#!/usr/bin/env bash
#
# Temporarily turn off Hyprland direct scanout. A direct-scanned fullscreen
# window bypasses the compositor, so it also bypasses screen shaders and
# layer-shell overlays. Each invocation extends one shared hold and restores
# the exact previous setting after the last visual effect is gone.
set -uo pipefail

seconds=${1:-1}
number='^[0-9]*\.?[0-9]+$'
[[ $seconds =~ $number ]] || seconds=1
command -v hyprctl >/dev/null 2>&1 || exit 0
command -v jq >/dev/null 2>&1 || exit 0

runtime=${XDG_RUNTIME_DIR:-/tmp}/attention-required
mkdir -p "$runtime" || exit 0
state=$runtime/composite-state
lock=$runtime/composite.lock

milliseconds=$(awk -v seconds="$seconds" 'BEGIN { printf "%d", (seconds + 0.3) * 1000 }')
now() { date +%s%3N; }
direct_scanout() { hyprctl -j getoption render:direct_scanout 2>/dev/null | jq -r '.int // empty'; }
set_direct_scanout() {
  hyprctl -q eval "hl.config({ render = { direct_scanout = $1 } })" >/dev/null 2>&1 \
    || hyprctl -q keyword render:direct_scanout "$1" >/dev/null 2>&1
}

exec 9>"$lock"
flock 9

current=$(direct_scanout)
[[ $current =~ ^[0-2]$ ]] || exit 0
until=$(( $(now) + milliseconds ))
previous=$current
if [[ -s $state ]]; then
  IFS=$'\t' read -r saved_previous saved_until < "$state" || true
  [[ $saved_previous =~ ^[0-2]$ ]] && previous=$saved_previous
  [[ $saved_until =~ ^[0-9]+$ && $saved_until -gt $until ]] && until=$saved_until
fi

printf '%s\t%s\n' "$previous" "$until" > "$state"
set_direct_scanout 0 || { rm -f "$state"; exit 0; }
flock -u 9

# Let parallel invocations extend the deadline. The final one restores the
# setting only if nothing else has changed it in the meantime.
sleep "$(awk -v deadline="$until" -v current="$(now)" 'BEGIN { printf "%.3f", (deadline - current) / 1000 + 0.05 }')"
flock 9

IFS=$'\t' read -r previous until < "$state" || exit 0
[[ $until =~ ^[0-9]+$ && $(now) -ge $until ]] || exit 0
current=$(direct_scanout)
if [[ $current == 0 && $previous =~ ^[0-2]$ ]]; then
  set_direct_scanout "$previous" || true
fi
rm -f "$state"