class Hilighter

# File lib/hilighter.rb, line 2
def self.disable(val = true)
    @@disable = val
end

# File lib/hilighter.rb, line 6
def self.disable?
    @@disable ||= false
    return @@disable
end

# File lib/hilighter.rb, line 13
def self.hex_to_x256(hex)
    @@cached_codes ||= Hash.new
    cache = @@cached_codes[hex]
    return "color_#{cache}" if (!cache.nil?)

    # For simplicity, assume RGB space is perceptually uniform.
    # There are 5 places where one of two outputs needs to be
    # chosen when the input is the exact middle:
    # - The r/g/b channels and the gray value:
    #     - the higher value output is chosen
    # - If the gray and color values have same distance from the
    #   input
    #     - color is chosen

    # Calculate the nearest 0-based color index at 16..231
    r = g = b = 0
    x = "[A-Fa-f0-9]{2}"
    hex.match(/^#?(#{x})(#{x})(#{x})(#{x})?$/) do |m|
        r = m[1].to_i(16)
        g = m[2].to_i(16)
        b = m[3].to_i(16)
    end

    # 0..5 each
    ir = (r < 48) ? 0 : (r < 115) ? 1 : ((r - 35) / 40)
    ig = (g < 48) ? 0 : (g < 115) ? 1 : ((g - 35) / 40)
    ib = (b < 48) ? 0 : (b < 115) ? 1 : ((b - 35) / 40)

    # 0..215 lazy evaluation
    cidx = (36 * ir) + (6 * ig) + ib + 16

    # Calculate the nearest 0-based gray index at 232..255
    average = (r + g + b) / 3

    # 0..23
    gidx = (average > 238) ? 23 : (average - 3) / 10

    # Calculate the represented colors back from the index
    i2cv = [0, 0x5f, 0x87, 0xaf, 0xd7, 0xff]

    # r/g/b  0..255 each
    cr = i2cv[ir]
    cg = i2cv[ig]
    cb = i2cv[ib]

    # same value for r/g/b  0..255
    gv = (10 * gidx) + 8

    # Return the one which is nearer to the original rgb
    # values
    clr_err = ((cr - r) ** 2 + (cg - g) ** 2 + (cb - b) ** 2)
    gray_err = ((gv - r) ** 2 + (gv - g) ** 2 + (gv - b) ** 2)

    if (clr_err <= gray_err)
        @@cached_codes[hex] = cidx.to_s.rjust(3, "0")
    else
        @@cached_codes[hex] = (gidx + 232).to_s.rjust(3, "0")
    end

    return "color_#{@@cached_codes[hex]}"
end

# File lib/hilighter.rb, line 75
def self.sample
    String.colors.keys[0..15].each do |fg|
        String.colors.keys[16..31].each do |bg|
            print(" mw ".send(fg).send(bg))
        end
        puts
    end
end

# File lib/hilighter.rb, line 84
def self.table
    (0..15).each do |i|
        bg = i.to_s.rjust(3, "0")
        print(" ".send("on_color_#{bg}"))
        print(bg.black.send("on_color_#{bg}"))
        print(" ".send("on_color_#{bg}"))
        print(bg.white.send("on_color_#{bg}"))
        print(" ".send("on_color_#{bg}"))
        puts if (((i + 1) % 8) == 0)
    end

    (16..255).each do |i|
        bg = i.to_s.rjust(3, "0")
        print(" ".send("on_color_#{bg}"))
        print(bg.black.send("on_color_#{bg}"))
        print(" ".send("on_color_#{bg}"))
        print(bg.white.send("on_color_#{bg}"))
        print(" ".send("on_color_#{bg}"))
        puts if (((i - 15) % 6) == 0)
    end
end