#!/usr/bin/env ruby

require 'rmagick'

class GoBoardPixel
  GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL = 65_536 / 8

  attr_reader :red, :green, :blue

  def self.from_magick(red:, green:, blue:)
    new(
      red: red / GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL,
      green: green / GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL,
      blue: blue / GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL
    )
  end

  def initialize(red:, green:, blue:)
    @red = red
    @green = green
    @blue = blue
  end

  def distance_from_real_pixel(red:, green:, blue:)
    (red - @red * GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL)**2 +
      (green - @green * GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL)**2 +
      (blue - @blue * GO_BOARD_CHANNEL_TO_RMAGICK_CHANNEL)**2
  end

  def distance_from_go_pixel(red:, green:, blue:)
    (red - @red)**2 +
      (green - @green)**2 +
      (blue - @blue)**2
  end

  def eql?(other)
    red == other.red && green == other.green && blue == other.blue
  end

  def hash
    [red, green, blue].hash
  end
end

ImagePixel = Data.define(:red, :green, :blue)

image = Magick::Image.read(ARGV[0]).first
image.change_geometry!('80x60^') do |cols, rows, img|
  img.resize!(cols, rows)
end
image.crop!(Magick::CenterGravity, 80, 60, true)

possible_colors = {}
image.each_pixel do |px|
  go_px = GoBoardPixel.from_magick(red: px.red, green: px.green, blue: px.blue)
  possible_colors[go_px] ||= 0
  possible_colors[go_px] += 1
end

pixels_by_usage = possible_colors.sort_by(&:last).reverse

go_board_palette = pixels_by_usage[0..31].map(&:first)
color_mapping = go_board_palette.each_with_index.each_with_object({}) do |(go_px, index), obj|
  obj[go_px] = index
end

pixels_by_usage[32..].map(&:first).each do |go_px|
  best_match = go_board_palette.each_with_index.map do |target_go_px, index|
    [
      target_go_px.distance_from_go_pixel(
        red: go_px.red,
        green: go_px.green,
        blue: go_px.blue,
      ), index
    ]
  end.sort_by(&:first).first

  color_mapping[go_px] = best_match.last
end

File.open('image_data.txt', 'w') do |fh|
  image.each_pixel do |px|
    magick_px = GoBoardPixel.from_magick(
      red: px.red, green: px.green, blue: px.blue
    )

    fh.puts format('%05b', color_mapping[magick_px])
  end
end

File.open('palette_data.txt', 'w') do |fh|
  go_board_palette.each do |color|
    fh.puts format('%09b', ((color.red << 6) + (color.green << 3) + color.blue))
  end
end

# [ ] load image
# [ ] downsample to 40x30
# [ ] change to indexed image with go board palette
# [ ] save out body data
# [ ] save out palette data