#!/usr/bin/env perl

use warnings;
use strict;

# ioreg might be more machine-readable than system_profiler, but I haven't been able to
# get it to produce useful output
my @output = qx(/usr/sbin/system_profiler SPUSBDataType);

my $parse_state = 0;
my $device      = {};

LINE: foreach my $line (@output) {

    chomp $line;

    if ( $parse_state == 0 ) {
        if ( $line =~ m/Model 01/ ) {
            $parse_state = 1;
            next LINE;
        }
    }

    if ( $parse_state == 1 ) {
        if ( $line =~ m/^\s*$/ ) {
            $parse_state = 2;
            next LINE;
        }
    }

    if ( $parse_state == 2 ) {
        if ( $line =~ m/Serial Number: (.+)$/ ) {
            $device->{'serial_number'} = $1;
            next LINE;
        }
        if ( $line =~ m/Location ID: (.+)$/ ) {
            $device->{'location_id'} = $1;
            next LINE;
        }
        if ( $line =~ m/Product ID: (.+)$/ ) {
            $device->{'product_id'} = $1;
            next LINE;
        }
        if ( $line =~ m/Vendor ID: (.+)$/ ) {
            $device->{'vendor_id'} = $1;
            next LINE;
        }
        if ( $line =~ m/^\s*$/ ) {
            last LINE;
        }
    }

}

die "Can't find Model 01" if ( $device == {} );

my $serial_port_name = "";

if ( exists( $device->{'serial_number'} ) ) {
    $serial_port_name = "/dev/cu.usbmodem" . $device->{'serial_number'};
    if ( -e $serial_port_name ) {
        print $serial_port_name;
        exit 0;
    }
}

if ( exists( $device->{'location_id'} ) ) {
    my $loc = substr( $device->{'location_id'}, 2, 4 );
    $serial_port_name = "/dev/cu.usbmodem" . $loc . 1;
    if ( -e $serial_port_name ) {
        print $serial_port_name;
        exit 0;
    }
}

die "Can't find Model 01 serial port name";