package creature

type Machine struct {
	stack   []int
	Program []int
	Block   []int
	counter int
	pointer int
}

func (machine *Machine) Execute (offset int) {
	machine.counter = offset

	for {
		switch machine.Program[machine.counter] {
		case 0x0:
		case 0x1:
		case 0x2:
		case 0x3:
		case 0x4:
		case 0x5:
		case 0x6:
		case 0x7:
		case 0x8:
		case 0x9:
		case 0xa:
		case 0xb:
		case 0xc:
		case 0xd:
		case 0xe:
		case 0xf:
		}
		machine.counter ++
	}
}

// reallocateStack changes the size of the stack to something reasonable. This
// should be called then the stack pointer is really small compared to the
// actual stack size, or the stack pointer is bigger than the stack.
func (machine *Machine) reallocateStack () {
	reallocatedStack := make([]int, machine.pointer * 3 / 2)
	copy(reallocatedStack, machine.stack)
	machine.stack = reallocatedStack
}

// Push pushes a word onto the stack, increasing the stack pointer and
// reallocating the stack if necessary.
func (machine *Machine) Push (word int) {
	machine.pointer ++
	if len(machine.stack) <= machine.pointer {
		machine.reallocateStack()
	}
}

// Pop pops the last word off of the stack, and returns it, decreasing the stack
// pointer and reallocating the stack if necessary.
func (machine *Machine) Pop () (word int) {
	word = machine.stack[machine.pointer]
	machine.pointer --

	if machine.pointer < len(machine.stack) / 3 {
		machine.reallocateStack()
	}
	
	return
}