// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/files/file_util.h"
#include "base/files/scoped_file.h"
#include "base/message_loop/message_loop.h"
#include "build/build_config.h"
#include "mojo/application/content_handler_factory.h"
#include "mojo/data_pipe_utils/data_pipe_utils.h"
#include "mojo/message_pump/message_pump_mojo.h"
#include "mojo/nacl/sfi/nacl_bindings/monacl_sel_main.h"
#include "mojo/public/c/system/main.h"
#include "mojo/public/cpp/application/application_impl_base.h"
#include "mojo/public/cpp/application/connect.h"
#include "mojo/public/cpp/application/run_application.h"
#include "mojo/public/cpp/application/service_provider_impl.h"
#include "mojo/services/network/interfaces/network_service.mojom.h"
#include "mojo/services/network/interfaces/url_loader.mojom.h"
#include "native_client/src/public/nacl_desc.h"
#include "url/gurl.h"

namespace nacl {
namespace content_handler {

namespace {
base::ScopedFILE TempFileForURL(mojo::URLLoaderPtr& url_loader,
                                const GURL& url) {
  mojo::URLRequestPtr request(mojo::URLRequest::New());
  request->url = url.spec();
  request->method = "GET";
  request->auto_follow_redirects = true;

  // Handle the callback synchonously.
  mojo::URLResponsePtr response;
  url_loader->Start(request.Pass(), [&response](mojo::URLResponsePtr r) {
    response = r.Pass();
  });
  url_loader.WaitForIncomingResponse();
  CHECK(!response.is_null()) << "Empty response (missed a callback?)";

  if (response->error) {
    LOG(ERROR) << "could not load " << url.spec() << " ("
               << response->error->code << ") "
               << response->error->description.get().c_str();
    return nullptr;
  }

  return mojo::common::BlockingCopyToTempFile(response->body.Pass());
}

NaClDesc* FileStreamToNaClDesc(FILE* file_stream) {
  // Get file handle
  int fd = fileno(file_stream);
  CHECK_NE(fd, -1) <<  "Could not open the stream pointer's file descriptor";

  // These file descriptors must be dup'd, since NaClDesc takes ownership
  // of the file descriptor. The descriptor is still needed to close
  // the file stream.
  fd = dup(fd);
  CHECK_NE(fd, -1) << "Could not dup the file descriptor";

  NaClDesc* desc = NaClDescCreateWithFilePathMetadata(fd, "");

  // Clean up.
  CHECK_EQ(fclose(file_stream), 0) << "Failed to close temp file";

  return desc;
}

}  // namespace

class NaClContentHandler : public mojo::ApplicationImplBase,
                           public mojo::ContentHandlerFactory::Delegate {
 public:
  NaClContentHandler() {}

 private:
  // Overridden from ApplicationImplBase:
  void OnInitialize() override {
    url_ = GURL(url());

    mojo::NetworkServicePtr network_service;
    mojo::ConnectToService(shell(), "mojo:network_service",
                           GetProxy(&network_service));

    network_service->CreateURLLoader(GetProxy(&url_loader_));
  }

  // Overridden from ApplicationImplBase:
  bool OnAcceptConnection(
      mojo::ServiceProviderImpl* service_provider_impl) override {
    service_provider_impl->AddService<mojo::ContentHandler>(
        mojo::ContentHandlerFactory::GetInterfaceRequestHandler(this));
    return true;
  }

  void LoadIRT(mojo::URLLoaderPtr& url_loader) {
    // TODO(ncbray): support other architectures.
    GURL irt_url;
#if defined(ARCH_CPU_X86_64)
    irt_url = url_.Resolve("irt_x64/irt_mojo.nexe");
#else
#error "Unknown / unsupported CPU architecture."
#endif
    CHECK(irt_url.is_valid()) << "Cannot resolve IRT URL";

    irt_fp_ = TempFileForURL(url_loader, irt_url);
    CHECK(irt_fp_) << "Could not acquire the IRT";
  }

  // Overridden from ContentHandlerFactory::Delegate:
  void RunApplication(
      mojo::InterfaceRequest<mojo::Application> application_request,
      mojo::URLResponsePtr response) override {
    // Needed to use Mojo interfaces on this thread.
    base::MessageLoop loop(mojo::common::MessagePumpMojo::Create());

    // Acquire the nexe.
    base::ScopedFILE nexe_fp =
        mojo::common::BlockingCopyToTempFile(response->body.Pass());
    CHECK(nexe_fp) << "could not redirect nexe to temp file";

    // Acquire the IRT.
    mojo::URLLoaderPtr url_loader = url_loader_.Pass();
    LoadIRT(url_loader);

    NaClDesc* irt_desc = FileStreamToNaClDesc(irt_fp_.release());
    NaClDesc* nexe_desc = FileStreamToNaClDesc(nexe_fp.release());

    // Run.
    int exit_code = mojo::LaunchNaCl(
        nexe_desc, irt_desc, 0, nullptr,
        application_request.PassMessagePipe().release().value());

    // Exits the process cleanly, does not return.
    mojo::NaClExit(exit_code);
    NOTREACHED();
  }

  GURL url_;
  base::ScopedFILE irt_fp_;

  mojo::URLLoaderPtr url_loader_;

  DISALLOW_COPY_AND_ASSIGN(NaClContentHandler);
};

}  // namespace content_handler
}  // namespace nacl

MojoResult MojoMain(MojoHandle application_request) {
  nacl::content_handler::NaClContentHandler nacl_content_handler;
  return mojo::RunMainApplication(application_request, &nacl_content_handler);
}