1 files changed, 99 insertions, 0 deletions
diff --git a/bin/backlight b/bin/backlight
new file mode 100755
index 0000000..ac8a466
--- /dev/null
+++ b/bin/backlight
@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+# set backlight through sysfs
+
+set -euo pipefail
+
+# brightness steps in percentage
+brightness_step_size=5
+brightness_device=/sys/class/backlight/intel_backlight/brightness
+brightness_max_device=/sys/class/backlight/intel_backlight/max_brightness
+calculated_brightness=0
+amount=0
+
+brightness_steps=$(echo "100/${brightness_step_size}" |bc -l)
+maximum_brightness_raw=$(cat $brightness_max_device)
+current_brightness_raw=$(cat $brightness_device)
+brightness_one_percent_raw=$(echo "${maximum_brightness_raw}/100" |bc -l)
+current_brightness_percentage=$(echo "${current_brightness_raw}/(${maximum_brightness_raw}/100)" |bc -l)
+current_brightness_remainder=$(echo "${current_brightness_percentage}%${brightness_step_size}"|bc -l)
+current_step=$(echo ${current_brightness_percentage}/${brightness_step_size}|bc -l)
+
+check_if_number() {
+  if [[ $1 =~ ^[!\-0-9]+$ ]]; then
+    echo "Not an Integer: $1"
+    exit 1
+  fi
+}
+
+calculate_increment() {
+  check_if_number $1
+  if [ $1 -eq 0 ]; then
+    echo "There's nothing to do."
+    exit 1
+  fi
+  if [ $1 -gt 0 ]; then
+    if [ $(printf '%.0f' $current_brightness_percentage) -eq 100 ]; then
+      echo "Already at 100%"
+      exit 0
+    elif [ $(printf '%.0f' $(echo "${current_brightness_percentage}+$1"| bc)) -gt 100 ]; then
+      calculated_brightness=100
+    else
+      calculated_brightness=$(printf '%.0f' $(echo "${current_brightness_percentage}+$1"| bc))
+    fi
+  else
+    if [ $(printf '%.0f' $current_brightness_percentage) -eq 0 ]; then
+      echo "Already at 0%"
+      exit 0
+    elif [ $(printf '%.0f' $(echo "${current_brightness_percentage}+$1"| bc)) -lt 0 ]; then
+      calculated_brightness=0
+    else
+      calculated_brightness=$(printf '%.0f' $(echo "${current_brightness_percentage}+$1"| bc))
+    fi
+  fi
+}
+
+calculate_percentage() {
+  check_if_number $1
+  if [ $1 -lt 0 ] || [ $1 -gt 100 ]; then
+    echo "Invalid range: $1"
+    exit 1
+  fi
+  calculated_brightness=$1
+}
+
+percentage_to_raw() {
+  printf '%.0f' $(echo "$1*${brightness_one_percent_raw}"|bc -l)
+}
+
+set_brightness() {
+  echo "$(percentage_to_raw $calculated_brightness)" > $brightness_device
+}
+
+print_help() {
+  echo -e "Usage:\n $0 -d <decrement_by_x_percent> \n or $0 -i <increment_by_x_percent>"
+  exit 1
+}
+
+if [ ${#@} -gt 0 ]; then
+  while getopts 'hi:s:' flag; do
+    case "${flag}" in
+      h)
+        print_help
+        ;;
+      i)
+        calculate_increment $OPTARG
+          ;;
+      s)
+        calculate_percentage $OPTARG
+        ;;
+      *)
+        echo "Error! Try '${0} -h'."
+        exit 1
+        ;;
+    esac
+  done
+else
+  print_help
+fi
+
+set_brightness