IdentifierColors.hs

{-|
Module      : Client.IdentifierColors
Description : Mapping from identifiers to console colors
Copyright   : (c) Eric Mertens, 2016
License     : ISC
Maintainer  : emertens@gmail.com

This module provides the color mapping for nick highlighting.

-}

module Client.IdentifierColors (identifierColor) where

import qualified Data.ByteString as B
import           Data.Vector (Vector)
import qualified Data.Vector as Vector
import           Irc.Identifier
import           Graphics.Vty.Image

-- | Compute a color from the denotation of an identifier.
-- This color will be consistent for different capitalizations
-- and will be consistent across program executions.
identifierColor :: Identifier -> Color
identifierColor ident = nickColorPalette Vector.! i
  where
    i = hashIdentity ident `mod` Vector.length nickColorPalette

hashIdentity :: Identifier -> Int
hashIdentity ident =
    let h1 = B.foldl' (\acc b -> fromIntegral b + 33 * acc) 0 (idDenote ident)
    in h1 + (h1 `quot` 32)

nickColorPalette :: Vector Color
nickColorPalette = Vector.fromList
  [cyan, magenta, green, yellow, blue,
   brightCyan, brightMagenta, brightGreen, brightBlue]