#!/bin/sh

# Triggered by <Control><Alt>n
# as defined in [org/gnome/settings-daemon/plugins/media-keys]
# in ~/.config/gnome-settings/key-bindings.ini
#
# Night Light control:
#
# - <Control><Alt>n => "when" toggle
#   + "Force" the screen to be warm right now!
#     (Turns Night Light on if it was off, and keeps it on all day)
#   + "Un-force" the Night Light into the local evening schedule
# - <Alt><Shift>n => "if" toggle
#   Plain on/off switch for the Night Light feature
# - <Alt><Shift>Left => Make the screen cooler
# - <Alt><Shift>Right => Make the screen warmer, and "force" warmness
#
#
# State machine:
#
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  |                       | "IF" toggle           | "WHEN" toggle         | "make COOLER"         | "make WARMER"         |
#  | Current STATE         | <Alt><Shift>n         | <Control><Alt>n       | <Alt><Shift>Left      | <Alt><Shift>Right     |
#  |                       |                       |                       |                       |                       |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | DISABLED              | ENABLE                | enabled               | still disabled        | enabled               |
#  | + scheduled           | + still scheduled     | + FORCED on           | + still scheduled     | + FORCED on           |
#  | => no tint            | => no or set tint     | => set tint           | => still no tint      | => set tint           |
#  |                       |    based on time   N? |                       |                    N! |                    *1 |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | DISABLED              | ENABLE                | enabled               | still disabled        | enabled               |
#  | + forced on           | + still forced        | + still FORCED on     | + still forced        | + still FORCED on     |
#  | => no tint            | => set tint           | => set tint           | => still no tint      | => set tint           |
#  |                       |                       |                       |                    N! |                    *1 |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | enabled               | DISABLE               | still enabled         | still enabled         | still enabled         |
#  | + SCHEDULED (day)     | + still scheduled     | + FORCED on           | + still scheduled     | + FORCED on           |
#  | => no tint yet        | => still no tint      | => set tint           | => still no tint      | => set tint           |
#  |                       |                    N! |                       |                    N! |                    *1 |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | enabled               | DISABLE               | still enabled         | still enabled         | still enabled         |
#  | + SCHEDULED (ramping) | + still scheduled     | + FORCED on           | + still scheduled     | + FORCED on           |
#  | => some tint already  | => no tint            | => set tint           | => no change in tint  | => set tint           |
#  |                       |                       |                       |                    N! |                       |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | enabled               | DISABLE               | still enabled         | still enabled         | still enabled         |
#  | + SCHEDULED (night)   | + still scheduled     | + FORCED on           | + still scheduled     | + FORCED on           |
#  | => set tint           | => no tint            | => set tint           | => LESS tint          | => MORE tint          |
#  |                       |                       |                    N! |                 *2 N? |                    N? |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  | enabled               | DISABLE               | still enabled         | still enabled         | still enabled         |
#  | + FORCED on           | + still forced on     | + back to SCHEDULED   | + still forced on     | + still forced on     |
#  | => set tint           | => no tint            | => no or set tint     | => LESS tint          | => MORE tint          |
#  |                       |                       |    based on time   N? |                 *2 N? |                    N? |
#  +-----------------------+-----------------------+-----------------------+-----------------------+-----------------------+
#  Legend:
#   - N! => A notification is shown for sure because there is no visible change on the screen
#   - N? => A notification is shown if there was no visible change on the screen
#   - *1 => The temperature is snapped to 2200K to ensure a visible effect
#   - *2 => The tint is turned off entirely when stepping over the maximum temperature
#
#  Notes:
#   - The main state property or state change is shown in CAPS
#   - Steps range from 1200K (warmest) to 4700K (coolest),
#     which is a bit more than the 1700K to 4700K in `gnome-control-center`
#   - If the range is already exhausted, so that the tint does not change, a notification is shown
#   - A 03:00 timer re-enables the Night Light feature and puts it back on the automatic schedule
#     with the `$_DEFAULT_TEMPERATURE` set
#

set -eu


notify() {
    ID_FILE="${XDG_RUNTIME_DIR}/night-light-notification-id"
    _id=$(cat "$ID_FILE" 2>/dev/null || true)

    if [ -n "$_id" ]; then
        notify-send -p -t 5000 --replace-id="$_id" "Night Light" "$1" > "$ID_FILE" || rm -f "$ID_FILE"
    else
        notify-send -p -t 5000 "Night Light" "$1" > "$ID_FILE" || rm -f "$ID_FILE"
    fi
}


Schema=org.gnome.settings-daemon.plugins.color


active_before=$(gdbus call --session \
    --dest org.gnome.SettingsDaemon.Color \
    --object-path /org/gnome/SettingsDaemon/Color \
    --method org.freedesktop.DBus.Properties.Get \
    org.gnome.SettingsDaemon.Color NightLightActive)

applied=$(gdbus call --session \
    --dest org.gnome.SettingsDaemon.Color \
    --object-path /org/gnome/SettingsDaemon/Color \
    --method org.freedesktop.DBus.Properties.Get \
    org.gnome.SettingsDaemon.Color Temperature \
    | sed -E 's/.*uint32 ([0-9]+).*/\1/')

automatic=$(gsettings get $Schema night-light-schedule-automatic)
enabled=$(gsettings get $Schema night-light-enabled)
target=$(gsettings get $Schema night-light-temperature | awk '{print $2}')


if [ "$automatic" = "true" ] || [ "$enabled" = "false" ]; then

    # Force "Night Light" enabled, enabling it if needed
    gsettings set $Schema night-light-enabled true
    gsettings set $Schema night-light-schedule-automatic false
    gsettings set $Schema night-light-schedule-from 0.0
    gsettings set $Schema night-light-schedule-to 24.0

    if [ "$active_before" = "(<true>,)" ] && [ "$automatic" = "true" ] \
            && [ $((applied - target)) -le 300 ]; then
        notify "is now forced to stay on and no longer on an automatic schedule"
    fi

else

    # Back to the live location's schedule
    gsettings set $Schema night-light-schedule-automatic true
    gsettings set $Schema night-light-schedule-from 18.0
    gsettings set $Schema night-light-schedule-to 6.0

    if [ "$active_before" = "(<true>,)" ]; then

        # Give the settings daemon a moment to recompute "NightLightActive"
        sleep 0.1

        active_after=$(gdbus call --session \
            --dest org.gnome.SettingsDaemon.Color \
            --object-path /org/gnome/SettingsDaemon/Color \
            --method org.freedesktop.DBus.Properties.Get \
            org.gnome.SettingsDaemon.Color NightLightActive)

        if [ "$active_after" = "(<true>,)" ]; then
            notify "is still on because of an automatic schedule"
        fi

    fi

fi