#!/usr/bin/env bash

PYODIDE_IMAGE_REPO="pyodide"
PYODIDE_IMAGE_TAG="20220525-py310-chrome102-firefox100"
PYODIDE_PREBUILT_IMAGE_TAG="0.20.0"
DEFAULT_PYODIDE_DOCKER_IMAGE="${PYODIDE_IMAGE_REPO}/pyodide-env:${PYODIDE_IMAGE_TAG}"
DEFAULT_PYODIDE_SYSTEM_PORT="none"
DOCKER_COMMAND="/bin/bash"
DOCKER_INTERACTIVE="--interactive"


USER_HOME="/src/.docker_home"
USER_NAME="$(id -u -n)"
USER_ID="$(id -u)"
USER_GID="$(id -g)"
USER_COMMENT_FIELD="${USER_NAME} pyodide user alias"
USER_INTERPRETER="/sbin/nologin"
USER_FLAG=("--user" "$USER_ID:$USER_GID")
HEALTHCHECK_MESSAGE="Done initialization"

set -eo pipefail


function usage() {
  cat > /dev/stdout <<EOF
Usage: run_docker [OPTIONS] [COMMAND] [ARG...]

Runs COMMAND in a new Pyodide docker container. If no COMMAND is provided, starts a bash
shell in the container.

Options:
  -h, --help                  Show this information and exit.
  --pre-built                 Use the prebuilt Pyodide image.
                              This is ignored if the env var PYODIDE_DOCKER_IMAGE is set.
  -p, --port <port>           System port to which to forward.
                              This is ignored if the env var PYODIDE_SYSTEM_PORT is set.
                              If set to 'none', docker instance will not bind to any port.
  --non-interactive           Run docker without the --interactive flag.
                              Useful for running in headless mode on CI server.
  --root                      Run as root user inside the container

Prerequisites:
  Docker has to be set up on your system.
EOF
}

function error() {
  usage
  exit 255
}

while [[ $# -gt 0 ]]
do
  key="$1"
  case $key in
      -h|--help)
        usage
        exit 0
      ;;
      --pre-built)
        if [[ -n ${PYODIDE_DOCKER_IMAGE} ]]; then
          echo "WARNING: will use the env var PYODIDE_DOCKER_IMAGE=${PYODIDE_DOCKER_IMAGE},
          the flag --pre-built has no effect"
        fi
        DEFAULT_PYODIDE_DOCKER_IMAGE="pyodide/pyodide:${PYODIDE_PREBUILT_IMAGE_TAG}"
        shift
      ;;
      -p|--port)
        if [ "$#" -lt 2 ]; then
          >&2 echo "port cannot be empty"
          error
        fi
        if [[ -n ${PYODIDE_SYSTEM_PORT} ]]; then
          echo "WARNING: will use the env var PYODIDE_SYSTEM_PORT=${PYODIDE_SYSTEM_PORT} instead of the provided port"
        else
          PYODIDE_SYSTEM_PORT=$2
        fi
        shift 2
      ;;
      --non-interactive)
        DOCKER_INTERACTIVE="--interactive=false"
        shift
      ;;
      --root)
        USER_FLAG=()
        shift
      ;;
      -*)
        >&2 echo "Unknown option $1"
        error
      ;;
      *)
        DOCKER_COMMAND="$*"
        break
      ;;
  esac
done

PYODIDE_DOCKER_PORT=${PYODIDE_DOCKER_PORT:-"8000"}
PYODIDE_SYSTEM_PORT=${PYODIDE_SYSTEM_PORT:-${DEFAULT_PYODIDE_SYSTEM_PORT}}
PYODIDE_DOCKER_IMAGE=${PYODIDE_DOCKER_IMAGE:-${DEFAULT_PYODIDE_DOCKER_IMAGE}}

# in case the port is not a number, do not bind the port
case $PYODIDE_SYSTEM_PORT in
  none)
  PORT_CONFIGURATION_LINE=()
  ;;
  ''|*[!0-9]*) # contains a non-digit character, therefore it is not a number
  echo "WARNING: Invalid port argument '$PYODIDE_SYSTEM_PORT'. Port binding disabled."
  PORT_CONFIGURATION_LINE=()
  ;;
  *)
  PORT_CONFIGURATION_LINE=("-p" "$PYODIDE_SYSTEM_PORT:$PYODIDE_DOCKER_PORT")
  ;;
esac

mkdir -p .docker_home

# Start a detached container as root, add the host uname and uid to /etc/passwd,
# then run forever
CONTAINER=$(\
  docker run \
    "${PORT_CONFIGURATION_LINE[@]}" \
    -d --rm \
    -v "$PWD":/src \
    --user root \
    --shm-size 2g \
    "${PYODIDE_DOCKER_IMAGE}" \
    /bin/bash -c " \
      groupadd --gid '$USER_GID' '$USER_NAME'; \
      useradd \
        --home '$USER_HOME' \
        --uid '$USER_ID' \
        --gid '$USER_GID' \
        --comment '$USER_COMMENT_FIELD' \
        --shell '$USER_INTERPRETER' \
        --groups sudo  \
        $USER_NAME \
      ; \
      echo '%sudo ALL=(ALL:ALL) NOPASSWD:ALL' >> /etc/sudoers ; \
      echo '$HEALTHCHECK_MESSAGE'; \
      tail -f /dev/null \
    " \
)

until docker logs "$CONTAINER" 2>&1 | grep -q "$HEALTHCHECK_MESSAGE"; do
  echo "Waiting for initialization to finish..."
  sleep 0.2
done

EXIT_STATUS=0
# Execute the provided command as the host user with HOME=/src
docker exec \
  "$DOCKER_INTERACTIVE" --tty \
  "${USER_FLAG[@]}" \
  "$CONTAINER" \
  /bin/bash -c "${DOCKER_COMMAND}" || EXIT_STATUS=$?

docker kill "$CONTAINER" > /dev/null
exit $EXIT_STATUS