#!/bin/bash
#
# list_ids_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
###

pkgdir=''

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

###
### functions
###

bundle_id_source_1 () {
    /usr/bin/find "$pkgdir" -name PackageInfo -print0 |                                \
    "$xargs" -0 /usr/bin/perl -0777 -ne                                                \
      'while (m{<pkg-info.*?\sid(?:entifier)?\s*=\s*"([^"]*?)"}sg) { print "$1\n" }'
}

bundle_id_source_2 () {
    /usr/bin/find "$pkgdir" -name Info.plist -print0 |                                 \
    "$xargs" -0 -I {} /usr/libexec/PlistBuddy {} -c 'Print :CFBundleIdentifier'
}

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

clean_sources () {
    /usr/bin/egrep -v '^com\.apple\.' |                                                \
    /usr/bin/egrep -v 'sparkle\.finish-installation$'
}

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

###
### main
###

_list_ids_in_pkg () {

    if [[ -d "$1" ]]; then
        pkgdir="$1"
        if [[ -h "$pkgdir" ]]; then
            pkgdir="$(/usr/bin/readlink "$pkgdir")"
        fi
    else
        local tmpdir="$(/usr/bin/mktemp -d -t list_ids_in_pkg)"
        trap "/bin/rm -rf -- '$tmpdir'" EXIT
        pkgdir="$tmpdir/unpack"
        /usr/sbin/pkgutil --expand "$1" "$tmpdir/unpack" "$pkgdir"
    fi

    {
      # emit strings that look like bundle ids
      bundle_id_source_1;
      bundle_id_source_2;
    } |                     \
    merge_sources |         \
    clean_sources |         \
    mark_up_sources

}

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

Given a package file, extract a list of candidate Package IDs
which may be useful in a Cask uninstall stanza, eg

    uninstall pkgutil: 'package.id.goes.here'

The given package file need not be installed.

The output of this script should be overly inclusive -- not
every candidate package id in the output will be needed at
uninstall time.

Package IDs designated by Apple or common development frameworks
will be excluded from the output.

If a package id is already installed, it will be followed by
a plus symbol '(+)' in the output.  This can be verified via
the command

    /usr/sbin/pkgutil --pkg-info 'package.id.goes.here'

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

"
    exit
fi

# dispatch main
_list_ids_in_pkg "${@}"

#