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package com.vertexvis.example;

import com.vertexvis.model.QueuedJob;

import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;

class JobPoller {
  private static final long DEFAULT_WAIT_TIME_MS = 3000;

  private static final ScheduledExecutorService scheduler =
      Executors.newScheduledThreadPool(4);

  public static CompletableFuture pollUntilJobDoneAsync(String type,
                                                              Supplier> f) {
    CompletableFuture cf = new CompletableFuture<>();

    startChecking(cf, type, f);

    return cf;
  }

  public static UUID pollUntilJobDone(String type, Supplier f)
      throws InterruptedException {
    // Don't do this -- use a proper scheduler
    Thread.sleep(DEFAULT_WAIT_TIME_MS);

    QueuedJob qj = f.get();

    if (qj.getData().getType().equals(type)) {
      return qj.getData().getId();
    } else {
      return pollUntilJobDone(type, f);
    }
  }

  private static void startChecking(CompletableFuture resultF, String type,
                                    Supplier> f) {
    scheduler.schedule(() -> {
      f.get().thenAccept(qj -> {
        if (qj.getData().getType().equals(type)) {
          resultF.complete(qj.getData().getId());
        } else {
          startChecking(resultF, type, f);
        }
      });

    }, DEFAULT_WAIT_TIME_MS, TimeUnit.MILLISECONDS);
  }
}