// Copyright 2023 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.metrics;

import static com.google.common.truth.Truth.assertThat;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.when;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Unit tests for the PsInfoCollector. */
@RunWith(JUnit4.class)
public final class PsInfoCollectorTest {

  private final PsInfoCollector spyCollector = spy(PsInfoCollector.instance());

  @Test
  public void testCollectStats_ignoreSpaces() {
    String psOutput = "    PID  \t  PPID \t  RSS\n   2 1 3216 \t\n  \t 3 1 \t 4096 \t";
    InputStream psStream = new ByteArrayInputStream(psOutput.getBytes(UTF_8));
    Process process = mock(Process.class);
    when(process.getInputStream()).thenReturn(psStream);

    ImmutableMap<Long, PsInfoCollector.PsInfo> pidToPsInfo =
        PsInfoCollector.collectDataFromPsProcess(process);

    ImmutableMap<Long, PsInfoCollector.PsInfo> expectedPidToPsInfo =
        ImmutableMap.of(
            2L,
            PsInfoCollector.PsInfo.create(2, 1, 3216),
            3L,
            PsInfoCollector.PsInfo.create(3, 1, 4096));
    assertThat(pidToPsInfo).isEqualTo(expectedPidToPsInfo);
  }

  @Test
  public void testCollectStats_multipleSubprocesses() {
    // pstree of these processes
    // 0-+-1---3-+-7
    //   |       `-8
    //   |-2-+-4
    //   |   `-9
    //   |-5
    //   `-10

    // ps command results:
    // PID PPID RSS
    // 1   0    3216
    // 2   0    4232
    // 3   1    1234
    // 4   2    1001
    // 5   0    40000
    // 7   3    2345
    // 8   3    3456
    // 9   2    1032
    // 10  0    1024
    ImmutableMap<Long, PsInfoCollector.PsInfo> psInfos =
        ImmutableMap.of(
            1L, PsInfoCollector.PsInfo.create(1, 0, 3216),
            2L, PsInfoCollector.PsInfo.create(2, 0, 4232),
            3L, PsInfoCollector.PsInfo.create(3, 1, 1234),
            4L, PsInfoCollector.PsInfo.create(4, 2, 1001),
            5L, PsInfoCollector.PsInfo.create(5, 0, 40000),
            7L, PsInfoCollector.PsInfo.create(7, 3, 2345),
            8L, PsInfoCollector.PsInfo.create(8, 3, 3456),
            9L, PsInfoCollector.PsInfo.create(9, 2, 1032),
            10L, PsInfoCollector.PsInfo.create(10, 0, 1024));
    ImmutableSet<Long> pids = ImmutableSet.of(1L, 2L, 5L, 6L);
    when(spyCollector.collectDataFromPs()).thenReturn(psInfos);

    PsInfoCollector.ResourceSnapshot resourceSnapshot = spyCollector.collectResourceUsage(pids);

    ImmutableMap<Long, Integer> expectedMemoryUsageByPid =
        ImmutableMap.of(1L, 3216 + 1234 + 2345 + 3456, 2L, 4232 + 1001 + 1032, 5L, 40000);
    assertThat(resourceSnapshot.getPidToMemoryInKb()).isEqualTo(expectedMemoryUsageByPid);
  }
}