import 'dart:async';

import 'package:flutter/widgets.dart';

import 'async_typeof.dart';
import 'cancel_future.dart';

class AsyncUtil {
  AsyncUtil._();

  static CancelableFuture<T> retryWithExponentialBackoff<T>(
      FutureCallback<T> callback,
      int maxRetry,
      Duration initialInterval,
      Predicate<dynamic> predicate) {
    Completer<T> completer = Completer<T>();
    int retryCount = 0;
    Timer? timer;

    void attempt() {
      callback().then((value) {
        if (!completer.isCompleted) {
          completer.complete(value);
        }
      }).catchError((error) {
        if (retryCount < maxRetry && predicate(error)) {
          retryCount++;
          Duration nextInterval = initialInterval * (1 << (retryCount - 1));
          timer = Timer(nextInterval, attempt);
        } else {
          if (!completer.isCompleted) {
            completer.completeError(error);
          }
        }
      });
    }

    attempt();

    return CancelableFuture<T>(() {
      timer?.cancel();
    });
  }

  static CancelableFuture<T> retryWhen<T>(FutureCallback<T> callback,
      int maxRetry, Duration interval, Predicate<dynamic> predicate) {
    Completer<T> completer = Completer<T>();
    int retryCount = 0;
    Timer? timer;

    void attempt() {
      callback().then((value) {
        if (!completer.isCompleted) {
          completer.complete(value);
        }
      }).catchError((error) {
        if (retryCount < maxRetry && predicate(error)) {
          retryCount++;
          timer = Timer(interval, attempt);
        } else {
          if (!completer.isCompleted) {
            completer.completeError(error);
          }
        }
      });
    }

    attempt();

    return CancelableFuture<T>(() {
      timer?.cancel();
    });
  }

  static CancelableFuture<T> retry<T>(
      FutureCallback<T> callback, int maxRetry, Duration interval) {
    return retryWhen(callback, maxRetry, interval, (error) => true);
  }

  static CancelableFuture<T> delay<T>(
      FutureCallback<T> callback, Duration interval) {
    Timer? timer;
    return CancelableFuture<T>(
      () {
        timer?.cancel();
      },
      futureCompleter: (completer) {
        timer = Timer(interval, () {
          callback()
              .then(completer.complete)
              .catchError(completer.completeError);
        });
      },
    );
  }

  ///实际delay第一次执行的时间为delay+interval
  static CancelableFuture<T> interval<T>(FutureCallback<T> callback,
      Duration delay, Duration interval, int times) {
    Timer? timer;
    Timer? delayTimer;
    int counter = 0;
    Completer<T> completer = Completer<T>();

    void tick() {
      if (counter < times) {
        callback().then((value) {
          if (!completer.isCompleted) {
            completer.complete(value);
          }
        }).catchError((error) {
          if (!completer.isCompleted) {
            completer.completeError(error);
          }
        });
        counter++;
      } else {
        timer?.cancel();
      }
    }

    delayTimer = Timer(delay, () {
      timer = Timer.periodic(interval, (Timer t) => tick());
    });

    return CancelableFuture<T>(() {
      delayTimer?.cancel();
      timer?.cancel();
    });
  }
}