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/*
 * Copyright 2016-2019 The jetcd authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.etcd.jetcd;

import static io.etcd.jetcd.common.exception.EtcdExceptionFactory.toEtcdException;

import com.google.common.util.concurrent.ListenableFuture;
import com.google.protobuf.ByteString;
import io.grpc.Status;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;

public final class Util {

  private Util() {
  }

  public static List toURIs(Collection uris) {
    return uris.stream().map(uri -> {
      try {
        return new URI(uri);
      } catch (URISyntaxException e) {
        throw new IllegalArgumentException("Invalid endpoint URI: " + uri, e);
      }
    }).collect(Collectors.toList());
  }

  /**
   * convert ListenableFuture of Type S to CompletableFuture of Type T.
   */
  static  CompletableFuture toCompletableFuture(
      ListenableFuture sourceFuture, Function resultConvert, Executor executor) {

    CompletableFuture targetFuture = new CompletableFuture() {
      // the cancel of targetFuture also cancels the sourceFuture.
      @Override
      public boolean cancel(boolean mayInterruptIfRunning) {
        super.cancel(mayInterruptIfRunning);
        return sourceFuture.cancel(mayInterruptIfRunning);
      }
    };

    sourceFuture.addListener(() -> {
      try {
        targetFuture.complete(resultConvert.apply(sourceFuture.get()));
      } catch (Exception e) {
        targetFuture.completeExceptionally(toEtcdException(e));
      }
    }, executor);

    return targetFuture;
  }

  static boolean isRetryable(Throwable e) {
    return isInvalidTokenError(Status.fromThrowable(e));
  }

  static boolean isInvalidTokenError(Status status) {
    return status.getCode() == Status.Code.UNAUTHENTICATED
      && "etcdserver: invalid auth token".equals(status.getDescription());
  }

  static  T supplyIfNull(T target, Supplier supplier) {
    return target != null ? target : supplier.get();
  }

  public static ByteString prefixNamespace(ByteString key, ByteSequence namespace) {
    return namespace.isEmpty() ? key : namespace.getByteString().concat(key);
  }

  public static ByteString prefixNamespaceToRangeEnd(ByteString end, ByteSequence namespace) {
    if (namespace.isEmpty()) {
      return end;
    }

    if (end.size() == 1 && end.toByteArray()[0] == 0) {
      // range end is '\0', calculate the prefixed range end by (key + 1)
      byte[] prefixedEndArray = namespace.getByteString().toByteArray();
      boolean ok = false;
      for (int i = (prefixedEndArray.length - 1); i >= 0; i--) {
        prefixedEndArray[i] = (byte) (prefixedEndArray[i] + 1);
        if (prefixedEndArray[i] != 0) {
          ok = true;
          break;
        }
      }
      if (!ok) {
        // 0xff..ff => 0x00
        prefixedEndArray = new byte[] {0};
      }
      return ByteString.copyFrom(prefixedEndArray);
    } else {
      return namespace.getByteString().concat(end);
    }
  }

  public static ByteString unprefixNamespace(ByteString key, ByteSequence namespace) {
    return namespace.isEmpty() ? key : key.substring(namespace.size());
  }

}