backlight

#!/usr/bin/bash
set -eu

source "$HOME/dotfiles/linux/variables.env"

declare -ar BRIGHTNESS_ICONS=("" "" "")
declare -ar BRIGHTNESS_IMAGES=(sun-dim sun-medium sun)

preferences_helper="$(dirname "$(readlink -f "$0")")/../config/system-settings/settings.py"
LOCK_FILE="${XDG_RUNTIME_DIR:-/tmp}/u_backlight.lock"
STEP=$(python3 "$(dirname "$(readlink -f "$0")")/../config/system-settings/settings.py" get display.brightnessStep)

get_value() {
  light -G 2>&- | cut -f1 -d .
}

adjust() { # inc|dec
  local direction=$1 current target
  current=$(get_value)
  case "$direction" in
    inc) target=$(( (current / STEP + 1) * STEP )) ;;
    dec) target=$(( ((current + STEP - 1) / STEP - 1) * STEP )) ;;
  esac
  (( target < 0 )) && target=0
  (( target > 100 )) && target=100
  (( target == current )) && return 1

  flock -n "$LOCK_FILE" light -S "$target" 2>&-
}

brightness_level() {
  local value=$1
  if (( value < 34 )); then
    printf '0'
  elif (( value < 67 )); then
    printf '1'
  else
    printf '2'
  fi
}

icon() {
  local index
  index=$(brightness_level "$1")
  printf '%s\n' "${BRIGHTNESS_ICONS[index]}"
}

audio_tick() {
  play "$HOME/dotfiles/sounds/audio-volume-change.oga" &> /dev/null &
}

show() {
  local value index
  value=$(get_value)
  index=$(brightness_level "$value")
  notify-send -a System \
    -i "$LUCIDE_PATH/${BRIGHTNESS_IMAGES[index]}.svg" \
    -h string:wired-tag:system \
    -h int:value:"$value" \
    "Brightness"
}

link_state() {
  python3 "$preferences_helper" get display.linkBrightness
}

link_toggle() {
  local enabled
  enabled=$(link_state)
  if [[ $enabled == true ]]; then enabled=false; else enabled=true; fi
  python3 "$preferences_helper" set display.linkBrightness "$enabled" > /dev/null
  link_state
}

## When "link devices" is on, dragging the laptop slider also drives the
## keyboard and any DDC-capable external displays at the same percentage.
maybe_link() {
  [[ "$(link_state)" == true ]] || return 0
  local pct=$1
  u_keeb-backlight set "$pct" quiet &> /dev/null &
  u_monitors brightness set "$pct" quiet &> /dev/null &
}

case $1 in
  icon)       echo "$(icon "$(get_value)")" ;;
  get)        get_value ;;
  set)        maybe_link "$2"; flock "$LOCK_FILE" light -S "$2" ;;
  dim)
    light -O -s sysfs/leds/tpacpi::kbd_backlight
    light -S 0 -s sysfs/leds/tpacpi::kbd_backlight
    ;;
  restore)
    light -I
    light -I -s sysfs/leds/tpacpi::kbd_backlight
    ;;
  show)       show ;;
  inc)
    adjust inc || exit 0
    [[ "${2:-}" == "quiet" ]] || audio_tick
    show ;;
  dec)
    adjust dec || exit 0
    [[ "${2:-}" == "quiet" ]] || audio_tick
    show ;;
  link-get)   link_state ;;
  link-toggle) link_toggle ;;
  if)
    light -L 2>&- | grep -q auto && echo true || echo false ;;
esac