#!/bin/bash
#
# list_url_attributes_on_file
#

###
### 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
###

file_arg=''
attribute_1='com.apple.metadata:kMDItemWhereFroms'

###
### functions
###

warn () {
    local message="$@"
    message="${message//\\t/$'\011'}"
    message="${message//\\n/$'\012'}"
    message="${message%"${message##*[![:space:]]}"}"
    printf "%s\n" "$message" 1>&2
}

die () {
    warn "$@"
    exit 1
}

xml_source_1 () {
    if /usr/bin/xattr -p "$attribute_1" "$file_arg" > /dev/null 2>&1; then
        /usr/bin/xattr -p "$attribute_1" "$file_arg" | /usr/bin/xxd -r -p | /usr/bin/plutil -convert xml1 -o - - 2> /dev/null
    fi
}

extract_string_elements () {
    /usr/bin/perl -ne 'print "$1\n" if m{\A\s*<\s*string\s*>(.+?)<\s*/\s*string\s*>\Z}'
}

###
### main
###

_list_url_attributes_on_file () {
    file_arg="$1"
    {
      xml_source_1;
    } |                \
    extract_string_elements
}

# process_args
if [[ $1 =~ ^-+h(elp)?$ || -z "$1" ]]; then
    printf "list_url_attributes_on_file <file>

Given a downloaded file, extract possible sources from macOS extended
attributes, which may be useful in a Cask url stanza.

Currently the only attribute examined is

    com.apple.metadata:kMDItemWhereFroms

This attribute will typically be set if the file was downloaded via a
browser, but not if the file was downloaded by a CLI utility such as
curl.

See CONTRIBUTING.md for more information.

"
    exit
fi

# dispatch main
_list_url_attributes_on_file "${@}"

#