#!/usr/bin/env bash

# Tool for converting between MXE patch files and git repos
# Imports and exports patch files in "git format-patch" format.

cmd=$1
pkg=$2

setupEnv() {
  # MXE directory
  export mxedir=$(cd $(dirname $0) && cd .. && pwd)

  # directory for unpacked tarballs/git repos
  export gitsdir=${mxedir}/gits

  mkdir -p ${gitsdir}


  # John Doe <John Doe@acme.org>
  export author=`git var GIT_AUTHOR_IDENT | sed 's/^\(.* [<].*[>]\).*$/\1/'`

  export pkg_version=$(sed -n "s/^.* id=\"${pkg}-version\">\([^<]*\)<.*$/\1/p" "${mxedir}/index.html")

  export pkg_short_version=`echo $pkg_version | sed s/'\(.*\)\.[^.]*$'/'\1'/`

  export pkg_subdir=`grep '^$(PKG)_SUBDIR' $mxedir/src/$pkg.mk  | \
    sed 's/.*:= \(.*\)/\1/' | \
    sed s/'$($(PKG)_VERSION)'/$pkg_version/ | \
    sed s/'$(call SHORT_PKG_VERSION,$(PKG))'/$pkg_short_version/ | \
    sed s/'$(PKG)'/$pkg/;`

  export pkg_file=`grep '^$(PKG)_FILE' $mxedir/src/$pkg.mk  | \
    sed 's/.*:= \(.*\)/\1/' | \
    sed s/'$($(PKG)_VERSION)'/$pkg_version/ | \
    sed s/'$(call SHORT_PKG_VERSION,$(PKG))'/$pkg_short_version/ | \
    sed s/'$($(PKG)_SUBDIR)'/$pkg_subdir/ | \
    sed s/'$(PKG)'/$pkg/;`

  #echo $pkg
  #echo $pkg_version
  #echo $pkg_subdir
  #echo $pkg_file

}
# init
function init_git {
  setupEnv
  cd $gitsdir

  if [ -d $gitsdir/$pkg_subdir ]; then
    echo "Error: $gitsdir/$pkg_subdir already exists. Cancelling init." >&2
    exit 1
  fi

  echo "Checking for cached $pkg_file"
  if [ ! -f $mxedir/pkg/$pkg_file ]; then
    make -C "$mxedir" download-$pkg
    echo "Building the mxe Makefile target 'download-$pkg' to get missing file"
    if [ ! $? -eq 0 ]; then
      echo "Could not build target download-$pkg - cancelling init." >&2
      exit 1
    fi
  fi

  echo "Unpacking archive..."
  echo $pkg_file | grep "\.tar\.gz"  >> /dev/null && tar xf $mxedir/pkg/$pkg_file
  echo $pkg_file | grep "\.tar\.bz2" >> /dev/null && tar xf $mxedir/pkg/$pkg_file
  echo $pkg_file | grep "\.tar\.xz"  >> /dev/null && xz -dc $mxedir/pkg/$pkg_file | tar xf -
  echo $pkg_file | grep "\.zip"      >> /dev/null && unzip  $mxedir/pkg/$pkg_file >> /dev/null

  echo "Initializing repo and adding all as first commit"
  cd $gitsdir/$pkg_subdir && \
  (git init; git add -A; git commit -m "init") > /dev/null

  echo "Creating 'dist' tag for distribution tarball state"
  git tag dist

  echo "Repository ready in $gitsdir/$pkg_subdir"
}

function export_patch {
  setupEnv
  if [ ! -d $gitsdir/$pkg_subdir ]; then
    echo "Error: $gitsdir/$pkg_subdir does not exist, so cannot export patches. Cancelling export." >&2
    exit 1
  fi

  cd $gitsdir/$pkg_subdir && \
  (
    echo 'This file is part of MXE.'
    echo 'See index.html for further information.'
    echo ''
    echo 'Contains ad hoc patches for cross building.'
    echo ''
    git format-patch -p --stdout dist..HEAD | \
    sed 's/^From: .*/From: MXE/g;'
  ) > $mxedir/src/$pkg-1-fixes.patch && \
  echo "Generated $mxedir/src/$pkg-1-fixes.patch"
}

function import_patch {
  setupEnv
  if [ ! -d $gitsdir/$pkg_subdir ]; then
    echo "Error: $gitsdir/$pkg_subdir does not exist, so cannot import patches. Cancelling import - try 'init' first." >&2
    exit 1
  fi

  if [ -f $mxedir/src/$pkg-1-fixes.patch ]; then
    cd $gitsdir/$pkg_subdir && \
    cat $mxedir/src/$pkg-1-fixes.patch | \
    sed '/^From/,$  !d' | \
    sed s/'^From: .*'/"From: $author"/'g;' | \
    git am --keep-cr && \
    echo "Imported $mxedir/src/$pkg-1-fixes.patch"
  else
    echo "patch-tool managed file $mxedir/src/$pkg-1-fixes.patch not found. Cancelling import." >&2
    exit 1
  fi
}

case "$cmd" in
  init)
    init_git $pkg
    ;;
  import)
    import_patch $pkg
    ;;
  export)
    export_patch $pkg
    ;;
  *)
    echo "Unrecognized command '${cmd}'" >&2
    cat <<EOS
    Usage: $0 COMMAND PACKAGENAME
    where COMMAND is one of:
      init - create a git directory for the package with the raw source
      import - apply the "pkgname-1-fixes.patch" patch commits
      export - create/replace the "pkgname-1-fixes.patch" patch with a patch of all commits since init.
EOS
    exit 1
    ;;
esac