#!/usr/bin/env bash

# This script serves as the
# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
# compiler.
#
# A [buildpack](http://devcenter.heroku.com/articles/buildpacks) is an
# adapter between a Python application and Heroku's runtime.
#
# You can intreract with the Heroku API directly with [heroku.py](https://github.com/heroku/heroku.py/).
#
# See also: [Release history](/changelog.html), [Detection](/detect.html).
#
# ## Usage
# Compiling an app into a slug is simple:
#
#     $ bin/compile <build-dir> <cache-dir>


# ## Assumptions
#
# This buildpack makes the following assumptions:
#
# - The desired Python VM is available on the base system.
# - Library dependencies are available on the base system.
# - Django applications should not require any platform-specific configuration.

# <hr />

# ## Context

# Fail fast and fail hard.
set -eo pipefail

# Prepend proper path for virtualenv hackery. This will be deprecated soon.
export PATH=:/usr/local/bin:$PATH

# Paths.
BIN_DIR=$(cd $(dirname $0); pwd) # absolute path
ROOT_DIR=$(dirname $BIN_DIR)
BUILD_DIR=$1
CACHE_DIR=$2

# Where to store the pip download cache.
CACHED_DIRS=".heroku"
PIP_DOWNLOAD_CACHE=${PIP_DOWNLOAD_CACHE:-$CACHE_DIR/pip_downloads}

# Static configurations for virtualenv caches.
VIRTUALENV_LOC=".heroku/venv"
LEGACY_TRIGGER="lib/python2.7"
PROFILE_PATH="$BUILD_DIR/.profile.d/python.sh"

# Python version. This will be used in the future to specify custom Pythons.
DEFAULT_PYTHON_VERSION="python-2.7.3"
PYTHON_EXE="/app/.heroku/python/bin/python"

# Sanitizing environment variables.
unset GIT_DIR PYTHONHOME PYTHONPATH LD_LIBRARY_PATH LIBRARY_PATH

# We'll need to send these statics to other scripts we `source`.
export PIP_DOWNLOAD_CACHE BUILD_DIR CACHE_DIR BIN_DIR PROFILE_PATH

# Syntax sugar.
source $BIN_DIR/utils

# Directory Hacks for path consistiency.
APP_DIR='/app'
TMP_APP_DIR=$CACHE_DIR/tmp_app_dir

# Copy Anvil app dir to temporary storage...
mkdir -p $TMP_APP_DIR
deep-mv $APP_DIR $TMP_APP_DIR

# Copy Application code in.
deep-mv $BUILD_DIR $APP_DIR

# Set new context.
ORIG_BUILD_DIR=$BUILD_DIR
BUILD_DIR=$APP_DIR

# Prepend proper path buildpack use.
export PATH=$BUILD_DIR/.heroku/python/bin:$PATH
export PYTHONUNBUFFERED=1

# ## Build Time
#

# Switch to the repo's context.
cd $BUILD_DIR

# Experimental pre_compile hook.
source $BIN_DIR/steps/hooks/pre_compile

# If no requirements given, assume `setup.py develop`.
if [ ! -f requirements.txt ]; then
  puts-step "No requirements.txt provided; assuming dist package."
  echo "-e ." > requirements.txt
fi

# If no runtime given, assume default version.
if [ ! -f runtime.txt ]; then
  puts-step "No runtime.txt provided; assuming $DEFAULT_PYTHON_VERSION."
  echo $DEFAULT_PYTHON_VERSION > runtime.txt
fi

# ### The Cache
mkdir -p $CACHE_DIR
[ ! "$(ls -A $CACHE_DIR)" ] && export FRESH_APP=1

# Purge "old-style" virtualenvs.
[ -d $CACHE_DIR/$LEGACY_TRIGGER ] && rm -fr $CACHE_DIR/*
[ -d $CACHE_DIR/$VIRTUALENV_LOC ] && rm -fr $CACHE_DIR/*

# Restore old artifacts from the cache.
for dir in $CACHED_DIRS; do
  cp -R $CACHE_DIR/$dir . &> /dev/null || true
done

set +e
# Create set-aside `.heroku` folder.
mkdir .heroku &> /dev/null
set -e

mkdir -p $(dirname $PROFILE_PATH)

set +e
PYTHON_VERSION=$(cat runtime.txt)

# Install Python.
if [ -f .heroku/python-version ]; then
  if [ ! $(cat .heroku/python-version) = $PYTHON_VERSION ]; then
    puts-step "Found $(cat .heroku/python-version), removing."
    rm -fr .heroku/python
  else
    SKIP_INSTALL=1
  fi
fi


if [ ! "$SKIP_INSTALL" ]; then
  puts-step "Preparing Python runtime ($PYTHON_VERSION)"
  curl http://envy-versions.s3.amazonaws.com/$PYTHON_VERSION.tar.bz2 -s | tar jx > /dev/null
  mv python .heroku/python

  # Record for future reference.
  echo $PYTHON_VERSION > .heroku/python-version
  WORKING_DIR=$(pwd)

  # Prepare it for the real world
  puts-step "Installing Distribute (0.6.34)"
  cd $ROOT_DIR/vendor/distribute-0.6.34/
  python setup.py install  &> /dev/null
  cd $WORKING_DIR

  puts-step "Installing pip (1.2.1)"
  cd $ROOT_DIR/vendor/pip-1.2.1/
  python setup.py install  &> /dev/null
  cd $WORKING_DIR

  hash -r
else
  puts-step "Using Python runtime ($PYTHON_VERSION)"
fi

set -e

# Pylibmc support.
# See [`bin/steps/pylibmc`](pylibmc.html).
source $BIN_DIR/steps/pylibmc

# Install Mercurial if it appears to be required.
if (in-req "hg+" requirements.txt) then
  pip install --use-mirrors mercurial | cleanup | indent
fi

# Install dependencies with Pip.
puts-step "Installing dependencies using pip (1.2.1)"
pip install --use-mirrors -r requirements.txt --exists-action=w --src=./.heroku/src | cleanup | indent

# Django collectstatic support.
source $BIN_DIR/steps/collectstatic

# ### Finalize
#

# Store new artifacts in cache.
for dir in $CACHED_DIRS; do
  rm -rf $CACHE_DIR/$dir
  cp -R $dir $CACHE_DIR/
done

# Set context environment variables.
set-env PATH '$HOME/.heroku/python/bin:$PATH'
# set-env PYTHONHOME /app/.heroku/python/
set-env PYTHONUNBUFFERED true
set-default-env LIBRARY_PATH /app/.heroku/vendor/lib
set-default-env LD_LIBRARY_PATH /app/.heroku/vendor/lib
set-default-env LANG en_US.UTF-8
set-default-env PYTHONHASHSEED random
set-default-env PYTHONPATH /app/
un-set-env PYTHONHOME


# ### Fin.

deep-mv $BUILD_DIR $ORIG_BUILD_DIR
deep-mv $TMP_APP_DIR $APP_DIR


# Experimental post_compile hook.
source $BIN_DIR/steps/hooks/post_compile
