Debounce brightness key bursts

bin/brightness-down-all

@@ -7,8 +7,4 @@ if [[ -f "$CONFIG" ]]; then
   source "$CONFIG"
 fi
 
-BACKLIGHT_DEVICE="${BRIGHTNESS_BACKLIGHT_DEVICE:-intel_backlight}"
-STEP="${BRIGHTNESS_STEP:-10}"
-
-brightnessctl -q -d "$BACKLIGHT_DEVICE" set "${STEP}%-"
-"$HOME/.local/bin/brightness-osd" || true
+"$HOME/.local/bin/brightness-step" down

bin/brightness-step

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+CONFIG="${BRIGHTNESS_AUTOMATION_CONFIG:-$HOME/.config/brightness-automation/env}"
+if [[ -f "$CONFIG" ]]; then
+  # shellcheck disable=SC1090
+  source "$CONFIG"
+fi
+
+BACKLIGHT_DEVICE="${BRIGHTNESS_BACKLIGHT_DEVICE:-intel_backlight}"
+BACKLIGHT_PATH="${BRIGHTNESS_SYNC_BACKLIGHT:-/sys/class/backlight/${BACKLIGHT_DEVICE}}"
+STEP="${BRIGHTNESS_STEP:-10}"
+DEBOUNCE_MS="${BRIGHTNESS_APPLY_DEBOUNCE_MS:-180}"
+STATE_DIR="${XDG_RUNTIME_DIR:-/tmp}/brightness-automation"
+STATE_FILE="$STATE_DIR/target-percent"
+STAMP_FILE="$STATE_DIR/target-stamp"
+LOCK_FILE="$STATE_DIR/lock"
+
+mkdir -p "$STATE_DIR"
+
+read_current_percent() {
+  local current max
+  current="$(<"${BACKLIGHT_PATH}/brightness")"
+  max="$(<"${BACKLIGHT_PATH}/max_brightness")"
+  printf '%s\n' "$(( (current * 100 + max / 2) / max ))"
+}
+
+clamp_percent() {
+  local value="$1"
+  if (( value < 1 )); then
+    value=1
+  elif (( value > 100 )); then
+    value=100
+  fi
+  printf '%s\n' "$value"
+}
+
+now_ms() {
+  date +%s%3N
+}
+
+apply_after_quiet_period() {
+  while true; do
+    sleep "$(awk "BEGIN { printf \"%.3f\", ${DEBOUNCE_MS} / 1000 }")"
+
+    local now stamp age target
+    now="$(now_ms)"
+    stamp="$(<"$STAMP_FILE")"
+    age="$(( now - stamp ))"
+
+    if (( age >= DEBOUNCE_MS )); then
+      target="$(<"$STATE_FILE")"
+      brightnessctl -q -d "$BACKLIGHT_DEVICE" set "${target}%"
+      exit 0
+    fi
+  done
+}
+
+if [[ "${1:-}" == "--apply-worker" ]]; then
+  apply_after_quiet_period
+fi
+
+if [[ "$#" -ne 1 || ! "$1" =~ ^(up|down)$ ]]; then
+  echo "Usage: $(basename "$0") up|down" >&2
+  exit 2
+fi
+
+(
+  flock 9
+
+  current="$(read_current_percent)"
+  if [[ -f "$STATE_FILE" ]]; then
+    base="$(<"$STATE_FILE")"
+  else
+    base="$current"
+  fi
+
+  case "$1" in
+    up) target="$(( base + STEP ))" ;;
+    down) target="$(( base - STEP ))" ;;
+  esac
+
+  target="$(clamp_percent "$target")"
+  printf '%s\n' "$target" >"$STATE_FILE"
+  now_ms >"$STAMP_FILE"
+
+  "$HOME/.local/bin/brightness-osd" "$target" || true
+) 9>"$LOCK_FILE"
+
+if ! pgrep -f "$HOME/.local/bin/brightness-step --apply-worker" >/dev/null 2>&1; then
+  nohup "$HOME/.local/bin/brightness-step" --apply-worker >/dev/null 2>&1 &
+fi

bin/brightness-up-all

@@ -7,8 +7,4 @@ if [[ -f "$CONFIG" ]]; then
   source "$CONFIG"
 fi
 
-BACKLIGHT_DEVICE="${BRIGHTNESS_BACKLIGHT_DEVICE:-intel_backlight}"
-STEP="${BRIGHTNESS_STEP:-10}"
-
-brightnessctl -q -d "$BACKLIGHT_DEVICE" set "+${STEP}%"
-"$HOME/.local/bin/brightness-osd" || true
+"$HOME/.local/bin/brightness-step" up