#!/bin/sh
set -e

# vlc-cache-gen uses readdir() which depends on the order in the filesystem

# Don't run if vlc is not installed
if [ ! -x /usr/lib/x86_64-linux-gnu/vlc/vlc-cache-gen ];
then
  exit 0
fi

# Don't run if the cache file does not exist
if [ ! -e /usr/lib/x86_64-linux-gnu/vlc/plugins/plugins.dat ];
then
  exit 0
fi

# Install disorderfs when needed and mark for removal at the end
_DISORDERFS_PREINSTALLED=yes
if [ ! -x /usr/bin/disorderfs ];
then
  _DISORDERFS_PREINSTALLED=no
  apt-get install --yes disorderfs
fi

# Install the fuse device (needed by disorderfs) and mark for removal at the end
_FUSE_DEVICE_PRESENT=yes
if [ ! -e /dev/fuse ];
then
  _FUSE_DEVICE_PRESENT=no
  mknod /dev/fuse c 10 229
fi

# Check for changes in the cache file, for suppressing the output if no change was made
_CHECK_FOR_CHANGES=yes
if [ ! -x /usr/bin/sha256sum ];
then
  _CHECK_FOR_CHANGES=no
fi


# Prepare a directory with a stable sorting order
_ORDERED_DIR=$(mktemp --directory)
disorderfs /usr/lib/x86_64-linux-gnu/vlc/plugins ${_ORDERED_DIR} --reverse-dirents=no --sort-dirents=yes --quiet

# The checksum of the original file
if [ "${_CHECK_FOR_CHANGES}" = "yes" ];
then
  sha256sum /usr/lib/x86_64-linux-gnu/vlc/plugins/plugins.dat > ${_ORDERED_DIR}/before.sha256sum
fi

# Regenerate the cache file in a directory which guarantees the sorting order of the files
/usr/lib/x86_64-linux-gnu/vlc/vlc-cache-gen ${_ORDERED_DIR}

# Verify the checksum for changes
if [ "${_CHECK_FOR_CHANGES}" = "yes" ];
then
  _HOOK_WAS_NEEDED=no
  sha256sum --check ${_ORDERED_DIR}/before.sha256sum --status || _HOOK_WAS_NEEDED=yes
  rm -f ${_ORDERED_DIR}/before.sha256sum
fi

# Cleanup
fusermount -u ${_ORDERED_DIR}
rmdir ${_ORDERED_DIR}

if [ "${_DISORDERFS_PREINSTALLED}" = "no" ];
then
  apt-get remove --yes --purge disorderfs
  apt-get autoremove --yes
fi

if [ "${_FUSE_DEVICE_PRESENT}" = "no" ];
then
  rm -f /dev/fuse
fi

# Report only when either a change was detected or not detectable (due to missing tools)
if [ "${_CHECK_FOR_CHANGES}" = "yes" ];
then
  if [ "${_HOOK_WAS_NEEDED}" = "yes" ];
  then
    echo "P: $(basename $0) Reproducible hook has been applied"
  fi
else
  echo "P: $(basename $0) Reproducible hook has been applied"
fi