package vm

type OpHandler func(*State, *Instruction)

var OpHandlers = map[OpCodeType]OpHandler{
	OpNoOp:   (*State).NoOp,
	OpCall:   (*State).Call,
	OpReturn: (*State).Return,

	OpMove: (*State).Move,

	OpAdd:            (*State).Add,
	OpSubtract:       (*State).Subtract,
	OpMultiply:       (*State).Multiply,
	OpDivideUnsigned: (*State).DivideUnsigned,
	OpDivideSigned:   (*State).DivideSigned,

	OpIsEqual:                      (*State).IsEqual,
	OpIsLessThanUnsigned:           (*State).IsLessThanUnsigned,
	OpIsLessThanSigned:             (*State).IsLessThanSigned,
	OpIsGreaterThanUnsigned:        (*State).IsGreaterThanUnsigned,
	OpIsGreaterThanSigned:          (*State).IsGreaterThanSigned,
	OpIsLessThanOrEqualUnsigned:    (*State).IsLessThanOrEqualUnsigned,
	OpIsLessThanOrEqualSigned:      (*State).IsLessThanOrEqualSigned,
	OpIsGreaterThanOrEqualUnsigned: (*State).IsGreaterThanOrEqualUnsigned,
	OpIsGreaterThanOrEqualSigned:   (*State).IsGreaterThanOrEqualSigned,

	OpJump:        (*State).Jump,
	OpJumpIfTrue:  (*State).JumpIfTrue,
	OpJumpIfFalse: (*State).JumpIfFalse,
}

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

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

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

func (state *State) Move(instr *Instruction) {
	in := state.ReadUnsigned(&instr.Operand2)
	state.WriteUnsigned(&instr.Operand1, in)
}

func (state *State) Add(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.WriteUnsigned(&instr.Operand1, in1+in2)
}

func (state *State) Subtract(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.WriteUnsigned(&instr.Operand1, in1-in2)
}

func (state *State) Multiply(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.WriteUnsigned(&instr.Operand1, in1*in2)
}

func (state *State) DivideUnsigned(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.WriteUnsigned(&instr.Operand1, in1/in2)
}

func (state *State) DivideSigned(instr *Instruction) {
	in1 := state.ReadSigned(&instr.Operand1)
	in2 := state.ReadSigned(&instr.Operand2)
	state.WriteSigned(&instr.Operand1, in1/in2)
}

func (state *State) IsEqual(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.ComparisonResult = (in1 == in2)
}

func (state *State) IsLessThanUnsigned(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.ComparisonResult = (in1 < in2)
}

func (state *State) IsLessThanSigned(instr *Instruction) {
	in1 := state.ReadSigned(&instr.Operand1)
	in2 := state.ReadSigned(&instr.Operand2)
	state.ComparisonResult = (in1 < in2)
}

func (state *State) IsGreaterThanUnsigned(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.ComparisonResult = (in1 > in2)
}

func (state *State) IsGreaterThanSigned(instr *Instruction) {
	in1 := state.ReadSigned(&instr.Operand1)
	in2 := state.ReadSigned(&instr.Operand2)
	state.ComparisonResult = (in1 > in2)
}

func (state *State) IsLessThanOrEqualUnsigned(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.ComparisonResult = (in1 <= in2)
}

func (state *State) IsLessThanOrEqualSigned(instr *Instruction) {
	in1 := state.ReadSigned(&instr.Operand1)
	in2 := state.ReadSigned(&instr.Operand2)
	state.ComparisonResult = (in1 <= in2)
}

func (state *State) IsGreaterThanOrEqualUnsigned(instr *Instruction) {
	in1 := state.ReadUnsigned(&instr.Operand1)
	in2 := state.ReadUnsigned(&instr.Operand2)
	state.ComparisonResult = (in1 >= in2)
}

func (state *State) IsGreaterThanOrEqualSigned(instr *Instruction) {
	in1 := state.ReadSigned(&instr.Operand1)
	in2 := state.ReadSigned(&instr.Operand2)
	state.ComparisonResult = (in1 >= in2)
}

func (state *State) Jump(instr *Instruction) {
	in := state.ReadSigned(&instr.Operand1)
	state.InstructionIndex += in - 1
}

func (state *State) JumpIfTrue(instr *Instruction) {
	if state.ComparisonResult == true {
		state.Jump(instr)
	}
}

func (state *State) JumpIfFalse(instr *Instruction) {
	if state.ComparisonResult == false {
		state.Jump(instr)
	}
}