#!/bin/bash

# Define function snore()
snore()
{
    local IFS
    [[ -n "${_snore_fd:-}" ]] || { exec {_snore_fd}<> <(:) && read -r -t 0 -u $_snore_fd; } 2>/dev/null ||
    {
        # workaround for MacOS and similar systems
        local fifo
        fifo=$(mktemp -u)
        mkfifo -m 700 "$fifo"
        exec {_snore_fd}<>"$fifo"
        rm "$fifo"
    }
    read ${1:+-t "$1"} -u $_snore_fd || :
}

# Define delimter as comma for brightnessctl -m list
IFS=","
#echo "New IFS is $IFS"

# Define hundred variable
hun=100

# Define highest illuminance sensor value expected
imax=3355

# Define top of linear slope: illuminance values above this amount will all be treated as go to full brightness
ipeak=100

# Define starting manual adjustment value
madj=0

# Get initial brightness value
  bctl=$(brightnessctl -m)
  set -- $bctl
  blast=$3

# Main Loop
while true
  do


  iraw=$(cat /sys/bus/iio/devices/iio:device0/in_illuminance_raw)
 #echo "iraw is $iraw"
  bctl=$(brightnessctl -m)
  set -- $bctl
 #echo $bctl
  #echo $3
  braw=$3
  #echo "braw is $braw"
  #echo $4
  bpct="${4//%}"
 #echo "bpct is $bpct"
  #echo $5
  bmax=$5

  #echo "Calculating bdiff from $braw and $blast"
  bdiff=$((braw - blast))
  #echo "bdiff is $bdiff"
  if [ "$bdiff" -ne "0" ]
  then
   #echo "Need to adjust ipeak.."
   #echo "ipeak is $ipeak"
   ipeak=$(( ipeak - ( bdiff * 100 / bmax ) ))
   if (( $(bc -l <<< "${ipeak/e/E} < 0") ))
   then
     ipeak=1
   fi
   #echo "ipeak changed to $ipeak"
  fi
  blast=$braw
 #echo $bctl
 #echo $3
  btarget=$((iraw * bmax / ipeak))
 #echo "btarget is $btarget"
  bstep=$(( (btarget-blast) / 10))
  if (( $(bc -l <<< "${bstep/e/E} > $bmax/100") ))
  then
    bstep=$(( bmax / 100 ))
  fi
 #echo "bstep is $bstep"
  bnext=$(( braw + bstep ))
  if [ $bnext -gt $bmax ]; then
   #echo "Bnext too high!, setting to $bmax"
    bnext=$bmax
    bstep=0
    #echo "Bnext is $bnext"
  fi
  brightnessctl -q set $bnext

  # Save last brightness value to compare against in next loop
  #bctl=$(brightnessctl -m)
  #set -- $bctl
  #echo $bctl
  #echo $3
  #braw=$3
  #echo "new braw is $braw"
  blast=$bnext
  #echo "blast is $blast"

  #Variable update amount based on last movement
  ssec=$(( 200 / ( 100 + ${bstep//-} ) ))
 #echo "initial ssec is $ssec"
  if (( $(bc -l <<< "${ssec/e/E} > 2") ))
  then
    ssec=2
  fi
  if (( $(bc -l <<< "${ssec/e/E} < .01") ))
  then
    ssec=.01
  fi

  #echo "ssec is now $ssec"
  #echo "------------SLEEPING----------"
  #ssec=1
  #sleep $ssec
  snore $ssec
done