#! /bin/sh -e

badp=nil
myarch=$(dpkg-architecture -qDEB_HOST_ARCH); unset myqarch
while getopts "a:q:" opt; do
  case $opt in
    a) myarch=$OPTARG ;;
    q) myqarch=$OPTARG ;;
    *) badp=t ;;
  esac
done
shift $(( $OPTIND - 1 ))
case $# in 0) badp=t ;; esac
case $badp in
  t)
    cat >&2 <<EOF
usage: $0 [-a MYARCH] [-q MYQARCH] DIST-ARCH ...
EOF
    exit 1
    ;;
esac
case ${myqarch+t} in t) ;; *) myqarch=$myarch ;; esac
mymulti=$(dpkg-architecture -a$myarch -qDEB_HOST_MULTIARCH)

for arg in "$@"; do
  d=${arg%-*} a=${arg#*-}

  if ! [ -d /usr/local.schroot/cross/$d-$myarch ]; then
    echo 2>&1 "$0: no tree for \`$d-$myarch'"; exit 1
  fi

  gnuarch=$(dpkg-architecture -A$a -qDEB_TARGET_GNU_TYPE)

  case $a in
    armel | armhf) qarch=arm ;;
    arm64) qarch=aarch64 ;;
    amd64) qarch=x86_64 ;;
    i386) qarch=i386 ;;
    *) echo >&2 "$0: no qemu arch for $a"; exit 1 ;;
  esac

  sess=$(schroot -bcsource:$d-$a)
  root=/schroot/$sess/fs
  qemudir=/usr/local.schroot/cross/$d-$myqarch/QEMU
  crossdir=/usr/local.schroot/cross/$d-$myarch

  schroot -uroot -rc$sess -- sh -ec '
	if ! mountpoint -q /mnt; then
	  mount -ttmpfs -omode=700,uid=0,gid=0 private /mnt
	fi'

  { echo $qemudir/qemu-$qarch-static
    echo $crossdir/lib/$mymulti
    echo $crossdir/usr/lib/$mymulti
    echo $crossdir/usr/lib/gcc-cross
    find $crossdir $crossdir/TOOLCHAIN/$gnuarch \
	 \( \(  -path "*/QEMU" -o -path "*/TOOLCHAIN" -o \
	 -path "*/lib/$mymulti" -o \
	 -path "*/lib/gcc-cross" \) -prune \) -o \
	 \( ! -type d -print \)
  } | while read t; do
    case $t in
      $qemudir/*)
	s=/usr/bin/${t#$qemudir/} ;;
      $crossdir/TOOLCHAIN/$gnuarch/*)
	s=/usr/bin/${t#$crossdir/TOOLCHAIN/$gnuarch/} ;;
      *)
	s=${t#$crossdir} ;;
    esac
    if [ -L $t ]; then t=$(readlink $t); fi
    if [ -d $t ]; then act=LINK; else act=DIVERT; fi
    echo $act $s $t
  done >$root/mnt/ALL.want
  sed -n '/^DIVERT \(.*\) .*$/s//\1/p' $root/mnt/ALL.want | \
    sort >$root/mnt/DIVERT.want
  sed -n '/^\(DIVERT\|LINK\) /s///p' $root/mnt/ALL.want | \
    sort >$root/mnt/LINK.want

  schroot -uroot -rc$sess -- sh -ec '
	dpkg-divert --list |
	  sed -n "/^diversion of \(.*\) to .* by install-cross-tools\$/s//\1/p" | \
	  sort >/mnt/DIVERT.have
	{ find / -xdev -lname "/usr/local.schroot/cross/*" -printf "%p %l\n"
	  while read s _; do
	    if ! [ -L "$s" ]; then continue; fi
	    t=$(readlink $s)
	    case $t in /usr/local.schroot/cross/*) continue ;; esac
	    echo "$s $t"
	  done </mnt/LINK.want
	} | sort >/mnt/LINK.have'

  schroot -uroot -rc$sess -- sh -ec '
	a=$1

	if dpkg-divert >/dev/null 2>&1 --no-rename --help
	then no_rename=--no-rename
	else no_rename=
	fi

	comm -13 /mnt/DIVERT.have /mnt/DIVERT.want | while read i; do
	  dpkg-divert --package "install-cross-tools" $no_rename \
	    --divert "$i.$a" --add "$i"
	done' - $a

  while read i; do
    if [ -e $root$i ] && ! [ -e $root$i.$a ]; then
      if [ -L $root$i ]; then
	t=$(readlink $root$i)
	case $t in
	  $crossdir/* | qemudir/* | /usr/local.schroot/qemu/*) continue ;;
	esac
	if [ -L $crossdir$i ]; then
	  u=$(readlink $crossdir$i)
	  case $t in "$u") continue ;; esac
	fi
      fi
      echo >&2 "$0: preserve old $i"
      ln $root$i $root$i.$a
    fi
  done <$root/mnt/DIVERT.want

  join -j1 -a1 -a2 -e- -o"0 1.2 2.2" \
       $root/mnt/LINK.have $root/mnt/LINK.want |
    while read s t0 t1; do
      case $t1 in
	"$t0")
	  continue
	  ;;
	-)
	  echo >&2 "$0: remove obsolete link $s -> $t0"
	  rm -f $root$s
	  ;;
	*)
	  case $s in */*) mkdir -p $root${s%/*} ;; esac
	  rm -f $root$s.new
	  ln -s $t1 $root$s.new
	  echo >&2 "$0: link $s -> $t1"
	  mv -T $root$s.new $root$s
	  ;;
      esac
    done

  schroot -uroot -rc$sess -- sh -ec '
	a=$1
	comm -23 /mnt/DIVERT.have /mnt/DIVERT.want | while read i; do
	  dpkg-divert --package "install-cross-tools" --rename \
	    --divert "$i.$a" --remove "$i"
	done' - $a

  schroot -ec$sess
done