def parse_line(line_str)
  line = {}
  i = 0
  line_str.chars.each do |c|
    case c 
    when '1'..'8'
      i += c.to_i
    else
      line[i] = c
      i += 1
    end
  end

  line
end

def is_capture_possible(board)
  last_line = {}

  board.split('/').each do |line_str|
    line = parse_line line_str

    return true if (0..8).any?{ |i| last_line[i] == 'p' && (line[i-1] == 'P' || line[i+1] == 'P')  }

    last_line = line
  end

  false
end



require 'minitest/autorun'

describe :parse_line do
  it('parses empty lines') { parse_line('8').must_equal({}) }
 
  it('recognizes pawns at correct indices') do
    parse_line('7p').must_equal({ 7 => 'p' })
    parse_line('2p2P2').must_equal({ 2 => 'p', 5 => 'P' })
    parse_line('pP1p4').must_equal({ 0 => 'p', 1 => 'P', 3 => 'p' })
  end
end

describe :is_capture_possible do
  it('recognizes when capture is possible') do 
    assert is_capture_possible('8/7p/6P1/8/8/8/8/8')
    assert is_capture_possible('8/8/p7/1P6/3P3p/8/8/8')
    assert is_capture_possible('8/2P5/8/4P1p1/2p2P2/3p4/3p1P2/8')
    assert is_capture_possible('8/P7/8/5P2/2pp4/3P2p1/3pP3/8')
    assert is_capture_possible('8/P7/p7/p1P1P3/1P3p2/8/1p6/8')
    assert is_capture_possible('8/4p1P1/2P2P1P/2p1pPpp/8/6P1/pP1p4/8')
  end

  it('recognizes when capture is impossible') do 
    refute is_capture_possible('8/8/8/8/8/8/8/8')
    refute is_capture_possible('8/7P/6p1/8/8/8/8/8')
    refute is_capture_possible('8/7p/7P/8/8/8/8/8')
    refute is_capture_possible('8/pppppppp/8/8/8/8/PPPPPPPP/8')
    refute is_capture_possible('8/p7/8/1p6/5P2/8/8/8')
    refute is_capture_possible('8/p7/P7/2P1p1p1/2p5/8/PP6/8')
  end
end