#! /usr/bin/perl

#
# FXEngine
# a bridge between the fxengine OCaml application
# and the rest of the FX Arbitrage application
#
#

package FXEngine;

use FXData;
use strict;

use constant USERDIR => "/tmp/";

# tempfile() -> temporary file name
sub tempfile {
    my $tmpfile;
    do {
        my $mid = $$ . srand(9999) . getppid();
        $tmpfile = USERDIR . "tmp$mid";
       } until (! -e($tmpfile) );
    return $tmpfile;
}

# FXEngine(FXData(), array) 
# FXData - FXData object
# array - array of currencies to be used to 
#   create arbitrage transactions.
sub new {
    my $class = shift;
    my $self = {};

    $self->{fxdata}   = shift;
    $self->{currency} = shift;
    $self->{limit}    = 10;
    $self->{positive_only} = 0;

    bless ($self, $class);
    return $self;
}

# set_limit(int)
# the number of transactions returned by get_transactions
sub set_limit {
    my $self = shift;
    $self->{limit} = shift;
}

# positive_only() 
# if called get_transactions
# only returns positive fx transactions.
sub positive_only {
    my $self = shift;
    $self->{positive_only} = 1;
}

# get_transactions() -> string 
# returns fx transactions
sub get_transactions {
    my $self = shift;

    my $list = join " ", @{$self->{currency}};
    
    my %table = $self->{fxdata}->rate_table();

    # create tempfile for fxengine data file
    my $tmpfile = tempfile() . ".fxe";
    open TMPFILE, ">$tmpfile" || die $!;

    print TMPFILE "$list\n";
    my ($key, $value);
    while (($key, $value) = each %table) {
        print TMPFILE "$key" . " " . $table{$key} . "\n";
    }

    close TMPFILE;

    # arguments to fxengine
    my @args = ();
    push(@args, "-p") if $self->{positive_only};
    my $sargs = join " ", @args;

    open ENGINE, "./fxengine $tmpfile $sargs |" || die $!; 
    
    my @records = <ENGINE>;

    close ENGINE;
    unlink $tmpfile;
    
    return @records[0..($self->{limit}-1)];;
}


1;