#!/bin/bash

## Set NO_DOCKER_RESTART to prevent restarting docker after upgrade.
## Set ALLOW_DOCKER_CHANGE to allow change your docker version.
## Set TARGET_DOCKER_VERSION to force a version (use cautiously!)
exname=${0##*/}
if [ "$exname" == "bash" ]; then
    ## probably launched through ``charm``
    if [ -n "$CHARM_NAME" ]; then
        exname="charm/${CHARM_NAME}"
    else
        echo "Error: cannot determine script name" >&2
        echo "  Please either run this script directly or through \`\`charm\`\`" >&2
        exit 1
    fi
fi
for bin in apt-get grep dpkg file lsb_release; do
    if ! type -p "$bin" >/dev/null; then
        echo "Error: \`\`$bin\`\` not found" >&2
        exit 1
    fi
done

STATIC_DOCKER_URL="https://download.docker.com/linux/static/stable/x86_64"

distro=$(lsb_release -is)
release=$(lsb_release -rs)
unsupported=
target_version=${TARGET_DOCKER_VERSION:-24}

declare -A distro_supported_version=(
    [Debian]="9 10 11 12"
    [Ubuntu]="20.04 22.04"
)


if [ "$distro" == "Debian" ]; then
    release=${release%%.*}
fi

if [ -z "${distro_supported_version[$distro]}" ] ||
       [[ " ${distro_supported_version[$distro]} " != *" $release "* ]]; then
    echo "Warning: possibly unsupported distribution/version $distro $release" >&2
    echo "  Supported distributions and versions:" >&2
    for dist in "${!distro_supported_version[@]}"; do
        echo -n "  $dist: " >&2
        ## comma separated list
        versions="${distro_supported_version[$dist]}"
        versions="${versions// /, }"
        echo "$versions" >&2
    done
    unsupported=1
fi


version_gt() { test "$(echo -e "$@" | tr " " "\n" | sort -V | head -n 1)" != "$1"; }


just_installed=
if ! docker_bin=$(type -p docker); then
    echo "Installing docker..."
    type -p curl >/dev/null ||
        apt-get install -y curl </dev/null

    curl -sSL https://get.docker.io | sh || exit 1
    just_installed=1
fi

is_static_docker() {
    local docker_bin=$1
    # check if this is a link
    [[ -L "$docker_bin" ]] && docker_bin=$(readlink -f "$docker_bin")

    ## XXXvlab: We need to handle a special case that happens on some systems
    ## having installed 0k-docker package that divert the docker
    ## binary to a shell script that then calls docker

    ## check if this a shell script (using file)
    if file "$docker_bin" | grep -q shell; then
        echo "INFO: using a shell script for docker in '$docker_bin'" >&2

        ## is the script mentioning "/usr/bin/docker" ?
        if grep -q '/usr/bin/docker' "$docker_bin"; then
            echo "INFO: docker script is calling '/usr/bin/docker'" >&2
            docker_bin=/usr/bin/docker
        else
            echo "ERROR: cannot determine docker binary from script '$docker_bin'" >&2
            return 1
        fi
    fi

    [[ "$(ldd "$docker_bin")" == *not\ a\ dynamic\ executable* ]]
}

is_static_docker_install=0
if is_static_docker "$docker_bin"; then
    echo "INFO: docker version is static" >&2
    is_static_docker_install=1
fi

read docker_client_version docker_server_version < <(
    docker version --format '{{.Client.Version}} {{.Server.Version}}'
)

mismatch_client_server=
## issue a warning if client and server versions are different
if [ "$docker_client_version" != "$docker_server_version" ]; then
    echo "WARNING: docker client and server versions differ!" >&2
    echo "  client: $docker_client_version" >&2
    echo "  server: $docker_server_version" >&2
    mismatch_client_server=1
fi

distrib_available_versions=$(apt-cache madison docker-ce | cut -f 2 -d "|" | sort -V)

deb_version_to_docker_version() {
    local deb_version=$1
    local docker_version
    docker_version="${deb_version%%~*}"
    docker_version="${docker_version%-*}"
    docker_version="${docker_version#*:}"
    echo "$docker_version"
}

declare -A docker_version_to_deb_version=()
for deb_version in $distrib_available_versions; do
    docker_version=$(deb_version_to_docker_version "$deb_version")
    docker_version_to_deb_version["$docker_version"]="$deb_version"
done

## expand docker version to one that is available in deb on the repository
candidate_deb_target_version=$(
    echo "${!docker_version_to_deb_version[@]}" |
        tr ' ' '\n' | grep "^${target_version}[^\d]" | sort -V | tail -n 1
)

if [ -z "$candidate_deb_target_version" ]; then
    ## No deb package seems to satisfy the target version

    # Fetch the HTML content and filter out the versions
    available_docker_static_versions=$(
        curl -sL "$STATIC_DOCKER_URL" | grep -oP 'docker-\d+\.\d+\.\d+\.tgz' |
            cut -d'-' -f2 | cut -d'.' -f1,2,3 | sort -uV
    )
    candidate_target_version=$(
        echo "$available_docker_static_versions" |
            grep "^${target_version}" | sort -V | tail -n 1
    )
    if [ -z "$candidate_target_version" ]; then
        echo "ERROR: no docker version matching '${target_version}' available" >&2
        echo "  Available versions for $distro $release:" >&2
        all_versions=(
            $(
                {
                    echo "${!docker_version_to_deb_version[@]}" | tr ' ' '\n'
                    echo "$available_docker_static_versions"
                } | cut -f 1,2 -d. | sort -uV
            )
        )
        for version in "${all_versions[@]}"; do
            candidate_deb_target_version=$(
                echo "${!docker_version_to_deb_version[@]}" |
                    tr ' ' '\n' | grep "^${version}[^\d]" | sort -V | tail -n 1
            )
            if [ -n "$candidate_deb_target_version" ]; then
                msg=" with deb"
            else
                msg=" with static version"
            fi
            printf "  - %-10s %s\n" "$version" "$msg" >&2
        done
        echo >&2
        echo "  1) You may need to contact your system administrator to upgrade this script." >&2
        echo "  2) Meanwhile, if you know what you are doing, you can set yourself a target version" >&2
        echo "     by setting TARGET_DOCKER_VERSION." >&2
        exit 1
    fi
    echo "INFO: target docker version $target_version is not supported by distrib" >&2
    echo "  Binary static version $candidate_target_version of docker will be used" >&2

    max_docker_version_available=
    for docker_version in ${!docker_version_to_deb_version[@]}; do
        if version_gt "$docker_version" "$target_version"; then
            continue
        fi
        if version_gt "$docker_version" "$max_docker_version_available"; then
            max_docker_version_available="$docker_version"
        fi
    done
    if [ -z "$max_docker_version_available" ]; then
        ## use lowest version available
        echo "INFO: no inferior docker version available in deb repository" \
             "to satisfy target version $target_version" >&2
        max_docker_version_available=$(
            echo "${!docker_version_to_deb_version[@]}" |
                tr ' ' '\n' |
                sort -V |
                head -n 1
                                    )
        if [ -z "$max_docker_version_available" ]; then
            echo "ERROR: no docker version available in deb repository" >&2
            exit 1
        fi
        echo "INFO: using lowest docker version available in deb repository" >&2
    fi

    echo "INFO: closest docker version supported by $distro $release:" \
         "$(deb_version_to_docker_version "$max_docker_version_available")" >&2

    target_deb_version="${docker_version_to_deb_version[$max_docker_version_available]}"
    target_version=$candidate_target_version
    echo "INFO: target maximal deb version: '$target_deb_version' (docker version: $(
    deb_version_to_docker_version "$target_deb_version"
))" >&2
    need_static=1
else
    ## a deb package is available to satisfy the target version

    target_deb_version="${docker_version_to_deb_version[$candidate_deb_target_version]}"
    target_version=$candidate_deb_target_version
    echo "INFO: target docker deb version: '$target_deb_version' " \
         "(docker version: $candidate_deb_target_version)" >&2
    need_static=0
fi

current_docker_ce_package_version=$(
    dpkg -s docker-ce | grep '^Version:' | cut -f 2 -d ' '
)
current_docker_ce_cli_package_version=$(
    dpkg -s docker-ce-cli | grep '^Version:' | cut -f 2 -d ' '
)

## Install deb version if required

if [ -z "$mismatch_client_server" ] &&
       [[ "$current_docker_ce_cli_package_version" == "$target_deb_version" ]] &&
       [[ "$current_docker_ce_package_version" == "$target_deb_version" ]]; then
    if [[ "$need_static" == 0 ]] && [[ "$is_static_docker_install" == 0 ]]; then
        ## current and target versions match, no upgrade needed
        echo "INFO: recommended target deb docker version $target_version already installed" >&2
        echo "  To set a different target version, set TARGET_DOCKER_VERSION" >&2
        exit 0
    fi
    ## Check static version and current version matches the target_version
    if [[ "$need_static" == 1 ]] && [[ "$is_static_docker_install" == 1 ]] &&
           [[ "$target_version" == "$docker_server_version" ]]; then
        ## current and target versions match, no upgrade needed
        echo "INFO: recommended target deb and static docker version $target_version already installed" >&2
        echo "  To set a different target version, set TARGET_DOCKER_VERSION" >&2
        exit 0
    fi
fi

## Should we skip upgrade?
if [ -z "$just_installed" ] && [ -z "$ALLOW_DOCKER_CHANGE" ]; then
    echo "WARN: You are not on the recommended setup (target docker version: $target_version)" >&2
    if [[ "$current_docker_ce_package_version" != "$target_deb_version" ]]; then
        echo "INFO: docker-ce recommended deb version available" >&2
        echo "  current: $current_docker_ce_package_version" >&2
        echo "  recommended: $target_deb_version" >&2
    fi
    if [[ "$current_docker_ce_cli_package_version" != "$target_deb_version" ]]; then
        echo "INFO: docker-ce-cli recommended deb version available" >&2
        echo "  current: $current_docker_ce_cli_package_version" >&2
        echo "  recommended: $target_deb_version" >&2
    fi
    if [[ "$need_static" != "$is_static_docker_install" ]]; then
        if [[ "$need_static" == 1 ]]; then
            echo "INFO: docker static version recommended to achieved version $target_version" >&2
        else
            echo "INFO: docker deb version recommended, fulfilled by deb version $target_deb_version" >&2
        fi
    fi
    echo "INFO: To change version, run this script with ALLOW_DOCKER_CHANGE=1" >&2
    exit 0
fi

install_static_version() {
    local docker_version="$1"
    local url="$STATIC_DOCKER_URL/docker-${docker_version}.tgz"
    local service

    ## ensure shadowlocal is set up

    if ! [ -e /etc/profile.d/shadowlocal.sh ]; then
        cat <<EOF > /etc/profile.d/shadowlocal.sh || return 1
## add /opt/merge/bin to PATH if not already there
if [[ ":$PATH:" != *":/opt/merge/bin:"* ]]; then
    export PATH="/opt/merge/bin:\$PATH"
fi
EOF
    fi

    if ! [ -e /etc/systemd/system.conf.d/shadowlocal.sh ]; then
        mkdir -p /etc/systemd/system.conf.d
        cat <<EOF > /etc/systemd/system.conf.d/shadowlocal.sh || return 1
[Manager]
DefaultEnvironment=PATH=/opt/merge/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
EOF
        systemctl daemon-reload
    fi


    ## install in /opt/apps/docker

    local base_install=/opt/apps/docker
    if [ -d "${base_install}" ]; then
        if [ -d "${base_install}".old ]; then
            rm -rfv "${base_install}".old || return 1
        fi
        mv -v "${base_install}"{,.old} || return 1
    fi
    echo "Fetching $url" >&2
    mkdir -p "${base_install}"/bin &&
    (
        set -o pipefail
        curl -sSL "$url" | tar -xz -C "${base_install}"/bin --strip-components=1
    ) || return 1

    for service in docker:dockerd containerd:containerd; do
        bin=${service#*:}
        service=${service%%:*}
        ## get the original ExecStart line
        if ! orig_exec_start=$(grep -m 1 '^ExecStart=' /lib/systemd/system/${service}.service); then
            echo "ERROR: cannot find ExecStart in /lib/systemd/system/${service}.service" >&2
            return 1
        fi
        ## override the ExecStart line by changing only the binary
        new_exec_start="$(echo "$orig_exec_start" | sed -r 's|ExecStart=[^ ]+|/opt/merge/bin/'"${bin}"'|')"
        mkdir -p "${base_install}/etc/systemd/system/${service}.service.d"
        mkdir -p "/etc/systemd/system/${service}.service.d"
        cat <<EOF > "${base_install}/etc/systemd/system/${service}.service.d/docker-static.conf"
[Service]
ExecStart=
ExecStart=$new_exec_start
EOF
        ## override systemd config
        ln -sf /opt/merge/etc/systemd/system/docker.service.d/docker-static.conf \
           /etc/systemd/system/docker.service.d/docker-static.conf
    done
    ## Create symlinks to /opt/merge/bin with /opt/apps/docker/bin/*
    shadowlocal add docker || return 1 ## requires kal-scripts

    if [ -z "$NO_DOCKER_RESTART" ]; then
        systemctl daemon-reload &&
            service containerd restart &&
            service docker restart
    fi
}

uninstall_static_version() {
    local base_install=/opt/apps/docker
    if [ -d "${base_install}" ]; then
        rm -rfv "${base_install}" || return 1
    fi
    find -L "/opt/merge/bin" -maxdepth 1 -type l -ilname "/opt/apps/docker"/\* -exec echo rm -v {} \; || return 1
    for service in docker containerd; do 
        rm -vf "/etc/systemd/system/${service}.service.d/docker-static.conf" || return 1
    done
}

## if currently static and it doesn't need it anymore, uninstall
if [[ "$is_static_docker_install" == 1 ]] && [[ "$need_static" == 0 ]]; then
    echo "INFO: uninstalling static docker version" >&2
    uninstall_static_version || exit 1
fi

## if current docker-ce debian version is not the target debian version, install it
if [[ "$current_docker_ce_package_version" != "$target_deb_version" ]]; then
    echo "INFO: installing docker-ce deb version $target_deb_version" >&2
    apt-get install -y --allow-downgrades \
            docker-ce="$target_deb_version" </dev/null || exit 1
    if [ -z "$NO_DOCKER_RESTART" ]; then
        systemctl daemon-reload &&
            service containerd restart &&
            service docker restart
    fi
fi

## if current docker-ce-cli debian version is not the target debian version, install it
if [[ "$current_docker_ce_cli_package_version" != "$target_deb_version" ]]; then
    echo "INFO: installing docker-ce-cli deb version $target_deb_version" >&2
    apt-get install -y --allow-downgrades \
            docker-ce-cli="$target_deb_version" </dev/null || exit 1
fi

## if we need a static version and it is not installed, install it
## and if we need a static version and it is installed but not the target version, install it
if [[ "$need_static" == 1 ]] && [[ "$is_static_docker_install" == 0 || "$target_version" != "$docker_server_version" ]]; then
    echo "INFO: installing static docker version $target_version" >&2
    install_static_version "$target_version" || exit 1
fi