ez

#!/usr/bin/env bash
# author: andreasl
set -eu

show_usage() {
    cat <<'EOF'
ez - resteazy
Blank the display after keyboard/mouse idle.

Usage:

  ez [<IDLE-SECONDS>]

Examples:

  ez      # Default to 5 seconds idle time
  ez 120  # Allow 120 seconds idle time
EOF
}

case ${1:-} in
-h | --help)
    show_usage
    exit 0
    ;;
esac

max_idle_time=${1:-5}

orig_idle_delay=$(gsettings get org.gnome.desktop.session idle-delay)
orig_lock_enabled=$(gsettings get org.gnome.desktop.screensaver lock-enabled)

restore() {
    gsettings set org.gnome.desktop.session idle-delay "$orig_idle_delay"
    gsettings set org.gnome.desktop.screensaver lock-enabled "$orig_lock_enabled"
}
trap restore EXIT INT TERM HUP

# Disable auto-lock for the duration; blanking must never lead to the lock screen.
gsettings set org.gnome.desktop.screensaver lock-enabled false

# Read idle time in whole seconds from GNOME Mutter's IdleMonitor over D-Bus.
get_idle_seconds() {
    local out ms
    out=$(gdbus call --session \
        --dest org.gnome.Mutter.IdleMonitor \
        --object-path /org/gnome/Mutter/IdleMonitor/Core \
        --method org.gnome.Mutter.IdleMonitor.GetIdletime 2>/dev/null) || return 1
    # Output format: (uint64 559,)
    ms=${out#*uint64 }
    ms=${ms%,*}
    [[ $ms =~ ^[0-9]+$ ]] || return 1
    printf '%s' $((ms / 1000))
}

blanked=0
while true; do
    if ! idle_time=$(get_idle_seconds); then
        sleep 1
        continue
    fi

    if ((idle_time >= max_idle_time)); then
        if ((blanked == 0)); then
            # Force GNOME to blank almost immediately; lock stays disabled.
            gsettings set org.gnome.desktop.session idle-delay 'uint32 1'
            blanked=1
        fi
        sleep 1
    else
        if ((blanked == 1)); then
            gsettings set org.gnome.desktop.session idle-delay "$orig_idle_delay"
            blanked=0
        fi
        sleep $((max_idle_time - idle_time))
    fi
done