module AnsiToIrc

# File lib/ansi_to_irc.rb, line 84
def ansi216_rgb(index)
  idx = index - 16
  r = (idx / 36) * 51
  g = ((idx % 36) / 6) * 51
  b = (idx % 6) * 51
  [r, g, b]
end

# File lib/ansi_to_irc.rb, line 70
def ansi256_to_extended(index)
  idx = index.to_i.clamp(0, 255)
  if idx < 16
    idx
  elsif idx < 232
    r, g, b = ansi216_rgb(idx)
    nearest_code(r, g, b)
  else
    grey = 8 + (idx - 232) * 10
    nearest_code(grey, grey, grey)
  end
end

# File lib/ansi_to_irc.rb, line 18
def convert(text)
  value = text.to_s
  return value if value.empty?

  out = +""
  pos = 0
  value.scan(ANSI_PATTERN) do
    match = Regexp.last_match
    out << value[pos...match.begin(0)]
    out << irc_code_for_sequence(match[0])
    pos = match.end(0)
  end
  out << value[pos..]
  out
end

# File lib/ansi_to_irc.rb, line 53
def irc_code_for_sequence(seq)
  if (match = seq.match(FG_256_PATTERN))
    code = ansi256_to_extended(match[1].to_i)
    return IrcFormat.color(code)
  end

  if (match = seq.match(FG_RGB_PATTERN))
    code = nearest_code(match[1].to_i, match[2].to_i, match[3].to_i)
    return IrcFormat.color(code)
  end

  return IrcFormat::RESET if seq.match?(RESET_PATTERN)

  ""
end

# File lib/ansi_to_irc.rb, line 102
def load_extended_colors!
  require_relative "irc_extended_colors" unless defined?(IrcExtendedColors)
end

# File lib/ansi_to_irc.rb, line 38
def nearest_code(r, g, b)
  load_extended_colors!
  hex = format("%02x%02x%02x", r.to_i.clamp(0, 255), g.to_i.clamp(0, 255), b.to_i.clamp(0, 255))
  best_code = 16
  best_dist = Float::INFINITY
  IrcExtendedColors::RGB.each do |code, rgb_hex|
    dist = rgb_distance(hex, rgb_hex)
    next unless dist < best_dist

    best_dist = dist
    best_code = code
  end
  best_code
end

# File lib/ansi_to_irc.rb, line 93
def rgb_distance(hex_a, hex_b)
  a = hex_a.to_s.ljust(6, "0")[0, 6]
  b = hex_b.to_s.ljust(6, "0")[0, 6]
  ar, ag, ab = [a[0, 2], a[2, 2], a[4, 2]].map { |x| x.to_i(16) }
  br, bg, bb = [b[0, 2], b[2, 2], b[4, 2]].map { |x| x.to_i(16) }
  ((ar - br)**2) + ((ag - bg)**2) + ((ab - bb)**2)
end

# File lib/ansi_to_irc.rb, line 34
def strip_irc_codes(text)
  text.to_s.gsub(/\x03(?:\d{2}(?:,\d{2})?)?/, "")
end