package lab08;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * Model a Pippin Program - a list of Pippin instructions.
 * @author cs140
 */
public class Program {
	
	private List<Instruction> program;
	
	/**
	 * Constructor - creates a new empty program (no instructions).
	 */
	public Program() {
		program=new ArrayList<Instruction>();
	}
	
	/**
	 * Constructor - creates a program from an object file
	 * @param objFileName
	 */
	public Program(String objFileName) {
		this(); // Instantiate the array list
		File objFile = new File(objFileName);
		try(Scanner objScan = new Scanner(objFile)) {
			while(objScan.hasNextInt()) {
				int instr = objScan.nextInt();
				add(new Instruction(instr));
			}
		} catch (FileNotFoundException e) {
			System.out.println("Object file " + objFileName + " not found.");
		}
	}

	/**
	 * Adds a new instruction to the program.
	 * @param e an instruction
	 * @return true if instruction was added, false otherwise
	 */
	public boolean add(Instruction e) { return program.add(e); }

	/**
	 * Remove all instructions from the program, leaving it empty.
	 */
	public void clear() { program.clear(); }

	/**
	 * Get the size of the program.
	 * @return number of instructions in the program
	 */
	public int size() { return program.size(); }
	
	/**
	 * Load the program into the CPU.
	 * <ul>
	 * <li>Store instructions into memory, starting at location 0
	 * <li>Set the CPU's instructionCounter to 0 (beginning of the program)
	 * <li>Set the CPU's dataMemoryBase to last instruction loaded + 1
	 * </ul>
	 * @param cpu CPU object in which to load this program
	 */
	public void load(CPU cpu) {
		load(cpu,0); // By default, load the program at location 0
	}
	
	/**
	 * Load the program into the CPU.
	 * <ul>
	 * <li>Store instructions into memory, starting at location specified in the parameter
	 * <li>Set the CPU's instructionCounter to 0 (beginning of the program)
	 * </ul>
	 * @param cpu CPU object in which to load this program
	 */
	public void load(CPU cpu,int instructionCounter) {
		cpu.setInstructionPointer(instructionCounter);
		Memory mem = cpu.getMemory();
		for(Instruction inst : program) {
			inst.store(mem,instructionCounter);
			instructionCounter ++;
		}
		// cpu.setDataMemoryBase(instructionCounter);
	}
	
	public void writeObject(String objectFileName) {
		File objFile = new File(objectFileName);
		try {
			objFile.createNewFile(); // Will create the file if it's not there
		} catch (IOException e1) {
			System.out.println("Unable to create output file: " + objectFileName + " " + e1.getMessage());
			return;
		} 
		try(PrintStream objStream = new PrintStream(objFile)) {
			for(Instruction inst : program) {
				objStream.println(inst.toInt());
			}
		} catch (FileNotFoundException e) {
			System.out.println("Unable to write program to file: " + objectFileName +" file not found.");
		}
	}
	
	public static void main(String[] args) {
		
		// Save the GCD program 
		Program prog = new Program();
		prog.add(new Instruction("CMZ","DIR",1)); // b==0
		prog.add(new Instruction("NOT","NOM",0)); // Invert for JMZ
		prog.add(new Instruction("JMZ","IMM",17)); // if (b==0) goto finished = 18
		prog.add(new Instruction("LOD","DIR",0)); // acc=a
		prog.add(new Instruction("SUB","DIR",1)); // acc=a-b
		prog.add(new Instruction("STO","DIR",2)); // temp=a-b
		prog.add(new Instruction("CML","DIR",2)); // if ((a-b)<0) or b>a
		prog.add(new Instruction("NOT","NOM",0)); // Invert for JMZ
		prog.add(new Instruction("JMZ","IMM",7)); // if (b>a) goto end-of-if = 13
		prog.add(new Instruction("LOD","DIR",0)); // acc=a
		prog.add(new Instruction("STO","DIR",2)); // temp=acc=a
		prog.add(new Instruction("LOD","DIR",1)); // acc=b
		prog.add(new Instruction("STO","DIR",0)); // a=acc=b
		prog.add(new Instruction("LOD","DIR",2)); // acc=temp
		prog.add(new Instruction("STO","DIR",1)); // b=temp
		prog.add(new Instruction("LOD","DIR",1)); // acc=b
		prog.add(new Instruction("SUB","DIR",0)); // acc=b-a
		prog.add(new Instruction("STO","DIR",1)); // b=b-a
		prog.add(new Instruction("JMP","IMM",-18)); // goto start=0
		prog.add(new Instruction("HLT","NOM",0));
		
		prog.writeObject("src/lab08/gcd.pexe");
	}
	
}