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// Copyright 2008, Google Inc.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//  2. Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//  3. Neither the name of Google Inc. nor the names of its contributors may be
//     used to endorse or promote products derived from this software without
//     specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "gears/base/common/dispatcher.h"
#include "gears/base/common/module_wrapper.h"
#include "gears/blob/blob.h"
#include "gears/blob/slice_blob.h"

DECLARE_GEARS_WRAPPER(GearsBlob);

template<>
void Dispatcher<GearsBlob>::Init() {
#ifdef DEBUG
  RegisterMethod("hasSameContentsAs", &GearsBlob::HasSameContentsAs);
#endif
  RegisterMethod("slice", &GearsBlob::Slice);
  RegisterProperty("length", &GearsBlob::GetLength, NULL);
}

const std::string GearsBlob::kModuleName("GearsBlob");

#ifdef DEBUG
void GearsBlob::HasSameContentsAs(JsCallContext *context) {
  ModuleImplBaseClass *other_module = NULL;
  JsArgument argv[] = {
    { JSPARAM_REQUIRED, JSPARAM_MODULE, &other_module },
  };
  context->GetArguments(ARRAYSIZE(argv), argv);
  if (context->is_exception_set()) return;
  if (GearsBlob::kModuleName != other_module->get_module_name()) {
    context->SetException(STRING16(L"First argument must be a Blob."));
    return;
  }

  bool result = true;
  scoped_refptr<BlobInterface> other_contents;
  static_cast<GearsBlob*>(other_module)->GetContents(&other_contents);
  assert(contents_.get());
  assert(other_contents.get());
  if (contents_.get() != other_contents.get()) {
    int64 this_length = contents_->Length();
    int64 that_length = other_contents->Length();
    if (this_length != that_length) {
      result = false;
    } else {
      // We have to compare the contents of the two Blobs.  Here, we have a
      // really naive implementation, reading and checking 1 byte at a time
      // (rather than, e.g. batching up reads into larger chunks).  So far,
      // however, GearsBlob::HasSameContentsAs is used only in unit-test code,
      // on small Blobs, and is unlikely to be a bottleneck.  If those
      // assumptions later turn out to be false, we'll optimize this code.
      assert(this_length >= 0);
      uint8 this_byte;
      uint8 that_byte;
      for (int64 i = 0; i < this_length; ++i) {
        if ((contents_->Read(&this_byte, i, 1) != 1) ||
            (other_contents->Read(&that_byte, i, 1) != 1) ||
            (this_byte != that_byte)) {
          result = false;
          break;
        }
      }
    }
  }
  context->SetReturnValue(JSPARAM_BOOL, &result);
}
#endif

void GearsBlob::GetLength(JsCallContext *context) {
  // A GearsBlob should never be let out in the JS world unless it has been
  // Initialize()d with valid contents_.
  assert(contents_.get());

  int64 length = contents_->Length();
  if (length < 0) {
    context->SetException(STRING16(L"error determining length."));
    return;
  }
  context->SetReturnValue(JSPARAM_INT64, &length);
}

void GearsBlob::Slice(JsCallContext *context) {
  int64 offset = 0;
  int64 length = 0;
  JsArgument argv[] = {
    { JSPARAM_REQUIRED, JSPARAM_INT64, &offset },
    { JSPARAM_OPTIONAL, JSPARAM_INT64, &length },
  };
  int argc = context->GetArguments(ARRAYSIZE(argv), argv);
  if (context->is_exception_set()) return;

  if (offset < 0) {
    context->SetException(STRING16(L"Offset must be a non-negative integer."));
    return;
  }
  if (argc != 2) {
    int64 blob_size = contents_->Length();
    length = (blob_size > offset) ? blob_size - offset : 0;
  }
  if (length < 0) {
    context->SetException(STRING16(L"Length must be a non-negative integer."));
    return;
  }

  // Slice the blob.
  scoped_refptr<BlobInterface> sliced(new SliceBlob(contents_.get(), offset,
                                                    length));

  scoped_refptr<GearsBlob> gears_blob;
  if (!CreateModule<GearsBlob>(module_environment_.get(),
                               context, &gears_blob)) {
    return;
  }
  gears_blob->Reset(sliced.get());
  context->SetReturnValue(JSPARAM_MODULE, gears_blob.get());
}

class MarshaledGearsBlob : public MarshaledModule {
 public:
  MarshaledGearsBlob(BlobInterface *contents) : contents_(contents) {}

  bool Unmarshal(ModuleEnvironment *module_environment,
                 JsScopedToken *out) {
    scoped_refptr<GearsBlob> gears_blob;
    if (!CreateModule<GearsBlob>(module_environment, NULL, &gears_blob)) {
      return false;
    }
    gears_blob->Reset(contents_.get());
    *out = gears_blob->GetWrapperToken();
    return true;
  }

 private:
  scoped_refptr<BlobInterface> contents_;
  DISALLOW_EVIL_CONSTRUCTORS(MarshaledGearsBlob);
};

MarshaledModule *GearsBlob::AsMarshaledModule() {
  assert(contents_.get());
  return new MarshaledGearsBlob(contents_.get());
}