package vm

type opHandler func(*State, *Instruction)

var opHandlers = map[OpCodeType]opHandler{
	OpNoOp:   (*State).handleNoOp,
	OpCall:   (*State).handleCall,
	OpReturn: (*State).handleReturn,

	OpMove: (*State).handleMove,

	OpAdd:            (*State).handleAdd,
	OpSubtract:       (*State).handleSubtract,
	OpMultiply:       (*State).handleMultiply,
	OpDivideUnsigned: (*State).handleDivideUnsigned,
	OpDivideSigned:   (*State).handleDivideSigned,

	OpIsEqual:                      (*State).handleIsEqual,
	OpIsLessThanUnsigned:           (*State).handleIsLessThanUnsigned,
	OpIsLessThanSigned:             (*State).handleIsLessThanSigned,
	OpIsGreaterThanUnsigned:        (*State).handleIsGreaterThanUnsigned,
	OpIsGreaterThanSigned:          (*State).handleIsGreaterThanSigned,
	OpIsLessThanOrEqualUnsigned:    (*State).handleIsLessThanOrEqualUnsigned,
	OpIsLessThanOrEqualSigned:      (*State).handleIsLessThanOrEqualSigned,
	OpIsGreaterThanOrEqualUnsigned: (*State).handleIsGreaterThanOrEqualUnsigned,
	OpIsGreaterThanOrEqualSigned:   (*State).handleIsGreaterThanOrEqualSigned,

	OpJump:        (*State).handleJump,
	OpJumpIfTrue:  (*State).handleJumpIfTrue,
	OpJumpIfFalse: (*State).handleJumpIfFalse,
}

func (state *State) handleNoOp(instr *Instruction) {
}

func (state *State) handleCall(instr *Instruction) {
	in := state.readSigned(&instr.Operand1)
	state.call(in)
}

func (state *State) handleReturn(instr *Instruction) {
	state.ret()
}

func (state *State) handleMove(instr *Instruction) {
	in := state.readUnsigned(&instr.Operand2)
	state.writeUnsigned(&instr.Operand1, in)
}

func (state *State) handleAdd(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.writeUnsigned(&instr.Operand1, in1+in2)
}

func (state *State) handleSubtract(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.writeUnsigned(&instr.Operand1, in1-in2)
}

func (state *State) handleMultiply(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.writeUnsigned(&instr.Operand1, in1*in2)
}

func (state *State) handleDivideUnsigned(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.writeUnsigned(&instr.Operand1, in1/in2)
}

func (state *State) handleDivideSigned(instr *Instruction) {
	in1 := state.readSigned(&instr.Operand1)
	in2 := state.readSigned(&instr.Operand2)
	state.writeSigned(&instr.Operand1, in1/in2)
}

func (state *State) handleIsEqual(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.comparisonResult = (in1 == in2)
}

func (state *State) handleIsLessThanUnsigned(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.comparisonResult = (in1 < in2)
}

func (state *State) handleIsLessThanSigned(instr *Instruction) {
	in1 := state.readSigned(&instr.Operand1)
	in2 := state.readSigned(&instr.Operand2)
	state.comparisonResult = (in1 < in2)
}

func (state *State) handleIsGreaterThanUnsigned(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.comparisonResult = (in1 > in2)
}

func (state *State) handleIsGreaterThanSigned(instr *Instruction) {
	in1 := state.readSigned(&instr.Operand1)
	in2 := state.readSigned(&instr.Operand2)
	state.comparisonResult = (in1 > in2)
}

func (state *State) handleIsLessThanOrEqualUnsigned(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.comparisonResult = (in1 <= in2)
}

func (state *State) handleIsLessThanOrEqualSigned(instr *Instruction) {
	in1 := state.readSigned(&instr.Operand1)
	in2 := state.readSigned(&instr.Operand2)
	state.comparisonResult = (in1 <= in2)
}

func (state *State) handleIsGreaterThanOrEqualUnsigned(instr *Instruction) {
	in1 := state.readUnsigned(&instr.Operand1)
	in2 := state.readUnsigned(&instr.Operand2)
	state.comparisonResult = (in1 >= in2)
}

func (state *State) handleIsGreaterThanOrEqualSigned(instr *Instruction) {
	in1 := state.readSigned(&instr.Operand1)
	in2 := state.readSigned(&instr.Operand2)
	state.comparisonResult = (in1 >= in2)
}

func (state *State) handleJump(instr *Instruction) {
	in := state.readSigned(&instr.Operand1)
	state.jump(in)
}

func (state *State) handleJumpIfTrue(instr *Instruction) {
	if state.comparisonResult == true {
		state.handleJump(instr)
	}
}

func (state *State) handleJumpIfFalse(instr *Instruction) {
	if state.comparisonResult == false {
		state.handleJump(instr)
	}
}