/*
 * Copyright (C) Artem S. Povalyukhin
 * Copyright (C) NGINX, Inc.
 */


#include <njs_main.h>


struct njs_value_iterator_s {
    njs_value_t        target;
    int64_t            next;
    njs_object_enum_t  kind;
};


typedef struct njs_value_iterator_s  njs_array_iterator_t;


static njs_int_t njs_iterator_object_handler(njs_vm_t *vm,
    njs_iterator_handler_t handler, njs_iterator_args_t *args,
    njs_value_t *key, int64_t i, njs_value_t *retval);

static njs_int_t njs_iterator_to_array_handler(njs_vm_t *vm,
    njs_iterator_args_t *args, njs_value_t *value, int64_t index,
    njs_value_t *retval);


njs_int_t
njs_array_iterator_create(njs_vm_t *vm, const njs_value_t *target,
    njs_value_t *retval, njs_object_enum_t kind)
{
    njs_object_value_t    *iterator;
    njs_array_iterator_t  *it;

    iterator = njs_object_value_alloc(vm, NJS_OBJ_TYPE_ARRAY_ITERATOR, 0, NULL);
    if (njs_slow_path(iterator == NULL)) {
        njs_memory_error(vm);
        return NJS_ERROR;
    }

    it = njs_mp_alloc(vm->mem_pool, sizeof(njs_array_iterator_t));
    if (njs_slow_path(it == NULL)) {
        njs_memory_error(vm);
        return NJS_ERROR;
    }

    it->target = *target;
    it->next = 0;
    it->kind = kind;

    njs_set_data(&iterator->value, it, NJS_DATA_TAG_ARRAY_ITERATOR);
    njs_set_object_value(retval, iterator);

    return NJS_OK;
}


njs_int_t
njs_array_iterator_next(njs_vm_t *vm, njs_value_t *iterator,
    njs_value_t *retval)
{
    int64_t               length;
    njs_int_t             ret;
    njs_array_t           *array, *entry;
    njs_typed_array_t     *tarray;
    const njs_value_t     *value;
    njs_array_iterator_t  *it;

    if (njs_slow_path(!njs_is_valid(njs_object_value(iterator)))) {
        return NJS_DECLINED;
    }

    it = njs_object_data(iterator);
    value = &njs_value_undefined;

    if (njs_is_fast_array(&it->target)) {
        array = njs_array(&it->target);
        length = array->length;

        if (it->next >= length) {
            goto release;
        }

        if (it->kind > NJS_ENUM_KEYS && njs_is_valid(&array->start[it->next])) {
            value = &array->start[it->next];
        }

    } else if (njs_is_typed_array(&it->target)) {
        tarray = njs_typed_array(&it->target);

        if (njs_slow_path(njs_is_detached_buffer(tarray->buffer))) {
            njs_type_error(vm, "detached buffer");
            return NJS_ERROR;
        }

        length = njs_typed_array_length(tarray);

        if (it->next >= length) {
            goto release;
        }

        if (it->kind > NJS_ENUM_KEYS) {
            njs_set_number(retval, njs_typed_array_prop(tarray, it->next));
            value = retval;
        }

    } else {
        ret = njs_object_length(vm, &it->target, &length);
        if (njs_slow_path(ret == NJS_ERROR)) {
            return ret;
        }

        if (it->next >= length) {
            goto release;
        }

        if (it->kind > NJS_ENUM_KEYS) {
            ret = njs_value_property_i64(vm, &it->target, it->next, retval);
            if (njs_slow_path(ret == NJS_ERROR)) {
                return ret;
            }

            value = njs_is_valid(retval) ? retval
                                         : &njs_value_undefined;
        }
    }

    switch (it->kind) {
    case NJS_ENUM_KEYS:
        njs_set_number(retval, it->next++);
        break;

    case NJS_ENUM_VALUES:
        it->next++;
        *retval = *value;
        break;

    case NJS_ENUM_BOTH:
        entry = njs_array_alloc(vm, 0, 2, 0);
        if (njs_slow_path(entry == NULL)) {
            return NJS_ERROR;
        }

        njs_set_number(&entry->start[0], it->next++);
        entry->start[1] = *value;

        njs_set_array(retval, entry);
        break;

    default:
        njs_internal_error(vm, "invalid enum kind");
        return NJS_ERROR;
    }

    return NJS_OK;

release:

    njs_mp_free(vm->mem_pool, it);
    njs_set_invalid(njs_object_value(iterator));

    return NJS_DECLINED;
}


static njs_int_t
njs_iterator_prototype_get_this(njs_vm_t *vm, njs_value_t *args,
    njs_uint_t nargs, njs_index_t unused, njs_value_t *retval)
{
    njs_value_assign(retval, njs_argument(args, 0));

    return NJS_OK;
}


static const njs_object_prop_init_t  njs_iterator_prototype_properties[] =
{
    NJS_DECLARE_PROP_NATIVE(SYMBOL_iterator,
                            njs_iterator_prototype_get_this, 0, 0),
};


static const njs_object_init_t  njs_iterator_prototype_init = {
    njs_iterator_prototype_properties,
    njs_nitems(njs_iterator_prototype_properties),
};


const njs_object_type_init_t  njs_iterator_type_init = {
    .prototype_props = &njs_iterator_prototype_init,
    .prototype_value = { .object = { .type = NJS_OBJECT } },
};


static njs_int_t
njs_array_iterator_prototype_next(njs_vm_t *vm, njs_value_t *args,
    njs_uint_t nargs, njs_index_t tag, njs_value_t *retval)
{
    njs_int_t          ret;
    njs_bool_t         check;
    njs_value_t        *this;
    njs_object_t       *object;
    njs_object_prop_t  *prop_value, *prop_done;

    this = njs_argument(args, 0);

    check = njs_is_object_value(this)
            && (njs_is_object_data(this, NJS_DATA_TAG_ARRAY_ITERATOR)
                || !njs_is_valid(njs_object_value(this)));

    if (njs_slow_path(!check)) {
        njs_type_error(vm, "Method [Array Iterator].prototype.next"
                           " called on incompatible receiver");
        return NJS_ERROR;
    }

    object = njs_object_alloc(vm);
    if (njs_slow_path(object == NULL)) {
        return NJS_ERROR;
    }

    njs_set_object(retval, object);

    prop_value = njs_object_property_add(vm, retval, NJS_ATOM_STRING_value, 0);
    if (njs_slow_path(prop_value == NULL)) {
        return NJS_ERROR;
    }

    prop_done = njs_object_property_add(vm, retval, NJS_ATOM_STRING_done, 0);
    if (njs_slow_path(prop_done == NULL)) {
        return NJS_ERROR;
    }

    ret = njs_array_iterator_next(vm, this, njs_prop_value(prop_value));
    if (njs_slow_path(ret == NJS_ERROR)) {
        return ret;
    }

    if (njs_slow_path(ret == NJS_DECLINED)) {
        njs_set_undefined(njs_prop_value(prop_value));
        njs_set_boolean(njs_prop_value(prop_done), 1);

        return NJS_OK;
    }

    njs_set_boolean(njs_prop_value(prop_done), 0);

    return NJS_OK;
}


static const njs_object_prop_init_t  njs_array_iterator_prototype_properties[] =
{
    NJS_DECLARE_PROP_NATIVE(STRING_next, njs_array_iterator_prototype_next,
                            0, NJS_DATA_TAG_ARRAY_ITERATOR),

    NJS_DECLARE_PROP_VALUE(SYMBOL_toStringTag,
                           njs_ascii_strval("Array Iterator"),
                           NJS_OBJECT_PROP_VALUE_C),
};


static const njs_object_init_t  njs_array_iterator_prototype_init = {
    njs_array_iterator_prototype_properties,
    njs_nitems(njs_array_iterator_prototype_properties),
};


const njs_object_type_init_t  njs_array_iterator_type_init = {
    .prototype_props = &njs_array_iterator_prototype_init,
    .prototype_value = { .object = { .type = NJS_OBJECT } },
};


njs_int_t
njs_object_iterate(njs_vm_t *vm, njs_iterator_args_t *args,
    njs_iterator_handler_t handler, njs_value_t *retval)
{
    double              idx;
    int64_t             length, i, from, to;
    njs_int_t           ret;
    njs_array_t         *array, *keys;
    njs_value_t         *value, *entry, prop, character;
    const u_char        *p, *end, *pos;
    njs_string_prop_t   string_prop;

    value = njs_value_arg(&args->value);
    from = args->from;
    to = args->to;

    if (njs_is_array(value)) {
        array = njs_array(value);

        for (; from < to; from++) {
            if (njs_slow_path(!array->object.fast_array)) {
                goto process_object;
            }

            if (njs_fast_path(from < array->length
                              && njs_is_valid(&array->start[from])))
            {
                ret = handler(vm, args, &array->start[from], from, retval);

            } else {
                entry = njs_value_arg(&njs_value_invalid);
                ret = njs_value_property_i64(vm, value, from, &prop);
                if (njs_slow_path(ret != NJS_DECLINED)) {
                    if (ret == NJS_ERROR) {
                        return NJS_ERROR;
                    }

                    entry = &prop;
                }

                ret = handler(vm, args, entry, from, retval);
            }

            if (njs_slow_path(ret != NJS_OK)) {
                if (ret == NJS_DONE) {
                    return NJS_DONE;
                }

                return NJS_ERROR;
            }
        }

        return NJS_OK;
    }

    if (njs_is_string(value) || njs_is_object_string(value)) {

        if (!njs_is_string(value)) {
            value = njs_object_value(value);
        }

        length = njs_string_prop(vm, &string_prop, value);

        p = string_prop.start;
        end = p + string_prop.size;

        if ((size_t) length == string_prop.size) {
            /* ASCII string. */

            for (i = from; i < to; i++) {
                ret = njs_string_new(vm, &character, p + i, 1, 1);
                if (njs_slow_path(ret != NJS_OK)) {
                    return NJS_ERROR;
                }

                ret = handler(vm, args, &character, i, retval);
                if (njs_slow_path(ret != NJS_OK)) {
                    if (ret == NJS_DONE) {
                        return NJS_DONE;
                    }

                    return NJS_ERROR;
                }
            }

        } else {
            /* UTF-8 string. */

            for (i = from; i < to; i++) {
                pos = njs_utf8_next(p, end);

                ret = njs_string_new(vm, &character, p, pos - p, 1);
                if (njs_slow_path(ret != NJS_OK)) {
                    return NJS_ERROR;
                }

                ret = handler(vm, args, &character, i, retval);
                if (njs_slow_path(ret != NJS_OK)) {
                    if (ret == NJS_DONE) {
                        return NJS_DONE;
                    }

                    return NJS_ERROR;
                }

                p = pos;
            }
        }

        return NJS_OK;
    }

    if (!njs_is_object(value)) {
        return NJS_OK;
    }

process_object:

    if (!njs_fast_object(to - from)) {
        keys = njs_array_indices(vm, value);
        if (njs_slow_path(keys == NULL)) {
            return NJS_ERROR;
        }

        for (i = 0; i < keys->length; i++) {
            idx = njs_string_to_index(&keys->start[i]);

            if (idx < from || idx >= to) {
                continue;
            }

            ret = njs_iterator_object_handler(vm, handler, args,
                                              &keys->start[i], idx, retval);
            if (njs_slow_path(ret != NJS_OK)) {
                njs_array_destroy(vm, keys);
                return ret;
            }
        }

        njs_array_destroy(vm, keys);

        return NJS_OK;
    }

    for (i = from; i < to; i++) {
        ret = njs_iterator_object_handler(vm, handler, args, NULL, i, retval);
        if (njs_slow_path(ret != NJS_OK)) {
            return ret;
        }
    }

    return NJS_OK;
}


njs_int_t
njs_object_iterate_reverse(njs_vm_t *vm, njs_iterator_args_t *args,
    njs_iterator_handler_t handler, njs_value_t *retval)
{
    double              idx;
    int64_t             i, from, to, length;
    njs_int_t           ret;
    njs_array_t         *array, *keys;
    njs_value_t         *entry, *value, prop, character;
    const u_char        *p, *end, *pos;
    njs_string_prop_t   string_prop;

    value = njs_value_arg(&args->value);
    from = args->from;
    to = args->to;

    if (njs_is_array(value)) {
        array = njs_array(value);

        from += 1;

        while (from-- > to) {
            if (njs_slow_path(!array->object.fast_array)) {
                goto process_object;
            }

            if (njs_fast_path(from < array->length
                              && njs_is_valid(&array->start[from])))
            {
                ret = handler(vm, args, &array->start[from], from, retval);

            } else {
                entry = njs_value_arg(&njs_value_invalid);
                ret = njs_value_property_i64(vm, value, from, &prop);
                if (njs_slow_path(ret != NJS_DECLINED)) {
                    if (ret == NJS_ERROR) {
                        return NJS_ERROR;
                    }

                    entry = &prop;
                }

                ret = handler(vm, args, entry, from, retval);
            }

            if (njs_slow_path(ret != NJS_OK)) {
                if (ret == NJS_DONE) {
                    return NJS_DONE;
                }

                return NJS_ERROR;
            }
        }

        return NJS_OK;
    }

    if (njs_is_string(value) || njs_is_object_string(value)) {

        if (!njs_is_string(value)) {
            value = njs_object_value(value);
        }

        length = njs_string_prop(vm, &string_prop, value);
        end = string_prop.start + string_prop.size;

        if ((size_t) length == string_prop.size) {
            /* Byte or ASCII string. */

            p = string_prop.start + from;

            i = from + 1;

            while (i-- > to) {
                ret = njs_string_new(vm, &character, p, 1, 1);
                if (njs_slow_path(ret != NJS_OK)) {
                    return NJS_ERROR;
                }

                ret = handler(vm, args, &character, i, retval);
                if (njs_slow_path(ret != NJS_OK)) {
                    if (ret == NJS_DONE) {
                        return NJS_DONE;
                    }

                    return NJS_ERROR;
                }

                p--;
            }

        } else {
            /* UTF-8 string. */

            p = NULL;
            i = from + 1;

            if (i > to) {
                p = njs_string_utf8_offset(string_prop.start, end, from);
                p = njs_utf8_next(p, end);
            }

            while (i-- > to) {
                pos = njs_utf8_prev(p, string_prop.start);

                ret = njs_string_new(vm, &character, pos, p - pos , 1);
                if (njs_slow_path(ret != NJS_OK)) {
                    return NJS_ERROR;
                }

                ret = handler(vm, args, &character, i, retval);
                if (njs_slow_path(ret != NJS_OK)) {
                    if (ret == NJS_DONE) {
                        return NJS_DONE;
                    }

                    return NJS_ERROR;
                }

                p = pos;
            }
        }

        return NJS_OK;
    }

    if (!njs_is_object(value)) {
        return NJS_OK;
    }

process_object:

    if (!njs_fast_object(from - to)) {
        keys = njs_array_indices(vm, value);
        if (njs_slow_path(keys == NULL)) {
            return NJS_ERROR;
        }

        i = keys->length;

        while (i > 0) {
            idx = njs_string_to_index(&keys->start[--i]);

            if (idx < to || idx > from) {
                continue;
            }

            ret = njs_iterator_object_handler(vm, handler, args,
                                              &keys->start[i], idx, retval);
            if (njs_slow_path(ret != NJS_OK)) {
                njs_array_destroy(vm, keys);
                return ret;
            }
        }

        njs_array_destroy(vm, keys);

        return NJS_OK;
    }

    i = from + 1;

    while (i-- > to) {
        ret = njs_iterator_object_handler(vm, handler, args, NULL, i, retval);
        if (njs_slow_path(ret != NJS_OK)) {
            return ret;
        }
    }

    return NJS_OK;
}


static njs_int_t
njs_iterator_object_handler(njs_vm_t *vm, njs_iterator_handler_t handler,
    njs_iterator_args_t *args, njs_value_t *key, int64_t i, njs_value_t *retval)
{
    njs_int_t    ret;
    njs_value_t  prop, *entry;

    if (key != NULL) {
        ret = njs_value_property_val(vm, njs_value_arg(&args->value), key,
                                     &prop);
        if (njs_slow_path(ret == NJS_ERROR)) {
            return ret;
        }

    } else {
        ret = njs_value_property_i64(vm, njs_value_arg(&args->value), i, &prop);
        if (njs_slow_path(ret == NJS_ERROR)) {
            return ret;
        }
    }

    entry = (ret == NJS_OK) ? &prop : njs_value_arg(&njs_value_invalid);

    ret = handler(vm, args, entry, i, retval);
    if (njs_slow_path(ret != NJS_OK)) {
        if (ret == NJS_DONE) {
            return NJS_DONE;
        }

        return NJS_ERROR;
    }

    return ret;
}


njs_array_t *
njs_iterator_to_array(njs_vm_t *vm, njs_value_t *iterator, njs_value_t *retval)
{
    int64_t              length;
    njs_int_t            ret;
    njs_iterator_args_t  args;

    njs_memzero(&args, sizeof(njs_iterator_args_t));

    ret = njs_object_length(vm, iterator, &length);
    if (njs_slow_path(ret != NJS_OK)) {
        return NULL;
    }

    args.data = njs_array_alloc(vm, 0, 0,
                                njs_min(length, NJS_ARRAY_LARGE_OBJECT_LENGTH));
    if (njs_slow_path(args.data == NULL)) {
        return NULL;
    }

    njs_value_assign(&args.value, iterator);
    args.to = length;

    ret = njs_object_iterate(vm, &args, njs_iterator_to_array_handler, retval);
    if (njs_slow_path(ret == NJS_ERROR)) {
        njs_mp_free(vm->mem_pool, args.data);
        return NULL;
    }

    return args.data;
}


static njs_int_t
njs_iterator_to_array_handler(njs_vm_t *vm, njs_iterator_args_t *args,
    njs_value_t *value, int64_t index, njs_value_t *retval)
{
    njs_value_t  array;

    njs_set_array(&array, args->data);

    return njs_value_property_i64_set(vm, &array, index, value);
}