import java.io.InputStreamReader;
import java.io.FileNotFoundException;
import java.io.BufferedReader;
import java.io.IOException;

/**
 * This is a front end for executing a SaM program from a console
 */
public class SamText implements Video {

	public static void main(String[] args) {
		String fname = null;
		Program prg;
		SamText txt = new SamText();
		Sys sys = new Sys();
		Processor cpu = sys.cpu();
		Memory mem = sys.mem();
		sys.setVideo(txt);
		int il = -1, tl = -1; //limits

		/* Argument parser */
		boolean err = false;
		for (int a = 0; a < args.length; a++) {
			if (args[a].equals("+tl") && args.length > a + 1) 	//time limit	
				try { tl = Integer.parseInt(args[++a]); }
				catch (NumberFormatException e) 
					{ err = true; break; }
			else if (args[a].equals("+il") && args.length > a + 1) 	//instruction limit
				try { il = Integer.parseInt(args[++a]); }
				catch (NumberFormatException e) 
					{ err = true; break; }
			else if (args[a].equals("+il") || args[a].equals("+tl")) //limit without argument
				{ err = true; break; }

			else if (fname == null) 	//filename
				{ fname = args[a]; }

			else { err = true; break; }	// 2nd string
		}

		if (err) {
			System.err.println("Usage: java SamText <filename> <options>");
			System.err.println("If the options are omitted, the program runs without limits.");
			System.err.println("If the filename is omitted, System.in is used for input. ");
			System.err.println("Options: +tl <integer>: Time limit in milliseconds.");
			System.err.println("Options: +il <integer>: Instruction limit.");
			return;
		}

		try {
			if (fname != null)
				prg = SamAssembler.assemble(fname);
			else {
				System.out.println("Type SAM Code, EOF to end. ");
				System.out.println("(CTRL-D on Unix/Minix/Linux/OS X, CTRL-Z on DOS/Windows/Longhorn)" );
				System.out.println("============================");
				prg = SamAssembler.assemble(new InputStreamReader(System.in));
			}

			System.out.println("Program assembled.");
			cpu.load(prg);
			System.out.println("Program loaded. Executing.");
			System.out.println("==========================");

			final boolean ilim = (il < 0) ? false : true; //instruction limit on?
			final boolean tlim = (tl < 0) ? false : true; //time limit on?

			/* Execute */
			if (!ilim && !tlim)
				cpu.run();
			else {
				long start = 0;
				if (tlim)
					start = System.currentTimeMillis();

				while (cpu.get(Processor.HALT) == 0) {
					cpu.step();
					if (ilim && il-- == 0)
						throw new SystemException("Program exceeded instruction limit. Terminating.");
					if (tlim && (System.currentTimeMillis() - start > tl))
						throw new SystemException("Program exceeded time limit. Terminating.");
				}
			}

			/* Exit code */
			if (mem.getType(0) == Memory.FLOAT)
				System.out.println("Exit Status: " + Float.intBitsToFloat(mem.getMem(0)));
			else if (mem.getType(0) == Memory.CH)
				System.out.println("Exit Status: " + (char)mem.getMem(0));
			else
				System.out.println("Exit Status: " + mem.getMem(0));
		}

		catch (AssemblerException e) 	{ System.err.println("Assembler Error: " + e); 	return; }
		catch (TokenizerException e) 	{ System.err.println("Tokenizer Error: " + e); 	return; }
		catch (FileNotFoundException e) { System.err.println("File not found: " + e); 	return; }
		catch (SystemException e) 	{ System.err.println("Stack Machine Error: " + e); return; }
		catch (Exception e) {
			System.err.println("Internal Error, please report to the SaM Development Group " + e);
			e.printStackTrace(System.err);
			return;
		}

	}

	/* Video interface methods */
	private final static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

	public int readInt() {
		while (true) {
			try {
				System.out.print("Processor Input (enter integer): ");
				return Integer.parseInt(in.readLine());
			}
			catch (NumberFormatException e) { continue; }
			catch (IOException e) { return 0; }
		}
	}

	public String readString() {
		try {
			System.out.print("Processor Input (enter string): ");
			return in.readLine();
		}
		catch (IOException e) { return ""; }
	}

	public char readChar() {
		while (true) {
			try {
				System.out.print("Processor Input (enter character): ");
				String s = in.readLine();
				if(s != null && s.length() >= 1) return s.charAt(0);
			}
			catch (IOException e) { return 0; }
		}
	}


	public float readFloat() {
		while (true) {
			try {
				System.out.print("Processor Input (enter float): ");
				return Float.parseFloat(in.readLine());
			}
			catch (NumberFormatException e) { continue; }
			catch (IOException e) { return 0; }
		}
	}

	public void writeInt(int a)
		{ System.out.println("Processor Output: " + a); }

	public void writeFloat(float a)
		{ System.out.println("Processor Output: " + a); }

	public void writeChar(char a)
		{ System.out.println("Processor Output: " + a); }

	public void writeString(String a)
		{ System.out.println("Processor Output: " + a); }
}