import { Query } from './internal/match.js';
import { StorageAdapter } from './storage.js';
import { Modifier } from './internal/modifier.js';
type Projected<TDoc, TPrj> = keyof TPrj extends never ? TDoc : Pick<TDoc, Extract<keyof TPrj, keyof TDoc>>;
type Projection<TDoc> = Partial<Record<keyof TDoc, 1>>;
type Sort<TDoc> = Partial<Record<keyof TDoc, 1 | -1>>;
type WithId<T = {}> = T & {
    id: string;
};
type WithoutId<T = {}> = Omit<T, 'id'>;
type WithOptionalId<T = {}> = WithoutId<T> & {
    id?: string;
};
export type Document = WithId<Record<string, any>>;
export interface Observer {
    id: string;
    stop: () => void;
}
interface UpdateResult<T> {
    matchedCount: number;
    modifiedCount: number;
    upsertedCount: number;
    upsertedId: string | null;
}
interface FindOptions<TDoc extends Document, TPrj = Projection<TDoc>> {
    projection?: TPrj;
    sort?: Sort<TDoc>;
    skip?: number;
    limit?: number;
}
interface UpdateOptions {
    upsert?: boolean;
}
interface TtlIndex {
    field: string;
    expireAfterSeconds: number;
}
interface Change<T> {
    type: 'added' | 'removed' | 'changed';
    doc: T;
}
declare class Cursor<TDoc extends Document, TOut = TDoc> {
    #private;
    constructor(queryFn: () => Array<TDoc>, options?: FindOptions<TDoc>);
    sort(sort: Sort<TDoc>): Cursor<TDoc, TOut>;
    limit(limit: number): Cursor<TDoc, TOut>;
    skip(skip: number): Cursor<TDoc, TOut>;
    project<TProjection = Projection<TDoc>, TOut = Cursor<TDoc, Projected<TDoc, TProjection>>>(projection: TProjection): TOut;
    paginate(page: number, perPage: number): Cursor<TDoc, TOut>;
    observe(fn: (change: Change<TDoc>) => void): Observer;
    watch(callback: (results: TOut[]) => void, options?: {
        immediate?: boolean;
    }): Observer;
    toArray(): Array<TOut>;
    map<U>(fn: (doc: TDoc) => U): Array<U>;
    forEach(fn: (doc: TDoc) => void): void;
    count(): number;
    first(): TOut | undefined;
    last(): TOut | undefined;
    exists(): boolean;
    group<TGroup extends GroupExpression<TDoc>, TOut = GroupResult<TDoc, TGroup>>(group: TGroup): Cursor<TDoc, TOut>;
    distinct<K extends keyof TOut>(key: K): Array<TOut[K]>;
}
export declare class Collection<TDoc extends Document, TMeta extends WithoutId<Document> = {}> {
    #private;
    get meta(): Meta<WithId<TMeta>>;
    constructor(name: string, options?: {
        storage?: StorageAdapter;
        ttlIndexes?: TtlIndex[];
        ttlInterval?: number;
    });
    dispose(): void;
    onReady(callback: () => void): void;
    get ready(): Promise<void>;
    batch<Fn extends () => any>(fn: Fn): ReturnType<Fn> extends Promise<any> ? Promise<void> : void;
    insert(doc: WithOptionalId<TDoc>): void;
    update(query: Query<TDoc>, modifier: Modifier<TDoc>, opts?: UpdateOptions): UpdateResult<TDoc>;
    remove(query: Query<TDoc>): void;
    transaction(fn: () => Promise<void>): Promise<void>;
    find<TPrj extends Projection<TDoc> = {}, TOut = Projected<TDoc, TPrj>>(query?: Query<TDoc>, opts?: FindOptions<TDoc, TPrj>): Cursor<TDoc, TOut>;
    findOne<TPrj extends Projection<TDoc> = {}, TOut = Projected<TDoc, TPrj>>(query: Query<TDoc>, opts?: FindOptions<TDoc, TPrj>): TOut | undefined;
    count(query?: Query<TDoc>): number;
}
type SumAccumulator = {
    $sum: 1;
};
type PushAccumulator<T extends Document> = {
    $push: '$$ROOT';
} | {
    $push: keyof T;
};
type GroupAccumulator<T extends Document> = SumAccumulator | PushAccumulator<T>;
type GroupExpression<T extends Document> = {
    key: Extract<keyof T, string>;
    [key: string]: GroupAccumulator<T> | keyof T;
};
type GroupResult<TDoc extends Document, TGroup extends GroupExpression<TDoc>> = {
    [K in keyof TGroup]: K extends 'key' ? TGroup[K] extends keyof TDoc ? TDoc[TGroup[K]] : unknown : TGroup[K] extends {
        $sum: 1;
    } ? number : TGroup[K] extends {
        $push: '$$ROOT';
    } ? TDoc[] : TGroup[K] extends {
        $push: keyof TDoc;
    } ? Array<TDoc[TGroup[K]['$push']]> : never;
};
declare class Meta<TMeta extends Document> extends Collection<WithId<TMeta>, {}> {
    #private;
    constructor(name: string, options: {
        storage?: StorageAdapter;
    });
    get<K extends keyof TMeta>(key: K): TMeta[K] | undefined;
    set<K extends keyof TMeta>(key: K, value: TMeta[K]): void;
}
export {};