Lauch alacritty with a random hue shift on foreground and background colors

alacritty_color.sh

#!/bin/bash
DEFAULT_BACKGROUND='#012b36'
DEFAULT_FOREGROUND='#839496'

HEX_RGB_RET=(0 0 0)
RGB_HEX_IN=("0" "0" "0")
RGB_HEX_RET=""
function _hex_to_rgb {
  first=${1: 0:1}
  if [[ "$first" = "#" ]]; then
    HEX_RGB_RET[0]=$((16#${1: 1:2}))
    HEX_RGB_RET[1]=$((16#${1: 3:2}))
    HEX_RGB_RET[2]=$((16#${1: 5:2}))
  else
    echo "Bad HEX code, should be '#aabbcc'"
  fi
}

function _rgb_to_hex {
  printf -v RGB_HEX_RET "#%02x%02x%02x" ${RGB_HEX_IN[0]} ${RGB_HEX_IN[1]} ${RGB_HEX_IN[2]}  
}

function _rgb_to_hsl {
echo "$1,$2,$3" | awk -F "[,]+" '\
# Returns minimum number
function abs(num) {
  if (num < 0.0)
    return num*-1.0
  return num
}
function find_min(num1, num2, num3){
   if (num1 < num2)
     a=num1
   else
     a=num2
   if (a < num3)
    return a
  return num3
}
# Returns maximum number
function find_max(num1, num2, num3){
   if (num1 > num2)
     a=num1
   else
     a=num2
  if (a > num3)
    return a
  return num3
}
function to_hsl(Rd, Gd, Bd){
   Rf=Rd/255.0
   Gf=Gd/255.0
   Bf=Bd/255.0
   # Find minimum number
   m=find_min(Rf, Gf, Bf)
   
   # Find maximum number
   M=find_max(Rf, Gf, Bf)
   chroma=M-m
   L=(M+m)/2.0
   if (chroma == 0.0) {
    H=0.0
    S=0.0
   } else {
    if (M == Bf)
      Hprime=((Rf-Gf)/chroma)+4.0
    else if (M == Gf)
      Hprime=((Bf-Rf)/chroma)+2.0
    else
      Hprime=((Gf-Bf)/chroma)%6.0
    H=Hprime*60.0
    S=chroma/(1.0-abs((2.0*L)-1.0))
   }
   print H "," S "," L
}
# Script execution starts here
{
   to_hsl($1, $2, $3)
}'
}

function _hsl_to_rgb {
echo "$1,$2,$3" | awk -F "[,]+" '\
function abs(num) {
  if (num < 0.0)
    return num*-1.0
  return num
}
function to_rgb(H, S, L){
   H=H%360.0
   S=abs(S)
   if (S < 0.0) S=0.0
   if (S > 1.0) S=1.0
   L=abs(L)
  if (L < 0.0) L=0.0
  if (L > 1.0) L=1.0
  C=(1.0-abs((2.0*L)-1.0))*S
  X=C*(1.0-abs(((H/60.0)%2.0)-1.0))
  m=L-(C/2.0)
  if (H >= 300.0) {
    Rp=C; Gp=0.0; Bp=X 
  } else if (H >= 240.0) {
    Rp=X; Gp=0.0; Bp=C
  } else if (H >= 180.0) {
    Rp=0.0; Gp=X; Bp=C
  } else if (H >= 120.0) {
    Rp=0.0; Gp=C; Bp=X
  } else if (H >= 60.0) {
    Rp=X; Gp=C; Bp=0.0
  } else {
    Rp=C; Gp=X; Bp=0.0
  }
  R=(Rp+m)*255.0
  G=(Gp+m)*255.0
  B=(Bp+m)*255.0
  print int(R+0.5) "," int(G+0.5) "," int(B+0.5)
}
{
   to_rgb($1*1.0, $2*1.0, $3*1.0)
}'
}

function _rotate_angle {
echo "$1,$2" | awk -F "[,]+" '\
function rotate_angle(A, R){
   R=R%32768.0
   amount=1.0+((R/32767.0) * 358.0)
   print (A+amount)%360.0
}
{rotate_angle($1*1.0, $2*1.0)}'
}

function _add_offset {
echo "$1,$2,$3" | awk -F "[,]+" '\
function add_offset(S,D,R){
  R=R%32768.0
  amount=((R/32767.0)*D*2.0)-D
  S=S+amount
  if (S < 0.0) S=0.0
  if (S > 1.0) S=1.0
  print S
}
{add_offset($1*1.0, $2*1.0, $3*1.0)}'
}


_hex_to_rgb "$DEFAULT_FOREGROUND"
HSLstring="$(_rgb_to_hsl ${HEX_RGB_RET[0]} ${HEX_RGB_RET[1]} ${HEX_RGB_RET[2]})"
readarray -td, FOREGROUND_HSL <<<"$HSLstring,";
_hex_to_rgb "$DEFAULT_BACKGROUND"
HSLstring="$(_rgb_to_hsl ${HEX_RGB_RET[0]} ${HEX_RGB_RET[1]} ${HEX_RGB_RET[2]})"
readarray -td, BACKGROUND_HSL <<<"$HSLstring,";
RAND1=$RANDOM
RAND2=$RANDOM
FOREGROUND_HSL[0]=$(_rotate_angle ${FOREGROUND_HSL[0]} $RAND1)
BACKGROUND_HSL[0]=$(_rotate_angle ${BACKGROUND_HSL[0]} $RAND1)
FOREGROUND_HSL[1]=$(_add_offset ${FOREGROUND_HSL[1]} "0.4" $RAND2)
BACKGROUND_HSL[1]=$(_add_offset ${BACKGROUND_HSL[1]} "0.4" $RAND2)
RGBstring="$(_hsl_to_rgb ${FOREGROUND_HSL[0]} ${FOREGROUND_HSL[1]} ${FOREGROUND_HSL[2]})"
readarray -td, RGB_HEX_IN <<<"$RGBstring,";
_rgb_to_hex
NEW_FOREGROUND="-o colors.primary.foreground='$RGB_HEX_RET'"
RGBstring="$(_hsl_to_rgb ${BACKGROUND_HSL[0]} ${BACKGROUND_HSL[1]} ${BACKGROUND_HSL[2]})"
readarray -td, RGB_HEX_IN <<<"$RGBstring,";
_rgb_to_hex
NEW_BACKGROUND="-o colors.primary.background='$RGB_HEX_RET'"

exec alacritty $NEW_FOREGROUND $NEW_BACKGROUND "$@"