class Term::ANSIColor::PPMReader

def each_row
  reset_io
  @height.times do
    yield parse_row
  end
end

def initialize(io, options = {})
  @io      = io
  @options = options
  @buffer  = ''
end

def next_line
  while line = @io.gets and line =~ /^#|^\s$/
  end
  line
end

def parse_header
  (line = next_line) =~ /^P([36])$/ or raise "unknown type #{line.to_s.chomp.inspect}"
  @type = $1.to_i
  if next_line =~ /^(\d+)\s+(\d+)$/
    @width, @height = $1.to_i, $2.to_i
  else
    raise "missing dimensions"
  end
  unless next_line =~ /^255$/
    raise "only 255 max color images allowed"
  end
end

def parse_next_pixel
  pixel = nil
  case @type
  when 3
    @buffer.empty? and @buffer << next_line
    @buffer.sub!(/(\d+)\s+(\d+)\s+(\d+)\s*/) do
      pixel = [ $1.to_i, $2.to_i, $3.to_i ]
      ''
    end
  when 6
    @buffer.size < 3 and @buffer << @io.read(8192)
    pixel = @buffer.slice!(0, 3).unpack('C3')
  end
  pixel
end

def parse_row
  row = []
  @width.times do
    row << parse_next_pixel
  end
  row
end

def reset_io
  begin
    @io.rewind
  rescue Errno::ESPIPE
  end
  parse_header
end

def to_a
  enum_for(:each_row).to_a
end

def to_s
  result = ''
  each_row do |row|
    last_pixel = nil
    for pixel in row
      if pixel != last_pixel
        color = Attribute.nearest_rgb_color(pixel, @options)
        result << on_color(color)
        last_pixel = pixel
      end
      result << ' '
    end
    result << reset << "\n"
  end
  result
end