#include "../src/meshoptimizer.h"

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

void fuzzDecoder(const uint8_t* data, size_t size, size_t stride, int (*decode)(void*, size_t, size_t, const unsigned char*, size_t))

{

  size_t count = 66; // must be divisible by 3 for decodeIndexBuffer; should be >=64 to cover large vertex blocks

  void* destination = malloc(count * stride);

  assert(destination);

  int rc = decode(destination, count, stride, reinterpret_cast<const unsigned char*>(data), size);

  (void)rc;

  free(destination);

}

void fuzzRoundtrip(const uint8_t* data, size_t size, size_t stride, int level)

{

  size_t count = size / stride;

  size_t bound = meshopt_encodeVertexBufferBound(count, stride);

  void* encoded = malloc(bound);

  void* decoded = malloc(count * stride);

  assert(encoded && decoded);

  size_t res = meshopt_encodeVertexBufferLevel(static_cast<unsigned char*>(encoded), bound, data, count, stride, level, -1);

  assert(res > 0 && res <= bound);

  // encode again at the boundary to check for memory safety

  // this should produce the same output because encoder is deterministic

  size_t rese = meshopt_encodeVertexBufferLevel(static_cast<unsigned char*>(encoded) + bound - res, res, data, count, stride, level, -1);

  assert(rese == res);

  int rc = meshopt_decodeVertexBuffer(decoded, count, stride, static_cast<unsigned char*>(encoded) + bound - res, res);

  assert(rc == 0);

  assert(memcmp(data, decoded, count * stride) == 0);

  free(decoded);

  free(encoded);

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)

{

  // decodeIndexBuffer supports 2 and 4-byte indices

  fuzzDecoder(data, size, 2, meshopt_decodeIndexBuffer);

  fuzzDecoder(data, size, 4, meshopt_decodeIndexBuffer);

  // decodeIndexSequence supports 2 and 4-byte indices

  fuzzDecoder(data, size, 2, meshopt_decodeIndexSequence);

  fuzzDecoder(data, size, 4, meshopt_decodeIndexSequence);

  // decodeVertexBuffer supports any strides divisible by 4 in 4-256 interval

  // it's a waste of time to check all of them, so we'll just check a few with different alignment mod 16

  fuzzDecoder(data, size, 4, meshopt_decodeVertexBuffer);

  fuzzDecoder(data, size, 16, meshopt_decodeVertexBuffer);

  fuzzDecoder(data, size, 24, meshopt_decodeVertexBuffer);

  fuzzDecoder(data, size, 32, meshopt_decodeVertexBuffer);

  // encodeVertexBuffer/decodeVertexBuffer should roundtrip for any stride, check a few with different alignment mod 16

  // this also checks memory safety properties of the encoder

  // to conserve time, we only check one version/level combination, biased towards version 1

  uint8_t data0 = size > 0 ? data[0] : 0;

  int level = data0 % 5;

  meshopt_encodeVertexVersion(level < 4 ? 1 : 0);

  fuzzRoundtrip(data, size, 4, level);

  fuzzRoundtrip(data, size, 16, level);

  fuzzRoundtrip(data, size, 24, level);

  fuzzRoundtrip(data, size, 32, level);

  return 0;

}