/* -*- 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),
		size_known(false) { }
    size_t encode_srcwin_maxsz;
    size_t block_size;
    bool size_known;
  };

#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 = 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 = Constants::WINDOW_SIZE;

    // TODO! the smatcher setup isn't working,
  //   if (options.large_cksum_step) {
  //     encode_config.smatch_cfg = XD3_SMATCH_SOFT;
  //     encode_config.smatcher_soft.large_step = options.large_cksum_step;
  //   }
  //   if (options.large_cksum_size) {
  //     encode_config.smatch_cfg = XD3_SMATCH_SOFT;
  //     encode_config.smatcher_soft.large_look = options.large_cksum_size;
  //   }

    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::READ_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[%"Q"u] target %"Q"u[%lu] winsize %lu\n",
		  source_file.Size(), options.block_size,
		  target_file.Size(), Constants::READ_SIZE,
		  Constants::WINDOW_SIZE));

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

      xoff_t blks = target_iterator.Blocks();

      IF_DEBUG2(XPR(NTR "target in %s: %llu..%llu %"Q"u(%"Q"u) verified %"Q"u\n",
		   encoding ? "encoding" : "decoding",
		   target_iterator.Offset(),
		   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_DEBUG1(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 buf[16];
    snprintf(buf, sizeof(buf), "-B%"Q"u", options.encode_srcwin_maxsz);
    ecmd.push_back("xdelta3");
    ecmd.push_back(buf);
    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(buf);  
    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()));
  }

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

 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);
  }
}

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);
  }
}

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);

    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::DELETE, 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);

    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);

    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);

    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);

  cl1.clear();
  cl1.push_back(Change(Change::COPYOVER, 10, 20, (xoff_t)0));
  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 TestNonBlockingProgress() {
  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);
}

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

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

  InMemoryEncodeDecode(spec0, spec1, &block);

  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);

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

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

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

  // Create a half-block copy, 2.5 blocks apart, from the second half
  // of the source version to the first half of the target version.
  //       0             1             2             3
  // spec0 [bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb][ccccc][bbbbb]
  // spec1 [aaaaa][ccccc][aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]
  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 * 3,  // offset
		       Constants::BLOCK_SIZE / 2));
  cl1.push_back(Change(Change::MODIFY,
		       Constants::BLOCK_SIZE * 3,
		       Constants::BLOCK_SIZE));
  spec0.ModifyTo(ChangeListMutator(cl1), &spec1);

  const int onecopy_adds = 
    4 * Constants::BLOCK_SIZE - Constants::BLOCK_SIZE / 2;
  const int nocopy_adds = 4 * Constants::BLOCK_SIZE;

  // Note the case b=4 is contrived: the caller should use a single block 
  // containing the entire source, if possible.
  for (int b = 1; b <= 4; b++)
    {
      Options options;
      options.encode_srcwin_maxsz = Constants::BLOCK_SIZE * b;

      Block block0;
      Block block1;
      InMemoryEncodeDecode(spec0, spec1, &block0, options);
      InMemoryEncodeDecode(spec1, spec0, &block1, options);
      Delta delta0(block0);
      Delta delta1(block1);

      // The first block never copies from the last source block, by
      // design, because if the last source block is available when
      // the first target block is ready, the caller is expected to
      // use a single block.
      CHECK_EQ(nocopy_adds, delta0.AddedBytes());
      if (Constants::BLOCK_SIZE < 8192 || b > 2)
      	{
	  // For small-block inputs, the entire file is read into one
	  // block (the min source window size is 16kB).
	  // 
	  // For large blocks, at least 3 blocks of source window are
	  // needed.
      	  CHECK_EQ(onecopy_adds, delta1.AddedBytes());
      	}
      else
      	{
	  // When there are fewer than 3 source blocks.
      	  CHECK_EQ(nocopy_adds, delta1.AddedBytes());
      	}
      // XPR(NT "0=%zu 1=%zu\n", delta0.AddedBytes(), delta1.AddedBytes());
    }

  Options options;
  options.encode_srcwin_maxsz = Constants::BLOCK_SIZE * 4;
  options.block_size = Constants::BLOCK_SIZE * 4;

  // Test the whole-buffer case.
  Block block0;
  Block block1;
  InMemoryEncodeDecode(spec0, spec1, &block0, options);
  InMemoryEncodeDecode(spec1, spec0, &block1, options);
  Delta delta0(block0);
  Delta delta1(block1);
  // This <= >= are only for blocksize = 512, which has irregular readsize.
  CHECK_LE(onecopy_adds, delta0.AddedBytes());
  CHECK_GE(onecopy_adds + 1, delta0.AddedBytes());

  CHECK_EQ(onecopy_adds, delta1.AddedBytes());
  // XPR(NT "0=%zu 1=%zu\n", delta0.AddedBytes(), 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::DELETE, 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::DELETE, size0 - size1, 0));
	  cl2.push_back(Change(Change::DELETE, size0 - size2, 0));
	  cl3.push_back(Change(Change::DELETE, 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);
	}
      }
    }
  }
}

};  // 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(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 readsize %"Q"u windowsize %"Q"u\n", 
      T::BLOCK_SIZE, T::READ_SIZE, T::WINDOW_SIZE);
  Regtest<T> regtest;
  TEST(TestEmptyInMemory);
  TEST(TestBlockInMemory);
  TEST(TestNonBlockingProgress);
  TEST(TestHalfBlockCopy);
  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<PrimeBlock>();
  MainTest<OversizeBlock>();
  MainTest<LargeBlock>();

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

  return 0;
}