#!/usr/bin/env bash

ALPINE="https://dl-cdn.alpinelinux.org/alpine/v3.20/releases/x86_64/alpine-minirootfs-3.20.3-x86_64.tar.gz"
CHROOTDIR="./alpine_chroot"

log()
{
    case "$2" in
        error)
            printf "\e[1m\e[31mERROR:\e[0m \e[1m%s\e[0m\n" "$1">&2;;
        internal)
            printf "\e[1m\e[96m  >>\e[0m \e[1m%s\e[0m\n" "$1">&2;;
        ierror)
            printf "\e[1m\e[31m  >>\e[0m \e[1m%s\e[0m\n" "$1">&2;;
        *)
            printf "\e[1m\e[92m>>>\e[0m \e[1m%s\e[0m\n" "$1">&2;;
    esac
}

mkdir_if_not_exists()
{
   [ -d "$1" ] && return 0
   [ -f "$1" ] && rm -f "$1"
   mkdir "$1"
}

umount_if_mouted()
{   
    [ ! -d "$1" ] && return 0
    if grep -qs "$(realpath "$1")" /proc/mounts; then
        umount "$1"
        return $?
    else
        return 0
    fi
}

require ()
{
    which "$1" > /dev/null 2>&1 ||
    {
        log "$1 not found" error
        exit 1
    }
}

# shellcheck disable=SC2161
# shellcheck disable=SC2086
arguments() {
    while [[ $# -gt 0 ]]; do
        opt="$1"

        shift

        case "$(echo ${opt} | tr '[:upper:]' '[:lower:]')" in
            install)
                install_chroot 
                break 2 ;;

            remove)
                remove_chroot 
                break 2 ;;

            chroot)
                chroot_into
                break 2 ;;

            -h | -help | --help)
                usage ;;
        
            *)
                log "Unknown option: $opt" error
                break 2 ;;
        esac
    done
}

usage() {
    log "Usage commands:"

    cat <<EOF
    # Help screen (this)
    $0 --help or $0 -h

    # Setup build chroot
    $0 install

    # Remove build chroot
    $0 uninstall

    # Chroot into
    $0 chroot
EOF
    exit 0
}

# shellcheck disable=SC2317
_shutdown()
{
    detach_chroot
    if [ -z ${1+x} ]; then
        exit 0
    else
        exit "$1"
    fi
}

sigterm_handler()
{
    sig=$?
    printf "\e[1m\e[31m>>\e[0m \e[1m%s\e[0m\n" "Shutdown signal received."
    _shutdown $sig
}

trap 'trap " " SIGINT SIGTERM SIGHUP; kill 0; wait; sigterm_handler' SIGINT SIGTERM SIGHUP


# Chroot functions
require "lsof"
require "tar"
require "gzip"
require "wget"

setup_inet()
{
    [ ! -d "$CHROOTDIR" ] && {
        log "Rootdir [$CHROOTDIR] does not exists" ierror
        return 2
    }
    echo "nameserver 1.1.1.1" > "$CHROOTDIR/etc/resolv.conf"
    echo "makelnichroot" > "$CHROOTDIR/etc/hostname"
    echo "127.0.0.1 localhost" > "$CHROOTDIR/etc/hosts"
}

prepare_chroot()
{
    [ ! -d "$CHROOTDIR" ] && {
        log "Rootdir [$CHROOTDIR] does not exists" ierror
        return 2
    }

    export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:\$PATH
    
    mount --bind "$CHROOTDIR" "$CHROOTDIR"
    mount -t proc proc "$CHROOTDIR/proc"
    mount -t sysfs sysfs "$CHROOTDIR/sys"
    mount -t devtmpfs devtmpfs "$CHROOTDIR/dev"
    mount -t devpts devpts "$CHROOTDIR/dev/pts"
    mount -t tmpfs devshm "$CHROOTDIR/dev/shm"
    
    if uname -m | grep -q aarch64 || [ -f "/proc/sys/fs/binfmt_misc/qemu-aarch64" ]; then
        log "Cancel qemu-aarch64-static register"
    else

        # shellcheck disable=SC2028
        echo ':aarch64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:'"$(realpath $CHROOTDIR/qemu-aarch64-static):PF" > /proc/sys/fs/binfmt_misc/register 2> /dev/null || true
         
        # shellcheck disable=SC2028
        echo ':aarch64ld:M::\x7fELF\x02\x01\x01\x03\x00\x00\x00\x00\x00\x00\x00\x00\x03\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:'"$(realpath $CHROOTDIR/qemu-aarch64-static):PF" > /proc/sys/fs/binfmt_misc/register 2> /dev/null || true
    fi
}

detach_chroot()
{
    [ ! -d "$CHROOTDIR" ] && {
        log "Rootdir [$CHROOTDIR] does not exists" ierror
        return 2
    }
    
    umount_if_mouted "$CHROOTDIR/sys"
    umount_if_mouted "$CHROOTDIR/dev/pts"
    umount_if_mouted "$CHROOTDIR/dev/shm"
    umount_if_mouted "$CHROOTDIR/dev"
    umount_if_mouted "$CHROOTDIR/proc"
    umount_if_mouted "$CHROOTDIR"
    
    if [ -f "/proc/sys/fs/binfmt_misc/aarch64" ]; then
        echo -1 > /proc/sys/fs/binfmt_misc/aarch64 2> /dev/null
    fi
    if [ -f "/proc/sys/fs/binfmt_misc/aarch64ld" ]; then
        echo -1 > /proc/sys/fs/binfmt_misc/aarch64ld 2> /dev/null
    fi
}

install_chroot()
{
    [ -d "$CHROOTDIR" ] && {
        log "Chroot already installed" error
        exit 1
    }
    mkdir "$CHROOTDIR"
    [ ! -f "./alpine.tar.gz" ] && {
        log "Downloading alpine rootfs tarball"
        wget -q --show-progress "$ALPINE" -O "./alpine.tar.gz" || {
            ec=$?
            log "Failed to download rootfs tarball" error
            exit "$ec"
        }
    }
    
    log "Extracting alpine rootfs tarball"
    tar -xzf "./alpine.tar.gz" -C "$CHROOTDIR/" || {
        log "Failed to extract rootfs" error
    }
    setup_inet
    prepare_chroot || {
        log "Failed to setup chroot" error
        exit 1
    }
    log "Updating apk repos"
    chroot "$CHROOTDIR" apk update || {
        log "Failed to update apk repos" error
        exit 1
    }
    log "Installing pakages"
    chroot "$CHROOTDIR" apk add shadow fish bash git debootstrap pixz losetup rsync pv wget e2fsprogs libarchive-tools coreutils || {
        log "Failed to install packages" error
        exit 1
    }
    chroot "$CHROOTDIR" chsh -s /usr/bin/fish root
    log "Cloning makelni repo"
    chroot "$CHROOTDIR" git clone "https://git.timoxa0.su/timoxa0/makelni.git" /makelni || {
        log "Failed to clone makelni repo" error
        exit 1
    }
    log "Installing qemu-aarch64-static"
    {
        wget  -q --show-progress -N https://github.com/multiarch/qemu-user-static/releases/download/v7.2.0-1/qemu-aarch64-static -O "$CHROOTDIR/qemu-aarch64-static" && chmod 755 "$CHROOTDIR/qemu-aarch64-static"
    } || {
        log "Failed to install qemu-aarch64-static" error
        exit 1
    }
    detach_chroot || {
        log "Failed to detach chroot" error
        exit 1
    }
    log "Done!"
    exit 0
}

remove_chroot()
{
    [ ! -d "$CHROOTDIR" ] && {
        log "Chroot not installed" error
        exit 1
    }
    detach_chroot || {
        log "Failed to umount chroot" error
        exit 1
    }
    log "Done!"
    rm -rf "${CHROOTDIR:?}/"
}

chroot_into()
{
    prepare_chroot || {
        log "Failed to setup chroot" error
        exit 1
    }
    chroot "$CHROOTDIR" /usr/bin/fish
    detach_chroot || {
        log "Failed to detach chroot" error
        exit 1
    }
}