#!/usr/bin/perl -w
# Please run with -h for help
# Please run with -c for configuration (first time)
use strict;
# use Date::Calc; -- for later
my ($i, %conf);
CheckArg(@ARGV) if @ARGV;
die "file simplemoney.conf does not exist, please run -c to configure\n" unless (-e "simplemoney.conf"); #check for existance of configuration file

open (RCONF, "simplemoney.conf")  || die "Could not open simplemoney.conf $!";

foreach ("rt", "balance", "transaction"){ #load config variables into a hash
    chomp ($conf{$_} = <RCONF>);
}
close (RCONF) || die "Could not close simplemoney.conf $!"; 
unless (-e $conf{rt} && -e $conf{balance} && -e $conf{transaction}) {  
   die "One of the required files is missing, please run with -c to configure\n";
}
while (1) {
    my ($command, $arg1, $arg2);
    print "Your command (help for list of commands):\n";
    chomp ($command = <STDIN>);
    if ($command =~ /^balance/) {
	 print CalcBalance($conf{balance});
    } elsif ($command =~ /^help/i) {
	PrintHelp();
    } elsif ($command =~ /^deposit/i) {
	(undef, $arg1, $arg2) = split (/\s+/, $command); 
	CalcBalance($conf{balance},$arg1);
	AddTransaction($conf{transaction},$arg2);
    } elsif ($command =~ /^withdraw/i) {
	(undef, $arg1, $arg2) = split (/\s+/, $command); 
	$arg1 = -$arg1;
	CalcBalance($conf{balance},$arg1);
	AddTransaction($conf{transaction},$arg2);
    } elsif ($command =~ /^rt/i) {
	print "RT is not yet supported.";
    } elsif ($command =~ /^exit/i || $command =~ /^quit/i || $command =~ /^e/i || $command =~ /^q/i) {
	exit 0;
    } else { #must be undefined command, try again.
	print "\nBad Command\n";
	next;
    }
}



###Subs### 

sub PrintHelp {
print "This program calculates your money balance, please run with the -c flag to configure.\n";
	    print "Flags:\n";
	    print "     -c -- Configure\n";
	    print "     -h -- This file\n";
	    print "Default Files:\n";
	    print "     rt.log -- Reocuring transaction configuration\n";
	    print "     balance.log -- Backlog of user's balance\n";
	    print "     transaction.log -- Backlog of transaction descriptions\n";
	    print "     Configuration File: simplemoney.conf\n";
	    
print "Commands:\n";
	print "      help -- show this file.\n";
	print "      deposit <arg1> <arg2> -- deposit <arg1> dollars with <arg2> description in the log.\n";
	print "      withdraw <arg1> <arg2> -- same as above, but withdraw.\n";
	print "      rt -- not yet supported.\n";  
	print "      exit, quit, e, or q -- quit the program.\n";          
print "Note: running deposit or withdraw with no arguments will do nothing, running with only a value will print 'this description is intentionaly left blank' in balance.log\n"  
}

sub CheckArg {
    my $rargs = (shift @_);
    my $arg;
    foreach ($rargs) {
	if ($_ =~ /^-h/) {
	    PrintHelp();
	    exit 0;
	}
	elsif ($_ =~ /^-c/) {
	    Configure();
	}
	else { #must be an undefined option
	    die"Undefined Option: Please run the program with the -h flag for help\n";
	}
    }

}
sub Configure {
    my ($rt, $balance, $transaction);
    print "Welcome, please follow the instructions to configure this program (this will overwrite your current configuration)\n";
   
    print "Reoccuring transaction file (rt.log by default)?";
    chomp ($rt = <STDIN>);
    $rt        = "rt.log" unless ($rt); #assumes default if user gave no input.
    open  (WRT, ">$rt");
    close (WRT);
    
    print "Balance file (balance.log by default)";
    chomp ($balance = <STDIN>);
    $balance = "balance.log" unless ($balance); #assumes default if user gave no input.
    open  (WBALANCE, ">$balance") || die "could not open balance.log $!";
    print WBALANCE "0\n";
    close (WBALANCE) || die "could not close balance.log $!";
    
    print "Transaction file (transaction.log by default)";
    chomp ($transaction = <STDIN>);
    $transaction = "transaction.log" unless ($transaction); #assumes default if user gave no input.
    open  (WTRANSACTION, ">$transaction") || die "could not open transaction.log $!";
    print WTRANSACTION "start\n";
    close (WTRANSACTION) || die "could not close transaction.log $!";

    #write everything into configuration file
    open  (WCONF, ">simplemoney.conf") || die "could not open simplemoeny.conf $!";
    print WCONF "$rt\n$balance\n$transaction";
    close (WCONF) || die "could not close simplemoney.conf $!";
}

sub CalcBalance {
    my ($balance, @log);
    my  $location = shift(@_);
    open (RBALANCE, $location) || die "Can't open $location $!";
    @log = <RBALANCE>;
    close (RBALANCE) || die "Can't close $location $!";
    $balance = $log[-1];
    if ($_[0]) {     # we check to see if there is another 
	                              # argument (the amount to change) and 
	                              # it is not 0.
	my $toChange = shift(@_);     # we only declare this if another 
	                              # argument exists to make the test 
	                              # above work. 
	$balance += $toChange;
	open (WBALANCE, ">>$location") || die "Can't open $location $!";
	print WBALANCE "$balance\n";
	close (WBALANCE) || die "Can't close $location $!";
    }
    return $balance;
}

sub AddTransaction {
    my ($location) = shift(@_); 
    my ($description) = shift(@_) || "This description is intentionaly left blank";
    open (WTRANSACTION, ">>$location") || die "Can't open $location $!";
	print WTRANSACTION "$description\n";
    close (WTRANSACTION) || die "Can't close $location $!";

}