#!/bin/bash

# Script to automate backporting for CRAN
# Creates a source package and binary packages for the following architecture
ARCH=i386
export ARCH

# R version against which the software is compiled
Rversion=3.3.3
reposversion="cran3"
iteration=1

# Where the buildresults should be stored and where to look for current backports
rcrandir=/home/jranke/svn/website/www/ranke/r-cran

# Author: Johannes Ranke <jranke@uni-bremen.de>

# Preconditions: 
#  - up to date R version specified above, for packages depending on R
#  - sudo and pbuilder configuration (see README)
#  - sid sources in /etc/apt/sources/list
#  - cdbs installed (and maybe more)
#  - shell variables DEBEMAIL and DEBFULLNAME

usage()
{
echo "Usage: ./backport [options] sourcepackage stretch|jessie|wheezy"
echo "Options:"
echo " -k, --keep    Keep copied source package and directory used for package building"
echo " -s, --skip    Skip apt-get update/upgrade and pbuilder update"
}

# Loop over options
skip=false
keep=false
while test -n "${1}"; do
  case "$1" in
    -k | --keep)
      keep=true
      shift
      ;;
    -s | --skip)
      skip=true
      shift
      ;;
    -*)
      echo "Error: Unknown option: $1" >&2
      usage
      exit 1
      ;;
    *) # No more options
      break
      ;;
  esac
done

# Positional arguments
if [ $# -lt 2 ]; then usage; exit 1; fi
pkg=$1
DIST=$2

# Validate distribution argument
if [ $DIST != "stretch" ] && [ $DIST != "jessie" ] && [ $DIST != "wheezy" ]; then usage; exit 1; fi
export DIST

# Set required r-base-dev version for packages build-depending on R
rbasedev="r-base-dev (>= $Rversion)"

# Remove previously extracted sources
if [ -d $pkg-* ]
then
    sudo rm -rf `ls -d $pkg-*`
fi

# Get current source from unstable
if [ "$skip" = false ]
then
  sudo apt-get update
  sudo apt-get upgrade
fi
sudo apt-get source $pkg

# Copy sources to $DIST directory to enable parallel builds
mkdir -p $DIST
cp -r $pkg\_* $DIST
cp -r $pkg-* $DIST

# Go to package building directory
cd $DIST/$pkg-*

# Determine the version of the upstream Debian package
upstreamversion=`dpkg-parsechangelog | grep ^Version | cut -f2 -d " "`

# Define the version to be used for the backport
cranversion=$upstreamversion"~"$DIST"cran.$iteration"

# Only do a backport if not already available
# This avoids recompiling packages resulting in different sizes which 
# would make an update of the archive index inside the loop in backport_others 
# necessary

new_dsc=$rcrandir/$DIST-cran3/${pkg}_${cranversion}.dsc

if [ -e $new_dsc ]; then

  echo backport.sh: $new_dsc already present

else 

  echo backport.sh: Upstream version is $upstreamversion
  echo backport.sh: New CRAN version is $cranversion

  # Add new version to changelog
  dch -v "${cranversion}" --force-distribution -D $DIST-cran -b "Backport from Debian unstable to Debian $DIST"

  # Adapt build dependency on r-base-dev if present
  if grep -q "^Build-Depends.*r-base-dev" debian/control
  then 
      ssed -i -R "/^Build-Depends/s/r-base-dev \(>= .*?\)/$rbasedev/" debian/control
      ssed -i -R "/^Build-Depends-Indep/s/r-base-dev \(>= .*?\)/$rbasedev/" debian/control

      dch -a "debian/control: Adapt build dependency on r-base-dev to current backport"
  fi

  # Check for a script doing modifications required for backporting
  script=../\_reverts\_$pkg\.sh

  if [ -f $script ]; then source $script; fi

  if [ "$skip" = false ]
  then
    sudo -E pbuilder update \
      --distribution $DIST \
      --basetgz /var/cache/pbuilder/$DIST-$ARCH-base.tgz \
      --aptcache /var/cache/pbuilder/$DIST-$ARCH/aptcache 
  fi
  sudo -E pdebuild --debbuildopts '-sa' \
    --buildresult $rcrandir/$DIST-cran3/ \
    -- --distribution $DIST --basetgz /var/cache/pbuilder/$DIST-$ARCH-base.tgz \
       --aptcache /var/cache/pbuilder/$DIST-$ARCH/aptcache \
       --buildplace /var/cache/pbuilder/$DIST-$ARCH/build
  if [ $? -ne 0 ]; then
      exit 
  fi
fi

cd ../..

# Clean sources from $DIST directory
if [ "$keep" = false ]
then
  rm -f $DIST/$pkg\_*
  rm -rf $DIST/$pkg-*
fi