#!/usr/bin/env bash

uses_sysd_resolve() {
    local rootfs_dir="$1" _res
    local resconf="${rootfs_dir}/etc/resolv.conf" sysd_resolvedir="${rootfs_dir}/run/systemd/resolve"
    if [[ -d "$sysd_resolvedir" ]]; then return 0; fi
    if [[ -f "${rootfs_dir}/etc/systemd/resolved.conf" ]]; then return 0; fi
    if grep -q "nameserver 127.0.0." "$resconf"; then return 0; fi
    if grep -qi "systemd-resolved" "$resconf"; then return 0; fi
    if grep -qi "stub" "$resconf"; then return 0; fi
    return 1
}

_inj_ns() {
    local pdir="$(dirname "$1")"
    [[ ! -d "$pdir" ]] && echo -en " >> Parent folder $pdir not found. Creating it... " && mkdir -pv "$pdir"
    touch "$1"
    echo "nameserver 185.130.44.20" >> "$1"
    echo "nameserver 1.1.1.1" >> "$1"
    echo "nameserver 2a07:e00::333" >> "$1"
}

fix_resolve() {
    local rootfs_dir="$1" 
    local res_dir="${rootfs_dir}/run/systemd/resolve"
    local res_stub="${res_dir}/stub-resolv.conf" resolv_conf="${rootfs_dir}/etc/resolv.conf"

    if uses_sysd_resolve "$rootfs_dir"; then
        echo -e " >> System at '${rootfs_dir}' appears to use systemd-resolved. Initialising ${res_stub} ..."
        _inj_ns "$res_stub"
    else
        echo -e " >> System at '${rootfs_dir}' doesn't appear to use systemd-resolved. Writing directly to $resolv_conf ..."
        _inj_ns "$resolv_conf"
    fi
}

bind_mounts() {
    cd "$1"
    if [[ ! -d proc ]] || [[ -z "$(ls proc)" ]]; then
        echo -e " [...] ${1}/proc not mounted. Mounting now."
        echo -e "         -> $(mount -v -t proc proc proc/) \n"
    else
        echo -e " [+++] ${1}/proc is non-empty - must be already mounted. Skipping.\n"
    fi
    if [[ ! -d sys ]] || [[ -z "$(ls sys)" ]]; then
        echo -e " [...] ${1}/sys not mounted. Mounting now."
        echo -e "         -> $(mount -v --bind /sys sys/) \n"
    else
        echo -e " [+++] ${1}/sys is non-empty - must be already mounted. Skipping.\n"
    fi
    if [[ ! -d dev ]] || [[ -z "$(ls dev)" ]] || ! grep -q "${1}/dev" <<< "$(mount)"; then
        echo -e " [...] ${1}/dev not mounted. Mounting now."
        echo -e "         -> $(mount -v --bind /dev dev/) \n"
    else
        echo -e " [+++] ${1}/dev is non-empty - must be already mounted. Skipping.\n"
    fi
    cd - &>/dev/null
}

umount_all() {
    local bdir="$1"
    cd /
    umount -v "${bdir}/sys"
    umount -v "${bdir}/proc"
    umount -v "${bdir}/dev"
    if grep -q "${bdir}/boot" <<< "$(mount)"; then umount -v "${bdir}/boot"; fi
    if grep -q "${bdir}/home" <<< "$(mount)"; then umount -v "${bdir}/home"; fi
    if grep -q "${bdir}/root" <<< "$(mount)"; then umount -v "${bdir}/root"; fi
    if grep -q "${bdir}/var/log" <<< "$(mount)"; then umount -v "${bdir}/var/log"; fi
    if grep -q "${bdir}/var" <<< "$(mount)"; then umount -v "${bdir}/var"; fi
    if grep -q "${bdir}/usr" <<< "$(mount)"; then umount -v "${bdir}/usr"; fi
}

if (( $# < 1 )); then
    echo -e "Usage: $0 [chroot_dir]"
    echo
    echo -e "Runs post-setup commands within a newly created debootstrap chroot,"
    echo -e "to ensure a good user experience e.g. via generating and configuring"
    echo -e "locales as to prevent locale errors.\n"
    exit 1
fi

CHR_OUT="$1"
LANGUAGE=C.UTF-8
LANG=C.UTF-8
LC_ALL=C.UTF-8
LC_CTYPE=C.UTF-8

echo -e "\n >>> Generating default locale config at ${CHR_OUT}/etc/default/locale\n"
cat > "${CHR_OUT}/etc/default/locale" <<"EOF"
LANGUAGE=en_US.UTF-8
LANG=en_US.UTF-8
LC_ALL=en_US.UTF-8
LC_CTYPE=en_US.UTF-8

EOF
echo -e "\n >>> Mounting proc/sys/dev inside of ${CHR_OUT}\n"
bind_mounts "$CHR_OUT"
echo -e "\n >>> Setting up DNS in ${CHR_OUT}\n"
fix_resolve "$CHR_OUT"

echo -e "\n >>> Ensuring 'locales' is installed in ${CHR_OUT} - then cleaning up apt using autoremove + clean\n"
chroot "$CHR_OUT" /bin/bash -c 'apt update -qy; apt install -qy locales; apt autoremove -qy; apt clean -qy;'

echo -e "\n >>> Enabling en_US and en_GB in ${CHR_OUT}/etc/locale.gen\n"
sed -i "/^#.* en_US.*/s/^# //g" "${CHR_OUT}/etc/locale.gen"
sed -i "/^#.* en_GB.*/s/^# //g" "${CHR_OUT}/etc/locale.gen"

echo -e "\n >>> Running locale-gen inside of ${CHR_OUT}\n"
chroot "$CHR_OUT" /bin/bash -c 'locale-gen'

echo -e "\n >>> Generating default locale config at ${CHR_OUT}/etc/default/locale\n"
cat > "${CHR_OUT}/etc/default/locale" <<"EOF"
LANGUAGE=en_US.UTF-8
LANG=en_US.UTF-8
LC_ALL=en_US.UTF-8
LC_CTYPE=en_US.UTF-8

EOF

umount_all "$CHR_OUT"


echo -e "\n [+++] FINISHED POST-SETUP for chroot dir: $CHR_OUT \n"