package okhttp3;

import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import okhttp3.internal.SingleInetAddressDns;
import okhttp3.internal.http2.Header;

public final class TestUtil {
  public static final InetSocketAddress UNREACHABLE_ADDRESS
      = new InetSocketAddress("198.51.100.1", 8080);

  private TestUtil() {
  }

  private static final ConnectionPool connectionPool = new ConnectionPool();
  private static final Dispatcher dispatcher = new Dispatcher();

  /**
   * Returns an OkHttpClient for all tests to use as a starting point.
   *
   * <p>The shared instance allows all tests to share a single connection pool, which prevents idle
   * connections from consuming unnecessary resources while connections wait to be evicted.
   *
   * <p>This client is also configured to be slightly more deterministic, returning a single IP
   * address for all hosts, regardless of the actual number of IP addresses reported by DNS.
   */
  public static OkHttpClient defaultClient() {
    return new OkHttpClient.Builder()
        .connectionPool(connectionPool)
        .dispatcher(dispatcher)
        .dns(new SingleInetAddressDns()) // Prevent unexpected fallback addresses.
        .build();
  }

  public static List<Header> headerEntries(String... elements) {
    List<Header> result = new ArrayList<>(elements.length / 2);
    for (int i = 0; i < elements.length; i += 2) {
      result.add(new Header(elements[i], elements[i + 1]));
    }
    return result;
  }

  public static String repeat(char c, int count) {
    char[] array = new char[count];
    Arrays.fill(array, c);
    return new String(array);
  }

  /**
   * See FinalizationTester for discussion on how to best trigger GC in tests.
   * https://android.googlesource.com/platform/libcore/+/master/support/src/test/java/libcore/
   * java/lang/ref/FinalizationTester.java
   */
  public static void awaitGarbageCollection() throws InterruptedException {
    Runtime.getRuntime().gc();
    Thread.sleep(100);
    System.runFinalization();
  }
}