import { FirebaseFirestoreTypes } from '../index';

import DocumentReference = FirebaseFirestoreTypes.DocumentReference;
import DocumentSnapshot = FirebaseFirestoreTypes.DocumentSnapshot;
import SnapshotListenOptions = FirebaseFirestoreTypes.SnapshotListenOptions;
import QuerySnapshot = FirebaseFirestoreTypes.QuerySnapshot;
import Query = FirebaseFirestoreTypes.Query;

export type Unsubscribe = () => void;
export type FirestoreError = Error;

/**
 * Attaches a listener for `DocumentSnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param reference - A reference to the document to listen to.
 * @param observer - A single object containing `next` and `error` callbacks.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  reference: DocumentReference<T>,
  observer: {
    next?: (snapshot: DocumentSnapshot<T>) => void;
    error?: (error: FirestoreError) => void;
    complete?: () => void;
  },
): Unsubscribe;
/**
 * Attaches a listener for `DocumentSnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param reference - A reference to the document to listen to.
 * @param options - Options controlling the listen behavior.
 * @param observer - A single object containing `next` and `error` callbacks.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  reference: DocumentReference<T>,
  options: SnapshotListenOptions,
  observer: {
    next?: (snapshot: DocumentSnapshot<T>) => void;
    error?: (error: FirestoreError) => void;
    complete?: () => void;
  },
): Unsubscribe;
/**
 * Attaches a listener for `DocumentSnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param reference - A reference to the document to listen to.
 * @param onNext - A callback to be called every time a new `DocumentSnapshot`
 * is available.
 * @param onError - A callback to be called if the listen fails or is
 * cancelled. No further callbacks will occur.
 * @param onCompletion - Can be provided, but will not be called since streams are
 * never ending.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  reference: DocumentReference<T>,
  onNext: (snapshot: DocumentSnapshot<T>) => void,
  onError?: (error: FirestoreError) => void,
  onCompletion?: () => void,
): Unsubscribe;
/**
 * Attaches a listener for `DocumentSnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param reference - A reference to the document to listen to.
 * @param options - Options controlling the listen behavior.
 * @param onNext - A callback to be called every time a new `DocumentSnapshot`
 * is available.
 * @param onError - A callback to be called if the listen fails or is
 * cancelled. No further callbacks will occur.
 * @param onCompletion - Can be provided, but will not be called since streams are
 * never ending.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  reference: DocumentReference<T>,
  options: SnapshotListenOptions,
  onNext: (snapshot: DocumentSnapshot<T>) => void,
  onError?: (error: FirestoreError) => void,
  onCompletion?: () => void,
): Unsubscribe;
/**
 * Attaches a listener for `QuerySnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks. The listener can be cancelled by
 * calling the function that is returned when `onSnapshot` is called.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param query - The query to listen to.
 * @param observer - A single object containing `next` and `error` callbacks.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  query: Query<T>,
  observer: {
    next?: (snapshot: QuerySnapshot<T>) => void;
    error?: (error: FirestoreError) => void;
    complete?: () => void;
  },
): Unsubscribe;
/**
 * Attaches a listener for `QuerySnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks. The listener can be cancelled by
 * calling the function that is returned when `onSnapshot` is called.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param query - The query to listen to.
 * @param options - Options controlling the listen behavior.
 * @param observer - A single object containing `next` and `error` callbacks.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  query: Query<T>,
  options: SnapshotListenOptions,
  observer: {
    next?: (snapshot: QuerySnapshot<T>) => void;
    error?: (error: FirestoreError) => void;
    complete?: () => void;
  },
): Unsubscribe;
/**
 * Attaches a listener for `QuerySnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks. The listener can be cancelled by
 * calling the function that is returned when `onSnapshot` is called.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param query - The query to listen to.
 * @param onNext - A callback to be called every time a new `QuerySnapshot`
 * is available.
 * @param onCompletion - Can be provided, but will not be called since streams are
 * never ending.
 * @param onError - A callback to be called if the listen fails or is
 * cancelled. No further callbacks will occur.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  query: Query<T>,
  onNext: (snapshot: QuerySnapshot<T>) => void,
  onError?: (error: FirestoreError) => void,
  onCompletion?: () => void,
): Unsubscribe;
/**
 * Attaches a listener for `QuerySnapshot` events. You may either pass
 * individual `onNext` and `onError` callbacks or pass a single observer
 * object with `next` and `error` callbacks. The listener can be cancelled by
 * calling the function that is returned when `onSnapshot` is called.
 *
 * NOTE: Although an `onCompletion` callback can be provided, it will
 * never be called because the snapshot stream is never-ending.
 *
 * @param query - The query to listen to.
 * @param options - Options controlling the listen behavior.
 * @param onNext - A callback to be called every time a new `QuerySnapshot`
 * is available.
 * @param onCompletion - Can be provided, but will not be called since streams are
 * never ending.
 * @param onError - A callback to be called if the listen fails or is
 * cancelled. No further callbacks will occur.
 * @returns An unsubscribe function that can be called to cancel
 * the snapshot listener.
 */
export function onSnapshot<T>(
  query: Query<T>,
  options: SnapshotListenOptions,
  onNext: (snapshot: QuerySnapshot<T>) => void,
  onError?: (error: FirestoreError) => void,
  onCompletion?: () => void,
): Unsubscribe;

/**
 * Returns true if the provided snapshots are equal.
 *
 * @param left	DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>	A snapshot to compare.
 * @param right	DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>	A snapshot to compare.
 *
 * @returns boolean true if the snapshots are equal.
 */
export function snapshotEqual<AppModelType, DbModelType extends DocumentData>(
  left: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>,
  right: DocumentSnapshot<AppModelType, DbModelType> | QuerySnapshot<AppModelType, DbModelType>,
): boolean;

/**
 * Returns true if the provided queries point to the same collection and apply the same constraints.
 *
 * @param left	Query<AppModelType, DbModelType> A Query to compare.
 * @param right	Query<AppModelType, DbModelType> A Query to compare.
 *
 * @return boolean true if the references point to the same location in the same Firestore database.
 */
export declare function queryEqual<AppModelType, DbModelType extends DocumentData>(
  left: Query<AppModelType, DbModelType>,
  right: Query<AppModelType, DbModelType>,
): boolean;