#! /bin/sh -e
###
### Build a Debian package on supported architectures
###
### (c) 2016 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This program is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### This program is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with this program; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

###--------------------------------------------------------------------------
### Configuration.

unset buildroot default_targets parallel
for i in \
  "/etc/mdw-sbuild.conf" \
  "${XDG_CONFIG_HOME-$HOME/.config}/mdw-sbuild.conf"
do
  if [ -f "$i" ]; then . "$i"; fi
done
: ${buildroot=$HOME/build}
: ${default_targets="wheezy-amd64 wheezy-i386"}
: ${parallel=-j3}
: ${DEB_BUILD_OPTIONS=parallel=4}; export DEB_BUILD_OPTIONS

###--------------------------------------------------------------------------
### Some utilities.

prog=${0##*/}

fail () { echo >&2 "$prog: $*"; exit 1; }
usage () { echo "usage: $prog [-ain] [-t TARGET] COMMAND [ARGUMENTS ...]"; }
fail_usage () { usage >&2; exit 1; }

want_1 () {
  what=$1 pat=$2 type=$3; shift 3
  for i in "$@"; do
    [ $type "$i" ] || fail "$what not found: \`$i'"
  done
  case $# in
    1) ;;
    *) fail "expected exactly one $what matching \`$pat', but found $#" ;;
  esac
  echo "$1"
}

###--------------------------------------------------------------------------
### Parse options.

bogusp=nil archp=nil indepp=nil makeopts=""
unset targets

while getopts "haint:" opt; do
  case $opt in
    h)
      usage
      cat <<EOF

Options:
	-h		Show this help text.
	-a		Build only architecture-dependent packages.
	-i		Build only architecture-neutral packages.
	-n		Don't actually do the build.
	-t TARGET	Build in TARGET build environment.

Commands available:

	dir PROJECT/VERSION
		Return a freshly-made directory for the source code to
		go in.

	build BUILDDIR
		Build the package placed in BUILDDIR, which should contain
		exactly one \`.dsc' file, and whatever source archive files
		are necessary.
EOF
      exit
      ;;
    a) archp=t ;;
    i) indepp=t ;;
    n) makeopts="${makeopts+$makeopts }-n" ;;
    t) targets="${targets+$targets }$OPTARG" ;;
    *) bogusp=nil ;;
  esac
done
shift $(( $OPTIND - 1 ))

case $bogusp in t) fail_usage ;; esac
case $archp,$indepp in nil,nil) archp=t indepp=t ;; esac
case ${targets+t} in t) ;; *) targets=$default_targets ;; esac

###--------------------------------------------------------------------------
### Main work.

case "$#,$1" in
  0,*) fail_usage ;;
  *,*,*) fail "bad command name \`$1'" ;;

  2,dir)
    ## dirname PROJECT/VERSION

    ## Try to create a fresh build directory.
    dist=$2
    case "$dist" in */*/*) fail "bad distribution name \`$dist'" ;; esac
    proj=${dist%/*} ver=${dist#*/}
    cd "$buildroot"
    mkdir -p "$proj"
    cd "$proj"
    i=0
    winp=nil
    while [ $i -lt 50 ]; do
      i=$(( $i + 1 ))

      ## Find a sequence number different from all of the existing builds of
      ## this version.
      nn=1
      for j in "$ver#"*; do
	case "$j" in "$ver#*") break ;; esac
	n=${j##*\#}
	if [ $nn -le $n ]; then nn=$(( $n + 1 )); fi
      done

      ## Try to make the build directory.  This might not work if we're
      ## racing with another process, but that's why we're trying in a loop.
      if mkdir "$ver#$nn" >/dev/null 2>&1; then
	winp=t
	cd "$ver#$nn"
	break
      fi

      ## Make sure it actually failed because a directory appeared, rather
      ## than for some other reason.
      [ -e "$ver#$nn" ] || \
	fail "unexpectedly couldn't create \`$buildroot/$dist#$nn'"
    done

    ## Make sure we actually succeeded.
    case $winp in t) ;; *) fail "failed to create build directory" ;; esac

    ## Make an empty directory for dependency packages.
    mkdir -p pkgs/

    ## Done.
    echo "$buildroot/$dist#$nn"
    ;;

  *,dir)
    echo >&2 "usage: $prog dir PROJECT/VERSION"; exit 1 ;;

  2,build)
    ## build BUILDDIR

    ## Track down the build directory.
    builddir=$2
    cd "$builddir"
    dsc=$(want_1 "file" "*.dsc" -f *.dsc)

    ## Figure out which targets need building.  If the `.dsc' file isn't
    ## telling, assume it needs building everywhere and let sbuild(1) sort
    ## out the mess.
    os=$(dpkg-architecture -qDEB_HOST_ARCH_OS)
    unset first rest; anyp=nil depp=nil allp=nil
    wantarchs=$(sed -n '/^[Aa]rchitecture:/ s/^[^:]*: *//p' "$dsc")
    : ${wantarchs:=any}
    unset buildarchs buildarchs_seen=:

    ## Work through the available targets assigning builds to them.  This is
    ## actually a little tricky.
    for t in $targets; do

      ## Dissect the target name.
      suite=${t%%-*} archs=${t#*-}
      case $archs in
	*/*) target=${archs%/*} host=${archs#*/} ;;
	*) target=$archs host=$archs; t=$suite-$target/$host ;;
      esac
      case $buildarchs_seen in
	*:$target:*)
	  ;;
	*)
	  buildarchs=${buildarchs+$buildarchs }$target
	  buildarchs_seen=$buildarchs_seen$target:
	  ;;
      esac

      ## Work through the architectures which we can build.
      for arch in $wantarchs; do
	case $arch in
	  all)
	    ## Package suitable for all architectures.

	    ## If we don't want to build architecture-neutral packages then
	    ## there's nothing to do.
	    case $indepp in nil) continue ;; esac

	    ## Pick this up if nobody has volunteered.  However, we should be
	    ## ready to let some other architecture build this if it's going
	    ## to build some architecture-dependent package too.
	    case $anyp in nil) first=$t anyp=t allp=t ;; esac
	    ;;
	  *)
	    ## There's at least one architecture-specific package.

	    ## If we don't want to build architecture-specific packages then
	    ## there's nothing to do.
	    case $archp in nil) continue ;; esac

	    ## If we can't build it then we shouldn't try.
	    if ! dpkg-architecture -a"$os-$target" -i"$arch"; then
	      continue
	    fi

	    ## Decide whether we should take responsibility for the
	    ## architecture-neutral packages.  If nobody's claimed them yet,
	    ## or the previous claimant wasn't building architecture-specific
	    ## packages, we should take over.
	    case $depp in
	      nil) first=$t depp=t anyp=t ;;
	      t) rest="${rest+$rest }$t" ;;
	    esac
	    ;;
	esac
      done
    done

    ## If we never found a match then we can't do anything.
    case $anyp in nil) echo "$prog: no packages to build"; exit 0 ;; esac

    ## Figure out the right options to use.
    case $indepp in
      t) firstopt="--arch-all" ;;
      nil) firstopt="--no-arch-all" ;;
    esac
    case $archp in
      t) ;;
      nil) firstopt="$firstopt --debbuildopt=-A" ;;
    esac

    ## Sort out the additional packages.  This is rather annoying, because
    ## sbuild(1) does this in a really stupid way.
    rm -rf pkgs.*
    for a in $buildarchs; do
      mkdir pkgs.$a
      for f in $(dpkg-scanpackages -a$a pkgs/ |
		    sed -n '/^Filename: /s///p')
      do
	ln $f pkgs.$a/
      done
    done

    ## Build a cheesy makefile to run these in parallel.
    cat >build.mk <<EOF
### -*-makefile-*-
DSC = $dsc
FIRST = $first
REST = $rest
sbuild-wrap = \\
	t=\$@; \\
	host=\$\${t\#\#*/} full=\$\${t%/*}; \\
	suite=\$\${full%%-*} target=\$\${full\#*-}; \\
	{ echo started >build-status.\$\$full; \\
	  sbuild \\
		--extra-package=pkgs.\$\$target/ \\
		--dist=\$\$suite --build=\$\$host --host=\$\$target \\
		--chroot=\$\$suite-\$\$host --verbose \$1 \$(DSC); \\
	  rc=\$\$?; case \$\$rc in \\
	    0) echo ok >build-status.\$\$full ;; \\
	    *) echo failed rc=\$\$rc >build-status.\$\$full ;; \\
	  esac; } | \\
	while IFS= read -r line; do \\
	  printf "%s: %s\n" "\$\$full" "\$\$line"; \\
	done; \\
	read st _ <build-status.\$\$full && \\
	case \$\$st in ok) exit 0 ;; *) exit 1 ;; esac
all: \$(FIRST) \$(REST)
\$(FIRST):; \$(call sbuild-wrap,$firstopt)
\$(REST):; \$(call sbuild-wrap,--no-arch-all)
EOF

    ## Make some marker files to say things are in progress.
    for i in $first $rest; do echo "starting" >build-status.${i%/*}; done

    ## And we're ready to go.
    mkfifo pipeout
    cat pipeout& catpid=$!
    set +e; make -fbuild.mk $parallel $makeopts -k all >pipeout
    rc=$?; set -e
    wait $!
    rm build.mk pipeout build-status.*
    find . -maxdepth 1 -type l -exec rm {} \;
    exit $rc
    ;;
  build,*)
    echo >&2 "usage: $prog build BUILDDIR"; exit 1 ;;

  *)
    fail "unknown command \`$1'"
    ;;
esac

###----- That's all, folks --------------------------------------------------