#include <assert.h>
#include <stddef.h>

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

// TODO: remove string.h
#include <string.h>

struct ucl_object *ucl_evaluate_builtin_form(struct ucl_scope *scope, struct ucl_object *list) {
    // TODO: Reasonably split builtin and non-builtin evaluation
    struct ucl_object *evaluated_list = ucl_nil_create();

    FOREACH_LIST(list, iter, item) {
        struct ucl_object *obj = ucl_evaluate(scope, item);
        UCL_RET_IF_ERROR(obj);
        ucl_list_append(evaluated_list, obj);
    };

    struct ucl_object *fun = ucl_car(evaluated_list);
    struct ucl_object *result = NULL;

    if (fun->type == UCL_TYPE_BUILTIN) {
        struct ucl_object *args = ucl_cdr(evaluated_list);
        result = fun->builtin(scope, args);
    } else if (fun->type == UCL_TYPE_CELL) {
        struct ucl_scope *fun_scope = ucl_scope_create_child(scope);
        struct ucl_object *fun_arg_syms = ucl_car(fun);
        struct ucl_object *fun_forms = ucl_cdr(fun);
        int i = 0;
        FOREACH_LIST(fun_arg_syms, iter, sym) {
            ucl_scope_put(fun_scope, sym->symbol, ucl_list_nth(evaluated_list, i + 1));
            i++;
        }
        result = ucl_progn(fun_scope, fun_forms);
        ucl_scope_delete(fun_scope);
    } else {
        assert(0);
    }

    return (result == NULL) ? ucl_nil_create() : result;
}

struct ucl_object *ucl_evaluate_special_form(struct ucl_scope *scope, struct ucl_object *list) {
    const char *fun_sym = ucl_car(list)->symbol;

    struct ucl_object *fun = ucl_scope_get(scope, fun_sym);
    struct ucl_object *args = ucl_cdr(list);
    struct ucl_object *result = NULL;

    result = fun->special(scope, args);

    return result;
}

struct ucl_object *ucl_evaluate_list(struct ucl_scope *scope, struct ucl_object *list) {
    if (list->cell.car == NULL) {
        return list;
    }

    struct ucl_object *fun = ucl_evaluate(scope, ucl_car(list));
    UCL_RET_IF_ERROR(fun);

    if (fun->type == UCL_TYPE_SPECIAL) {
        return ucl_evaluate_special_form(scope, list);
    } else if (fun->type == UCL_TYPE_BUILTIN || fun->type == UCL_TYPE_CELL) {
        return ucl_evaluate_builtin_form(scope, list);
    } else {
        assert(0);
    }
}

struct ucl_object *ucl_evaluate(struct ucl_scope *scope, struct ucl_object *obj) {
    assert(obj != NULL);

    switch (obj->type) {
        case UCL_TYPE_CELL:
            return ucl_evaluate_list(scope, obj);
        case UCL_TYPE_SYMBOL:
            return ucl_scope_get(scope, obj->symbol);
        case UCL_TYPE_INT:
        case UCL_TYPE_STRING:
        case UCL_TYPE_ERROR:
            return obj;
        case UCL_TYPE_BUILTIN:
        case UCL_TYPE_SPECIAL:
        case UCL_TYPE_COUNT:
            assert(0);
            return NULL;
    }
}