#!/bin/bash
#
# list_payload_in_pkg
#

###
### settings
###

set -e                # exit on any uncaught error
set +o histexpand     # don't expand history expressions
shopt -s nocasematch  # case-insensitive regular expressions

###
### global variables
###

pkg_arg=''
tmp_boms=''

# prefer GNU xargs
xargs="$(/usr/bin/which gxargs || printf '/usr/bin/xargs')"

trap cleanup_tmp_boms EXIT

###
### functions
###

cleanup_tmp_boms () {
    if [[ -n "$tmp_boms" ]]; then
        # tmpfile ensures that rmdir -p is not too destructive
        local tmpfile="/tmp/list_payload_in_pkg.$$";
        /usr/bin/touch "$tmpfile";
        echo "$tmp_boms" |                            \
        /usr/bin/perl -pe 's{\n}{\000}sg' |           \
        "$xargs" -0 /bin/rm -f --;
        {
         echo "$tmp_boms" |                           \
         /usr/bin/perl -pe 's{[^/]+\n}{\000}sg' |     \
         "$xargs" -0 /bin/rmdir -p -- || true
        } 2>/dev/null
        /bin/rm -- "$tmpfile";
    fi
}

bom_source_1 () {
    /usr/bin/find "$pkg_arg" -iname '*.pkg' -print0 | \
    "$xargs" -0 -I{} -n1 /usr/sbin/pkgutil --bom "{}" 2>/dev/null
}

bom_source_2 () {
    /usr/bin/find "$pkg_arg" -name '*.bom'
}

expand_sources () {
    /usr/bin/perl -pe 's{\n}{\000}sg' |               \
    "$xargs" -0 lsbom --
}

merge_sources () {
    /usr/bin/sort | /usr/bin/uniq
}

clean_sources () {
    /usr/bin/cut -f1 |                                \
    /usr/bin/perl -pe 's{\A\.}{}' |                   \
    /usr/bin/egrep '.'
}

mark_up_sources () {
    /usr/bin/perl -pe 's{\n}{\000}sg' |               \
    "$xargs" -0 -I{} -n1 /bin/bash -c                 \
      'printf "{}"; /bin/test -e "{}" >/dev/null 2>&1 && printf " (+)"; printf "\n"'
}

###
### main
###

_list_payload_in_pkg () {

    pkg_arg="$1"
    if [[ -h "$pkg_arg" ]]; then
        pkg_arg="$(/usr/bin/readlink "$pkg_arg")"
    fi

    tmp_boms="$(bom_source_1)";
    {
      # find BOM files
      echo "$tmp_boms";
      bom_source_2;
    } |                  \
    expand_sources  |    \
    clean_sources   |    \
    merge_sources   |    \
    mark_up_sources

}

# process args
if [[ $1 =~ ^-+h(elp)?$ || -z "$1" ]]; then
    printf "list_payload_in_pkg <file.pkg>

Given a package file, show what files may be installed by that
pkg, which may be useful when writing a Cask uninstall stanza.

The given package file need not be installed.

The output attempts to be overly inclusive. However, since
pkg files are allowed to run arbitrary scripts, there can be
no guarantee that the output is exact.

If a given file is already installed, it will be followed by
a plus symbol '(+)' in the output.

Note that Apple's xargs utility has a limitation of processing
up to 255 bytes. Therefore long payload paths might be printed
as '{}' instead. To overcome this limitation, please consider
installing the GNU xargs utility instead using:

brew install findutils

See CONTRIBUTING.md and 'man pkgutil' for more information.

"
    exit
fi

# dispatch main
_list_payload_in_pkg "${@}"

#