#!/usr/bin/env ruby
# -*- ruby -*-
#
# Reads in a bitmap and outputs strings with terminal-escaped colors.
#
# WARNING: This has been tested only on a picture of spudtrooper, so
# don't venture into more complicated images unless you are willing to
# accept the consequences.
#

class Bitmap

  # HEADER  
  attr_accessor :type              # unsigned short: Magic identifier           
  attr_accessor :filesize          # unsigned int: File size in bytes         
  attr_accessor :reserved1         # unsigned short reserved1;
  attr_accessor :reserved2         # unsigned short reserved2;
  attr_accessor :offset            # unsigned int: Offset to image data, bytes

  # INFOHEADER
  attr_accessor :headersize        # unsigned int: Header size in bytes     
  attr_accessor :width             # int: Width and height of image
  attr_accessor :height            # int: Width and height of image
  attr_accessor :planes            # unsigned short: Number of colour planes  
  attr_accessor :bits              # unsigned short: Bits per pixel           
  attr_accessor :compression       # unsigned int: Compression type         
  attr_accessor :imagesize         # unsigned int: Image size in bytes      
  attr_accessor :xresolution       # int: Pixels per meter         
  attr_accessor :yresolution       # int: Pixels per meter         
  attr_accessor :ncolours          # unsigned int: Number of colours        
  attr_accessor :importantcolours  # unsigned int: Important colours        

  # IMAGE_DATA
  attr_accessor :data

  # int int -> Bitmap::Color
  def color(row,col)
    Color.new @data[height-1-row][col]
  end

  # string -> Bitmap
  def self.read(file)
    BitmapReader.new(file).read_bitmap
  end

  class Color
    def initialize(v)
      @v = v
    end
    def alpha
      Bitmap::alpha @v
    end
    def red
      Bitmap::red @v
    end
    def green
      Bitmap::green @v
    end
    def blue
      Bitmap::blue @v
    end
  end
  
  def self.alpha(v)
    (v >> 24) & 0xff
  end

  def self.red(v)
    (v >> 16) & 0xff
  end

  def self.green(v)
    (v >> 8) & 0xff
  end

  def self.blue(v)
    (v >> 0) & 0xff
  end

  private

  class BitmapReader
    def initialize(file)
      @file = File.new file,'r'
    end   
    def read_bitmap

      file = @file
      res = Bitmap.new
      
      # header
      res.type,
      res.filesize,
      res.reserved1,
      res.reserved2,
      res.offset =
        file.read(2+4+2+2+4).unpack('SLSSL')
      
      # infoheader
      res.headersize,
      res.width,
      res.height,
      res.planes,
      res.bits,
      res.compression,
      res.imagesize,
      res.xresolution,
      res.yresolution,
      res.ncolours,
      res.importantcolours =
        file.read(4+4+4+2+2+4+4+4+4+4+4).unpack('LllSSLLllLL')

      # image data
      res.data = []
      res.height.times do
        res.data << file.read(4*res.width).unpack('l*')
      end

      return res
    end

  end

end

class Color
  
  ESC = "\033"
  CLOSE =  ESC + "[0m"

  def initialize(code,str)
    @code = code
    @str = str
  end
  
  def colorize(s)
    color + s.to_s + CLOSE
  end

  def backgroundize(s)
    background + s.to_s + CLOSE
  end
  
  def color
    "\033[" + @code.to_s + "m"
    end
  
  def background
    "\033[" + (@code+10).to_s + "m"
  end
  
  BLACK = Color.new 30,'BLACK'
  RED = Color.new 31,'RED'
  GREEN = Color.new 32,'GREEN'
  YELLOW = Color.new 33,'YELLOW'
  BLUE = Color.new 34,'BLUE'
  MAGENTA = Color.new 35,'MAGENTA'
  CYAN = Color.new 36,'CYAN'
  WHITE = Color.new 37,'WHITE'
  
end


class ToTerminal

  def main(argv)
    argv.each do |arg|
      to_terminal arg
    end
  end
  
  private

  def to_terminal(file)
    b = Bitmap.read file
    b.height.times do |row|
      b.width.times do |col|
        print find_nearest_color(b.color row,col).colorize '##'
      end
      puts
    end
  end

  # Bitmap::Color -> Color  
  def find_nearest_color(c)
    if c.alpha < 10
      return Color::CYAN
    end
    if c.red > 0xa0 and c.green > 0xa0 and c.blue > 0xa0
      return Color::WHITE
    end
    if c.red < 0x10 and c.green < 0x10 and c.blue < 0x10
      return Color::BLUE
    end
    if c.red > 0x70
      return Color::RED
    end
    if c.red > 0x50
      return Color::MAGENTA
    end
    return Color::BLACK
  end

end

ToTerminal.new.main ARGV