// Copyright 2014 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 "extensions/browser/api/sockets_tcp_server/tcp_server_socket_event_dispatcher.h"

#include <utility>

#include "base/lazy_instance.h"
#include "extensions/browser/api/socket/tcp_socket.h"
#include "extensions/browser/event_router.h"
#include "extensions/browser/extensions_browser_client.h"
#include "net/base/net_errors.h"

namespace extensions {
namespace api {

using content::BrowserThread;

static base::LazyInstance<
    BrowserContextKeyedAPIFactory<TCPServerSocketEventDispatcher> > g_factory =
    LAZY_INSTANCE_INITIALIZER;

// static
BrowserContextKeyedAPIFactory<TCPServerSocketEventDispatcher>*
TCPServerSocketEventDispatcher::GetFactoryInstance() {
  return g_factory.Pointer();
}

// static
TCPServerSocketEventDispatcher* TCPServerSocketEventDispatcher::Get(
    content::BrowserContext* context) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  return BrowserContextKeyedAPIFactory<TCPServerSocketEventDispatcher>::Get(
      context);
}

TCPServerSocketEventDispatcher::TCPServerSocketEventDispatcher(
    content::BrowserContext* context)
    : thread_id_(Socket::kThreadId), browser_context_(context) {
  ApiResourceManager<ResumableTCPServerSocket>* server_manager =
      ApiResourceManager<ResumableTCPServerSocket>::Get(browser_context_);
  DCHECK(server_manager)
      << "There is no server socket manager. "
         "If this assertion is failing during a test, then it is likely that "
         "TestExtensionSystem is failing to provide an instance of "
         "ApiResourceManager<ResumableTCPServerSocket>.";
  server_sockets_ = server_manager->data_;

  ApiResourceManager<ResumableTCPSocket>* client_manager =
      ApiResourceManager<ResumableTCPSocket>::Get(browser_context_);
  DCHECK(client_manager)
      << "There is no client socket manager. "
         "If this assertion is failing during a test, then it is likely that "
         "TestExtensionSystem is failing to provide an instance of "
         "ApiResourceManager<ResumableTCPSocket>.";
  client_sockets_ = client_manager->data_;
}

TCPServerSocketEventDispatcher::~TCPServerSocketEventDispatcher() {}

TCPServerSocketEventDispatcher::AcceptParams::AcceptParams() {}

TCPServerSocketEventDispatcher::AcceptParams::AcceptParams(
    const AcceptParams& other) = default;

TCPServerSocketEventDispatcher::AcceptParams::~AcceptParams() {}

void TCPServerSocketEventDispatcher::OnServerSocketListen(
    const std::string& extension_id,
    int socket_id) {
  DCHECK_CURRENTLY_ON(thread_id_);

  StartSocketAccept(extension_id, socket_id);
}

void TCPServerSocketEventDispatcher::OnServerSocketResume(
    const std::string& extension_id,
    int socket_id) {
  DCHECK_CURRENTLY_ON(thread_id_);

  StartSocketAccept(extension_id, socket_id);
}

void TCPServerSocketEventDispatcher::StartSocketAccept(
    const std::string& extension_id,
    int socket_id) {
  DCHECK_CURRENTLY_ON(thread_id_);

  AcceptParams params;
  params.thread_id = thread_id_;
  params.browser_context_id = browser_context_;
  params.extension_id = extension_id;
  params.server_sockets = server_sockets_;
  params.client_sockets = client_sockets_;
  params.socket_id = socket_id;

  StartAccept(params);
}

// static
void TCPServerSocketEventDispatcher::StartAccept(const AcceptParams& params) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  ResumableTCPServerSocket* socket =
      params.server_sockets->Get(params.extension_id, params.socket_id);
  if (!socket) {
    // This can happen if the socket is closed while our callback is active.
    return;
  }
  DCHECK(params.extension_id == socket->owner_extension_id())
      << "Socket has wrong owner.";

  // Don't start another accept if the socket has been paused.
  if (socket->paused())
    return;

  socket->Accept(
      base::Bind(&TCPServerSocketEventDispatcher::AcceptCallback, params));
}

// static
void TCPServerSocketEventDispatcher::AcceptCallback(
    const AcceptParams& params,
    int result_code,
    scoped_ptr<net::TCPClientSocket> socket) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  if (result_code >= 0) {
    ResumableTCPSocket* client_socket =
        new ResumableTCPSocket(std::move(socket), params.extension_id, true);
    client_socket->set_paused(true);
    int client_socket_id = params.client_sockets->Add(client_socket);

    // Dispatch "onAccept" event.
    sockets_tcp_server::AcceptInfo accept_info;
    accept_info.socket_id = params.socket_id;
    accept_info.client_socket_id = client_socket_id;
    scoped_ptr<base::ListValue> args =
        sockets_tcp_server::OnAccept::Create(accept_info);
    scoped_ptr<Event> event(new Event(events::SOCKETS_TCP_SERVER_ON_ACCEPT,
                                      sockets_tcp_server::OnAccept::kEventName,
                                      std::move(args)));
    PostEvent(params, std::move(event));

    // Post a task to delay the "accept" until the socket is available, as
    // calling StartAccept at this point would error with ERR_IO_PENDING.
    BrowserThread::PostTask(
        params.thread_id,
        FROM_HERE,
        base::Bind(&TCPServerSocketEventDispatcher::StartAccept, params));
  } else {
    // Dispatch "onAcceptError" event but don't start another accept to avoid
    // potential infinite "accepts" if we have a persistent network error.
    sockets_tcp_server::AcceptErrorInfo accept_error_info;
    accept_error_info.socket_id = params.socket_id;
    accept_error_info.result_code = result_code;
    scoped_ptr<base::ListValue> args =
        sockets_tcp_server::OnAcceptError::Create(accept_error_info);
    scoped_ptr<Event> event(new Event(
        events::SOCKETS_TCP_SERVER_ON_ACCEPT_ERROR,
        sockets_tcp_server::OnAcceptError::kEventName, std::move(args)));
    PostEvent(params, std::move(event));

    // Since we got an error, the socket is now "paused" until the application
    // "resumes" it.
    ResumableTCPServerSocket* socket =
        params.server_sockets->Get(params.extension_id, params.socket_id);
    if (socket) {
      socket->set_paused(true);
    }
  }
}

// static
void TCPServerSocketEventDispatcher::PostEvent(const AcceptParams& params,
                                               scoped_ptr<Event> event) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::Bind(&DispatchEvent, params.browser_context_id, params.extension_id,
                 base::Passed(std::move(event))));
}

// static
void TCPServerSocketEventDispatcher::DispatchEvent(
    void* browser_context_id,
    const std::string& extension_id,
    scoped_ptr<Event> event) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  content::BrowserContext* context =
      reinterpret_cast<content::BrowserContext*>(browser_context_id);
  if (!extensions::ExtensionsBrowserClient::Get()->IsValidContext(context))
    return;
  EventRouter* router = EventRouter::Get(context);
  if (router)
    router->DispatchEventToExtension(extension_id, std::move(event));
}

}  // namespace api
}  // namespace extensions