#include "eval.h"

#include "env.h"

#include <assert.h>

static void eval_atom(am_t *am)
{
	switch (AM_EXPR(am)->atom.type) {
	case ATOM_TYPE_EMPTY_LIST:
	case ATOM_TYPE_INTEGER:
	case ATOM_TYPE_PRIM_PROC:
		am_assign(am, VAL, EXPR);
		break;
	case ATOM_TYPE_SYMBOL:
		env_fetch(am);
		break;
	}
}

static void eval_list(am_t *am)
{
	AM_ARGL(am) = expr_empty_list(am);
	am_cdr(am, UNEV, EXPR);
	am_car(am, EXPR, EXPR);

	env_fetch(am);
	am_push(am, VAL);

	while (!AM_UNEV(am)->is_atom) {
		am_push(am, ARGL);
		am_car(am, EXPR, UNEV);
		am_cdr(am, UNEV, UNEV);
		am_push(am, UNEV);

		eval(am);

		am_pop(am, UNEV);
		am_pop(am, ARGL);
		am_append(am, ARGL, VAL);
	}

	am_pop(am, VAL);
	am_call(am, VAL);
}

void eval(am_t *am)
{
	if (AM_EXPR(am)->is_atom)
		eval_atom(am);
	else
		eval_list(am);
}