// 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 "components/html_viewer/html_document_application_delegate.h"

#include "base/bind.h"
#include "components/html_viewer/global_state.h"
#include "components/html_viewer/html_document.h"
#include "mojo/application/public/cpp/application_connection.h"
#include "mojo/application/public/cpp/application_delegate.h"
#include "mojo/application/public/cpp/connect.h"

namespace html_viewer {

// ServiceConnectorQueue records all incoming service requests and processes
// them once PushRequestsTo() is called. This is useful if you need to delay
// processing incoming service requests.
class HTMLDocumentApplicationDelegate::ServiceConnectorQueue
    : public mojo::ServiceConnector {
 public:
  ServiceConnectorQueue() {}
  ~ServiceConnectorQueue() override {}

  void PushRequestsTo(mojo::ApplicationConnection* connection) {
    ScopedVector<Request> requests;
    requests_.swap(requests);
    for (Request* request : requests) {
      connection->GetLocalServiceProvider()->ConnectToService(
          request->interface_name, request->handle.Pass());
    }
  }

 private:
  struct Request {
    std::string interface_name;
    mojo::ScopedMessagePipeHandle handle;
  };

  // mojo::ServiceConnector:
  void ConnectToService(mojo::ApplicationConnection* application_connection,
                        const std::string& interface_name,
                        mojo::ScopedMessagePipeHandle handle) override {
    scoped_ptr<Request> request(new Request);
    request->interface_name = interface_name;
    request->handle = handle.Pass();
    requests_.push_back(request.Pass());
  }

  ScopedVector<Request> requests_;

  DISALLOW_COPY_AND_ASSIGN(ServiceConnectorQueue);
};

HTMLDocumentApplicationDelegate::HTMLDocumentApplicationDelegate(
    mojo::InterfaceRequest<mojo::Application> request,
    mojo::URLResponsePtr response,
    GlobalState* global_state,
    scoped_ptr<mojo::AppRefCount> parent_app_refcount,
    const mojo::Callback<void()>& destruct_callback)
    : app_(this,
           request.Pass(),
           base::Bind(&HTMLDocumentApplicationDelegate::OnTerminate,
                      base::Unretained(this))),
      parent_app_refcount_(parent_app_refcount.Pass()),
      url_(response->url),
      initial_response_(response.Pass()),
      global_state_(global_state),
      html_factory_(this),
      destruct_callback_(destruct_callback),
      weak_factory_(this) {}

HTMLDocumentApplicationDelegate::~HTMLDocumentApplicationDelegate() {
  // Deleting the documents is going to trigger a callback to
  // OnHTMLDocumentDeleted() and remove from |documents_|. Copy the set so we
  // don't have to worry about the set being modified out from under us.
  std::set<HTMLDocument*> documents2(documents2_);
  for (HTMLDocument* doc : documents2)
    doc->Destroy();
  DCHECK(documents2_.empty());
  destruct_callback_.Run();
}

// Callback from the quit closure. We key off this rather than
// ApplicationDelegate::Quit() as we don't want to shut down the messageloop
// when we quit (the messageloop is shared among multiple
// HTMLDocumentApplicationDelegates).
void HTMLDocumentApplicationDelegate::OnTerminate() {
  delete this;
}

// ApplicationDelegate;
void HTMLDocumentApplicationDelegate::Initialize(mojo::ApplicationImpl* app) {
  app_.ConnectToService("mojo:network_service", &url_loader_factory_);
}

bool HTMLDocumentApplicationDelegate::ConfigureIncomingConnection(
    mojo::ApplicationConnection* connection) {
  if (initial_response_) {
    OnResponseReceived(nullptr, mojo::URLLoaderPtr(), connection, nullptr,
                       initial_response_.Pass());
  } else if (url_ == "about:blank") {
    // This is a little unfortunate. At the browser side, when starting a new
    // app for "about:blank", the application manager uses
    // mojo::runner::AboutFetcher to construct a response for "about:blank".
    // However, when an app for "about:blank" already exists, it is reused and
    // we end up here. We cannot fetch the URL using mojo::URLLoader because it
    // is not an actual Web resource.
    // TODO(yzshen): find out a better approach.
    mojo::URLResponsePtr response(mojo::URLResponse::New());
    response->url = url_;
    response->status_code = 200;
    response->mime_type = "text/html";
    OnResponseReceived(nullptr, mojo::URLLoaderPtr(), connection, nullptr,
                       response.Pass());
  } else {
    // HTMLDocument provides services, but is created asynchronously. Queue up
    // requests until the HTMLDocument is created.
    scoped_ptr<ServiceConnectorQueue> service_connector_queue(
        new ServiceConnectorQueue);
    connection->SetServiceConnector(service_connector_queue.get());

    mojo::URLLoaderPtr loader;
    url_loader_factory_->CreateURLLoader(GetProxy(&loader));
    mojo::URLRequestPtr request(mojo::URLRequest::New());
    request->url = url_;
    request->auto_follow_redirects = true;

    // |loader| will be passed to the OnResponseReceived method through a
    // callback. Because order of evaluation is undefined, a reference to the
    // raw pointer is needed.
    mojo::URLLoader* raw_loader = loader.get();
    // The app needs to stay alive while waiting for the response to be
    // available.
    scoped_ptr<mojo::AppRefCount> app_retainer(
        app_.app_lifetime_helper()->CreateAppRefCount());
    raw_loader->Start(
        request.Pass(),
        base::Bind(&HTMLDocumentApplicationDelegate::OnResponseReceived,
                   weak_factory_.GetWeakPtr(), base::Passed(&app_retainer),
                   base::Passed(&loader), connection,
                   base::Passed(&service_connector_queue)));
  }
  return true;
}

void HTMLDocumentApplicationDelegate::OnHTMLDocumentDeleted2(
    HTMLDocument* document) {
  DCHECK(documents2_.count(document) > 0);
  documents2_.erase(document);
}

void HTMLDocumentApplicationDelegate::OnResponseReceived(
    scoped_ptr<mojo::AppRefCount> app_refcount,
    mojo::URLLoaderPtr loader,
    mojo::ApplicationConnection* connection,
    scoped_ptr<ServiceConnectorQueue> connector_queue,
    mojo::URLResponsePtr response) {
  // HTMLDocument is destroyed when the hosting view is destroyed, or
  // explicitly from our destructor.
  HTMLDocument* document = new HTMLDocument(
      &app_, connection, response.Pass(), global_state_,
      base::Bind(&HTMLDocumentApplicationDelegate::OnHTMLDocumentDeleted2,
                 base::Unretained(this)),
      html_factory_);
  documents2_.insert(document);

  if (connector_queue) {
    connector_queue->PushRequestsTo(connection);
    connection->SetServiceConnector(nullptr);
  }
}

HTMLFrame* HTMLDocumentApplicationDelegate::CreateHTMLFrame(
    HTMLFrame::CreateParams* params) {
  return new HTMLFrame(params);
}

HTMLWidgetRootLocal* HTMLDocumentApplicationDelegate::CreateHTMLWidgetRootLocal(
    HTMLWidgetRootLocal::CreateParams* params) {
  return new HTMLWidgetRootLocal(params);
}

}  // namespace html_viewer