#!/bin/bash
set -e

: ${KERNEL_URL:="https://github.com/rancher/linux/archive/Ubuntu-3.19.0-27.29.tar.gz"}
: ${KERNEL_SHA1:="84b9bc53bbb4dd465b97ea54a71a9805e27ae4f2"}
: ${ARTIFACTS:=$(pwd)/assets}
: ${BUILD:=$(pwd)/build}
: ${CONFIG:=$(pwd)/config}
: ${DIST:=$(pwd)/dist}

DOCKER_FILE=${CONFIG}/.dockerfile

mkdir -p ${BUILD} ${DIST}

busybox_install()
{
    local conf=$1
    local bbconf=$2
    local target=$3

    if [ "$#" = "2" ]; then
        target=$2
        bbconf=
    fi

    apt-get update
    apt-get install -y build-essential wget libncurses5-dev unzip bc

    cd ${BUILD}

    local buildroot=$(ls -1 ${ARTIFACTS}/buildroot-*.tar.bz2)

    if [ ! -e "${buildroot}" ]; then
        echo "Failed to find busybox archive, found : ${buildroot}" 1>&2
        return 1
    else
        buildroot=$(basename $buildroot)
    fi

    rm -rf ${buildroot/.tar.bz2//}
    tar xvjf ${ARTIFACTS}/${buildroot}
    cd ${buildroot/.tar.bz2//}

    cp $conf .config
    if [ -n "$bbconf" ]; then
        cp $bbconf package/busybox/
    fi
    make oldconfig
    make

    cp output/images/rootfs.tar $target
}

write_base()
{
    if [ "${BASE_WRITTEN}" = "true" ]; then
        return
    fi

    mkdir -p $(dirname ${DOCKER_FILE})

    cat > ${DOCKER_FILE} << EOF
FROM ${DOCKER_BASE:=ubuntu:14.04.2}
ENV TERM xterm
WORKDIR /source
EOF

    BASE_WRITTEN=true
}

run()
{
    local content

    while [ $# -gt 1 ]; do
        case $1 in
            --assets)
                shift 1
                if [ -e "$1" ]; then
                content="$content\nCOPY $1 /source/$1"
                else
                    content="$content\nCOPY $1 /source/"
                fi
                ;;
        esac

        shift 1
    done

    write_base
    if [ -n "$content" ]; then
        echo -e "$content" >> ${DOCKER_FILE}
    fi
    if [ -n "$1" ]; then
    echo -e "\nCOPY $1 /source/$1" >> ${DOCKER_FILE}
    echo -e "RUN /source/$1" >> ${DOCKER_FILE}
    fi

    if [ "$RUN_EXEC" = "true" ]; then
        $1
    fi
}

finish()
{
    if [ "$RUN_EXEC" = true ]; then
        return 0
    fi
    local cmd="docker build -t ${DOCKER_IMAGE} -f ${DOCKER_FILE} ."
    echo Running $cmd
    echo Pwd $(pwd)

    cat ${DOCKER_FILE}

    $cmd
}

reset_docker_build()
{
    BASE_WRITTEN=false
}

check()
{
    local hash=$1
    local file=$2

    if [ ! -e "$file" ]; then
        return 1
    fi

    CURRENT=$(sha1sum $file | awk '{print $1}')

    [ "$hash" = "$CURRENT" ]
}

download()
{
    mkdir -p ${ARTIFACTS}

    local url=$2
    local file=${ARTIFACTS}/$(basename $2)
    local hash=$1

    if ! check $hash $file; then
        curl -sL $url > $file
    fi

    if ! check $hash $file; then
        echo "ERROR: $file does not match checksum $hash, got $CURRENT" 1>&2
        return 1
    fi
}