#!/bin/bash
set -e

## build ARGs
NCPUS=${NCPUS:--1}

JULIA_VERSION=${1:-${JULIA_VERSION:-latest}}

# a function to install apt packages only if they are not installed
function apt_install() {
    if ! dpkg -s "$@" >/dev/null 2>&1; then
        if [ "$(find /var/lib/apt/lists/* | wc -l)" = "0" ]; then
            apt-get update
        fi
        apt-get install -y --no-install-recommends "$@"
    fi
}

ARCH_LONG=$(uname -p)
ARCH_SHORT=$ARCH_LONG

if [ "$ARCH_LONG" = "x86_64" ]; then
    ARCH_SHORT="x64"
fi

apt_install wget

install2.r --error --skipmissing --skipinstalled -n "$NCPUS" \
    yaml \
    JuliaCall \
    JuliaConnectoR

# Get the latest Julia version by using R and the R yaml package.
if [ "$JULIA_VERSION" = "latest" ]; then
    # shellcheck disable=SC2016
    JULIA_VERSION=$(Rscript -e '
js <- yaml::read_yaml("https://julialang-s3.julialang.org/bin/versions.json")
versions <- names(js)
is_stable <- unlist(Map(function(x) x$stable, js))
latest_version <- sort(versions[is_stable], decreasing = TRUE)[1]
cat(latest_version)
')
fi

JULIA_MINOR_VERSION=${JULIA_VERSION%.*}

# Download Julia and create a symbolic link.
wget "https://julialang-s3.julialang.org/bin/linux/${ARCH_SHORT}/${JULIA_MINOR_VERSION}/julia-${JULIA_VERSION}-linux-${ARCH_LONG}.tar.gz"
mkdir /opt/julia
tar zxvf "julia-${JULIA_VERSION}-linux-${ARCH_LONG}.tar.gz" -C /opt/julia --strip-components 1
rm -f "julia-${JULIA_VERSION}-linux-${ARCH_LONG}.tar.gz"
ln -s /opt/julia/bin/julia /usr/local/bin/julia

julia --version

# Clean up
rm -rf /var/lib/apt/lists/*
rm -rf /tmp/downloaded_packages