#!/usr/bin/env perl

#
# AGI script that uses Google Translate API v2 for text translation.
#
# Copyright (C) 2012 - 2014, Lefteris Zafiris <zaf@fastmail.com>
#
# This program is free software, distributed under the terms of
# the GNU General Public License Version 2. See the COPYING file
# at the top of the source tree.
#
# -----
# Usage
# -----
# agi(googletranslate.agi,"text",[target language],[source language]):
# The text string will be send to google translate for translation to target language.
# The translated text will be stored as a channel variable named 'gtranslation'.
# The setting of source language is optional, if not set the tranlator engine
# will try to auto detect it.
# If both target language and source language are omitted the script performs language
# detection on the given text string and returns the two-character language code
# as the value of the channel variable 'glang'
#
# An API Key from google is required.
#

use warnings;
use strict;
use URI::Escape;
use JSON qw(decode_json);
use LWP::UserAgent;

binmode(STDOUT, ":encoding(UTF-8)");
$| = 1;

# ----------------------------- #
#   User defined parameters:    #
# ----------------------------- #
#  App ID from google           #
my $appid = "";

# Verbose debugging messages    #
my $debug = 0;

# ----------------------------- #

my %AGI;
my $text;
my $in_lang;
my $out_lang;
my $url = "https://www.googleapis.com/language/translate/v2";

# Store AGI input #
($AGI{arg_1}, $AGI{arg_2}, $AGI{arg_3}) = @ARGV;
while (<STDIN>) {
	chomp;
	last if (!length);
	$AGI{$1} = $2 if (/^agi_(\w+)\:\s+(.*)$/);
}

my $name = " -- $AGI{request}:";

# Reset channel variable. #
foreach ("gtranslation", "glang") {
	print "SET VARIABLE \"$_\" \"-1\"\n";
	checkresponse();
}

# Abort if there is not API key. #
die "$name No API key found. Aborting.\n" if (!$appid);

# Sanitising input #
for ($AGI{arg_1}) {
	s/[\\|*~<>^\(\)\[\]\{\}[:cntrl:]]/ /g;
	s/\s+/ /g;
	s/^\s|\s$//g;
	die "$name No text passed. Aborting\n" if (!length);
	$text = $_;
}

# Setting source and target language  #
if (length($AGI{arg_2})) {
	if ($AGI{arg_2} =~ /[a-zA-Z\-]{2,}/) {
		$out_lang = $AGI{arg_2};
	} else {
		die "$name Invalid output language setting.\n";
	}
	if (length($AGI{arg_3})) {
		if ($AGI{arg_3} =~ /[a-zA-Z\-]{2,}/) {
			$in_lang = $AGI{arg_3};
		} else {
			warn "$name Invalid input language setting. Using auto-detect.\n";
		}
	}
} else {
	warn "$name Performing Language detection.\n";
}

warn "$name Text passed for translation: $text\ntarget lang: $out_lang\n" if ($debug && $out_lang);
warn "$name Text passed for language detection: $text\n" if ($debug && !$out_lang);

# Translate text using Google Translate API #
my $ua = LWP::UserAgent->new(ssl_opts => {verify_hostmane => 1});
$ua->agent("Asterisk Google Translate module");
$ua->env_proxy;
$ua->timeout(10);
$text = uri_escape($text);

if ($in_lang && $out_lang) {
	$url .= "?key=$appid&q=$text&source=$in_lang&target=$out_lang";
} elsif (!$in_lang && $out_lang) {
	$url .= "?key=$appid&q=$text&target=$out_lang";
} elsif (!$out_lang) {
	$url .= "/detect?key=$appid&q=$text";
}

my $response = $ua->post("$url", "X-HTTP-Method-Override" => "GET");
die "$name Failed to fetch file.\n" if (!$response->is_success);
# export resulted text to channel variable #
my $jdata = decode_json $response->content;

if ($out_lang) {
	print "SET VARIABLE \"gtranslation\" \"$$jdata{data}{translations}[0]{translatedText}\"\n";
	checkresponse();
} else {
	print "SET VARIABLE \"glang\" \"$$jdata{data}{detections}[0][0]{language}\"\n";
	checkresponse();
}

exit;

sub checkresponse {
	my $input = <STDIN>;
	my @values;

	chomp $input;
	if ($input =~ /^200 result=(-?\d+)\s?(.*)$/) {
		warn "$name Command returned: $input\n" if ($debug);
		@values = ("$1", "$2");
	} else {
		$input .= <STDIN> if ($input =~ /^520-Invalid/);
		warn "$name Unexpected result: $input\n";
		@values = (-1, -1);
	}
	return @values;
}