#include "uclisp.h"
#include "internal.h"
#include "state.h"
#include "utility.h"

#include <assert.h>
#include <string.h>
#include <stdlib.h>

// Implements state as a giant alist
// TODO: Consider generalizing the alist concept

struct ucl_state {
    struct ucl_object *list;
    struct ucl_state *parent;
};

#define NAME_POSITION 0
#define DATA_POSITION 1

static struct ucl_object *ucl_state_get_cell(struct ucl_state *state, const char *name) {
    FOREACH_LIST(state->list, iter, item) {
        assert(item->type == UCL_TYPE_CELL);
        const char *item_name = ucl_list_nth(item, NAME_POSITION)->string;
        if (!strcmp(name, item_name)) {
            return item;
        }
    }

    return NULL;
}

struct ucl_object *ucl_state_get(struct ucl_state *state, const char *name) {
    struct ucl_object *cell = ucl_state_get_cell(state, name);
    if (cell == NULL) {
        if (state->parent == NULL) {
            return ucl_error_create("Unknown error");
        } else {
            return ucl_state_get(state->parent, name);
        }
    }
    return ucl_list_nth(cell, DATA_POSITION);
}

void ucl_state_put(struct ucl_state *state, const char *name, struct ucl_object *obj) {
    struct ucl_object *cell = ucl_state_get_cell(state, name);
    if (cell == NULL) {
        ucl_list_append(state->list,
                       ucl_tuple_create(
                           ucl_string_create(name),
                           obj));
    } else {
        // TODO: Refcounting / cleanup
        cell->cell.cdr->cell.car = obj;
    }
}

struct ucl_state *ucl_state_create() {
    struct ucl_state *state = malloc(sizeof(struct ucl_state));
    state->list = ucl_nil_create();
    state->parent = NULL;
    return state;
}

struct ucl_state *ucl_state_create_child(struct ucl_state *parent) {
    struct ucl_state *state = ucl_state_create();
    state->parent = parent;
    return state;
}

void ucl_state_delete(struct ucl_state *state) {
    // TODO: Cleanup
    // ucl_object_delete(state->list);
}