Lib: Add color functions

lib/color.nix

@@ -0,0 +1,133 @@
+{
+  inputs,
+  pkgs,
+  lib,
+  ...
+}: let
+  # This code was blatantly stolen from here:
+  # https://github.com/Misterio77/nix-colors/blob/b92df8f5eb1fa20d8e09810c03c9dc0d94ef2820/lib/core/conversions.nix#L87
+  hexToDecMap = {
+    "0" = 0;
+    "1" = 1;
+    "2" = 2;
+    "3" = 3;
+    "4" = 4;
+    "5" = 5;
+    "6" = 6;
+    "7" = 7;
+    "8" = 8;
+    "9" = 9;
+    "a" = 10;
+    "b" = 11;
+    "c" = 12;
+    "d" = 13;
+    "e" = 14;
+    "f" = 15;
+  };
+
+  pow = base: exponent: let
+    inherit (lib) mod;
+  in
+    if exponent > 1
+    then let
+      x = pow base (exponent / 2);
+      odd_exp = mod exponent 2 == 1;
+    in
+      x
+      * x
+      * (
+        if odd_exp
+        then base
+        else 1
+      )
+    else if exponent == 1
+    then base
+    else if exponent == 0 && base == 0
+    then throw "undefined"
+    else if exponent == 0
+    then 1
+    else throw "undefined";
+
+  base16To10 = exponent: scalar: scalar * (pow 16 exponent);
+
+  hexCharToDec = hex: let
+    inherit (lib) toLower;
+    lowerHex = toLower hex;
+  in
+    if builtins.stringLength hex != 1
+    then throw "Function only accepts a single character."
+    else if hexToDecMap ? ${lowerHex}
+    then hexToDecMap."${lowerHex}"
+    else throw "Character ${hex} is not a hexadecimal value.";
+in rec {
+  /*
+  Converts from hexadecimal to decimal.
+
+    Type: hexToDec :: string -> int
+
+    Args:
+      hex: A hexadecimal string.
+
+    Example:
+      hexadecimal "12"
+      => 18
+      hexadecimal "FF"
+      => 255
+      hexadecimal "abcdef"
+      => 11259375
+  */
+  hexToDec = hex: let
+    inherit (lib) stringToCharacters reverseList imap0 foldl;
+    decimals = builtins.map hexCharToDec (stringToCharacters hex);
+    decimalsAscending = reverseList decimals;
+    decimalsPowered = imap0 base16To10 decimalsAscending;
+  in
+    foldl builtins.add 0 decimalsPowered;
+
+  /*
+  Converts a 6 character hexadecimal string to RGB values.
+
+  Type: hexToRGB :: string => [int]
+
+  Args:
+    hex: A hexadecimal string of length 6.
+
+  Example:
+    hexToRGB "012345"
+    => [ 1 35 69 ]
+    hexToRGB "abcdef"
+    => [171 205 239 ]
+    hexToRGB "000FFF"
+    => [ 0 15 255 ]
+  */
+  hexToRGB = hex: let
+    rgbStartIndex = [0 2 4];
+    hexList = builtins.map (x: builtins.substring x 2 hex) rgbStartIndex;
+    hexLength = builtins.stringLength hex;
+  in
+    if hexLength != 6
+    then
+      throw ''
+        Unsupported hex string length of ${builtins.toString hexLength}.
+        Length must be exactly 6.
+      ''
+    else builtins.map hexToDec hexList;
+
+  /*
+  Converts a 6 character hexadecimal string to an RGB string seperated by a
+  delimiter.
+
+  Type: hexToRGBString :: string -> string
+
+  Args:
+    sep: The delimiter or seperator.
+    hex: A hexadecimal string of length 6.
+  */
+  hexToRGBString = sep: hex: let
+    inherit (builtins) map toString;
+    inherit (lib) concatStringsSep;
+    hexInRGB = hexToRGB hex;
+    hexInRGBString = map toString hexInRGB;
+  in
+    concatStringsSep sep hexInRGBString;
+}

lib/default.nix

@@ -12,4 +12,5 @@
   networking = import ./networking.nix {inherit inputs pkgs lib;};
   rofi = import ./rofi.nix {inherit inputs pkgs lib;};
   generators = import ./generators.nix {inherit inputs pkgs lib;};
+  color = import ./color.nix {inherit inputs pkgs lib;};
 }