#!/usr/bin/perl

# DOG interpreter 0.3
# Language and intepreter made by Jeremy Ruten (jeremy.ruten@gmail.com)
# http://bio-gaming.com/jeremy/dog

# -------------------------------------------------------------
# History
# -------------------------------------------------------------
#
# Version 0.3
# -----------
#
# - "clear" command added
# - Changed behaviour of interpreter when trying to execute a
#   command a negative number of times.
#
# Version 0.2
# -----------
#
# - Checks for errors
# - Can use dish1, dish2, dish3, etc. instead of just dish1 &
#   dish2. Also, can use plate1, plate2, plate3, etc. instead
#   of just plate.
#
# Version 0.1
# -----------
#
# - First release
#
# -------------------------------------------------------------


# -------------------------------------------------------------
# Open the file and read it
# -------------------------------------------------------------

if ($#ARGV + 1 != 1) {
	die ("Usage: dog.pl program.dog\n");
}

open (PROGRAM, "<" . $ARGV[0]);
my(@lines) = <PROGRAM>;

# -------------------------------------------------------------
# Get rid of all the useless white-space
# -------------------------------------------------------------

foreach $line (@lines) {
	chop $line;
	$line =~ s/\t//g;
	$line =~ s/  / /g;
	$line =~ s/  / /g;
	if (substr($line, 0, 1) eq " ") { $line = substr($line, 1); }
	if (substr($line, length($line) + 1, 1) eq " ") { $line = substr($line, 0, length($line)); }
}

# -------------------------------------------------------------
# Set up some variables
# -------------------------------------------------------------

$PC = 0;
@dish = (0);
@plate = (0);
@floor = (0);
$dogmouth = 0;

# -------------------------------------------------------------
# Subs
# -------------------------------------------------------------

sub get_random_floor {
	$current_value = 0;
	until ($current_value != 0) {
		$random = int(rand($#floor + 1));
		$current_value = $floor[$random];
	}
	return $random;
}

sub valid_value {
	$s = $_[0];
	if ($s =~ /dish[0-9]/ || $s =~ /plate[0-9]/ || $s eq "floor") { return 1; }
	else { return 0; }
}

sub print_error {
	$txt = $_[0];
	$line_num = $_[1] + 1;
	print("*Error* $txt [Line $line_num]\n");
	exit();
}

# -------------------------------------------------------------
# Start the interpreting!
# -------------------------------------------------------------

while ($PC != -1) {
	@instruction_parts = split(/ /, $lines[$PC]);

	# Check for a number or variable before the rest of the instruction
	$command_start = 1;
	if ($instruction_parts[0] =~ /dish[0-9]/) {
		$execute_times = $dish[substr($instruction_parts[0], 4)];
	} elsif ($instruction_parts[0] =~ /plate[0-9]/) {
		$execute_times = $plate[substr($instruction_parts[0], 5)];
		if ($execute_times != 0) { $execute_times = 1; }
	} elsif ($instruction_parts[0] eq "floor") {
		$floor_number = &get_random_floor;
		$execute_times = $floor[$floor_number];
	} elsif ($instruction_parts[0] =~ /[0-9]/) {
		$execute_times = $instruction_parts[0];
	} else {
		$execute_times = 1;
		$command_start = 0;
	}

	if ($execute_times < 0) { $execute_times = 0; }

	# Now the command should only be split into two parts
	if ($command_start == 0) {
		@instruction_parts = ($instruction_parts[0], substr($lines[$PC], length($instruction_parts[0]) + 1));
	} else {
		@instruction_parts = ($instruction_parts[1], substr($lines[$PC], length($instruction_parts[0]) + 1 + length($instruction_parts[1]) + 1));
	}

	$cmd = $instruction_parts[0];
	$rest_cmd = $instruction_parts[1];

	for ($i = 0; $i < $execute_times; $i++) {
		if ($cmd eq "fetch") {
			if (&valid_value($rest_cmd) == 1 || $rest_cmd =~ /[0-9]/) {
				if ($rest_cmd =~ /dish[0-9]/) { $dogmouth += $dish[substr($rest_cmd, 4)]; }
				elsif ($rest_cmd =~ /plate[0-9]/) { $dogmouth += $plate[substr($rest_cmd, 5)]; }
				elsif ($rest_cmd eq "floor") { $dogmouth += $floor[&get_random_floor]; }
				else { $dogmouth += $rest_cmd; }
			} else {
				&print_error("Invalid value", $PC);
			}
		}
		elsif ($cmd eq "drop") {
			if (&valid_value($rest_cmd) == 1) {
				if ($rest_cmd =~ /dish[0-9]/) { $dish[substr($rest_cmd, 4)] += $dogmouth; }
				elsif ($rest_cmd =~ /plate[0-9]/) { $plate[substr($rest_cmd, 5)] += $dogmouth; }
				elsif ($rest_cmd eq "floor") { push(@floor, $dogmouth); }
				$dogmouth = 0;
			} else {
				&print_error("Invalid value", $PC);
			}
		}
		elsif ($cmd eq "pickup") {
			if (&valid_value($rest_cmd) == 1) {
				if ($rest_cmd =~ /dish[0-9]/) { $dogmouth += $dish[substr($rest_cmd, 4)]; $dish[substr($rest_cmd, 4)] = 0; }
				elsif ($rest_cmd =~ /plate[0-9]/) { $dogmouth += $plate[substr($rest_cmd, 5)]; $plate[substr($rest_cmd, 5)] = 0; }
				elsif ($rest_cmd eq "floor") { $floor_pile = &get_random_floor; $dogmouth += $floor[$floor_pile]; $floor[$floor_pile] = 0; }
			} else {
				&print_error("Invalid value", $PC);
			}
		}
		elsif ($cmd eq "eat") {
			if (&valid_value($rest_cmd) == 1 || $rest_cmd =~ /[0-9]/ || $rest_cmd eq "") {
				if ($rest_cmd =~ /dish[0-9]/) { $dogmouth -= $dish[substr($rest_cmd, 4)]; }
				elsif ($rest_cmd =~ /plate[0-9]/) { $dogmouth -= $plate[substr($rest_cmd, 5)]; }
				elsif ($rest_cmd eq "floor") { $dogmouth -= $floor[&get_random_floor]; }
				elsif ($rest_cmd eq "") { $dogmouth = 0; }
				else { $dogmouth -= $rest_cmd; }
			} else {
				&print_error("Invalid value", $PC);
			}
		}
		elsif ($cmd eq "clear") {
			if (&valid_value($rest_cmd) == 1) {
				if ($rest_cmd =~ /dish[0-9]/) { $dish[substr($rest_cmd, 4)] = 0; }
				elsif ($rest_cmd =~ /plate[0-9]/) { $plate[substr($rest_cmd, 5)] = 0; }
				elsif ($rest_cmd eq "floor") { @floor = (0); }
			} else {
				&print_error("Invalid value", $PC);
			}
		}
		elsif ($cmd eq "die") {
			print ("\n");
			exit();
		}
		elsif ($cmd eq "take") {
			$input = "";
			until ($input =~ /[0-9]\n/) {
				$input = <STDIN>;
			}
			chop $input;
			$dogmouth += $input;
		}
		elsif ($cmd eq "show") {
			print ($dogmouth);
		}
		elsif ($cmd eq "give") {
			print ($dogmouth);
			$dogmouth = 0;
		}
		elsif ($cmd eq "bark") {
			if (substr($rest_cmd, 0, 1) == '"' && substr($rest_cmd, length($rest_cmd) + 1, 1) == '"') {
				$string_to_print = substr($rest_cmd, 1, length($rest_cmd) - 2);
				$string_to_print =~ s/\\n/\n/g;
				print($string_to_print);
			} else {
				&print_error("Invalid string", $PC);
			}
		}
		elsif ($cmd eq "jump") {
			if ($rest_cmd ne "") {
				$t_PC = 0;
				$label_found = 0;
				foreach $line (@lines) {
					if ($line eq "label " . $rest_cmd) {
						$PC = $t_PC;
						$label_found = 1;
					}
					$t_PC++;	
				}
				if ($label_found == 0) {
					&print_error("Label '$rest_cmd' not found", $PC);
				}
			} else {
				&print_error("No label given", $PC);
			}
		}
		elsif ($cmd eq "label") {
			# Do nothing
		}
		elsif ($cmd eq "") {
			# Do nothing
		}
		else {
			&print_error("Invalid command", $PC);
		}
	}

	$PC++;

	if ($PC > $#lines) { $PC = -1; }
}

print ("\n");