#! /bin/bash

# Run R interpreter, optionally launching inside a docker container
# Launch in docker iff a file called '.rundocker' exists and contains
# the name of a valid image in the current directory

## TODO the env args here are not DRY
system_r=(env "MAKEFLAGS=-j8" /bin/R --quiet "$@")

# launch in docker if we find a .rundocker file
if [ -f ".rundocker" ]; then
    image=$(cat .rundocker)

    if ! docker info > /dev/null 2>&1; then
        echo "Docker daemon not running"
        echo "Using Systemwide R Installation"
        "${system_r[@]}"
    fi
    
    if ! docker image inspect "$image" > /dev/null 2>&1; then
        echo "Invalid image: $image"
        echo "Using Systemwide R Installation"
        "${system_r[@]}"
    fi

    # TODO what about host user's environ file and such?

    # TODO not all images have a docker user
    # start container using the docker user
    user=docker

    # start container in docker's home directory
    work_dir=/home/docker

    # mount the current host directory to docker's user home
    pwd_mnt="type=bind,source=$(pwd),target=/home/docker"

    # add X11 socket/env so we can see pretty plots
    # from here https://github.com/rocker-org/rocker-versioned/tree/master/X11
    xsock=/tmp/.X11-unix/X0
    xauth=/tmp/.docker.xauth
    touch "$xauth"
    xauth nlist "$DISPLAY" | sed -e 's/^..../ffff/' | \
        xauth -f "$xauth" nmerge -
    x11=(-v "$xsock:$xsock"
         -v "$xauth:$xauth"
         -e "XAUTHORITY=${xauth}"
         -e "DISPLAY=$DISPLAY")

    # for some reason this won't work if you aren't root
    opts=(-ti --rm -w "$work_dir" --mount "$pwd_mnt" -u 0 #--user "$user"
          "${x11[@]}")

    # TODO not all images have the same path for R
    # TODO add env vars somehow
    cmd=(/usr/local/bin/R --quiet "$@")

    # if we are in Emacs, do some special tricks to satisfy ESS
    if [[ -n "$INSIDE_EMACS" ]]; then
        # TODO do we need to pass any environmental variables?

        # ESS sends some 'source' commands to the running R process
        # after it starts; these are in the emacs user directory
        emacs_home="$XDG_CONFIG_HOME/emacs"
        emacs_mnt="type=bind,source=$emacs_home,target=$emacs_home"
        opts+=(--mount "$emacs_mnt")

        # ESS gets confused if lines are terminated with \r\n (which
        # unfortunately is the default in docker). Set the terminal
        # to not echo inputs before starting R
        docker run "${opts[@]}" "$image" /bin/sh -c "stty -echo -onlcr && ${cmd[*]}"
    else
        docker run "${opts[@]}" "$image" "${cmd[@]}"
    fi

    ## remove X11 auth file
    rm -f "$xauth"
else
    "${system_r[@]}"
fi