#!/usr/bin/env perl

#
# AGI script that uses iSpeech text to speech engine.
# http://www.ispeech.org/
#
# Copyright (C) 2011 - 2014, Lefteris Zafiris <zaf.000@gmail.com>
#
# This program is free software, distributed under the terms of
# the GNU General Public License Version 2. See the LICENSE file
# at the top of the source tree.
#
# The Asterisk ispeech plugin developmend was funded by ifbyphone http://ifbyphone.com/
#
# -----
# Usage
# -----
# agi(ispeech-tts.agi,"text",[voice],[intkey],[speed]): This will invoke the iSpeech TTS
# engine, render the text string to speech and play it back to the user.
# If 'intkey' is set the script will wait for user input. Any given interrupt keys will
# cause the playback to immediately terminate and the dialplan to proceed to the
# matching extension (this is mainly for use in IVR, see README for examples).
# If 'speed' is set the speech rate is altered by that factor.
#
#
# Parameters like default voice, max wold number, speed, caching, cache dir and
# use of SSL can be set up by altering the following variables:
# Default voice:     $voice
# Max word count:    $word_limit
# Speed factor:      $speed
# Chace:             $usecache
# SSL:               $use_ssl
#
# An API key is a password that is required for access. To obtain an API key please visit:
# http://www.ispeech.org/developers and register for a developer account.

use warnings;
use strict;
use Encode qw(decode encode);
use Digest::MD5 qw(md5_hex);
use File::Path qw(mkpath);
use URI::Escape;
use LWP::UserAgent;
use LWP::ConnCache;
$| = 1;


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

# Default voice                 #
my $voice = "usenglishfemale";

# API word limit
my $word_limit  = 50;

# Output speed factor           #
my $speed = 1;

# Use of cache mechanism        #
my $usecache = 0;

# Cache directory path          #
my $cachedir = "/tmp";

# Use SSL                       #
my $use_ssl = 1;

# Verbose debugging messages    #
my $debug = 1;

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

my %AGI;
my @text;
my $ua;
my $filename;
my @result;
my $name;
my $url;
my $frequency = 8000;
my $format    = "wav";
my $intkey    = "";
my $timeout   = 10;
my $maxlen    = 4096;
my $host      = "api.ispeech.org/api/rest";

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

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


# Sanitising input #
$AGI{arg_1} = uri_unescape($AGI{arg_1});
$AGI{arg_1} = decode('utf8', $AGI{arg_1});
for ($AGI{arg_1}) {
	s/[\\|*~<>^\(\)\[\]\{\}[:cntrl:]]/ /g;
	s/\s+/ /g;
	s/^\s|\s$//g;
	die "$name No text passed for synthesis.\n" if (!length);
	# Split input to comply with word limits #
	$_ .= "." unless (/^.+[.,?!:;]$/);
	@text = /(?:\W*\w+){1,$word_limit}[.,?!:;]+|(?:\W*\w+){1,$word_limit}\s+/g;
}

# Setting voice, interrupt keys and speed rate #
if (length($AGI{arg_2})) {
	if ($AGI{arg_2} =~ /^[a-z]+$/) {
		$voice = $AGI{arg_2};
	} else {
		warn "$name Invalid voice setting. Using default.\n";
	}
}

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})) {
	$speed = $AGI{arg_4} if ($AGI{arg_4} =~ /^\d+(\.\d+)?$/ and ($AGI{arg_4} <= 10 and $AGI{arg_4} >= 0));
}

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

# Check cache path size: dir length + md5 + file extension #
if ($usecache && ((length($cachedir) + 32 + 6) < $maxlen)) {
	mkpath("$cachedir") unless (-d "$cachedir");
} else {
	warn "$name Cache path size exceeds limit. Disabling cache.\n";
	$usecache = 0;
}

# 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";
	}
}

# Initialise User angent #
if ($use_ssl) {
	$url = "https://" . $host;
	$ua  = LWP::UserAgent->new(ssl_opts => {verify_hostname => 1});
} else {
	$url = "http://" . $host;
	$ua  = LWP::UserAgent->new;
}
$ua->agent("Asterisk iSpeech TTS module");
$ua->env_proxy;
$ua->conn_cache(LWP::ConnCache->new());
$ua->timeout($timeout);

foreach my $line (@text) {
	$line = encode('utf8', $line);
	$line =~ s/^\s+|\s+$//g;
	next if (length($line) == 0);
	if ($debug) {
		warn "$name Text passed for synthesis: $line\n",
			"$name Voice: $voice, Interrupt keys: $intkey, Speed: $speed\n",
			"$name Caching: $usecache, Cache dir: $cachedir\n";
	}
	$filename = md5_hex("$line.$speed.$voice");
	if ($usecache) {
		# Stream file from cache if it exists #
		if (-r "$cachedir/$filename.$format") {
			warn "$name File already in cache.\n" if ($debug);
			my $res = playback("$cachedir/$filename", $intkey);
			last if ($res > 0);
			die if ($res < 0);
			next;
		}
	}
	$line = uri_escape($line);
	die "$name No API key found. Aborting.\n" if (!$key);
	warn "$name URL passed: $url?apikey=$key&action=convert&text=$line&voice=$voice&format=$format&frequency=$frequency&speed=$speed\n" if ($debug);

	open(my $fh, "+>", "$cachedir/$filename.$format")
		or die "$name Unable to open file for writing: $cachedir/$filename.$format\n";
	my $ua_response = $ua->get(
		"$url?apikey=$key&action=convert&text=$line&voice=$voice&format=$format&frequency=$frequency&speed=$speed",
		':content_file' => "$cachedir/$filename.$format",
	);

	warn "$name The response was: ", $ua_response->decoded_content if ($debug);
	die "$name Failed to fetch voice data.\n" unless ($ua_response->is_success);
	if ($ua_response->code != 200) {
		my $error = <$fh>;
		close($fh);
		unlink "$cachedir/$filename.$format";
		$error = uri_unescape($error);
		die "$name An iSpeech API error occured: $error\n";
	}
	close($fh);
	# Playback and delete file if no caching is set #
	my $res = playback("$cachedir/$filename", $intkey);
	unlink "$cachedir/$filename.$format" if (!$usecache);
	last if ($res > 0);
	die if ($res < 0);
}
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;
}

sub playback {
	my ($file, $keys) = @_;
	my @response;

	print "STREAM FILE $file \"$keys\"\n";
	@response = checkresponse();
	if ($response[0] >= 32 && chr($response[0]) =~ /[\w*#]/) {
		warn "$name Got digit ", chr($response[0]), "\n" if ($debug);
		print "SET EXTENSION ", chr($response[0]), "\n";
		checkresponse();
		print "SET PRIORITY 1\n";
		checkresponse();
	} elsif ($response[0] == -1) {
		warn "$name Failed to play $file\n";
	}
	return $response[0];
}