import { CreateStatePersistentConfigInterface, EnhancedState, StateIngestConfigInterface, StateObserversInterface } from '../../state';
import type { Collection, DefaultItem, ItemKey } from '../collection';
import { GroupIngestConfigInterface, GroupObserver } from './group.observer';
import type { Item } from '../item';
export declare class Group<DataType extends DefaultItem = DefaultItem> extends EnhancedState<Array<ItemKey>> {
    collection: () => Collection<DataType>;
    static rebuildGroupSideEffectKey: string;
    _output: Array<DataType>;
    nextGroupOutput: Array<DataType>;
    _preciseItemKeys: Array<ItemKey>;
    observers: GroupObservers<ItemKey[], DataType>;
    notFoundItemKeys: Array<ItemKey>;
    loadedInitialValue: boolean;
    /**
     * An extension of the State Class that categorizes and preserves the ordering of structured data.
     * It allows us to cluster together data from a Collection as an array of Item keys.
     *
     * Note that a Group doesn't store the actual Items. It only keeps track of the Item keys
     * and retrieves the fitting Items when needed.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/)
     *
     * @public
     * @param collection - Collection to which the Group belongs.
     * @param initialItems - Key/Name identifiers of the Items to be clustered by the Group.
     * @param config - Configuration object
     */
    constructor(collection: Collection<DataType>, initialItems?: Array<ItemKey>, config?: GroupConfigInterface);
    /**
     * Returns the values of the Items clustered by the Group.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/properties#output)
     *
     * @public
     */
    get output(): Array<DataType>;
    set output(value: DataType[]);
    /**
     * Returns a boolean indicating whether an Item with the specified `itemKey`
     * is clustered in the Group or not.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods/#has)
     *
     * @public
     * @param itemKey - Key/Name identifier of the Item.
     */
    has(itemKey: ItemKey): boolean;
    /**
     * Returns the count of Items clustered by the Group.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/properties#size)
     *
     * @public
     */
    get size(): number;
    /**
     * Removes an Item with the specified key/name identifier from the Group,
     * if it exists in the Group.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods#remove)
     *
     * @public
     * @param itemKeys - Key/Name identifier/s of the Item/s to be removed.
     * @param config - Configuration object
     */
    remove(itemKeys: ItemKey | ItemKey[], config?: GroupRemoveConfigInterface): this;
    /**
     * Appends new Item/s to the end of the Group.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods#add)
     *
     * @public
     * @param itemKeys - Key/Name identifier/s of Item/s to be added.
     * @param config - Configuration object
     */
    add(itemKeys: ItemKey | ItemKey[], config?: GroupAddConfigInterface): this;
    /**
     * Replaces the old `itemKey` with a new specified `itemKey`.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods#replace)
     *
     * @public
     * @param oldItemKey - Old `itemKey` to be replaced.
     * @param newItemKey - New `itemKey` to replace the before specified old `itemKey`.
     * @param config - Configuration object
     */
    replace(oldItemKey: ItemKey, newItemKey: ItemKey, config?: StateIngestConfigInterface): this;
    /**
     * Retrieves all existing Items of the Group from the corresponding Collection and returns them.
     * Items that aren't present in the Collection are skipped.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods#getitems)
     *
     * @public
     */
    getItems(): Array<Item<DataType>>;
    /**
     * Preserves the Group `value` in the corresponding external Storage.
     *
     * The Group key/name is used as the unique identifier for the Persistent.
     * If that is not desired or the Group has no unique identifier,
     * please specify a separate unique identifier for the Persistent.
     *
     * [Learn more..](https://agile-ts.org/docs/core/state/methods/#persist)
     *
     * @public
     * @param config - Configuration object
     */
    persist(config?: GroupPersistConfigInterface<Array<ItemKey>>): this;
    /**
     * Rebuilds the output of the Group
     * and ingests it into the runtime.
     *
     * In doing so, it traverses the Group `value` (Item identifiers)
     * and fetches the fitting Items accordingly.
     *
     * [Learn more..](https://agile-ts.org/docs/core/collection/group/methods#rebuild)
     *
     * @internal
     * @param trackedChanges - Changes that were tracked between two rebuilds.
     * @param config - Configuration object
     */
    rebuild(trackedChanges?: TrackedChangeInterface[], config?: GroupIngestConfigInterface): this;
}
export declare type GroupKey = string | number;
export interface GroupObservers<ValueType = any, DataType extends DefaultItem = any> extends StateObserversInterface<ValueType> {
    /**
     * Observer responsible for the output of the Group.
     */
    output: GroupObserver<DataType>;
}
export interface GroupAddConfigInterface extends StateIngestConfigInterface {
    /**
     * In which way the `itemKey` should be added to the Group.
     * - 'push' =  at the end
     * - 'unshift' = at the beginning
     * https://www.tutorialspoint.com/what-are-the-differences-between-unshift-and-push-methods-in-javascript
     * @default 'push'
     */
    method?: 'unshift' | 'push';
    /**
     * Whether to soft rebuild the Group.
     * -> only rebuild the parts of the Group that have actually changed
     * instead of rebuilding the whole Group.
     * @default true
     */
    softRebuild?: boolean;
}
export interface GroupRemoveConfigInterface extends StateIngestConfigInterface {
    /**
     * Whether to soft rebuild the Group.
     * -> only rebuild the parts of the Group that have actually changed
     * instead of rebuilding the whole Group.
     * @default true
     */
    softRebuild?: boolean;
}
export interface GroupConfigInterface {
    /**
     * Key/Name identifier of the Group.
     * @default undefined
     */
    key?: GroupKey;
    /**
     * Whether the Group should be a placeholder
     * and therefore should only exist in the background.
     * @default false
     */
    isPlaceholder?: boolean;
}
export interface GroupPersistConfigInterface<ValueType = any> extends CreateStatePersistentConfigInterface<ValueType> {
    /**
     * Whether to format the specified Storage key following the Collection Group Storage key pattern.
     * `_${collectionKey}_group_${groupKey}`
     * @default true
     */
    followCollectionPersistKeyPattern?: boolean;
}
export declare enum TrackedChangeMethod {
    ADD = 0,
    REMOVE = 1,
    UPDATE = 2
}
export interface TrackedChangeInterface {
    /**
     * What type of change the tracked change is.
     * @default undefined
     */
    method: TrackedChangeMethod;
    /**
     * Item key of the tracked change.
     * @default undefined
     */
    key: ItemKey;
    /**
     * Current index in the Group value of the tracked change.
     * @default undefined
     */
    index: number;
}