#!/usr/bin/env perl

#
# AGI script that renders speech to text using Google's Cloud Speech API.
#
# Copyright (C) 2011 - 2016, 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(speech-recog.agi,[lang],[timeout],[intkey],[NOBEEP],[rtimeout],[speechContexts])
# Records from the current channel until 2 seconds of silence are detected
# (this can be set by the user by the 'timeout' argument, -1 for no timeout) or the
# interrupt key (# by default) is pressed. If NOBEEP is set, no beep sound is played
# back to the user to indicate the start of the recording. If 'rtimeout' is set, 
# overwrite to the absolute recording timeout. 'SpeechContext' provides hints to 
# favor specific words and phrases in the results. Usage: [Agamemnon,Midas]
# The recorded sound is send over to Google speech recognition service and the
# returned text string is assigned as the value of the channel variable 'utterance'.
# The scripts sets the following channel variables:
# utterance  : The generated text string.
# confidence : A value between 0 and 1 indicating how 'confident' the recognition engine
#     feels about the result. Values bigger than 0.95 usually mean that the
#     resulted text is correct.
#
# User defined parameters:
# Speech API key from Google:
#	$key
#
# Default language:
#	$language
#
# Default timeout:
#	$timeout (value in seconds of silence before recording is stopped)
#
# Default interrupt key:
#	$intkey (can be any digit from 0 to 9 or # and *, or a combination of them)
#
# Sample rate:
#	$samplerate (value in Hz. 0 for automatic detection per channel/call, 16000 for
#   use with wideband codecs, 8000 for traditional codecs.
#
# Profanity filter:
#	$pro_filter ('false':disable, 'true': remove profanities)
#

use warnings;
use strict;
use File::Copy qw(move);
use File::Temp qw(tempfile);
use LWP::UserAgent;
use JSON;
use Encode qw(encode);
use MIME::Base64;

$| = 1;

# ----------------------------- #
#   User defined parameters:    #
# ----------------------------- #
# Speech API key                #
my $key = "";

# Default language              #
my $language = "en-US";

# Default max silence timeout   #
my $timeout = 2;

# Absolute Recording timeout    #
my $abs_timeout = -1;

# Default interrupt key         #
my $intkey = "#";

# Input audio sample rate       #
# Leave blank to auto-detect    #
my $samplerate = "";

# Profanity filter              #
my $pro_filter = "false";

# Verbose debugging messages    #
my $debug = 0;

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

my %AGI;
my $format;
my @result;
my $silence;
my $results    = 1;
my $beep       = "BEEP";
my $comp_level = -8;
my $ua_timeout = 30;
my $tmpdir     = "/tmp";
my $url        = "https://speech.googleapis.com/v1/speech";
my $phrases    = "";
my @phrases    = [];

# Store AGI input #
($AGI{arg_1}, $AGI{arg_2}, $AGI{arg_3}, $AGI{arg_4}, $AGI{arg_5}, $AGI{arg_6}) = @ARGV;
while (<STDIN>) {
	chomp;
	last if (!length);
	$AGI{$1} = $2 if (/^agi_(\w+)\:\s+(.*)$/);
}

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

# Reset variables. #
warn "$name Clearing channel variables.\n" if ($debug);
my %response = (
	utterance  => -1,
	confidence => -1,
);
set_channel_vars(%response);

# Abort if key is missing or required programs not found. #
if (!$key) {
	print "VERBOSE \"API key is missing. Aborting.\" 3\n";
	checkresponse();
	die "$name API key is missing. Aborting.\n";
}
my $flac = `/usr/bin/which flac`;
die "$name flac is missing. Aborting.\n" if (!$flac);
chomp($flac);
warn "$name Found flac in: $flac\n" if ($debug);

# Setting language, timeout, interrupt keys and BEEP indication #
if (length($AGI{arg_1})) {
	$language = $AGI{arg_1} if ($AGI{arg_1} =~ /^[a-z]{2}(-[a-zA-Z]{2,6})?$/);
}

if (length($AGI{arg_2})) {
	if ($AGI{arg_2} == -1) {
		$silence = "";
	} elsif ($AGI{arg_2} =~ /^\d+$/) {
		$silence = "s=$AGI{arg_2}";
	} else {
		$silence = "s=$timeout";
	}
} else {
	$silence = "s=$timeout";
}

if (length($AGI{arg_3})) {
	$intkey = "0123456789#*" if ($AGI{arg_3} eq "any");
	$intkey = $AGI{arg_3} if ($AGI{arg_3} =~ /^[0-9*#]+$/);
}

if (length($AGI{arg_4})) {
	$beep = "" if ($AGI{arg_4} eq "NOBEEP");
}

if (length($AGI{arg_5})) {
	$abs_timeout = $AGI{arg_5};
}

if (length($AGI{arg_6})) {
	$phrases = $AGI{arg_6};
	$phrases = substr($phrases,1,-1);
	@phrases = split(',',$phrases);
}

# Answer channel if not already answered #
warn "$name Checking channel status.\n" if ($debug);
print "CHANNEL STATUS\n";
@result = checkresponse();
if ($result[0] == 4) {
	warn "$name Answering channel.\n" if ($debug);
	print "ANSWER\n";
	@result = checkresponse();
	if ($result[0] != 0) {
		die "$name Failed to answer channel.\n";
	}
}

# Setting recording file format according to sample rate. #
if    (!$samplerate)         { ($format, $samplerate) = detect_format(); }
elsif ($samplerate == 12000) { $format = "sln12"; }
elsif ($samplerate == 16000) { $format = "sln16"; }
elsif ($samplerate == 32000) { $format = "sln32"; }
elsif ($samplerate == 44100) { $format = "sln44"; }
elsif ($samplerate == 48000) { $format = "sln48"; }
else                         { ($format, $samplerate) =  ("sln", 8000); }

# Initialize User agent #
my $ua = LWP::UserAgent->new(ssl_opts => {verify_hostname => 1});
$ua->agent("Asterisk AGI speech recognition script");
$ua->env_proxy;
$ua->timeout($ua_timeout);

# Handle interrupts #
$SIG{'INT'} = \&int_handler;
$SIG{'HUP'} = \&int_handler;

# Record file #
my ($fh, $tmpname) = tempfile("stt_XXXXXX", DIR => $tmpdir, UNLINK => 1);
print "RECORD FILE $tmpname $format \"$intkey\" \"$abs_timeout\" $beep \"$silence\"\n";
@result = checkresponse();
die "$name Failed to record file, aborting...\n" if ($result[0] == -1);

if ($debug) {
	warn "$name Recording Format: $format, Rate: $samplerate Hz, ",
		"Language: $language, ", "$silence, Interrupt keys: $intkey\n";
}

# Encode audio data to flac #
my $endian = (unpack("h*", pack("s", 1)) =~ /01/) ? "big" : "little";
system($flac, $comp_level, "--totally-silent", "--channels=1", "--endian=$endian",
	"--sign=signed", "--bps=16", "--force-raw-format", "--sample-rate=$samplerate",
	"$tmpname.$format") == 0 or die "$name $flac failed: $?\n";
open($fh, "<", "$tmpname.flac") or die "Can't read file: $!";

my $audio = do { local $/; <$fh> };
close($fh);

my %config = (
	"encoding"         => "FLAC",
	"sampleRateHertz"  => $samplerate,
	"languageCode"     => $language,
	"profanityFilter"  => $pro_filter,
	"speechContexts"   => {"phrases" => \@phrases},
);
my %audio = ( "content" => encode_base64($audio, "") );

my %json = (
	"config" => \%config,
	"audio"  => \%audio,
);
# Send audio data for analysis #
my $uaresponse = $ua->post(
	"$url:recognize?key=$key",
	Content_Type => "application/json",
	Content      => encode_json(\%json),
);

warn "$name The response was:\n", $uaresponse->content if ($debug);
if (!$uaresponse->is_success) {
	print "VERBOSE \"Unable to get recognition data.\" 3\n";
	checkresponse();
	die "$name Unable to get recognition data.\n";
}
my $jdata = decode_json($uaresponse->content);
$response{utterance} = encode('utf8', $jdata->{"results"}[0]->{"alternatives"}[0]->{"transcript"});
$response{confidence} = $jdata->{"results"}[0]->{"alternatives"}[0]->{"confidence"};

set_channel_vars(%response);
exit;

sub set_channel_vars {
	my %resp = @_;
	foreach (keys %resp) {
		warn "$name Setting variable: $_ = $response{$_}\n" if ($debug);
		print "SET VARIABLE \"$_\" \"$response{$_}\"\n";
		checkresponse();
	}
}

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;
}

sub detect_format {
# Detect the sound format used #
	my @format;
	print "GET FULL VARIABLE \${CHANNEL(audionativeformat)}\n";
	my @reply = checkresponse();
	for ($reply[1]) {
		if    (/(silk|sln)12/)                    { @format = ("sln12", 12000); }
		elsif (/(speex|slin|silk)16|g722|siren7/) { @format = ("sln16", 16000); }
		elsif (/(speex|slin|celt)32|siren14/)     { @format = ("sln32", 32000); }
		elsif (/(celt|slin)44/)                   { @format = ("sln44", 44100); }
		elsif (/(celt|slin)48/)                   { @format = ("sln48", 48000); }
		else                                      { @format = ("sln",    8000); }
	}
	return @format;
}

sub int_handler {
	die "$name Interrupt signal received, terminating...\n";
}

END {
	if ($tmpname) {
		warn "$name Cleaning temp files.\n" if ($debug);
		unlink glob "$tmpname.*";
	}
}