/* -*- Mode: C++ -*-  */
#include "test.h"
#include "random.h"
#include "sizes.h"

template <typename Constants>
class Regtest {
public:
  typedef typename Constants::Sizes Sizes;

  struct Options {
    Options()
      : encode_srcwin_maxsz(1<<20),
	block_size(Constants::BLOCK_SIZE),
	window_size(Constants::WINDOW_SIZE),
	size_known(false),
	iopt_size(XD3_DEFAULT_IOPT_SIZE),
	smatch_cfg(XD3_SMATCH_DEFAULT) { }

    xoff_t encode_srcwin_maxsz;
    size_t block_size;
    xoff_t window_size;
    bool size_known;
    usize_t iopt_size;
    xd3_smatch_cfg smatch_cfg;
  };

#include "segment.h"
#include "modify.h"
#include "file.h"
#include "cmp.h"
#include "delta.h"

  void InMemoryEncodeDecode(const FileSpec &source_file,
			    const FileSpec &target_file,
			    Block *coded_data,
			    const Options &options) {
    xd3_stream encode_stream;
    xd3_config encode_config;
    xd3_source encode_source;

    xd3_stream decode_stream;
    xd3_config decode_config;
    xd3_source decode_source;
    xoff_t verified_bytes = 0;
    xoff_t encoded_bytes = 0;

    if (coded_data) {
      coded_data->Reset();
    }

    memset(&encode_stream, 0, sizeof (encode_stream));
    memset(&encode_source, 0, sizeof (encode_source));

    memset(&decode_stream, 0, sizeof (decode_stream));
    memset(&decode_source, 0, sizeof (decode_source));

    xd3_init_config(&encode_config, XD3_ADLER32);
    xd3_init_config(&decode_config, XD3_ADLER32);

    encode_config.winsize = options.window_size;
    encode_config.iopt_size = options.iopt_size;
    encode_config.smatch_cfg = options.smatch_cfg;

    CHECK_EQ(0, xd3_config_stream (&encode_stream, &encode_config));
    CHECK_EQ(0, xd3_config_stream (&decode_stream, &decode_config));

    encode_source.blksize = options.block_size;
    decode_source.blksize = options.block_size;

    encode_source.max_winsize = options.encode_srcwin_maxsz;
    decode_source.max_winsize = options.encode_srcwin_maxsz;

    if (!options.size_known)
      {
	xd3_set_source (&encode_stream, &encode_source);
	xd3_set_source (&decode_stream, &decode_source);
      }
    else
      {
	xd3_set_source_and_size (&encode_stream, &encode_source,
				 source_file.Size());
	xd3_set_source_and_size (&decode_stream, &decode_source,
				 source_file.Size());
      }

    BlockIterator source_iterator(source_file, options.block_size);
    BlockIterator target_iterator(target_file, Constants::WINDOW_SIZE);
    Block encode_source_block, decode_source_block;
    Block decoded_block, target_block;
    bool encoding = true;
    bool done = false;
    bool done_after_input = false;

    IF_DEBUG1 (XPR(NTR "source %" Q "u[%" Z "u] target %" Q "u winsize %" Z "u\n",
		   source_file.Size(), options.block_size,
		   target_file.Size(),
		   Constants::WINDOW_SIZE));

    while (!done) {
      target_iterator.Get(&target_block);

      xoff_t blks = target_iterator.Blocks();

      IF_DEBUG2(XPR(NTR "target in %s: %" Q "u[%" Z "u] %" Q "u(%" Q "u) "
		    "verified %" Q "u\n",
		    encoding ? "encoding" : "decoding",
		    target_iterator.Offset(),
		    target_block.Size(),
		    target_iterator.Blkno(),
		    blks,
		    verified_bytes));

      if (blks == 0 || target_iterator.Blkno() == (blks - 1)) {
	xd3_set_flags(&encode_stream, XD3_FLUSH | encode_stream.flags);
      }

      xd3_avail_input(&encode_stream, target_block.Data(), target_block.Size());
      encoded_bytes += target_block.Size();

    process:
      int ret;
      const char *msg;
      if (encoding) {
	ret = xd3_encode_input(&encode_stream);
	msg = encode_stream.msg;
      } else {
	ret = xd3_decode_input(&decode_stream);
	msg = decode_stream.msg;
      }
      (void) msg;

      switch (ret) {
      case XD3_OUTPUT:
	if (encoding) {
	  if (coded_data != NULL) {
	    // Optional encoded-output to the caller
	    coded_data->Append(encode_stream.next_out,
			       encode_stream.avail_out);
	  }
	  // Feed this data to the decoder.
	  xd3_avail_input(&decode_stream,
			  encode_stream.next_out,
			  encode_stream.avail_out);
	  xd3_consume_output(&encode_stream);
	  encoding = false;
	} else {
	  decoded_block.Append(decode_stream.next_out,
			       decode_stream.avail_out);
	  xd3_consume_output(&decode_stream);
	}
	goto process;

      case XD3_GETSRCBLK: {
	xd3_source *src = (encoding ? &encode_source : &decode_source);
	Block *block = (encoding ? &encode_source_block : &decode_source_block);
	if (encoding) {
	  IF_DEBUG2(XPR(NTR "[srcblock] %" Q "u last srcpos %" Q "u "
			"encodepos %" Q "u\n",
			encode_source.getblkno,
			encode_stream.match_last_srcpos,
			encode_stream.input_position + encode_stream.total_in));
	}

	source_iterator.SetBlock(src->getblkno);
	source_iterator.Get(block);
	src->curblkno = src->getblkno;
	src->onblk = block->Size();
	src->curblk = block->Data();

	goto process;
      }

      case XD3_INPUT:
	if (!encoding) {
	  encoding = true;
	  goto process;
	} else {
	  if (done_after_input) {
	    done = true;
	    continue;
	  }

	  if (target_block.Size() < target_iterator.BlockSize()) {
	    encoding = false;
	  } else {
	    target_iterator.Next();
	  }
	  continue;
	}

      case XD3_WINFINISH:
	if (encoding) {
	  if (encode_stream.flags & XD3_FLUSH) {
	    done_after_input = true;
	  }
	  encoding = false;
	} else {
	 CHECK_EQ(0, CmpDifferentBlockBytesAtOffset(decoded_block,
						    target_file,
						    verified_bytes));
	 verified_bytes += decoded_block.Size();
	 decoded_block.Reset();
	 encoding = true;
       }
       goto process;

     case XD3_WINSTART:
     case XD3_GOTHEADER:
       goto process;

     default:
       XPR(NTR "%s = %s %s\n", encoding ? "E " : " D",
	   xd3_strerror(ret),
	   msg == NULL ? "" : msg);

       CHECK_EQ(0, ret);
       CHECK_EQ(-1, ret);
     }
   }

   CHECK_EQ(target_file.Size(), encoded_bytes);
   CHECK_EQ(target_file.Size(), verified_bytes);
   CHECK_EQ(0, xd3_close_stream(&decode_stream));
   CHECK_EQ(0, xd3_close_stream(&encode_stream));
   xd3_free_stream(&encode_stream);
   xd3_free_stream(&decode_stream);
 }

  void MainEncodeDecode(const TmpFile &source_file,
			const TmpFile &target_file,
			ExtFile *coded_data,
			const Options &options) {
    vector<const char*> ecmd;
    char bbuf[16];
    snprintf(bbuf, sizeof(bbuf), "-B%" Q "u", options.encode_srcwin_maxsz);
    ecmd.push_back("xdelta3");
    ecmd.push_back(bbuf);
    ecmd.push_back("-s");
    ecmd.push_back(source_file.Name());
    ecmd.push_back(target_file.Name());
    ecmd.push_back(coded_data->Name());
    ecmd.push_back(NULL);

    CHECK_EQ(0, xd3_main_cmdline(ecmd.size() - 1,
				 const_cast<char**>(&ecmd[0])));

    vector<const char*> dcmd;
    ExtFile recon_file;
    dcmd.push_back("xdelta3");
    ecmd.push_back(bbuf);
    dcmd.push_back("-d");
    dcmd.push_back("-s");
    dcmd.push_back(source_file.Name());
    dcmd.push_back(coded_data->Name());
    dcmd.push_back(recon_file.Name());
    dcmd.push_back(NULL);

    CHECK_EQ(0, xd3_main_cmdline(dcmd.size() - 1,
				 const_cast<char**>(&dcmd[0])));

    CHECK_EQ(0, test_compare_files(recon_file.Name(),
				   target_file.Name()));
  }

  // Similar to xd3_process_memory, with support for test Options.
  // Exercises xd3_process_stream.
  int TestProcessMemory (int            is_encode,
			 int          (*func) (xd3_stream *),
			 const uint8_t *input,
			 usize_t        input_size,
			 const uint8_t *source,
			 usize_t        source_size,
			 uint8_t       *output,
			 usize_t       *output_size,
			 usize_t        output_size_max,
			 const Options &options) {
    xd3_stream stream;
    xd3_config config;
    xd3_source src;
    int ret;

    memset (& stream, 0, sizeof (stream));
    memset (& config, 0, sizeof (config));

    if (is_encode)
      {
	config.winsize = input_size;
	config.iopt_size = options.iopt_size;
	config.sprevsz = xd3_pow2_roundup (config.winsize);
      }

    if ((ret = xd3_config_stream (&stream, &config)) != 0)
      {
	goto exit;
      }

    if (source != NULL)
      {
	memset (& src, 0, sizeof (src));

	src.blksize = source_size;
	src.onblk = source_size;
	src.curblk = source;
	src.curblkno = 0;
	src.max_winsize = source_size;

	if ((ret = xd3_set_source_and_size (&stream, &src, source_size)) != 0)
	  {
	    goto exit;
	  }
      }

    if ((ret = xd3_process_stream (is_encode,
				   & stream,
				   func, 1,
				   input, input_size,
				   output,
				   output_size,
				   output_size_max)) != 0)
      {
	goto exit;
      }

  exit:
    if (ret != 0)
      {
	IF_DEBUG2 (DP(RINT "test_process_memory: %d: %s\n", ret, stream.msg));
      }
    xd3_free_stream(&stream);
    return ret;
  }

  void EncodeDecodeAPI(const FileSpec &spec0, const FileSpec &spec1, 
		       Block *delta, const Options &options) {
    Block from;
    Block to;
    spec0.Get(&from, 0, spec0.Size());
    spec1.Get(&to, 0, spec1.Size());

    delta->SetSize(to.Size() * 1.5);
    usize_t out_size;
    int enc_ret = TestProcessMemory(true,
				    &xd3_encode_input,
				    to.Data(),
				    to.Size(),
				    from.Data(),
				    from.Size(),
				    delta->Data(),
				    &out_size,
				    delta->Size(),
				    options);
    CHECK_EQ(0, enc_ret);
    delta->SetSize(out_size);

    Block recon;
    recon.SetSize(to.Size());
    usize_t recon_size;
    int dec_ret = xd3_decode_memory(delta->Data(),
				    delta->Size(),
				    from.Data(),
				    from.Size(),
				    recon.Data(),
				    &recon_size,
				    recon.Size(),
				    0);
    CHECK_EQ(0, dec_ret);
    CHECK_EQ(0, CmpDifferentBlockBytes(to, recon));
  }

//////////////////////////////////////////////////////////////////////

void TestPrintf() {
  char buf[64];
  xoff_t x = XOFF_T_MAX;
  snprintf_func (buf, sizeof(buf), "%" Q "u", x);
  const char *expect = XD3_USE_LARGEFILE64 ?
    "18446744073709551615" : "4294967295";
  XD3_ASSERT(strcmp (buf, expect) == 0);
}

void TestRandomNumbers() {
  MTRandom rand;
  int rounds = 1<<20;
  uint64_t usum = 0;
  uint64_t esum = 0;

  for (int i = 0; i < rounds; i++) {
    usum += rand.Rand32();
    esum += rand.ExpRand32(1024);
  }

  double allowed_error = 0.01;

  uint32_t umean = usum / rounds;
  uint32_t emean = esum / rounds;

  uint32_t uexpect = UINT32_MAX / 2;
  uint32_t eexpect = 1024;

  if (umean < uexpect * (1.0 - allowed_error) ||
      umean > uexpect * (1.0 + allowed_error)) {
    XPR(NT "uniform mean error: %u != %u\n", umean, uexpect);
    abort();
  }

  if (emean < eexpect * (1.0 - allowed_error) ||
      emean > eexpect * (1.0 + allowed_error)) {
    XPR(NT "exponential mean error: %u != %u\n", emean, eexpect);
    abort();
  }
}

void TestRandomFile() {
  MTRandom rand1;
  FileSpec spec1(&rand1);
  BlockIterator bi(spec1);

  spec1.GenerateFixedSize(0);
  CHECK_EQ(0, spec1.Size());
  CHECK_EQ(0, spec1.Segments());
  CHECK_EQ(0, spec1.Blocks());
  bi.SetBlock(0);
  CHECK_EQ(0, bi.BytesOnBlock());

  spec1.GenerateFixedSize(1);
  CHECK_EQ(1, spec1.Size());
  CHECK_EQ(1, spec1.Segments());
  CHECK_EQ(1, spec1.Blocks());
  bi.SetBlock(0);
  CHECK_EQ(1, bi.BytesOnBlock());

  spec1.GenerateFixedSize(Constants::BLOCK_SIZE);
  CHECK_EQ(Constants::BLOCK_SIZE, spec1.Size());
  CHECK_EQ(1, spec1.Segments());
  CHECK_EQ(1, spec1.Blocks());
  bi.SetBlock(0);
  CHECK_EQ(Constants::BLOCK_SIZE, bi.BytesOnBlock());
  bi.SetBlock(1);
  CHECK_EQ(0, bi.BytesOnBlock());

  spec1.GenerateFixedSize(Constants::BLOCK_SIZE + 1);
  CHECK_EQ(Constants::BLOCK_SIZE + 1, spec1.Size());
  CHECK_EQ(2, spec1.Segments());
  CHECK_EQ(2, spec1.Blocks());
  bi.SetBlock(0);
  CHECK_EQ(Constants::BLOCK_SIZE, bi.BytesOnBlock());
  bi.SetBlock(1);
  CHECK_EQ(1, bi.BytesOnBlock());

  spec1.GenerateFixedSize(Constants::BLOCK_SIZE * 2);
  CHECK_EQ(Constants::BLOCK_SIZE * 2, spec1.Size());
  CHECK_EQ(2, spec1.Segments());
  CHECK_EQ(2, spec1.Blocks());
  bi.SetBlock(0);
  CHECK_EQ(Constants::BLOCK_SIZE, bi.BytesOnBlock());
  bi.SetBlock(1);
  CHECK_EQ(Constants::BLOCK_SIZE, bi.BytesOnBlock());
}

void TestFirstByte() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(0);
  spec1.GenerateFixedSize(1);
  CHECK_EQ(0, CmpDifferentBytes(spec0, spec0));
  CHECK_EQ(0, CmpDifferentBytes(spec1, spec1));
  CHECK_EQ(1, CmpDifferentBytes(spec0, spec1));
  CHECK_EQ(1, CmpDifferentBytes(spec1, spec0));

  spec0.GenerateFixedSize(1);
  spec0.ModifyTo(Modify1stByte(), &spec1);
  CHECK_EQ(1, CmpDifferentBytes(spec0, spec1));

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE + 1);
  spec0.ModifyTo(Modify1stByte(), &spec1);
  CHECK_EQ(1, CmpDifferentBytes(spec0, spec1));

  SizeIterator<size_t, Sizes> si(&rand, Constants::TEST_ROUNDS);

  for (; !si.Done(); si.Next()) {
    size_t size = si.Get();
    if (size == 0) {
      continue;
    }
    spec0.GenerateFixedSize(size);
    spec0.ModifyTo(Modify1stByte(), &spec1);
    InMemoryEncodeDecode(spec0, spec1, NULL, Options());
  }
}

void TestModifyMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 3);

  struct {
    size_t size;
    size_t addr;
  } test_cases[] = {
    { Constants::BLOCK_SIZE, 0 },
    { Constants::BLOCK_SIZE / 2, 1 },
    { Constants::BLOCK_SIZE, 1 },
    { Constants::BLOCK_SIZE * 2, 1 },
  };

  for (size_t i = 0; i < SIZEOF_ARRAY(test_cases); i++) {
    ChangeList cl1;
    cl1.push_back(Change(Change::MODIFY, test_cases[i].size,
			 test_cases[i].addr));
    spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
    CHECK_EQ(spec0.Size(), spec1.Size());

    size_t diff = CmpDifferentBytes(spec0, spec1);
    CHECK_LE(diff, test_cases[i].size);

    // There is a 1/256 probability of the changed byte matching the
    // original value.  The following allows double the probability to
    // pass.
    CHECK_GE(diff, test_cases[i].size - (2 * test_cases[i].size / 256));

    InMemoryEncodeDecode(spec0, spec1, NULL, Options());
  }
}

void TestAddMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 2);
  // TODO: fix this test (for all block sizes)!  it's broken because
  // the same byte could be added?

  struct {
    size_t size;
    size_t addr;
    size_t expected_adds;
  } test_cases[] = {
    { 1, 0,                         2 /* 1st byte, last byte (short block) */ },
    { 1, 1,                         3 /* 1st 2 bytes, last byte */ },
    { 1, Constants::BLOCK_SIZE - 1, 2 /* changed, last */ },
    { 1, Constants::BLOCK_SIZE,     2 /* changed, last */ },
    { 1, Constants::BLOCK_SIZE + 1, 3 /* changed + 1st of 2nd block, last */ },
    { 1, 2 * Constants::BLOCK_SIZE, 1 /* last byte */ },
  };

  for (size_t i = 0; i < SIZEOF_ARRAY(test_cases); i++) {
    ChangeList cl1;
    cl1.push_back(Change(Change::ADD, test_cases[i].size, test_cases[i].addr));
    spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
    CHECK_EQ(spec0.Size() + test_cases[i].size, spec1.Size());

    Block coded;
    InMemoryEncodeDecode(spec0, spec1, &coded, Options());

    Delta delta(coded);
    CHECK_EQ(test_cases[i].expected_adds,
	     delta.AddedBytes());
  }
}

void TestDeleteMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 4);

  struct {
    size_t size;
    size_t addr;
  } test_cases[] = {
    // Note: an entry { Constants::BLOCK_SIZE, 0 },
    // does not work because the xd3_srcwin_move_point logic won't
    // find a copy if it occurs >= double its size into the file.
    { Constants::BLOCK_SIZE / 2, 0 },
    { Constants::BLOCK_SIZE / 2, Constants::BLOCK_SIZE / 2 },
    { Constants::BLOCK_SIZE, Constants::BLOCK_SIZE / 2 },
    { Constants::BLOCK_SIZE * 2, Constants::BLOCK_SIZE * 3 / 2 },
    { Constants::BLOCK_SIZE, Constants::BLOCK_SIZE * 2 },
  };

  for (size_t i = 0; i < SIZEOF_ARRAY(test_cases); i++) {
    ChangeList cl1;
    cl1.push_back(Change(Change::DELRANGE, test_cases[i].size,
			 test_cases[i].addr));
    spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
    CHECK_EQ(spec0.Size() - test_cases[i].size, spec1.Size());

    Block coded;
    InMemoryEncodeDecode(spec0, spec1, &coded, Options());

    Delta delta(coded);
    CHECK_EQ(0, delta.AddedBytes());
  }
}

void TestCopyMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 3);

  struct {
    size_t size;
    size_t from;
    size_t to;
  } test_cases[] = {
    // Copy is difficult to write tests for because where Xdelta finds
    // copies, it does not enter checksums.  So these tests copy data from
    // later to earlier so that checksumming will start.
    { Constants::BLOCK_SIZE / 2, Constants::BLOCK_SIZE / 2, 0 },
    { Constants::BLOCK_SIZE, 2 * Constants::BLOCK_SIZE,
      Constants::BLOCK_SIZE, },
  };

  for (size_t i = 0; i < SIZEOF_ARRAY(test_cases); i++) {
    ChangeList cl1;
    cl1.push_back(Change(Change::COPY, test_cases[i].size,
			 test_cases[i].from, test_cases[i].to));
    spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
    CHECK_EQ(spec0.Size() + test_cases[i].size, spec1.Size());

    Block coded;
    InMemoryEncodeDecode(spec0, spec1, &coded, Options());

    Delta delta(coded);
    CHECK_EQ(0, delta.AddedBytes());
  }
}

void TestMoveMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 3);

  struct {
    size_t size;
    size_t from;
    size_t to;
  } test_cases[] = {
    // This is easier to test than Copy but has the same trouble as Delete.
    { Constants::BLOCK_SIZE / 2, Constants::BLOCK_SIZE / 2, 0 },
    { Constants::BLOCK_SIZE / 2, 0, Constants::BLOCK_SIZE / 2 },
    { Constants::BLOCK_SIZE, Constants::BLOCK_SIZE, 2 *
      Constants::BLOCK_SIZE },
    { Constants::BLOCK_SIZE, 2 * Constants::BLOCK_SIZE,
      Constants::BLOCK_SIZE },
    { Constants::BLOCK_SIZE * 3 / 2, Constants::BLOCK_SIZE,
      Constants::BLOCK_SIZE * 3 / 2 },

    // This is a no-op
    { Constants::BLOCK_SIZE, Constants::BLOCK_SIZE * 2,
      3 * Constants::BLOCK_SIZE },
  };

  for (size_t i = 0; i < SIZEOF_ARRAY(test_cases); i++) {
    ChangeList cl1;
    cl1.push_back(Change(Change::MOVE, test_cases[i].size,
			 test_cases[i].from, test_cases[i].to));
    spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
    CHECK_EQ(spec0.Size(), spec1.Size());

    Block coded;
    InMemoryEncodeDecode(spec0, spec1, &coded, Options());

    Delta delta(coded);
    CHECK_EQ(0, delta.AddedBytes());
  }
}

void TestOverwriteMutator() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE);

  ChangeList cl1;
  cl1.push_back(Change(Change::COPYOVER, 10, 0, 20));
  spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
  CHECK_EQ(spec0.Size(), spec1.Size());

  Block b0, b1;
  BlockIterator(spec0).Get(&b0);
  BlockIterator(spec1).Get(&b1);

  CHECK(memcmp(b0.Data(), b1.Data() + 20, 10) == 0);
  CHECK(memcmp(b0.Data(), b1.Data(), 20) == 0);
  CHECK(memcmp(b0.Data() + 30, b1.Data() + 30,
	       Constants::BLOCK_SIZE - 30) == 0);

  xoff_t zero = 0;
  cl1.clear();
  cl1.push_back(Change(Change::COPYOVER, 10, 20, zero));
  spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
  CHECK_EQ(spec0.Size(), spec1.Size());

  BlockIterator(spec0).Get(&b0);
  BlockIterator(spec1).Get(&b1);

  CHECK(memcmp(b0.Data() + 20, b1.Data(), 10) == 0);
  CHECK(memcmp(b0.Data() + 10, b1.Data() + 10,
	       Constants::BLOCK_SIZE - 10) == 0);
}

// Note: this test is written to expose a problem, but the problem was
// only exposed with BLOCK_SIZE = 128.
void TestNonBlocking() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  FileSpec spec2(&rand);

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 3);

  // This is a lazy target match
  Change ct(Change::COPYOVER, 22,
	    Constants::BLOCK_SIZE + 50,
	    Constants::BLOCK_SIZE + 20);

  // This is a source match just after the block boundary, shorter
  // than the lazy target match.
  Change cs1(Change::COPYOVER, 16,
	     Constants::BLOCK_SIZE + 51,
	     Constants::BLOCK_SIZE - 1);

  // This overwrites the original source bytes.
  Change cs2(Change::MODIFY, 108,
	     Constants::BLOCK_SIZE + 20);

  // This changes the first blocks
  Change c1st(Change::MODIFY, Constants::BLOCK_SIZE - 2, 0);

  ChangeList csl;
  csl.push_back(cs1);
  csl.push_back(cs2);
  csl.push_back(c1st);

  spec0.ModifyTo(ChangeListMutator(csl), &spec1);

  ChangeList ctl;
  ctl.push_back(ct);
  ctl.push_back(c1st);

  spec0.ModifyTo(ChangeListMutator(ctl), &spec2);

  InMemoryEncodeDecode(spec1, spec2, NULL, Options());
}

void TestEmptyInMemory() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  Block block;

  spec0.GenerateFixedSize(0);
  spec1.GenerateFixedSize(0);

  InMemoryEncodeDecode(spec0, spec1, &block, Options());

  Delta delta(block);
  CHECK_LT(0, block.Size());
  CHECK_EQ(1, delta.Windows());
}

void TestBlockInMemory() {
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  Block block;

  spec0.GenerateFixedSize(Constants::BLOCK_SIZE);
  spec1.GenerateFixedSize(Constants::BLOCK_SIZE);

  InMemoryEncodeDecode(spec0, spec1, &block, Options());

  Delta delta(block);
  CHECK_EQ(spec1.Blocks(Constants::WINDOW_SIZE), delta.Windows());
}

void TestSmallStride() {
  MTRandom rand;
  FileSpec spec0(&rand);
  usize_t size = Constants::BLOCK_SIZE * 4;
  spec0.GenerateFixedSize(size);

  // Note: Not very good performance due to hash collisions, note 3x
  // multiplier below.
  for (int s = 15; s < 101; s++) {
    usize_t changes = 0;
    ChangeList cl;
    for (usize_t j = s; j < size; j += s, ++changes)
      {
	cl.push_back(Change(Change::MODIFY, 1, j));
      }

    FileSpec spec1(&rand);
    spec0.ModifyTo(ChangeListMutator(cl), &spec1);

    Options options;
    options.encode_srcwin_maxsz = size;
    options.iopt_size = 128;
    options.smatch_cfg = XD3_SMATCH_SLOW;
    options.size_known = false;

    Block block;
    InMemoryEncodeDecode(spec0, spec1, &block, options);
    Delta delta(block);

    IF_DEBUG1(DP(RINT "[stride=%d] changes=%" W "u adds=%" Q "u\n",
		 s, changes, delta.AddedBytes()));
    double allowance = Constants::BLOCK_SIZE < 8192 || s < 30 ? 3.0 : 1.1;
    CHECK_GE(allowance * changes, (double)delta.AddedBytes());
  }
}

void TestCopyWindow() {
  // Construct an input that has many copies, to fill the IOPT buffer
  // and force a source window decision.  "srclen" may be set to a
  // value that goes beyond the end-of-source.
  const int clen = 16;
  const int size = 4096;
  const int nmov = size / clen;
  const int iters = 16;
  uint32_t added_01 = 0;
  uint32_t added_10 = 0;
  for (int i = 1; i <= iters; i++) {
    MTRandom rand(MTRandom::TEST_SEED1 * i);
    FileSpec spec0(&rand);
    ChangeList cl;

    spec0.GenerateFixedSize(size);

    for (int j = 0; j < nmov; j += 2)
      {
	cl.push_back(Change(Change::MOVE,
			    clen, (j + 1) * clen, j * clen));
      }

    FileSpec spec1(&rand);
    spec0.ModifyTo(ChangeListMutator(cl), &spec1);

    Options options;
    options.encode_srcwin_maxsz = size;
    options.iopt_size = 128;
    options.smatch_cfg = XD3_SMATCH_SLOW;

    Block block1;
    InMemoryEncodeDecode(spec0, spec1, &block1, options);
    Delta delta1(block1);
    // Allow one missed window (e.g., hash collisions)
    added_01 += delta1.AddedBytes();

    Block block2;
    InMemoryEncodeDecode(spec1, spec0, &block2, options);
    Delta delta2(block2);
    // Allow one missed window (e.g., hash collisions)
    added_10 += delta2.AddedBytes();

    Block block3;
    Block block4;
    EncodeDecodeAPI(spec0, spec1, &block3, options);
    EncodeDecodeAPI(spec1, spec0, &block4, options);
  }
  // Average less than 0.5 misses (of length clen) per iteration.
  CHECK_GE(clen * iters / 2, added_01);
  CHECK_GE(clen * iters / 2, added_10);
}

void TestCopyFromEnd() {
  // Copies from the end of the source buffer, which reach a block
  // boundary end-of-file.
  const int size = 4096;
  const int clen = 16;
  const int nmov = (size / 2) / clen;
  const int iters = 16;
  uint32_t added_01 = 0;
  uint32_t added_10 = 0;
  for (int i = 1; i <= iters; i++) {
    MTRandom rand(MTRandom::TEST_SEED1 * i);
    FileSpec spec0(&rand);
    ChangeList cl;

    spec0.GenerateFixedSize(size);

    cl.push_back(Change(Change::MODIFY, 2012, 2048));

    for (int j = 0; j < nmov; j += 2)
      {
	cl.push_back(Change(Change::MOVE,
			    clen, (j + 1) * clen, j * clen));
      }

    cl.push_back(Change(Change::COPYOVER, 28, 4068, 3000));
    cl.push_back(Change(Change::COPYOVER, 30, 4066, 3100));
    cl.push_back(Change(Change::COPYOVER, 32, 4064, 3200));

    FileSpec spec1(&rand);
    spec0.ModifyTo(ChangeListMutator(cl), &spec1);

    Options options;
    options.encode_srcwin_maxsz = size;
    options.iopt_size = 128;
    options.smatch_cfg = XD3_SMATCH_SLOW;

    Block block1;
    InMemoryEncodeDecode(spec0, spec1, &block1, options);
    Delta delta1(block1);
    added_01 += delta1.AddedBytes();

    Block block2;
    InMemoryEncodeDecode(spec1, spec0, &block2, options);
    Delta delta2(block2);
    added_10 += delta2.AddedBytes();

    Block block3;
    Block block4;
    EncodeDecodeAPI(spec0, spec1, &block3, options);
    EncodeDecodeAPI(spec1, spec0, &block4, options);
  }
  CHECK_GE(2000 * iters, added_01);
  CHECK_LE(2000 * iters, added_10);
}

void TestHalfBlockCopy() {
  // Create a half-block copy, 7.5 blocks apart, in a pair of files:
  //       0             1     ...     6             7
  // spec0 [bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb][ccccc][bbbb_]
  // spec1 [aaaaa][ccccc][aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_]
  // where stage=
  // 0: the final block is full
  //   a. (source)spec1->(target)spec0 copies block C: reads 8 source
  //      blocks during target block 0.
  //   b. (source)spec0->(target)spec1 does not copy block C b/c attempt
  //      to read past EOF empties block 0 from (virtual) block cache
  // 1: the final block is less than full.
  //   a. (same) copies block C
  //   b. (same) copies block C, unlike 0a, no attempt to read past EOF
  //
  // "virtual" above refers to XD3_TOOFARBACK, since there is no caching
  // in the API, there is simply a promise not to request blocks that are
  // beyond source->max_winsize from the last known source file position.
  for (int stage = 0; stage < 2; stage++)
    {
      IF_DEBUG1 (DP(RINT "half_block_copy stage %d\n", stage));

      MTRandom rand;
      FileSpec spec0(&rand);
      FileSpec spec1(&rand);

      spec0.GenerateFixedSize(Constants::BLOCK_SIZE * 8 - stage);

      ChangeList cl1;
      cl1.push_back(Change(Change::MODIFY,
			   Constants::BLOCK_SIZE / 2,  // size
			   0));
      cl1.push_back(Change(Change::COPYOVER,
			   Constants::BLOCK_SIZE / 2,  // size
			   Constants::BLOCK_SIZE * 7,  // offset
			   Constants::BLOCK_SIZE / 2));
      cl1.push_back(Change(Change::MODIFY,
			   Constants::BLOCK_SIZE * 7,
			   Constants::BLOCK_SIZE - stage));
      spec0.ModifyTo(ChangeListMutator(cl1), &spec1);

      Options options;
      options.encode_srcwin_maxsz = Constants::BLOCK_SIZE * 8;

      Block block0;
      Block block1;
      InMemoryEncodeDecode(spec0, spec1, &block0, options);
      InMemoryEncodeDecode(spec1, spec0, &block1, options);

      Delta delta0(block0);
      Delta delta1(block1);

      const int yes =
	Constants::BLOCK_SIZE * 8 - Constants::BLOCK_SIZE / 2;
      const int no =
	Constants::BLOCK_SIZE * 8 - Constants::BLOCK_SIZE / 2;

      if (stage == 0)
	{
	  CHECK_EQ(yes, delta0.AddedBytes());
	  CHECK_EQ(no, delta1.AddedBytes());
	}
      else
	{
	  CHECK_EQ(yes, delta0.AddedBytes());
	  CHECK_EQ(yes, delta1.AddedBytes());
	}
    }
}

void FourWayMergeTest(const FileSpec &spec0,
		      const FileSpec &spec1,
		      const FileSpec &spec2,
		      const FileSpec &spec3) {
  TmpFile f0, f1, f2, f3;
  ExtFile d01, d12, d23;
  Options options;
  options.encode_srcwin_maxsz =
    std::max(spec0.Size(), options.encode_srcwin_maxsz);

  spec0.WriteTmpFile(&f0);
  spec1.WriteTmpFile(&f1);
  spec2.WriteTmpFile(&f2);
  spec3.WriteTmpFile(&f3);

  MainEncodeDecode(f0, f1, &d01, options);
  MainEncodeDecode(f1, f2, &d12, options);
  MainEncodeDecode(f2, f3, &d23, options);

  // Merge 2
  ExtFile out;
  vector<const char*> mcmd;
  mcmd.push_back("xdelta3");
  mcmd.push_back("merge");
  mcmd.push_back("-m");
  mcmd.push_back(d01.Name());
  mcmd.push_back(d12.Name());
  mcmd.push_back(out.Name());
  mcmd.push_back(NULL);

  // XPR(NTR "Running one merge: %s\n", CommandToString(mcmd).c_str());
  CHECK_EQ(0, xd3_main_cmdline(mcmd.size() - 1,
			       const_cast<char**>(&mcmd[0])));

  ExtFile recon;
  vector<const char*> tcmd;
  tcmd.push_back("xdelta3");
  tcmd.push_back("-d");
  tcmd.push_back("-s");
  tcmd.push_back(f0.Name());
  tcmd.push_back(out.Name());
  tcmd.push_back(recon.Name());
  tcmd.push_back(NULL);

  // XPR(NTR "Running one recon! %s\n", CommandToString(tcmd).c_str());
  CHECK_EQ(0, xd3_main_cmdline(tcmd.size() - 1,
			       const_cast<char**>(&tcmd[0])));
  // XPR(NTR "Should equal! %s\n", f2.Name());

  CHECK(recon.EqualsSpec(spec2));

  // Merge 3
  ExtFile out3;
  vector<const char*> mcmd3;
  mcmd3.push_back("xdelta3");
  mcmd3.push_back("merge");
  mcmd3.push_back("-m");
  mcmd3.push_back(d01.Name());
  mcmd3.push_back("-m");
  mcmd3.push_back(d12.Name());
  mcmd3.push_back(d23.Name());
  mcmd3.push_back(out3.Name());
  mcmd3.push_back(NULL);

  // XPR(NTR "Running one 3-merge: %s\n", CommandToString(mcmd3).c_str());
  CHECK_EQ(0, xd3_main_cmdline(mcmd3.size() - 1,
			       const_cast<char**>(&mcmd3[0])));

  ExtFile recon3;
  vector<const char*> tcmd3;
  tcmd3.push_back("xdelta3");
  tcmd3.push_back("-d");
  tcmd3.push_back("-s");
  tcmd3.push_back(f0.Name());
  tcmd3.push_back(out3.Name());
  tcmd3.push_back(recon3.Name());
  tcmd3.push_back(NULL);

  // XPR(NTR "Running one 3-recon %s\n", CommandToString(tcmd3).c_str());
  CHECK_EQ(0, xd3_main_cmdline(tcmd3.size() - 1,
			       const_cast<char**>(&tcmd3[0])));
  // XPR(NTR "Should equal %s\n", f3.Name());

  CHECK(recon3.EqualsSpec(spec3));
}

void TestMergeCommand1() {
  /* Repeat random-input testing for a number of iterations.
   * Test 2, 3, and 4-file scenarios (i.e., 1, 2, and 3-delta merges). */
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  FileSpec spec2(&rand);
  FileSpec spec3(&rand);

  SizeIterator<size_t, Sizes> si0(&rand, 10);

  for (; !si0.Done(); si0.Next()) {
    size_t size0 = si0.Get();

    SizeIterator<size_t, Sizes> si1(&rand, 10);
    for (; !si1.Done(); si1.Next()) {
      size_t change1 = si1.Get();

      if (change1 == 0) {
	continue;
      }

      // XPR(NTR "S0 = %lu\n", size0);
      // XPR(NTR "C1 = %lu\n", change1);
      // XPR(NTR ".");

      size_t add1_pos = size0 ? rand.Rand32() % size0 : 0;
      size_t del2_pos = size0 ? rand.Rand32() % size0 : 0;

      spec0.GenerateFixedSize(size0);

      ChangeList cl1, cl2, cl3;

      size_t change3 = change1;
      size_t change3_pos;

      if (change3 >= size0) {
	change3 = size0;
	change3_pos = 0;
      } else {
	change3_pos = rand.Rand32() % (size0 - change3);
      }

      cl1.push_back(Change(Change::ADD, change1, add1_pos));
      cl2.push_back(Change(Change::DELRANGE, change1, del2_pos));
      cl3.push_back(Change(Change::MODIFY, change3, change3_pos));

      spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
      spec1.ModifyTo(ChangeListMutator(cl2), &spec2);
      spec2.ModifyTo(ChangeListMutator(cl3), &spec3);

      FourWayMergeTest(spec0, spec1, spec2, spec3);
      FourWayMergeTest(spec3, spec2, spec1, spec0);
    }
  }
}

void TestMergeCommand2() {
  /* Same as above, different mutation pattern. */
  /* TODO: run this with large sizes too */
  /* TODO: run this with small sizes too */
  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  FileSpec spec2(&rand);
  FileSpec spec3(&rand);

  SizeIterator<size_t, Sizes> si0(&rand, 10);
  for (; !si0.Done(); si0.Next()) {
    size_t size0 = si0.Get();

    SizeIterator<size_t, Sizes> si1(&rand, 10);
    for (; !si1.Done(); si1.Next()) {
      size_t size1 = si1.Get();

      SizeIterator<size_t, Sizes> si2(&rand, 10);
      for (; !si2.Done(); si2.Next()) {
	size_t size2 = si2.Get();

	SizeIterator<size_t, Sizes> si3(&rand, 10);
	for (; !si3.Done(); si3.Next()) {
	  size_t size3 = si3.Get();

	  // We're only interested in three sizes, strictly decreasing. */
	  if (size3 >= size2 || size2 >= size1 || size1 >= size0) {
	    continue;
	  }

	  // XPR(NTR "S0 = %lu\n", size0);
	  // XPR(NTR "S1 = %lu\n", size1);
	  // XPR(NTR "S2 = %lu\n", size2);
	  // XPR(NTR "S3 = %lu\n", size3);
	  // XPR(NTR ".");

	  spec0.GenerateFixedSize(size0);

	  ChangeList cl1, cl2, cl3;

	  cl1.push_back(Change(Change::DELRANGE, size0 - size1, 0));
	  cl2.push_back(Change(Change::DELRANGE, size0 - size2, 0));
	  cl3.push_back(Change(Change::DELRANGE, size0 - size3, 0));

	  spec0.ModifyTo(ChangeListMutator(cl1), &spec1);
	  spec0.ModifyTo(ChangeListMutator(cl2), &spec2);
	  spec0.ModifyTo(ChangeListMutator(cl3), &spec3);

	  FourWayMergeTest(spec0, spec1, spec2, spec3);
	  FourWayMergeTest(spec3, spec2, spec1, spec0);
	}
      }
    }
  }
}

void TestLastFrontierBlock() {
  // This test constructs an input that can expose
  // https://github.com/jmacd/xdelta/issues/188
  // when run through the command-line with source via a FIFO.
  // That is not tested here, but the test stays.
  if (Constants::WINDOW_SIZE < XD3_ALLOCSIZE)
    {
      return;
    }

  MTRandom rand;
  FileSpec spec0(&rand);
  FileSpec spec1(&rand);
  const xoff_t size = XD3_ALLOCSIZE * 64;  // == XD3_MINSRCWINSZ * 2
  const xoff_t edit = XD3_ALLOCSIZE;

  Options options;
  options.encode_srcwin_maxsz = XD3_MINSRCWINSZ;
  options.block_size = XD3_ALLOCSIZE;
  options.window_size = XD3_MINSRCWINSZ;
  options.size_known = false;

  spec0.GenerateFixedSize(size);

  ChangeList cl;

  // Modify the 0th byte in order to induce indexing of subsequent
  // bytes, but allow copying most of the file to keep the test fast.
  cl.push_back(Change(Change::MODIFY, 1, edit * 31));
  cl.push_back(Change(Change::COPYOVER, edit, edit * 31, edit * 63));

  spec0.ModifyTo(ChangeListMutator(cl), &spec1);

  Block noblock;
  InMemoryEncodeDecode(spec0, spec1, &noblock, options);
  InMemoryEncodeDecode(spec1, spec0, &noblock, options);
}

};  // class Regtest<Constants>

#define TEST(x) XPR(NTR #x "...\n"); regtest.x()

// These tests are primarily tests of the testing framework itself.
template <class T>
void UnitTest() {
  Regtest<T> regtest;
  TEST(TestPrintf);
  TEST(TestRandomNumbers);
  TEST(TestRandomFile);
  TEST(TestFirstByte);
  TEST(TestModifyMutator);
  TEST(TestAddMutator);
  TEST(TestDeleteMutator);
  TEST(TestCopyMutator);
  TEST(TestMoveMutator);
  TEST(TestOverwriteMutator);
}

// These are Xdelta tests.
template <class T>
void MainTest() {
  XPR(NT "Blocksize %" Q "u windowsize %" Z "u\n",
      T::BLOCK_SIZE, T::WINDOW_SIZE);
  Regtest<T> regtest;
  TEST(TestEmptyInMemory);
  TEST(TestBlockInMemory);
  TEST(TestSmallStride);
  TEST(TestCopyWindow);
  TEST(TestCopyFromEnd);
  TEST(TestNonBlocking);
  TEST(TestHalfBlockCopy);
  TEST(TestLastFrontierBlock);
  TEST(TestMergeCommand1);
  TEST(TestMergeCommand2);
}

#undef TEST

int main(int argc, char **argv)
{
  vector<const char*> mcmd;
  string pn;
  const char *sp = strrchr(argv[0], '/');
  if (sp != NULL) {
    pn.append(argv[0], sp - argv[0] + 1);
  }
  pn.append("xdelta3");
  mcmd.push_back(pn.c_str());
  mcmd.push_back("test");
  mcmd.push_back(NULL);

  UnitTest<SmallBlock>();
  MainTest<SmallBlock>();
  MainTest<MixedBlock>();
  MainTest<OversizeBlock>();
  MainTest<LargeBlock>();

  CHECK_EQ(0, xd3_main_cmdline(mcmd.size() - 1,
  			       const_cast<char**>(&mcmd[0])));

  return 0;
}