITIAL_MARKER}.keys.first
  else
    nil
  end
end

def computer_turn!(brd)
  comp_choice = nil

  WINNING_LINES.each do |line|
    comp_choice = find_at_risk_squares(line, brd, COMPUTER_MARKER)
    break if comp_choice
  end

  if !comp_choice
    WINNING_LINES.each do |line|
      comp_choice = find_at_risk_squares(line, brd, PLAYER_MARKER)
      break if comp_choice
    end
  end

  if !comp_choice
    if brd[5] == ' '
      comp_choice = 5
    end
  end

  if !comp_choice
    comp_choice = empty_squares(brd).sample
  end

  brd[comp_choice] = COMPUTER_MARKER
end

def board_full?(brd)
  empty_squares(brd).empty?
end

def who_wins?(brd)
  WINNING_LINES.each do |line|
    if brd.values_at(*line).count(PLAYER_MARKER) == 3
      return 'Player'
    elsif brd.values_at(*line).count(COMPUTER_MARKER) == 3
      return 'Computer'
    end
  end
  nil
end

def winner?(brd)
  !!who_wins?(brd)
end

def score(winner, arr)
  if winner == "Player"
    arr[0] += 1
  elsif winner == "Computer"
    arr[1] += 1
  end
end

# Main logic
loop do
  prompt "Welcome to our TicTacToe game!"

  prompt "Who goes first?(0 for player, 1 for computer)"
  first = gets.chomp.to_i

  if first == 0
    prompt "Player goes first"
  elsif first == 1
    prompt "Computer goes first"
  end
  sleep(1)

  loop do
    board = initialize_game

    loop do
      display_board(board, score_arr)

      if first == 0
        player_turn!(board)
        break if winner?(board) || board_full?(board)

        computer_turn!(board)
        break if winner?(board) || board_full?(board)
      elsif first == 1
        computer_turn!(board)
        break if winner?(board) || board_full?(board)
        display_board(board, score_arr)

        player_turn!(board)
        break if winner?(board) || board_full?(board)
      end

    end
    display_board(board, score_arr)

    if winner?(board)
      prompt "#{who_wins?(board)} wins!"
    else
      prompt "Its a tie!"
    end
    sleep(2)
    score(who_wins?(board), score_arr)

    break if score_arr[0] == 5 or score_arr[1] == 5
    first = 1 - first
  end

  prompt "Would you like to play another game?(y for Yes)"
  repeat = gets.chomp
  break unless repeat.downcase.start_with?('y')
  score = [0, 0]
end

prompt "Thank you for playing TicTacToe! Goodbye!"