import { firstValueFrom, from, Observable, throwError, timer } from "rxjs";
import { retryWhen, mergeMap, catchError } from "rxjs/operators";
import Transport from "@ledgerhq/hw-transport";
import {
  WrongDeviceForAccount,
  WrongAppForCurrency,
  CantOpenDevice,
  UpdateYourApp,
  BluetoothRequired,
  TransportWebUSBGestureRequired,
  TransportInterfaceNotAvailable,
  FirmwareOrAppUpdateRequired,
  TransportStatusError,
  DeviceHalted,
  PeerRemovedPairing,
  PairingFailed,
} from "@ledgerhq/errors";
import { LocalTracer, TraceContext, trace } from "@ledgerhq/logs";
import { getEnv } from "@ledgerhq/live-env";
import { open, close } from ".";

const LOG_TYPE = "hw";

const initialErrorRemapping = (error: unknown, context?: TraceContext) => {
  let mappedError = error;

  if (error && error instanceof TransportStatusError) {
    if (error.statusCode === 0x6faa) {
      mappedError = new DeviceHalted(error.message);
    } else if (error.statusCode === 0x6b00) {
      mappedError = new FirmwareOrAppUpdateRequired(error.message);
    }
  }

  trace({
    type: LOG_TYPE,
    message: `Initial error remapping: ${error}`,
    data: { error, mappedError },
    context,
  });
  return throwError(() => mappedError);
};

let errorRemapping = e => throwError(() => e);

export const setErrorRemapping = (f: (arg0: Error) => Observable<never>): void => {
  errorRemapping = f;
};

const never = new Promise(() => {});

/**
 * Wrapper to pipe a "cleanup" function at then end of an Observable flow.
 *
 * The `finalize` is only called once if there is an error and a complete
 * (but normally an error event completes automatically the Observable pipes. Is it needed ?)
 */
function transportFinally(cleanup: () => Promise<void>) {
  return <T>(observable: Observable<T>): Observable<T> => {
    return new Observable(o => {
      let done = false;

      const finalize = () => {
        if (done) return never;
        done = true;
        return cleanup();
      };

      const sub = observable.subscribe({
        next: e => o.next(e),
        complete: () => {
          finalize().then(() => o.complete());
        },
        error: e => {
          finalize().then(() => o.error(e));
        },
      });

      return () => {
        sub.unsubscribe();
        finalize();
      };
    });
  };
}

const identifyTransport = t => (typeof t.id === "string" ? t.id : "");

const needsCleanup = {};
// When a series of APDUs are interrupted, this is called
// so we don't forget to cleanup on the next withDevice
export const cancelDeviceAction = (transport: Transport): void => {
  const transportId = identifyTransport(transport);
  trace({
    type: LOG_TYPE,
    message: "Cancelling device action",
    data: { transportId },
  });

  needsCleanup[transportId] = true;
};

export type QueuedJob = { job: Promise<void>; id: number };

/**
 * Manages queued jobs for each device (id)
 *
 * Careful: a USB-connected device has no unique id, and its `deviceId` will be an empty string.
 *
 * The queue object `queuedJobsByDevice` only stores, for each device, the latest void promise that will resolve
 * when the device is ready to be opened again.
 * They are scheduled to resolve whenever the job associated to the device is finished.
 * When calling withDevice several times, the new promise will be chained to the "then" of the previous promise:
 * open(device) -> execute job -> clean connection -> resolve promise -> next promise can start: open(device) -> etc.
 * So a queue is indeed created for each device, by creating a chain of promises, but only the end of the queue is stored for each device.
 */
export class DeviceQueuedJobsManager {
  // For each device, queue of linked Promises that wait after each other, blocking any future job for a given device
  private queuedJobsByDevice: { [deviceId: string]: QueuedJob };

  private static instance: DeviceQueuedJobsManager | null = null;

  // To be able to differentiate withDevice calls in our logs
  private static jobIdCounter: number = -1;

  private constructor() {
    this.queuedJobsByDevice = {};
  }

  /**
   * Get the singleton instance
   */
  static getInstance(): DeviceQueuedJobsManager {
    if (!this.instance) {
      this.instance = new DeviceQueuedJobsManager();
    }

    return this.instance;
  }

  /**
   * Returns the latest queued job for a given device id
   *
   * @param deviceId
   * @returns the latest QueuedJob. If none, return a queued job that can be resolved directly.
   */
  getLastQueuedJob(deviceId: string): QueuedJob {
    return this.queuedJobsByDevice[deviceId] || { job: Promise.resolve(), id: -1 };
  }

  /**
   * Sets the latest queue job for a given device id
   *
   * Also increments the job id counter and set the newly queued job id to this new incremented value.
   *
   * Note: we should be fine on race conditions when updating the jobId in our use cases.
   *
   * @param deviceId
   * @param jobToQueue a Promise that resolve to void, representing an async job
   * @returns the id of the queued job
   */
  setLastQueuedJob(deviceId: string, jobToQueue: Promise<void>): number {
    const id = ++DeviceQueuedJobsManager.jobIdCounter;
    this.queuedJobsByDevice[deviceId] = { job: jobToQueue, id };
    return id;
  }
}

/**
 * Provides a Transport instance to a given job
 *
 * @param deviceId
 * @param options contains optional configuration
 *   - openTimeoutMs: optional timeout that limits in time the open attempt of the matching registered transport.
 */
export const withDevice =
  (deviceId: string, options?: { openTimeoutMs?: number }) =>
  <T>(job: (t: Transport) => Observable<T>): Observable<T> =>
    new Observable(o => {
      const queuedJobManager = DeviceQueuedJobsManager.getInstance();
      const previousQueuedJob = queuedJobManager.getLastQueuedJob(deviceId);

      // When the new job is finished, this will unlock the associated device queue of jobs
      let resolveQueuedJob;

      const jobId = queuedJobManager.setLastQueuedJob(
        deviceId,
        new Promise(resolve => {
          resolveQueuedJob = resolve;
        }),
      );

      const tracer = new LocalTracer(LOG_TYPE, { jobId, deviceId, origin: "hw:withDevice" });
      tracer.trace(`New job for device: ${deviceId || "USB"}`);

      // To call to cleanup the current transport
      const finalize = async (transport: Transport, cleanups: Array<() => void>) => {
        tracer.trace("Closing and cleaning transport", { function: "finalize" });

        try {
          await close(transport, deviceId);
        } catch (error) {
          tracer.trace(`An error occurred when closing transport (ignoring it): ${error}`, {
            error,
            function: "finalize",
          });
        }
        cleanups.forEach(c => c());
      };

      let unsubscribed;
      let sub;

      tracer.trace("Waiting for the previous job in the queue to complete", {
        previousJobId: previousQueuedJob.id,
      });
      // For any new job, we'll now wait the exec queue to be available
      previousQueuedJob.job
        .then(() => {
          tracer.trace("Previous queued job resolved, now trying to get a Transport instance", {
            previousJobId: previousQueuedJob.id,
            currentJobId: jobId,
          });
          return open(deviceId, options?.openTimeoutMs, tracer.getContext());
        }) // open the transport
        .then(async transport => {
          tracer.trace("Got a Transport instance from open");

          if (unsubscribed) {
            tracer.trace("Unsubscribed (1) while processing job");
            // It was unsubscribed prematurely
            return finalize(transport, [resolveQueuedJob]);
          }

          if (needsCleanup[identifyTransport(transport)]) {
            delete needsCleanup[identifyTransport(transport)];
            await transport.send(0, 0, 0, 0).catch(() => {});
          }

          return transport;
        })
        // This catch is here only for errors that might happen at open or at clean up of the transport before doing the job
        .catch(e => {
          tracer.trace(`Error while opening Transport: ${e}`, { error: e });
          resolveQueuedJob();
          if (e instanceof BluetoothRequired) throw e;
          if (e instanceof TransportWebUSBGestureRequired) throw e;
          if (e instanceof TransportInterfaceNotAvailable) throw e;
          if (e instanceof PeerRemovedPairing) throw e;
          if (e instanceof PairingFailed) throw e;
          console.error(e);
          throw new CantOpenDevice(e.message);
        })
        // Executes the job
        .then(transport => {
          tracer.trace("Executing job", { hasTransport: !!transport, unsubscribed });
          if (!transport) return;

          // It was unsubscribed prematurely
          if (unsubscribed) {
            tracer.trace("Unsubscribed (2) while processing job");
            return finalize(transport, [resolveQueuedJob]);
          }

          sub = job(transport)
            .pipe(
              catchError(error => initialErrorRemapping(error, tracer.getContext())),
              catchError(errorRemapping),
              transportFinally(() => {
                // Closes the transport and cleans up everything
                return finalize(transport, [resolveQueuedJob]);
              }),
            )
            .subscribe({
              next: event => {
                // This kind of log should be a "debug" level for ex
                // tracer.trace("Job next", { event });
                o.next(event);
              },
              error: error => {
                tracer.trace("Job error", { error });
                if (error.statusCode) {
                  o.error(new TransportStatusError(error.statusCode));
                } else {
                  o.error(error);
                }
              },
              complete: () => {
                o.complete();
              },
            });
        })
        .catch(error => {
          tracer.trace(`Caught error on job execution step: ${error}`, { error });
          o.error(error);
        });

      // Returns function to unsubscribe from the job if we don't need it anymore.
      // This will prevent us from executing the job unnecessarily later on
      return () => {
        tracer.trace(`Unsubscribing withDevice flow. Ongoing job to unsubscribe from ? ${!!sub}`);
        unsubscribed = true;
        if (sub) sub.unsubscribe();
      };
    });

/**
 * Provides a Transport instance to the given function fn
 * @see withDevice
 */
export const withDevicePromise = <T>(deviceId: string, fn: (Transport) => Promise<T>) =>
  firstValueFrom(withDevice(deviceId)(transport => from(fn(transport))));

export const genericCanRetryOnError = (err: unknown): boolean => {
  if (err instanceof WrongAppForCurrency) return false;
  if (err instanceof WrongDeviceForAccount) return false;
  if (err instanceof CantOpenDevice) return false;
  if (err instanceof BluetoothRequired) return false;
  if (err instanceof UpdateYourApp) return false;
  if (err instanceof FirmwareOrAppUpdateRequired) return false;
  if (err instanceof DeviceHalted) return false;
  if (err instanceof TransportWebUSBGestureRequired) return false;
  if (err instanceof TransportInterfaceNotAvailable) return false;
  return true;
};

export const retryWhileErrors =
  (acceptError: (arg0: Error) => boolean) =>
  (attempts: Observable<any>): Observable<any> =>
    attempts.pipe(
      mergeMap(error => {
        if (!acceptError(error)) {
          return throwError(() => error);
        }

        return timer(getEnv("WITH_DEVICE_POLLING_DELAY"));
      }),
    );

export const withDevicePolling =
  (deviceId: string) =>
  <T>(
    job: (arg0: Transport) => Observable<T>,
    acceptError: (arg0: Error) => boolean = genericCanRetryOnError,
  ): Observable<T> =>
    withDevice(deviceId)(job).pipe(retryWhen(retryWhileErrors(acceptError)));