#!/bin/bash -eu
# vi: ts=4 expandtab
#
# Generate the compressed root directory for WSL manually.
# Type "plain" unfortunately does not execute lb_binary_* helpers.

case $ARCH in
    amd64|arm64)
        ;;
    *)
        echo "WSL root tarballs are not generated for $ARCH."
        exit 0;;
esac

## remove attributes not supported by WSL's tar
setfattr -x system.posix_acl_access chroot/var/log/journal
setfattr -x system.posix_acl_default chroot/var/log/journal

# is_lts returns true if the given release is a LTS.
is_lts() {
    release_version="$1"
    year=$(echo "${release_version}" | cut -d'.' -f1)
    month=$(echo "${release_version}" | cut -d'.' -f2)

    if [ "${month}" != "04" ]; then
        echo "false"
        return
    fi

    last_year_digit="${year: -1}"
    if [ $((last_year_digit % 2)) -ne 0 ]; then
        echo "false"
        return
    fi

    echo "true"
}

# is_current_lts_release returns for a given lts release is we are in the year preceeding or 2 years succeeding a release.
# Note that it will mark as "current" a lts release zeven if there is a next one released until the end of the +2 year.
is_current_lts_release() {
    release_version="$1"
    current_year="$2"
    year=$(echo "$release_version" | cut -d'.' -f1)

    if [ $(is_lts "${version}") != "true" ]; then
        echo "false"
        return
    fi

    if [ "$((year - 1))" -le "${current_year}" ] && [ "${current_year}" -le "$((year + 2))" ]; then
        echo "true"
        return
    fi

    echo "false"
}

# Function to check if a version is a development release
is_development_release() {
    local version=$1
    local current_year=$2
    local current_month=$3
    local year=$(echo $version | cut -d. -f1)
    local month=$(echo $version | cut -d. -f2)

    if [ "${year}" -gt "${current_year}" ] || ([ "${year}" -eq "${current_year}" ] && [ "${month}" -gt "${current_month}" ]); then
        echo "true"
        return
    fi

    echo "false"
}

# create_archive_with_upgrade_policy modifies the prompting upgrade policy
# and create a separate rootfs for this upgrade policy, named after app_id.
# The reason not using just tar .. -C chroot . is that using '.' was found
# not working once and checking if using the simpler command is safe needs
# verification of the app installation on all Windows 10 builds we support
# with WSL.
create_archive_with_upgrade_policy() {
    upgrade_policy=$1
    app_id=$2

    cd chroot
    sed -i "s#Prompt=.*#Prompt=${upgrade_policy}#" ./etc/update-manager/release-upgrades
    tar --xattrs --sort=name -czf ../livecd.${app_id}.ubuntu-wsl.rootfs.tar.gz *
    cd ..
}

# release-upgrader configuration, 3 cases:
# Ubuntu-Version: never
# ubuntu (latest LTS): lts
# preview (current dev): normal

# We produce the following tar with this policy:
# Any XY.04, where Y is pair: upgrade-never
# Any XY.04, where Y is pair and current year is between XY-1 to XY+2 (included): upgrade-lts
# Any releases, where XY.04, where current date is comprised within 6 months.

version=$(chroot chroot lsb_release --release --short)

if [ $(is_lts "${version}") = "true" ]; then
    create_archive_with_upgrade_policy "never" "ubuntu${version}lts"
fi

if [ $(is_current_lts_release "${version}" $(date +"%y")) = "true" ]; then
    create_archive_with_upgrade_policy "lts" "ubuntu"
fi

if [ $(is_development_release "${version}" $(date +"%y") $(date +"%m")) = "true" ]; then
    create_archive_with_upgrade_policy "normal" "ubuntupreview"
fi


# Remove initial ext4-formatted fs
rm -f binary/boot/filesystem.ext4