// Copyright 2022 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.lib.remote.util;

import static com.google.devtools.build.lib.testutil.TestUtils.tmpDirFile;
import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.shell.Subprocess;
import com.google.devtools.build.lib.shell.SubprocessBuilder;
import com.google.devtools.build.lib.util.OS;
import com.google.devtools.build.lib.vfs.PathFragment;
import com.google.devtools.build.runfiles.Runfiles;
import java.io.File;
import java.io.IOException;
import java.net.DatagramSocket;
import java.net.ServerSocket;
import java.net.SocketException;
import java.util.Random;

/** Integration test utilities. */
public final class IntegrationTestUtils {
  private IntegrationTestUtils() {}

  private static final PathFragment WORKER_PATH =
      PathFragment.create(
          "io_bazel/src/tools/remote/worker"
              + (OS.getCurrent() == OS.WINDOWS ? ".exe" : ""));

  private static boolean isPortAvailable(int port) {
    if (port < 1024 || port > 65535) {
      return false;
    }

    try (ServerSocket ss = new ServerSocket(port)) {
      ss.setReuseAddress(true);
    } catch (IOException e) {
      return false;
    }

    try (DatagramSocket ds = new DatagramSocket(port)) {
      ds.setReuseAddress(true);
    } catch (SocketException e) {
      return false;
    }

    return true;
  }

  public static int pickUnusedRandomPort() throws IOException, InterruptedException {
    Random rand = new Random();
    for (int i = 0; i < 128; ++i) {
      int port = rand.nextInt(64551) + 1024;
      if (isPortAvailable(port)) {
        return port;
      }
      if (Thread.interrupted()) {
        throw new InterruptedException("interrupted");
      }
    }

    throw new IOException("Failed to find available port");
  }

  public static WorkerInstance startWorker() throws IOException, InterruptedException {
    return startWorker(/* useHttp= */ false);
  }

  public static WorkerInstance startWorker(boolean useHttp)
      throws IOException, InterruptedException {
    PathFragment testTmpDir = PathFragment.create(tmpDirFile().getAbsolutePath());
    PathFragment workPath = testTmpDir.getRelative("remote.work_path");
    PathFragment casPath = testTmpDir.getRelative("remote.cas_path");
    PathFragment pidPath = testTmpDir.getRelative("remote.pid_file");
    int workerPort = pickUnusedRandomPort();
    ensureMkdir(workPath);
    ensureMkdir(casPath);
    String workerPath = Runfiles.create().rlocation(WORKER_PATH.getSafePathString());
    Subprocess workerProcess =
        new SubprocessBuilder()
            .setArgv(
                ImmutableList.of(
                    workerPath,
                    "--work_path=" + workPath.getSafePathString(),
                    "--cas_path=" + casPath.getSafePathString(),
                    (useHttp ? "--http_listen_port=" : "--listen_port=") + workerPort,
                    "--pid_file=" + pidPath))
            .start();

    File pidFile = new File(pidPath.getSafePathString());
    while (!pidFile.exists()) {
      if (!workerProcess.isAlive()) {
        String message = new String(workerProcess.getErrorStream().readAllBytes(), UTF_8);
        throw new IOException("Failed to start worker: " + message);
      }
      Thread.sleep(1);
    }

    return new WorkerInstance(workerProcess, workerPort, workPath, casPath, pidPath);
  }

  private static void ensureMkdir(PathFragment path) throws IOException {
    File dir = new File(path.getSafePathString());
    if (dir.exists()) {
      throw new IOException(path + " already exists");
    }
    if (!dir.mkdir()) {
      throw new IOException("Failed to create directory " + path);
    }
  }

  public static class WorkerInstance {
    private final Subprocess process;
    private final int port;
    private final PathFragment workPath;
    private final PathFragment casPath;
    private final PathFragment pidPath;

    private WorkerInstance(
        Subprocess process,
        int port,
        PathFragment workPath,
        PathFragment casPath,
        PathFragment pidPath) {
      this.process = process;
      this.port = port;
      this.workPath = workPath;
      this.casPath = casPath;
      this.pidPath = pidPath;
    }

    public void stop() {
      process.destroyAndWait();
    }

    public int getPort() {
      return port;
    }

    public PathFragment getWorkPath() {
      return workPath;
    }

    public PathFragment getCasPath() {
      return casPath;
    }

    public PathFragment getPidPath() {
      return pidPath;
    }
  }
}