#!/bin/bash
# This shell script used to fetch debian root file system

# this project absolute path
PRJ_PATH=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)

# the target board name and ARCH(armel/armhf/arm64)
BOARD=igkboard
ARCH=armhf
ARCH=arm64

# Debian 11 (bullseye)
CODENAME=bullseye
VERSION=11

# Debian 12 (bookworm)
CODENAME=bookworm
VERSION=12

# rootfs directory name
ROOTFS_DIR=rootfs-debian-$CODENAME

# rootfs configuration
DEF_PASSWD=12345

# shell script will exit once get command error
set -e

#+-------------------------+
#| Shell script functions  |
#+-------------------------+

function pr_error() {
    echo -e "\033[40;31m $1 \033[0m"
}

function pr_warn() {
    echo -e "\033[40;33m $1 \033[0m"
}

function pr_info() {
    echo -e "\033[40;32m $1 \033[0m"
}

# Debian 12 depends on the new keyring
# https://packages.debian.org/sid/all/debian-archive-keyring/download
function update_keyring()
{
    debname=debian-archive-keyring
    debversion=2023.3

    set +e
    dpkg -l $debname > /dev/null 2>&1
    if [ $? == 0 ] ; then
        dpkg -s debian-archive-keyring | grep Version: | grep $debversion > /dev/null 2>&1
        if [ $? != 0 ] ; then
            pr_info "updating $debname"
            apt purge -y $debname
        else
            pr_info "$debname is latest"
            return;
        fi
    fi
    set -e

    pr_info "install $debname now"
    wget http://ftp.us.debian.org/debian/pool/main/d/$debname/${debname}_${debversion}_all.deb > /dev/null
    dpkg -i ${debname}_${debversion}_all.deb
    rm -f ${debname}_${debversion}_all.deb
}

function do_install()
{
    pr_warn "\ninstall system tools"

    update_keyring

    debootstrap --version > /dev/null 2>&1
    if [ $? == 0 ] ; then
       pr_info "system tools installed already"
       return ;
    fi

    apt install binfmt-support qemu qemu-user-static debootstrap
}

function do_fetch()
{
    pr_warn "\ndebootstrap fetch"

    if [ -f ${ROOTFS_DIR}/bin/bash ] ; then
       pr_info "debain rootfs fetched already"
       return ;
    fi
    debootstrap --arch=${ARCH} --foreign ${CODENAME} ${ROOTFS_DIR} http://ftp.debian.org/debian/

    cp -f /usr/bin/qemu-arm-static ${ROOTFS_DIR}/usr/bin/
    DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true LC_ALL=C LANGUAGE=C LANG=C chroot ${ROOTFS_DIR} debootstrap/debootstrap --second-stage
    DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true LC_ALL=C LANGUAGE=C LANG=C chroot ${ROOTFS_DIR} dpkg --configure -a
    rm -f ${ROOTFS_DIR}/usr/bin/qemu-arm-static
}

function modify_rootfs()
{
    pr_warn "\nmodify rootfs environment"

    # update hostnmae and issue
    echo $BOARD > ${ROOTFS_DIR}/etc/hostname
    echo "Debian GNU/Linux $VERSION \n \l, default password '$DEF_PASSWD'" > ${ROOTFS_DIR}/etc/issue

    # update dns server
    echo "nameserver 223.5.5.5" > ${ROOTFS_DIR}/etc/resolv.conf
    echo "nameserver 114.114.114.114" >> ${ROOTFS_DIR}/etc/resolv.conf

    set +e
    # add ls alias for display with color
    grep "color=auto" ${ROOTFS_DIR}/etc/profile > /dev/null 2>&1
    if [ $? != 0 ] ; then
       echo "alias ls='ls --color=auto'" >> ${ROOTFS_DIR}/etc/profile
    fi

    grep "^PermitRootLogin" ${ROOTFS_DIR}/etc/ssh/sshd_config > /dev/null 2>&1
    if [ $? != 0 ] ; then
       echo "PermitRootLogin yes" >> ${ROOTFS_DIR}/etc/ssh/sshd_config
    fi
    set -e
}

function do_conf()
{
    EXTRA_APPS="vim net-tools network-manager tree file parted locales lsb-release tzdata wireless-tools openssh-server"

    pr_warn "\ndebootstrap configure"

    cp -f /usr/bin/qemu-arm-static ${ROOTFS_DIR}/usr/bin/
    DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true LC_ALL=C LANGUAGE=C LANG=C chroot ${ROOTFS_DIR} apt update
    DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true LC_ALL=C LANGUAGE=C LANG=C chroot ${ROOTFS_DIR} apt install -y ${EXTRA_APPS}
    DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true LC_ALL=C LANGUAGE=C LANG=C chroot ${ROOTFS_DIR} sh -c "echo root:${DEF_PASSWD} | chpasswd"
    rm -f ${ROOTFS_DIR}/usr/bin/qemu-arm-static

    modify_rootfs
}

function do_pack()
{
    pr_warn "\npackage $ROOTFS_DIR"

    cd $PRJ_PATH/$ROOTFS_DIR
    tar -cJf ../$ROOTFS_DIR.tar.xz *
}

#+-------------------------+
#| Shell script body start |
#+-------------------------+

if [ `id -u` != 0 ] ; then
   pr_error "ERRROR: This shell script must excuted as root privilege."
   exit 0;
fi

do_install

do_fetch

do_conf

do_pack