#include <stdbool.h>
#include <stdlib.h>

#include "encoding.h"
#include "heap.h"
#include "panic.h"
#include "slice.h"
#include "value.h"

#include "oper.h"

struct st {
	size_t i;
	value locals[NUM_LOCALS];
	struct heap heap;
};

static value read_arg(struct st *s, struct arg arg)
{
	if (arg.constant) {
		return arg.constant;
	}
	return s->locals[arg.local];
}

static void oalloc(struct st *s, struct op oper)
{
	s->locals[oper.alloc.out] = from_pointer(alloc(&s->heap, to_int(read_arg(s, oper.alloc.size))));
}

static void call(struct st *s)
{
	s->i = to_int(s->locals[0]);
}

static void poke(struct st *s, struct op oper)
{
	value *p = to_pointer(s->locals[oper.poke.pointer]);
	p[oper.poke.offset] = read_arg(s, oper.poke.value);
}

static void peek(struct st *s, struct op oper)
{
	value *p = to_pointer(read_arg(s, oper.peek.value));
	s->locals[oper.peek.out] = p[oper.peek.offset];
}

static void shuf(struct st *s, struct op oper)
{
	s->locals[oper.shuf.out] = read_arg(s, oper.shuf.value);
}

static void oexit(struct st *s, struct op oper)
{
	exit(to_int(read_arg(s, oper.exit.value)));
}

static void op(struct st *s, struct op oper)
{
	switch (oper.code) {
	case OALLOC:
		oalloc(s, oper);
		break;
	case OCALL:
		call(s);
		break;
	case OPOKE:
		poke(s, oper);
		break;
	case OPEEK:
		peek(s, oper);
		break;
	case OSHUF:
		shuf(s, oper);
		break;
	case OEXIT:
		oexit(s, oper);
		break;
	default:
		panicf("Invalid op: %x\n", oper.code);
	}
}

void run(struct slice prog)
{
	struct st s = {
		.i = 0,
		.locals = { 0 },
	};
	s.heap = new_heap((struct val_slice) { .size = NUM_LOCALS, .buf = s.locals });
	while (true) {
		struct result oper = parse(slice1(prog, s.i));
		s.i += oper.n;
		op(&s, oper.op);
	}
}