#! perl

# The international bank script. There are five commands one can
# give the banker in-game:
# - help, will show the usage information
# - deposit, can deposit a certain amount of a given currency unit
# - withdraw, can give out a certain amount of a given currency unit
#      provided, the bank account has this amount of money
# - exchange, will exchange between imperials and platinum coins
# - balance, simply shows how much money one has on his/her account.
#
# TODO:
# - Comment more steps

# The units are being used in each sub so they are declared globally.
my %unit = (
   silver => 1,
   gold => 10,
   platina => 50, 
   imperial => 10000, 
); 

# Subroutine just to calculate exchange rates.
sub calc_exchange_rate {
   my ($value, $from_cur, $to_cur) = @_;

   if ($unit{$from_cur} and $unit{$to_cur}) {
      return $value * $unit{$from_cur} / $unit{$to_cur};
   }
}

# Calculates and returns how much money someone has starting with the
# highest value currency going down. Think of it like having the date
# and time in the format of 2006-05-19 03:21:31 UTC instead of 1148001691
# seconds since 1970-01-01 00:00:00 UTC.
sub balance {
   my ($who) = @_;
   my $balance = $who->{bank_balance};

   if (!$balance or int($balance) == 0) {
      return "Sorry, you have no balance.";
   } else {

      my $imperials = calc_exchange_rate($balance, "silver", "imperial");
      my $platinum = calc_exchange_rate($imperials - int ($imperials), "imperial", "platina");
      my $gold = calc_exchange_rate($platinum - int ($platinum), "platina", "gold");
      my $silver = calc_exchange_rate($gold - int ($gold), "gold", "silver");

      return "You have ".int($imperials)." imperials, ".int($platinum)." platinum, ".int($gold)." gold and about ".int($silver)." silver coins.";
   }
}

sub transaction {
   my ($who, $action, $amount, $currency) = @_;
   my $pay = $amount * $unit{$currency};

   if (!$unit{$currency}) {
      return "We don't trade in that currency.";
   }

   # First check for possible overflow and user stupidity
   if ($amount > 10000) {
      return "Sorry, we do not handle more than 10000 units for one ".$action.".";
   } elsif ($amount == 0) {
      return "You can not ".$action." nothing.";
   } elsif ($amount < 0) {
      return "You can not ".$action." negative values.";
   }

   # Here we handle the transactions 
   if ($action eq "deposit") {
      if ($who->pay_amount ($pay)) {
         $who->{bank_balance} += $pay;
         return "$amount $currency received.";
      } else {
         return "You don't have enough money with you.";
      }
   } elsif ($action eq "withdraw") {
      if ($who->{bank_balance} - $pay > 0) {
         $who->{bank_balance} -= $pay;
         if ($currency eq "imperial") {
            my $money = cf::object::new ("imperial");
            $money->set_property (1, 24, $amount);
            $money->insert_in_ob ($who);
         } else {
            my $money = cf::object::new ($currency."coin");
            $money->set_property (1, 24, $amount);
            $money->insert_in_ob ($who);
         }
         return "Withdrew $amount $currency";
      }
   }
}

sub on_say {
   my ($event, $ob, $who, $msg) = @_;
   my ($cmd, $arguments) = split /\s+/, $msg, 2;
   my ($amount, $currency) = split /\s+/, $arguments, 2;
   my $service_charge = 5;
   my @units = sort keys %unit;
   my $units = join ", ", @units;
   my $fees = - ($service_charge / 100) + 1;

   if ($cmd eq "balance") {
      $who->message ($ob->name." says: ".balance ($who), cf::NDI_WHITE);
   }

   elsif ($cmd eq "deposit" and $currency) {
      $who->message ($ob->name." says: ".transaction($who, "deposit", $amount, $currency), cf::NDI_WHITE);
      $who->message ($ob->name." says: ".balance ($who), cf::NDI_WHITE);
   } elsif ($cmd eq "deposit" and $amount and $currency eq "") {
      $who->message ($ob->name." says: Deposit $amount of what: ".$units.".", cf::NDI_WHITE);
   } elsif ($cmd eq "deposit" and $amount eq "" and $currency eq "") {
      $who->message ($ob->name." says: How much do you want to deposit?", cf::NDI_WHITE);
   }

   elsif ($cmd eq "withdraw" and $currency) {
      $who->message ($ob->name." says: ".transaction($who, "withdraw", $amount, $currency), cf::NDI_WHITE);
      $who->message ($ob->name." says: ".balance ($who), cf::NDI_WHITE);
   } elsif ($cmd eq "withdraw" and $amount and $currency eq "") {
      $who->message ($ob->name." says: Withdraw $amount of what: ".$units.".", cf::NDI_WHITE);
   } elsif ($cmd eq "withdraw" and $amount eq "" and $currency eq "") {
      $who->message ($ob->name." says: How much do you want to withdraw?", cf::NDI_WHITE);
   }

   elsif ($cmd eq "help" or $cmd eq "yes") {
      $who->message ($ob->name." says: ".help($arguments), cf::NDI_WHITE);
   }

   else {
      $who->message ($ob->name." says: Do you need help?", cf::NDI_WHITE);
   }
}

sub help {
   my ($command) = @_;

   if ($command eq "") {
      return "You can:
      deposit <amount> <currency>
      withdraw <amount> <currency>
      balance
      exchange <amount> <direction>
      help <topic>";
   } elsif ($command eq "deposit") {
      return "You can deposit some of the money you don't currently use in our bank. To do this, ask me to:
      deposit <amount> <currency>\nSee help exchange for our currencies.";
   } elsif ($command eq "withdraw") {
      return "To get the money you stored in our system back, just say:
      withdraw <amount> <currency>";
   } elsif ($command eq "balance") {
      return "I can tell you how much money you are saving in our bank, just ask me about your balance.";
   } elsif ($command eq "exchange") {
      return "We exchange between imperial notes and platinum coins at a very low price. To change from platinum to imperials, say:
      exchange <amount> platina\nTo change from imperials to platinum, say:
      exchange <amount> imperial\nWe currently only exchange between these two currencies. If you want to know more about exchange rates, ask me:
      help exchange rates\nThanks for using our bank.";
   } elsif ($command eq "exchange rates") {
      my @units = sort { $unit{$b} <=> $unit{$a} } keys %unit;
      my $exchange_rates = "Here is a list of exchange rates:\n";

      for my $from_cur_nr (0 .. $#units) {
         for my $to_cur_nr ($from_cur_nr+1 .. $#units) {
            $exchange_rates = $exchange_rates."One $units[$from_cur_nr] is ".calc_exchange_rate(1, $units[$from_cur_nr], $units[$to_cur_nr])." $units[$to_cur_nr]\n";
         }
      }
      return $exchange_rates."This may change a bit with the stock markets but don't expect it to be much.";
   }
}