#pragma once
#include <stdint.h>
#include <assert.h>
#include <stdlib.h>

enum node_type {
    N_CONS,
    N_IDENT,
    N_INTEGER,
    N_STRING
};

struct node {
    enum node_type type;
    union {
        struct {
            struct node *car, *cdr;
        } n_cons;
        char *n_ident;
        char *n_string;
        intmax_t n_integer;
    };
};

static inline int cons_q(struct node *n) {
    return !n || n->type == N_CONS;
}

static inline int null_q(struct node *n) {
    return n == NULL;
}

static inline int pair_q(struct node *n) {
    return n && n->type == N_CONS;
}

static inline int ident_q(struct node *n) {
    return n && n->type == N_IDENT;
}

static inline int integer_q(struct node *n) {
    return n && n->type == N_INTEGER;
}

static inline int string_q(struct node *n) {
    return n && n->type == N_STRING;
}

static inline struct node *car(struct node *n) {
    assert(pair_q(n));
    return n->n_cons.car;
}

static inline struct node *cdr(struct node *n) {
    assert(pair_q(n));
    return n->n_cons.cdr;
}

static inline struct node *cadr(struct node *n) {
    return car(cdr(n));
}

static inline struct node *caddr(struct node *n) {
    return car(cdr(cdr(n)));
}

static inline struct node *cddr(struct node *n) {
    return cdr(cdr(n));
}

struct node *string_from_owned(char *ptr);
struct node *cons(struct node *a, struct node *b);
struct node *ident(const char *i);
struct node *integer(intmax_t v);
struct node *list(int n, ...);

void vm_print(const struct node *node, int depth);