import EventEmitter from "node:events";
import { ShuttleGetterSetterRepository } from "./ShuttleGetterSetterRepository";
import { IOrderedStop, IRoute, IShuttle, IStop, shuttleHasArrivedAtStop } from "../../entities/ShuttleRepositoryEntities";
import { IEntityWithId } from "../../entities/SharedEntities";
import {
  ShuttleRepositoryEvent,
  ShuttleRepositoryEventListener,
  ShuttleRepositoryEventName,
  ShuttleRepositoryEventPayloads,
  ShuttleStopArrival,
  ShuttleTravelTimeDataIdentifier,
  ShuttleTravelTimeDateFilterArguments,
} from "./ShuttleGetterRepository";

/**
 * An unoptimized in memory repository.
 * (I would optimize it with actual data structures, but I'm
 * switching to another data store later anyways)
 */
export class UnoptimizedInMemoryShuttleRepository
  extends EventEmitter
  implements ShuttleGetterSetterRepository {

  constructor(
    readonly shuttleStopArrivalDegreeDelta: number = 0.001,
  ) {
    super()
  }

  public override on<T extends ShuttleRepositoryEventName>(
    event: T,
    listener: ShuttleRepositoryEventListener<T>,
  ): this;
  public override on(event: string | symbol, listener: (...args: any[]) => void): this {
    return super.on(event, listener);
  }

  public override once<T extends ShuttleRepositoryEventName>(
    event: T,
    listener: ShuttleRepositoryEventListener<T>,
  ): this;
  public override once(event: string | symbol, listener: (...args: any[]) => void): this {
    return super.once(event, listener);
  }

  public override off<T extends ShuttleRepositoryEventName>(
    event: T,
    listener: ShuttleRepositoryEventListener<T>,
  ): this;
  public override off(event: string | symbol, listener: (...args: any[]) => void): this {
    return super.off(event, listener);
  }

  public override addListener<T extends ShuttleRepositoryEventName>(
    event: T,
    listener: ShuttleRepositoryEventListener<T>,
  ): this;
  public override addListener(event: string | symbol, listener: (...args: any[]) => void): this {
    return super.addListener(event, listener);
  }

  public override removeListener<T extends ShuttleRepositoryEventName>(
    event: T,
    listener: ShuttleRepositoryEventListener<T>,
  ): this;
  public override removeListener(event: string | symbol, listener: (...args: any[]) => void): this {
    return super.removeListener(event, listener);
  }

  public override emit<T extends ShuttleRepositoryEventName>(
    event: T,
    payload: ShuttleRepositoryEventPayloads[T],
  ): boolean;
  public override emit(event: string | symbol, ...args: any[]): boolean {
    return super.emit(event, ...args);
  }

  private stops: IStop[] = [];
  private routes: IRoute[] = [];
  private shuttles: IShuttle[] = [];
  private orderedStops: IOrderedStop[] = [];
  private shuttleLastStopArrivals: Map<string, ShuttleStopArrival> = new Map();
  private travelTimeData: Map<string, Array<{ timestamp: number; seconds: number }>> = new Map();
  private shuttlesAtStop: Set<string> = new Set();

  public async getStops(): Promise<IStop[]> {
    return this.stops;
  }

  public async getStopById(stopId: string) {
    return this.findEntityById(stopId, this.stops);
  }

  public async getRoutes(): Promise<IRoute[]> {
    return this.routes;
  }

  public async getRouteById(routeId: string) {
    return this.findEntityById(routeId, this.routes);
  }

  public async getShuttles(): Promise<IShuttle[]> {
    return this.shuttles;
  }

  public async getShuttlesByRouteId(routeId: string) {
    return this.shuttles.filter(shuttle => shuttle.routeId === routeId);
  }

  public async getShuttleById(shuttleId: string) {
    return this.findEntityById(shuttleId, this.shuttles);
  }

  public async getOrderedStopByRouteAndStopId(routeId: string, stopId: string) {
    return this.findEntityByMatcher<IOrderedStop>((value) => value.routeId === routeId && value.stopId === stopId, this.orderedStops)
  }

  public async getOrderedStopsByStopId(stopId: string) {
    return this.orderedStops.filter((value) => value.stopId === stopId);
  }

  public async getOrderedStopsByRouteId(routeId: string) {
    return this.orderedStops.filter((value) => value.routeId === routeId);
  }

  private findEntityById<T extends IEntityWithId>(entityId: string, arrayToSearchIn: T[]) {
    return this.findEntityByMatcher((value) => value.id === entityId, arrayToSearchIn);
  }

  private findEntityByMatcher<T>(callback: (value: T) => boolean, arrayToSearchIn: T[]): T | null {
    const entity = arrayToSearchIn.find(callback);
    if (!entity) {
      return null;
    }
    return entity;
  }

  public async addOrUpdateRoute(route: IRoute): Promise<void> {
    const index = this.routes.findIndex((r) => r.id === route.id);
    if (index !== -1) {
      this.routes[index] = route;
    } else {
      this.routes.push(route);
    }
  }

  public async addOrUpdateShuttle(
    shuttle: IShuttle,
    travelTimeTimestamp = Date.now(),
  ): Promise<void> {
    const index = this.shuttles.findIndex((s) => s.id === shuttle.id);
    if (index !== -1) {
      this.shuttles[index] = shuttle;
    } else {
      this.shuttles.push(shuttle);
    }

    this.emit(ShuttleRepositoryEvent.SHUTTLE_UPDATED, shuttle);

    await this.updateLastStopArrival(shuttle, travelTimeTimestamp);
  }

  public async addOrUpdateStop(stop: IStop): Promise<void> {
    const index = this.stops.findIndex((s) => s.id === stop.id);
    if (index !== -1) {
      this.stops[index] = stop;
    } else {
      this.stops.push(stop);
    }
  }

  public async addOrUpdateOrderedStop(orderedStop: IOrderedStop): Promise<void> {
    const index = this.orderedStops.findIndex((value) => value.stopId === orderedStop.stopId && value.routeId === orderedStop.routeId);
    if (index !== -1) {
      this.orderedStops[index] = orderedStop;
    } else {
      this.orderedStops.push(orderedStop);
    }
  }

  private async updateLastStopArrival(
    shuttle: IShuttle,
    travelTimeTimestamp = Date.now(),
  ) {
    const isAtStop = await this.checkIfShuttleIsAtStop(shuttle.id);

    let arrivedStop: IStop | undefined;

    if (isAtStop) {
      // Allow retrieval of the shuttle's current stop
      // Will still return undefined when the shuttle leaves the stop
      arrivedStop = await this.getArrivedStopIfNextStop(shuttle, true);
    } else {
      arrivedStop = await this.getArrivedStopIfNextStop(shuttle, false);
    }


    // Will not fire *any* events if the same stop
    const lastStop = await this.getShuttleLastStopArrival(shuttle.id);
    if (lastStop?.stopId === arrivedStop?.id) return;

    if (isAtStop) {
      if (lastStop) {
        this.emit(ShuttleRepositoryEvent.SHUTTLE_WILL_LEAVE_STOP, {
          stopArrivalThatShuttleIsLeaving: lastStop,
        });
      }
      await this.markShuttleAsNotAtStop(shuttle.id);
    }

    if (arrivedStop) {
      // stop if same stop
      const shuttleArrival = {
        stopId: arrivedStop.id,
        timestamp: new Date(travelTimeTimestamp),
        shuttleId: shuttle.id,
      };
      this.emit(ShuttleRepositoryEvent.SHUTTLE_WILL_ARRIVE_AT_STOP, {
        lastStopArrival: lastStop,
        willArriveAt: shuttleArrival,
      });
      await this.markShuttleAsAtStop(shuttleArrival.shuttleId);
      await this.updateShuttleLastStopArrival(shuttleArrival);
    }
  }

  private async markShuttleAsAtStop(shuttleId: string) {
    this.shuttlesAtStop.add(shuttleId);
  }

  private async markShuttleAsNotAtStop(shuttleId: string) {
    this.shuttlesAtStop.delete(shuttleId);
  }

  public async checkIfShuttleIsAtStop(shuttleId: string) {
    return this.shuttlesAtStop.has(shuttleId);
  }


  private async updateShuttleLastStopArrival(lastStopArrival: ShuttleStopArrival) {
    this.shuttleLastStopArrivals.set(lastStopArrival.shuttleId, lastStopArrival);
  }

  public async getAverageTravelTimeSeconds(
    { routeId, fromStopId, toStopId }: ShuttleTravelTimeDataIdentifier,
    { from, to }: ShuttleTravelTimeDateFilterArguments,
  ): Promise<number | undefined> {
    const key = `${routeId}:${fromStopId}:${toStopId}`;
    const dataPoints = this.travelTimeData.get(key);

    if (!dataPoints || dataPoints.length === 0) {
      return undefined;
    }

    const fromTimestamp = from.getTime();
    const toTimestamp = to.getTime();

    const filteredPoints = dataPoints.filter(
      (point) => point.timestamp >= fromTimestamp && point.timestamp <= toTimestamp
    );

    if (filteredPoints.length === 0) {
      return undefined;
    }

    const sum = filteredPoints.reduce((acc, point) => acc + point.seconds, 0);
    return sum / filteredPoints.length;
  }

  public async getArrivedStopIfNextStop(
    shuttle: IShuttle,
    canReturnShuttleCurrentStop: boolean = false,
  ): Promise<IStop | undefined> {
    const degreeDelta = this.shuttleStopArrivalDegreeDelta;

    const lastStopArrival = await this.getShuttleLastStopArrival(shuttle.id);
    if (lastStopArrival) {
      // Return the shuttle's current stop depending on the flag
      if (canReturnShuttleCurrentStop) {
        const lastStop = await this.getStopById(lastStopArrival.stopId);
        if (lastStop && shuttleHasArrivedAtStop(shuttle, lastStop, degreeDelta)) {
          return lastStop;
        }
      }

      const lastOrderedStop = await this.getOrderedStopByRouteAndStopId(shuttle.routeId, lastStopArrival.stopId);
      const orderedStopAfter = lastOrderedStop?.nextStop;
      if (orderedStopAfter) {
        const stopAfter = await this.getStopById(orderedStopAfter.stopId);
        if (stopAfter && shuttleHasArrivedAtStop(shuttle, stopAfter, degreeDelta)) {
          return stopAfter;
        }
      }
    } else {
      const orderedStops = await this.getOrderedStopsByRouteId(shuttle.routeId);

      for (const orderedStop of orderedStops) {
        const stop = await this.getStopById(orderedStop.stopId);
        if (stop != null && shuttleHasArrivedAtStop(shuttle, stop, degreeDelta)) {
          return stop;
        }
      }
    }

    return undefined;
  }

  public async getShuttleLastStopArrival(shuttleId: string): Promise<ShuttleStopArrival | undefined> {
    return this.shuttleLastStopArrivals.get(shuttleId);
  }

  private async removeEntityByMatcherIfExists<T>(callback: (value: T) => boolean, arrayToSearchIn: T[]) {
    const index = arrayToSearchIn.findIndex(callback);
    if (index > -1) {
      const entityToReturn = arrayToSearchIn[index];
      arrayToSearchIn.splice(index, 1);
      return entityToReturn;
    }

    return null;
  }

  private async removeEntityByIdIfExists<T extends IEntityWithId>(entityId: string, arrayToSearchIn: T[]) {
    return await this.removeEntityByMatcherIfExists((value) => value.id === entityId, arrayToSearchIn);
  }

  public async removeRouteIfExists(routeId: string): Promise<IRoute | null> {
    return await this.removeEntityByIdIfExists(routeId, this.routes);
  }

  public async removeShuttleIfExists(shuttleId: string): Promise<IShuttle | null> {
    const shuttle = await this.removeEntityByIdIfExists(shuttleId, this.shuttles);
    if (shuttle != null) {
      this.emit(ShuttleRepositoryEvent.SHUTTLE_REMOVED, shuttle);
      this.shuttlesAtStop.delete(shuttleId);
      await this.removeShuttleLastStopIfExists(shuttleId);
    }
    return shuttle;
  }

  public async removeStopIfExists(stopId: string): Promise<IStop | null> {
    return await this.removeEntityByIdIfExists(stopId, this.stops);
  }

  public async removeOrderedStopIfExists(stopId: string, routeId: string): Promise<IOrderedStop | null> {
    return await this.removeEntityByMatcherIfExists((orderedStop) => {
      return orderedStop.stopId === stopId
        && orderedStop.routeId === routeId
    }, this.orderedStops);
  }

  private async removeShuttleLastStopIfExists(shuttleId: string) {
    this.shuttleLastStopArrivals.delete(shuttleId);
  }

  public async clearShuttleData(): Promise<void> {
    this.shuttles = [];
    this.shuttlesAtStop.clear();
    await this.clearShuttleLastStopData();
  }

  public async clearOrderedStopData(): Promise<void> {
    this.orderedStops = [];
  }

  public async clearRouteData(): Promise<void> {
    this.routes = [];
  }

  public async clearStopData(): Promise<void> {
    this.stops = [];
  }

  private async clearShuttleLastStopData(): Promise<void> {
    this.shuttleLastStopArrivals.clear();
  }
}