#!/bin/bash

# This script uses these environment variables:
#
# APP_MODULE: Python dotted path to your WSGI application.
#             If not provided, tries to find the Python path to a 'wsgi.py' file
#             in the source tree.
#             That file is present in Django projects by default.
# APP_CONFIG: Optional configuration file for gunicorn.
# APP_FILE:   Optional path to Python script to run your application.
#             Defaults to 'app.py' if it exists.
#
# DISABLE_MIGRATE: if not empty, inhibits execution of 'manage.py migrate'.

BIND_ADDR="0.0.0.0:8080"

function run() {
  # For SCL enablement
  source .bashrc

  set -e

  # Try to run application with the strategies below, in precedence order.
  # The first successful strategy takes over this script's process via exec.
  # If no strategy succeed, report an error message and terminate.
  run_django
  run_gunicorn "$APP_MODULE"
  run_python_script "${APP_FILE:-app.py}"

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

function run_django() {
  ! pip show -q django && return

  # Find shallowest manage.py script, either ./manage.py or <project>/manage.py
  local MANAGE_FILE=$(find . -maxdepth 2 -type f -name 'manage.py' -printf '%d\t%P\n' | sort -nk1 | cut -f2 | head -1)

  django_migrate "$MANAGE_FILE"

  # try to use gunicorn
  run_gunicorn "$APP_MODULE"
  # or fallback to Django's development server
  django_runserver "$MANAGE_FILE"
}

function django_migrate() {
  [ -n "$DISABLE_MIGRATE" ] && return
  echo "---> Migrating database ..."
  django_manage_cmd "$1" migrate --noinput
}

function django_runserver() {
  echo "---> Serving application with 'manage.py runserver' ..."
  echo "---> WARNING: this is NOT a recommended way to run you application in production!"
  django_manage_cmd "$1" runserver "$BIND_ADDR"
}

function django_manage_cmd() {
  local MANAGE_FILE="$1"
  local CMD="${@:2}"

  if [ ! -f "$MANAGE_FILE" ]; then
    echo "WARNING: seems that you're using Django, but we could not find a 'manage.py' file."
    echo "'manage.py $CMD' ignored."
    return
  fi

  if [[ "$CMD" =~ ^runserver ]]; then
    exec python "$MANAGE_FILE" $CMD
  else
    python "$MANAGE_FILE" $CMD
  fi
}

function run_gunicorn() {
  ! pip show -q gunicorn && return

  local APP_MODULE="$1"

  if [ -z "$APP_MODULE" ]; then
    # Find shallowest wsgi.py file, one of ./wsgi.py, <project>/wsgi.py or <project>/<project>/wsgi.py,
    # replace "/" with "." and remove ".py" suffix
    APP_MODULE=$(find . -maxdepth 3 -type f -name 'wsgi.py' -printf '%d\t%P\n' | sort -nk1 | cut -f2 | head -1 | sed 's:/:.:;s:.py$::')
  fi

  if [ -z "$APP_MODULE" ]; then
    echo "WARNING: seems that you're trying to use gunicorn, but no WSGI application module was specified."
    return
  fi

  echo "---> Serving application with gunicorn ..."
  exec gunicorn "$APP_MODULE" --bind="$BIND_ADDR" --access-logfile=- --config "$APP_CONFIG"
}

function run_python_script() {
  local APP_FILE="$1"

  [ ! -f "$APP_FILE" ] && return

  echo "---> Running application from Python script ..."
  exec python -u "$APP_FILE"
}


run