#!/bin/bash

run_latehook() {
    echo

    # Remove /new_root/.successful-update if exists
    rm -f /new_root/.successful-update

    # Detect if update downloaded.
    if [[ -d /new_root/.update_rootfs ]]; then
        # Available, rename old /usr and move new /usr to /.
        mv /new_root/usr /new_root/.old.usr
        mv /new_root/.update_rootfs/usr /new_root/usr

        # Same for /var/cache/pacman.
        mv /new_root/var/cache/pacman /new_root/.old.pacmancache
        mv /new_root/.update_rootfs/var/cache/pacman /new_root/var/cache

        # Same for /var/lib/pacman.
        mv /new_root/var/lib/pacman /new_root/.old.var.lib.pacman
        mv /new_root/.update_rootfs/var/lib/pacman /new_root/var/lib

        # Move to /etc stage.
        touch /new_root/.etc-stage
    fi
    
    # Detect if /etc stage is active.
    if [[ -f /new_root/.etc-stage ]]; then
        # Create new /etc.
        rm -rf /new_root/.new_etc; cp -a /new_root/etc /new_root/.new_etc
        (cd /new_root/.new_etc && find . -type f -print0 | grep -Fxvz -f <(cd "/new_root/.update_rootfs/etc" && find . -type f) | xargs -0 rm -f)
        (cd /new_root/.new_etc && find . -type l -print0 | grep -Fxvz -f <(cd "/new_root/.update_rootfs/etc" && find . -type l) | xargs -0 rm -f)
        mkdir -p /.old.varlib
        (cd /new_root/var/lib && find . -maxdepth 1 -type d -print0 | grep -Fxvz -f <(cd "/new_root/.update_rootfs/var/lib" && find . -maxdepth 1 -type d) | grep -Fxvz './pacman' | xargs -0 sh -c 'mv "$@" /new_root/.old.varlib' sh)
        (cd /new_root/.update_rootfs/var/lib && find . -maxdepth 1 -type d -print0 | grep -Fxvz -f <(cd "/new_root/var/lib" && find . -maxdepth 1 -type d) | xargs -0 sh -c 'cp -r "$@" /new_root/var/lib' sh)
        cp /new_root/.update_rootfs/etc/pacman.conf /new_root/.new_etc/pacman.conf
        rm -rf /new_root/.new_etc/pacman.d
        cp -a /new_root/.update_rootfs/etc/pacman.d /new_root/.new_etc/pacman.d
        (cd /new_root/.update_rootfs/etc && find . -type f -print0 | grep -Fxvz -f <(cd "/new_root/.new_etc" && find . -type f -print0) | xargs -n 1 -0 sh -c 'mkdir -p "/new_root/.new_etc/$(dirname "$1")"; cp "$1" /new_root/.new_etc/$(dirname "$1")' sh)
        mv /new_root/etc /new_root/.old.etc || :
        mv /new_root/.new_etc /new_root/etc

        mv /new_root/etc/systemd/system /new_root/.old.etc.systemd.system
        mv /new_root/.update_rootfs/etc/systemd/system /new_root/etc/systemd

        # Successful update.
        rm -f /new_root/.etc-stage

        mv /new_root/.update_rootfs /new_root/.old.update_rootfs
        touch /new_root/.successful-update
    fi
}