#!/bin/sh
set -eu

if [ "$(id -u)" != 0 ]; then
    echo "This script needs root permissions!" 1>&2
    exit 1
fi

if [ "$#" -lt 1 ]; then
    echo "Usage: $0 [-a arch] [-m mirror] <chroot>" 1>&2
    exit 1
fi


arch="$(uname -m)"
mirror='https://mirrors.slackware.com/slackware/slackware64-current'

# Minimal amount of packages required to run installpkg, removepkg, upgradepkg, explodepkg and makepkg
# All of these exist in the 'a' package set
packages_pkgtools='
aaa_base
aaa_elflibs
bash
coreutils
etc
findutils
glibc-solibs
grep
pkgtools
sed
tar
util-linux
which
xz
'

# Minimal amount of packages required to run slackpkg without the dialog interface
# Supporting https, gpg, and upgrade-all.
# These exist over the 'a', 'ap', 'n' and 'l' package sets
# ca-certificates needs to be installed after openssl for the doinst.sh to run correctly
packages_extra='
bzip2
diffutils
gawk
gnupg
gzip
libpsl
libunistring
pcre2
slackpkg
wget

openssl
ca-certificates
'

# Parse arguments
while getopts "a:m:" opt; do
    case "$opt" in
        a) arch="$OPTARG" ;;
        m)
            if [ -d "$OPTARG" ]; then
                mirror="$(realpath "$OPTARG")"
            else
                mirror="$OPTARG"
            fi
            ;;
    esac
done
shift $(expr $OPTIND - 1)
[ "$#" -ge 1 ] && [ "$1" = "--" ] && shift

# Build final variables
case "$arch" in
    x86_64) pkgmain='slackware64' ;;
    *) pkgmain='slackware' ;;
esac
initrd='isolinux/initrd.img'
checksums='CHECKSUMS.md5'
chroot="$(realpath "$1")"

# Create working directory
temp="$(mktemp -d -t "$(basename "$0")".XXXXXX)"
cleanup() {
    if mountpoint -q "$temp/mnt/pkg"; then
        umount "$temp/mnt/pkg"
        rmdir "$temp/mnt/pkg"
    fi
    mountpoint -q "$temp/mnt" && umount "$temp/mnt"
    rm -rf "$temp"
}
trap 'cleanup' EXIT
cd "$temp"

# Function to download (or copy) a file
get() {
    if [ -d "$mirror" ]; then
        cp "$mirror/$1" "$2"
    else
        wget "$mirror/$1" -O "$2"
    fi
}

# Function to verify files based on the checksums file
check() {
    printf '%s' "$(tail +13 CHECKSUMS.md5 | grep "^[0-9a-f]*  ./$1$" | cut -d ' ' -f 1)  $2" | md5sum -c --quiet -
}

# Get the full path to a package
package() {
    tail +13 CHECKSUMS.md5 | grep "^[0-9a-f]*  ./$pkgmain/[^/]*/$1-[^-]*-[^-]*-[^-]*\.t.z$" | cut -d ' ' -f 3- | cut -c 3-
}

# Download checksums
get "$checksums" CHECKSUMS.md5

# Download installer initrd.img
get "$initrd" initrd.img
check "$initrd" initrd.img

# Unpack and prepare the installer
xz -cd initrd.img | cpio -id
rm -f initrd.img
mkdir -p pkg "$chroot"
mount --bind "$chroot" mnt
mkdir -p mnt/pkg
mount --bind pkg mnt/pkg

# Download packages
for pkg in $packages_pkgtools $packages_extra; do
    path="$(package "$pkg")"
    name="$(basename "$path")"
    get "$path" "pkg/$name"
    check "$path" "pkg/$name"
done
for pkg in $packages_pkgtools; do echo "$(basename "$(package "$pkg")")" >> pkg/__; done
for pkg in $packages_extra; do echo "$(basename "$(package "$pkg")")" >> pkg/_; done

# Bootstrap pkgtools and its dependencies
env -i chroot . sh -l -c 'while read pkg; do /sbin/installpkg --root /mnt --terse "/pkg/$pkg"; done < /pkg/__'

# Install slackpkg and its dependencies
env -i chroot mnt sh -l -c 'while read pkg; do /sbin/installpkg --terse "/pkg/$pkg"; done < /pkg/_'