module Colorizer

def colorize(object)
  # Inspired by Jeremy Ruten (http://stackoverflow.com/questions/1698318/ruby-generate-a-random-hex-color)
  hash = object.hash # hash an object, returns a Fixnum
  trimmed_hash = hash & 0xffffff # trim the hash to the size of 6 hex digits (& is bit-wise AND)
  hex_code = "%06x" % trimmed_hash # format as at least 6 hex digits, pad with zeros
  "##{hex_code}"
end

def colorize_similarly(object, saturation, lightness)
  rnd = ((XXhash.xxh64(object) * 7) % 100) * 0.01
  hsl_to_rgb(rnd, saturation, lightness)
end

def hex_color_component(i)
  (i * 255).floor.to_s(16).rjust(2, "0")
end

def hsl_to_rgb(h, sl, l)
  r = l
  g = l
  b = l
  v = (l <= 0.5) ? (l * (1.0 + sl)) : (l + sl - l * sl)
  if v > 0
    m = l + l - v
    sv = (v - m) / v
    h *= 6.0
    sextant = h.floor
    fract = h - sextant
    vsf = v * sv * fract
    mid1 = m + vsf
    mid2 = v - vsf
    case sextant
    when 0
      r = v
      g = mid1
      b = m
    when 1
      r = mid2
      g = v
      b = m
    when 2
      r = m
      g = v
      b = mid1
    when 3
      r = m
      g = mid2
      b = v
    when 4
      r = mid1
      g = m
      b = v
    when 5
      r = v
      g = m
      b = mid2
    end
  end
  "##{hex_color_component(r)}#{hex_color_component(g)}#{hex_color_component(b)}"
end