package lab07;

public enum Operation {
	NOP { 
		public boolean isModeValid(Mode mode) {
			return mode==Mode.NOM;
		}
		public String execute(CPU cpu, Instruction inst) {
			return "";
		}
	}, 
	LOD {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setAccumulator(inst.fetchOperand(cpu));
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	STO {
		public boolean isModeValid(Mode mode) {
			return mode==Mode.DIR;
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setData(inst.getArgument(),cpu.getAccumulator());
			return " data[" + inst.getArgument() + "]=" + cpu.getAccumulator();
		}
	}, 
	ADD {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setAccumulator(inst.fetchOperand(cpu)+cpu.getAccumulator());
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	SUB {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setAccumulator(cpu.getAccumulator()-inst.fetchOperand(cpu));
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	MUL {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setAccumulator(cpu.getAccumulator()*inst.fetchOperand(cpu));
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	DIV { 
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			if (inst.fetchOperand(cpu)==0) {
				System.out.println("Attempted to Divide by Zero ignored");
				return " ERROR: divide by zero!";
			}
			cpu.setAccumulator(cpu.getAccumulator()/inst.fetchOperand(cpu));
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	AND { 
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			int newValue = ((inst.fetchOperand(cpu) != 0) && (cpu.getAccumulator() != 0) ? 1 : 0);
			cpu.setAccumulator(newValue);
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	NOT {
		public boolean isModeValid(Mode mode) {
			return mode==Mode.NOM;
		}
		public String execute(CPU cpu, Instruction inst) {
			int newValue = ((cpu.getAccumulator() != 0) ? 0 : 1);
			cpu.setAccumulator(newValue);
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	CML {
		public boolean isModeValid(Mode mode) {
			return mode==Mode.DIR;
		}
		public String execute(CPU cpu, Instruction inst) {
			int newValue=(inst.fetchOperand(cpu)<0) ? 1 : 0;
			cpu.setAccumulator(newValue);
			return " acc=" + cpu.getAccumulator();
		}
	}, 
	CMZ { 
		public boolean isModeValid(Mode mode) {
			return mode==Mode.DIR;
		}
		public String execute(CPU cpu, Instruction inst) {
			int newValue=(inst.fetchOperand(cpu)==0) ? 1 : 0;
			cpu.setAccumulator(newValue);
			return " acc=" + cpu.getAccumulator();
		}
	},
	JMP {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		public String execute(CPU cpu, Instruction inst) {
			int currentIp=cpu.getInstructionPointer()-1;
			cpu.setInstructionPointer(currentIp + inst.fetchOperand(cpu));
			return " instructionPointer = " + cpu.getInstructionPointer(); 
		} 
	},
	JMZ {
		public boolean isModeValid(Mode mode) {
			return isModeIMMorDIR(mode);
		}
		
		public String execute(CPU cpu, Instruction inst) {
			if (cpu.getAccumulator()==0) { 
				int currentIp=cpu.getInstructionPointer()-1;
				cpu.setInstructionPointer(currentIp + inst.fetchOperand(cpu));
			}
			return " instructionPointer = " + cpu.getInstructionPointer(); 
		}
	},
	HLT { 
		public boolean isModeValid(Mode mode) {
			return mode==Mode.NOM;
		}
		public String execute(CPU cpu, Instruction inst) {
			cpu.setHalted(true);
			return " Program halted";
		}
	};
	
	public abstract boolean isModeValid(Mode mode);
	public abstract String execute(CPU cpu, Instruction inst);
	
	boolean isModeIMMorDIR(Mode mode) {
		if (mode==Mode.IMM || mode==Mode.DIR) return true;
		return false; 
	}
	
}