/*
 * Copyright (C) 2008 The Guava 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 com.google.common.io;

import static com.google.common.base.StandardSystemProperty.JAVA_IO_TMPDIR;
import static com.google.common.base.StandardSystemProperty.OS_NAME;
import static com.google.common.truth.Truth.assertThat;
import static java.lang.Math.min;
import static java.nio.file.attribute.PosixFilePermission.OWNER_READ;
import static java.nio.file.attribute.PosixFilePermission.OWNER_WRITE;
import static org.junit.Assert.assertThrows;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.file.attribute.PosixFileAttributeView;
import java.nio.file.attribute.PosixFileAttributes;
import java.util.Arrays;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for {@link FileBackedOutputStream}.
 *
 * <p>For a tiny bit more testing, see {@link FileBackedOutputStreamAndroidIncompatibleTest}.
 *
 * @author Chris Nokleberg
 */
@NullUnmarked
public class FileBackedOutputStreamTest extends IoTestCase {


  public void testThreshold() throws Exception {
    testThreshold(0, 100, true, false);
    testThreshold(10, 100, true, false);
    testThreshold(100, 100, true, false);
    testThreshold(1000, 100, true, false);
    testThreshold(0, 100, false, false);
    testThreshold(10, 100, false, false);
    testThreshold(100, 100, false, false);
    testThreshold(1000, 100, false, false);
  }

  private void testThreshold(
      int fileThreshold, int dataSize, boolean singleByte, boolean resetOnFinalize)
      throws IOException {
    byte[] data = newPreFilledByteArray(dataSize);
    FileBackedOutputStream out = new FileBackedOutputStream(fileThreshold, resetOnFinalize);
    ByteSource source = out.asByteSource();
    int chunk1 = min(dataSize, fileThreshold);
    int chunk2 = dataSize - chunk1;

    // Write just enough to not trip the threshold
    if (chunk1 > 0) {
      write(out, data, 0, chunk1, singleByte);
      assertTrue(ByteSource.wrap(data).slice(0, chunk1).contentEquals(source));
    }
    File file = out.getFile();
    assertNull(file);

    // Write data to go over the threshold
    if (chunk2 > 0) {
      if (JAVA_IO_TMPDIR.value().equals("/sdcard")) {
        assertThrows(IOException.class, () -> write(out, data, chunk1, chunk2, singleByte));
        return;
      }
      write(out, data, chunk1, chunk2, singleByte);
      file = out.getFile();
      assertEquals(dataSize, file.length());
      assertTrue(file.exists());
      assertThat(file.getName()).contains("FileBackedOutputStream");
      if (!isAndroid() && !isWindows()) {
        PosixFileAttributes attributes =
            java.nio.file.Files.getFileAttributeView(file.toPath(), PosixFileAttributeView.class)
                .readAttributes();
        assertThat(attributes.permissions()).containsExactly(OWNER_READ, OWNER_WRITE);
      }
    }
    out.close();

    // Check that source returns the right data
    assertTrue(Arrays.equals(data, source.read()));

    // Make sure that reset deleted the file
    out.reset();
    if (file != null) {
      assertFalse(file.exists());
    }
  }


  public void testThreshold_resetOnFinalize() throws Exception {
    testThreshold(0, 100, true, true);
    testThreshold(10, 100, true, true);
    testThreshold(100, 100, true, true);
    testThreshold(1000, 100, true, true);
    testThreshold(0, 100, false, true);
    testThreshold(10, 100, false, true);
    testThreshold(100, 100, false, true);
    testThreshold(1000, 100, false, true);
  }

  static void write(OutputStream out, byte[] b, int off, int len, boolean singleByte)
      throws IOException {
    if (singleByte) {
      for (int i = off; i < off + len; i++) {
        out.write(b[i]);
      }
    } else {
      out.write(b, off, len);
    }
    out.flush(); // for coverage
  }

  // TODO(chrisn): only works if we ensure we have crossed file threshold

  public void testWriteErrorAfterClose() throws Exception {
    byte[] data = newPreFilledByteArray(100);
    FileBackedOutputStream out = new FileBackedOutputStream(50);
    ByteSource source = out.asByteSource();

    if (JAVA_IO_TMPDIR.value().equals("/sdcard")) {
      assertThrows(IOException.class, () -> out.write(data));
      return;
    }
    out.write(data);
    assertTrue(Arrays.equals(data, source.read()));

    out.close();
    assertThrows(IOException.class, () -> out.write(42));

    // Verify that write had no effect
    assertTrue(Arrays.equals(data, source.read()));
    out.reset();
  }

  public void testReset() throws Exception {
    byte[] data = newPreFilledByteArray(100);
    FileBackedOutputStream out = new FileBackedOutputStream(Integer.MAX_VALUE);
    ByteSource source = out.asByteSource();

    out.write(data);
    assertTrue(Arrays.equals(data, source.read()));

    out.reset();
    assertTrue(Arrays.equals(new byte[0], source.read()));

    out.write(data);
    assertTrue(Arrays.equals(data, source.read()));

    out.close();
  }

  private static boolean isAndroid() {
    return System.getProperty("java.runtime.name", "").contains("Android");
  }

  private static boolean isWindows() {
    return OS_NAME.value().startsWith("Windows");
  }
}
