"istio.io/istio/pkg/test"
)

// AsBytes is a simple wrapper around os.ReadFile provided for completeness.
func AsBytes(filename string) ([]byte, error) {
	return os.ReadFile(filename)
}

// AsBytesOrFail calls AsBytes and fails the test if any errors occurred.
func AsBytesOrFail(t test.Failer, filename string) []byte {
	t.Helper()
	content, err := AsBytes(filename)
	if err != nil {
		t.Fatal(err)
	}

    // Trick the JVM to prevent it from using the hash function non-polymorphically
    result ^= Hashing.crc32().hashInt(reps).asBytes()[0];
    result ^= Hashing.adler32().hashInt(reps).asBytes()[0];
    for (int i = 0; i < reps; i++) {
      result ^= hashFunction.hashBytes(testBytes).asBytes()[0];
    }
    return result;
  }

            entry("Foo.class", INSTRUMENTED_CLASS)
            entry(MarkerResource.RESOURCE_NAME, MarkerResource.TRANSFORMED.asBytes())

            versionedEntry(currentJvmMajor, "Foo.class", INSTRUMENTED_VERSIONED_CLASS)
            versionedEntry(currentJvmMajor + 1, MarkerResource.RESOURCE_NAME, MarkerResource.NOT_TRANSFORMED.asBytes())
        }

        TransformedClassPath cp = classPath((original): transformed)

        expect:

      result ^= hashFunction.newHasher().putBytes(testBytes).hash().asBytes()[0];
    }
    return result;
  }

  @Benchmark
  int hashFunction(int reps) {
    HashFunction hashFunction = hashFunctionEnum.getHashFunction();
    int result = 37;
    for (int i = 0; i < reps; i++) {
      result ^= hashFunction.hashBytes(testBytes).asBytes()[0];
    }
    return result;
  }

  @Benchmark

    // Trick the JVM to prevent it from using the hash function non-polymorphically
    result ^= Hashing.crc32().hashInt(reps).asBytes()[0];
    result ^= Hashing.adler32().hashInt(reps).asBytes()[0];
    for (int i = 0; i < reps; i++) {
      result ^= hashFunction.hashBytes(testBytes).asBytes()[0];
    }
    return result;
  }

      public byte[] hash(Algorithm algorithm, byte[] input) {
        return algorithm.getHashFunction().hashBytes(input).asBytes();
      }
    },
    HASH_FUNCTION_VIA_HASHER() {
      @Override
      public byte[] hash(Algorithm algorithm, byte[] input) {
        return algorithm.getHashFunction().newHasher().putBytes(input).hash().asBytes();
      }
    };
    ;

    public abstract byte[] hash(Algorithm algorithm, byte[] input);
  }

      public byte[] hash(Algorithm algorithm, byte[] input) {
        return algorithm.getHashFunction().hashBytes(input).asBytes();
      }
    },
    HASH_FUNCTION_VIA_HASHER() {
      @Override
      public byte[] hash(Algorithm algorithm, byte[] input) {
        return algorithm.getHashFunction().newHasher().putBytes(input).hash().asBytes();
      }
    };
    ;

    public abstract byte[] hash(Algorithm algorithm, byte[] input);
  }

            if (hasUnsupportedVersionInJar()) {
                // Every Java version starting from lowestUnsupportedVersion should see this jar as unsupported.
                builder.put(JarUtil.toVersionedPath(lowestUnsupportedVersionInJar, MarkerResource.RESOURCE_NAME), MarkerResource.NOT_TRANSFORMED.asBytes());
            }
        }
    }

          @Override
          public byte[] hash(byte[] input, int seed) {
            Hasher hasher = murmur3_128(seed).newHasher();
            Funnels.byteArrayFunnel().funnel(input, hasher);
            return hasher.hash().asBytes();
          }
        };
    // Murmur3F, MurmurHash3 for x64, 128-bit (MurmurHash3_x64_128)
    // From http://code.google.com/p/smhasher/source/browse/trunk/main.cpp

  public void testParanoidHashBytes() {
    HashFn hf =
        new HashFn() {
          @Override
          public byte[] hash(byte[] input, int seed) {
            return murmur3_32(seed).hashBytes(input).asBytes();
          }
        };
    // Murmur3A, MurmurHash3 for x86, 32-bit (MurmurHash3_x86_32)
    // https://github.com/aappleby/smhasher/blob/master/src/main.cpp
    HashTestUtils.verifyHashFunction(hf, 32, 0xB0F57EE3);