#!/bin/sh

if [ "$1" = "install" ]
then
    hook="/etc/pacman.d/hooks/upds.hook"
    if [ "$(id -u)" -ne 0 ]
    then
        >&2 printf 'Please run as root.\n'; exit 1
    fi

    if [ -f "$hook" ]
    then
        >&2 printf 'Hook already installed.\n'; exit 1
    fi

    # Install the hook
    cat <<EOF > "$hook"
# Hook for keeping available updates in sync after upgrade
# relies on 'upds'
[Trigger]
Operation = Upgrade
Type = Package
Target = *
[Action]
Description = Sync upds
When = PostTransaction
Exec = /usr/bin/sh -c '/usr/bin/kill -s USR1 "\$(/usr/bin/pgrep upds | /usr/bin/head -n 1)"'
EOF
    >&2 printf 'Installed.\n'

    exit
fi

count_updates() { checkupdates | wc -l  > ~/.cache/updates; }

# Periodically count updates in background
(
    while true
    do
        count_updates
        sleep 60m
    done
) &

# update on USR1 signal
trap count_updates USR1

# wait for signal
while true
do sleep 1s
done