#!/bin/bash
source /opt/app-root/etc/generate_container_user

set -e

function is_gunicorn_installed() {
  hash gunicorn &>/dev/null
}

function is_django_installed() {
  python -c "import django" &>/dev/null
}

function should_migrate() {
  is_django_installed && [[ -z "$DISABLE_MIGRATE" ]]
}

# Guess the number of workers according to the number of cores
function get_default_web_concurrency() {
  limit_vars=$(cgroup-limits)
  local $limit_vars
  if [ -z "${NUMBER_OF_CORES:-}" ]; then
    echo 1
    return
  fi

  local max=$((NUMBER_OF_CORES*2))
  # Require at least 43 MiB and additional 40 MiB for every worker
  local default=$(((${MEMORY_LIMIT_IN_BYTES:-MAX_MEMORY_LIMIT_IN_BYTES}/1024/1024 - 43) / 40))
  default=$((default > max ? max : default))
  default=$((default < 1 ? 1 : default))
  # According to http://docs.gunicorn.org/en/stable/design.html#how-many-workers,
  # 12 workers should be enough to handle hundreds or thousands requests per second
  default=$((default > 12 ? 12 : default))
  echo $default
}

function maybe_run_in_init_wrapper() {
  if [[ -z "$ENABLE_INIT_WRAPPER" ]]; then
    exec "$@"
  else
    exec $STI_SCRIPTS_PATH/init-wrapper "$@"
  fi
}

APP_HOME=$(readlink -f "${APP_HOME:-.}")
# Change the working directory to APP_HOME
PYTHONPATH="$(pwd)${PYTHONPATH:+:$PYTHONPATH}"
cd "$APP_HOME"

if [ -z "$APP_SCRIPT" ] && [ -z "$APP_FILE" ] && [ -z "$APP_MODULE" ]; then
  # Set default values for APP_SCRIPT and APP_FILE only when all three APP_
  # variables are not defined by user. This prevents a situation when
  # APP_MODULE is defined to app:application but the app.py file is found as the
  # APP_FILE and then executed by Python instead of gunicorn.
  APP_SCRIPT="app.sh"
  APP_SCRIPT_DEFAULT=1
  APP_FILE="app.py"
  APP_FILE_DEFAULT=1
fi

if [ ! -z "$APP_SCRIPT" ]; then
  if [[ -f "$APP_SCRIPT" ]]; then
    echo "---> Running application from script ($APP_SCRIPT) ..."
    if [[ "$APP_SCRIPT" != /* ]]; then
      APP_SCRIPT="./$APP_SCRIPT"
    fi
    maybe_run_in_init_wrapper "$APP_SCRIPT"
  elif [[ -z "$APP_SCRIPT_DEFAULT" ]]; then
    echo "ERROR: file '$APP_SCRIPT' not found." && exit 1
  fi
fi

if [ ! -z "$APP_FILE" ]; then
  if [[ -f "$APP_FILE" ]]; then
    echo "---> Running application from Python script ($APP_FILE) ..."
    maybe_run_in_init_wrapper python "$APP_FILE"
  elif [[ -z "$APP_FILE_DEFAULT" ]]; then
    echo "ERROR: file '$APP_FILE' not found." && exit 1
  fi
fi

# Look for 'manage.py' in the current directory
manage_file=./manage.py

if should_migrate; then
  if [[ -f "$manage_file" ]]; then
    echo "---> Migrating database ..."
    python "$manage_file" migrate --noinput
  else
    echo "WARNING: seems that you're using Django, but we could not find a 'manage.py' file."
    echo "Skipped 'python manage.py migrate'."
  fi
fi

# If not set, use 8080 as the default port
if [ -z "$PORT" ]; then
  PORT=8080
fi

if is_gunicorn_installed; then
  setup_py=$(find "$HOME" -maxdepth 2 -type f -name 'setup.py' -print -quit)
  # Look for wsgi module in the current directory
  if [[ -z "$APP_MODULE" && -f "./wsgi.py" ]]; then
    APP_MODULE=wsgi
  elif [[ -z "$APP_MODULE" && -f "$setup_py" ]]; then
    APP_MODULE="$(python "$setup_py" --name)"
  fi

  if [[ "$APP_MODULE" ]]; then
    export WEB_CONCURRENCY=${WEB_CONCURRENCY:-$(get_default_web_concurrency)}

    # Default settings for gunicorn if none of the custom are set
    if [ -z "$APP_CONFIG" ] && [ -z "$GUNICORN_CMD_ARGS" ]; then
      GUNICORN_CMD_ARGS="--bind=0.0.0.0:$PORT --access-logfile=-"
      gunicorn_settings_source="default"
    else
      gunicorn_settings_source="custom"
    fi

    # Gunicorn can read GUNICORN_CMD_ARGS as an env variable but because this is not
    # supported in Gunicorn < 20 we still need for Python 2, we are using arguments directly.
    echo "---> Serving application with gunicorn ($APP_MODULE) with $gunicorn_settings_source settings ..."
    exec gunicorn "$APP_MODULE" $GUNICORN_CMD_ARGS --config "$APP_CONFIG"
  fi
fi

if is_django_installed; then
  if [[ -f "$manage_file" ]]; then
    echo "---> Serving application with 'manage.py runserver 0.0.0.0:$PORT' ..."
    echo "WARNING: this is NOT a recommended way to run you application in production!"
    echo "Consider using gunicorn or some other production web server."
    maybe_run_in_init_wrapper python "$manage_file" runserver 0.0.0.0:$PORT
  else
    echo "WARNING: seems that you're using Django, but we could not find a 'manage.py' file."
    echo "Skipped 'python manage.py runserver'."
  fi
fi

>&2 echo "ERROR: don't know how to run your application."
>&2 echo "Please set either APP_MODULE, APP_FILE or APP_SCRIPT environment variables, or create a file 'app.py' to launch your application."
exit 1