/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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
    *
    *      https://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 org.apache.commons.codec.binary;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assumptions.assumeTrue;
  
  import org.apache.commons.codec.binary.BaseNCodec.Context;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  public class BaseNCodecTest {
  
      /**
       * Extend BaseNCodec without implementation (no operations = NoOp).
       * Used for testing the memory allocation in {@link BaseNCodec#ensureBufferSize(int, Context)}.
       */
      private static final class NoOpBaseNCodec extends BaseNCodec {
          NoOpBaseNCodec() {
              super(0, 0, 0, 0);
          }
  
          @Override
          void decode(final byte[] pArray, final int i, final int length, final Context context) {
              // no-op
          }
  
          @Override
          void encode(final byte[] pArray, final int i, final int length, final Context context) {
              // no-op
          }
  
          @Override
          protected boolean isInAlphabet(final byte value) {
              return false;
          }
      }
  
      private static void assertEnsureBufferSizeExpandsToMaxBufferSize(final boolean exceedMaxBufferSize) {
          // This test is memory hungry.
          // By default expansion will double the buffer size.
          // Using a buffer that must be doubled to get close to 2GiB requires at least 3GiB
          // of memory for the test (1GiB existing + 2GiB new).
          // As a compromise we use an empty buffer and rely on the expansion switching
          // to the minimum required capacity if doubling is not enough.
  
          // To effectively use a full buffer of ~1GiB change the following for: 1 << 30.
          // Setting to zero has the lowest memory footprint for this test.
          final int length = 0;
  
          final long presumableFreeMemory = getPresumableFreeMemory();
          // 2GiB + 32 KiB + length
          // 2GiB: Buffer to allocate
          // 32KiB: Some headroom
          // length: Existing buffer
          final long estimatedMemory = (1L << 31) + 32 * 1024 + length;
          assumeTrue(presumableFreeMemory > estimatedMemory, "Not enough free memory for the test");
  
          final int max = Integer.MAX_VALUE - 8;
  
          // Check the conservative maximum buffer size can actually be exceeded by the VM
          // otherwise the test is not valid.
          if (exceedMaxBufferSize) {
              assumeCanAllocateBufferSize(max + 1);
              // Free-memory.
              // This may not be necessary as the byte[] is now out of scope
              System.gc();
          }
  
          final BaseNCodec ncodec = new NoOpBaseNCodec();
          final Context context = new Context();
  
          // Allocate the initial buffer
          context.buffer = new byte[length];
          context.pos = length;
          // Compute the extra to reach or exceed the max buffer size
          int extra = max - length;
          if (exceedMaxBufferSize) {
              extra++;
         }
         ncodec.ensureBufferSize(extra, context);
         assertTrue(context.buffer.length >= length + extra);
     }
 
     /**
      * Verify this VM can allocate the given size byte array. Otherwise skip the test.
      */
     private static void assumeCanAllocateBufferSize(final int size) {
         byte[] bytes = null;
         try {
             bytes = new byte[size];
         } catch (final OutOfMemoryError ignore) {
             // ignore
         }
         assumeTrue(bytes != null, "Cannot allocate array of size: " + size);
     }
 
     /**
      * Gets the presumable free memory; an estimate of the amount of memory that could be allocated.
      *
      * <p>This performs a garbage clean-up and the obtains the presumed amount of free memory
      * that can be allocated in this VM. This is computed as:<p>
      *
      * <pre>
      * System.gc();
      * long allocatedMemory = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
      * long presumableFreeMemory = Runtime.getRuntime().maxMemory() - allocatedMemory;
      * </pre>
      *
      * @return the presumable free memory
      * @see <a href="https://stackoverflow.com/a/18366283">
      *     Christian Fries StackOverflow answer on Java available memory</a>
      */
     static long getPresumableFreeMemory() {
         System.gc();
         final long allocatedMemory = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
         return Runtime.getRuntime().maxMemory() - allocatedMemory;
     }
 
     BaseNCodec codec;
     @BeforeEach
 
     public void setUp() {
         codec = new BaseNCodec(0, 0, 0, 0) {
             @Override
             void decode(final byte[] pArray, final int i, final int length, final Context context) {
             }
 
             @Override
             void encode(final byte[] pArray, final int i, final int length, final Context context) {
             }
 
             @Override
             protected boolean isInAlphabet(final byte b) {
                 return b == 'O' || b == 'K'; // allow OK
             }
         };
     }
 
     @Test
     public void testBaseNCodec() {
         assertNotNull(codec);
     }
 
     @Test
     public void testContainsAlphabetOrPad() {
         assertFalse(codec.containsAlphabetOrPad(null));
         assertFalse(codec.containsAlphabetOrPad(new byte[]{}));
         assertTrue(codec.containsAlphabetOrPad("OK".getBytes()));
         assertTrue(codec.containsAlphabetOrPad("OK ".getBytes()));
         assertFalse(codec.containsAlphabetOrPad("ok ".getBytes()));
         assertTrue(codec.containsAlphabetOrPad(new byte[]{codec.pad}));
     }
 
     /**
      * Test the Context string representation has debugging info.
      * This is not part of the API and the test should be changed if the string
      * format is updated.
      */
     @Test
     public void testContextToString() {
         final Context context = new Context();
         context.buffer = new byte[3];
         context.currentLinePos = 13;
         context.eof = true;
         context.ibitWorkArea = 777;
         context.lbitWorkArea = 999;
         context.modulus = 5;
         context.pos = 42;
         context.readPos = 981;
         final String text = context.toString();
         assertTrue(text.contains("[0, 0, 0]"));
         assertTrue(text.contains("13"));
         assertTrue(text.contains("true"));
         assertTrue(text.contains("777"));
         assertTrue(text.contains("999"));
         assertTrue(text.contains("5"));
         assertTrue(text.contains("42"));
         assertTrue(text.contains("981"));
     }
 
 //    @Test
 //    public void testGetEncodedLength() {
 //        fail("Not yet implemented");
 //    }
 
     @Test
     public void testEnsureBufferSize() {
         final BaseNCodec ncodec = new NoOpBaseNCodec();
         final Context context = new Context();
         assertNull(context.buffer, "Initial buffer should be null");
 
         // Test initialization
         context.pos = 76979;
         context.readPos = 273;
         ncodec.ensureBufferSize(0, context);
         assertNotNull(context.buffer, "buffer should be initialized");
         assertEquals(ncodec.getDefaultBufferSize(), context.buffer.length, "buffer should be initialized to default size");
         assertEquals(0, context.pos, "context position");
         assertEquals(0, context.readPos, "context read position");
 
         // Test when no expansion is required
         ncodec.ensureBufferSize(1, context);
         assertEquals(ncodec.getDefaultBufferSize(), context.buffer.length, "buffer should not expand unless required");
 
         // Test expansion
         int length = context.buffer.length;
         context.pos = length;
         int extra = 1;
         ncodec.ensureBufferSize(extra, context);
         assertTrue(context.buffer.length >= length + extra, "buffer should expand");
 
         // Test expansion beyond double the buffer size.
         // Hits the edge case where the required capacity is more than the default expansion.
         length = context.buffer.length;
         context.pos = length;
         extra = length * 10;
         ncodec.ensureBufferSize(extra, context);
         assertTrue(context.buffer.length >= length + extra, "buffer should expand beyond double capacity");
     }
 
     /**
      * Test to expand to beyond the max buffer size.
      *
      * <p>Note: If the buffer is required to expand to above the max buffer size it may not work
      * on all VMs and may have to be annotated with @Ignore.</p>
      */
     @Test
     public void testEnsureBufferSizeExpandsToBeyondMaxBufferSize() {
         assertEnsureBufferSizeExpandsToMaxBufferSize(true);
     }
 
     /**
      * Test to expand to the max buffer size.
      */
     @Test
     public void testEnsureBufferSizeExpandsToMaxBufferSize() {
         assertEnsureBufferSizeExpandsToMaxBufferSize(false);
     }
 
     @Test
     public void testEnsureBufferSizeThrowsOnOverflow() {
         final BaseNCodec ncodec = new NoOpBaseNCodec();
         final Context context = new Context();
 
         final int length = 10;
         context.buffer = new byte[length];
         context.pos = length;
         final int extra = Integer.MAX_VALUE;
         assertThrows(OutOfMemoryError.class, () -> ncodec.ensureBufferSize(extra, context));
     }
 
     //
 //    @Test
 //    public void testEncodeObject() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testEncodeToString() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testDecodeObject() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testDecodeString() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testDecodeByteArray() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testEncodeByteArray() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testEncodeAsString() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testEncodeByteArrayIntInt() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testDecodeByteArrayIntInt() {
 //        fail("Not yet implemented");
 //    }
 //
     @Test
     public void testIsInAlphabetByte() {
         assertFalse(codec.isInAlphabet((byte) 0));
         assertFalse(codec.isInAlphabet((byte) 'a'));
         assertTrue(codec.isInAlphabet((byte) 'O'));
         assertTrue(codec.isInAlphabet((byte) 'K'));
     }
 
     @Test
     public void testIsInAlphabetByteArrayBoolean() {
         assertTrue(codec.isInAlphabet(new byte[] {}, false));
         assertTrue(codec.isInAlphabet(new byte[] { 'O' }, false));
         assertFalse(codec.isInAlphabet(new byte[] { 'O', ' ' }, false));
         assertFalse(codec.isInAlphabet(new byte[] { ' ' }, false));
         assertTrue(codec.isInAlphabet(new byte[] {}, true));
         assertTrue(codec.isInAlphabet(new byte[] { 'O' }, true));
         assertTrue(codec.isInAlphabet(new byte[] { 'O', ' ' }, true));
         assertTrue(codec.isInAlphabet(new byte[] { ' ' }, true));
     }
 
     @Test
     public void testIsInAlphabetString() {
         assertTrue(codec.isInAlphabet("OK"));
         assertTrue(codec.isInAlphabet("O=K= \t\n\r"));
     }
 
     //    @Test
 //    public void testHasData() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testAvail() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testEnsureBufferSize() {
 //        fail("Not yet implemented");
 //    }
 //
 //    @Test
 //    public void testReadResults() {
 //        fail("Not yet implemented");
 //    }
 //
     @Test
     public void testIsWhiteSpace() {
         assertTrue(Character.isWhitespace((byte) ' '));
         assertTrue(Character.isWhitespace((byte) '\n'));
         assertTrue(Character.isWhitespace((byte) '\r'));
         assertTrue(Character.isWhitespace((byte) '\t'));
         assertTrue(Character.isWhitespace((byte) '\f'));
         assertTrue(Character.isWhitespace((byte) '\u000B'));
         for (byte b = Byte.MIN_VALUE; b < Byte.MAX_VALUE; b++) {
             final byte byteToCheck = b;
             assertEquals(Character.isWhitespace(b), Character.isWhitespace(byteToCheck));
         }
     }
 
     @Test
     public void testProvidePaddingByte() {
         // Given
         codec = new BaseNCodec(0, 0, 0, 0, (byte) 0x25) {
             @Override
             void decode(final byte[] pArray, final int i, final int length, final Context context) {
                 // no-op
             }
 
             @Override
             void encode(final byte[] pArray, final int i, final int length, final Context context) {
                 // no-op
             }
 
             @Override
             protected boolean isInAlphabet(final byte b) {
                 return b == 'O' || b == 'K'; // allow OK
             }
         };
 
         // When
         final byte actualPaddingByte = codec.pad;
 
         // Then
         assertEquals(0x25, actualPaddingByte);
     }
 }