// Copyright (c) 2010 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 "chrome/browser/io_thread.h"
#include "base/command_line.h"
#include "base/leak_tracker.h"
#include "base/logging.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/chrome_thread.h"
#include "chrome/browser/net/dns_global.h"
#include "chrome/browser/net/url_fetcher.h"
#include "chrome/common/chrome_switches.h"
#include "net/base/fixed_host_resolver.h"
#include "net/base/host_cache.h"
#include "net/base/host_resolver.h"
#include "net/url_request/url_request.h"

namespace {

net::HostResolver* CreateGlobalHostResolver() {
  net::HostResolver* global_host_resolver = NULL;

  const CommandLine& command_line = *CommandLine::ForCurrentProcess();

  // The FixedHostResolver allows us to send all network requests through
  // a designated test server.
  if (command_line.HasSwitch(switches::kFixedHost)) {
    std::string host =
        command_line.GetSwitchValueASCII(switches::kFixedHost);
    global_host_resolver = new net::FixedHostResolver(host);
  } else {
    global_host_resolver = net::CreateSystemHostResolver();

    if (command_line.HasSwitch(switches::kDisableIPv6))
      global_host_resolver->SetDefaultAddressFamily(net::ADDRESS_FAMILY_IPV4);
  }

  return global_host_resolver;
}

}  // namespace

// The IOThread object must outlive any tasks posted to the IO thread before the
// Quit task.
template <>
struct RunnableMethodTraits<IOThread> {
  void RetainCallee(IOThread* /* io_thread */) {}
  void ReleaseCallee(IOThread* /* io_thread */) {}
};

IOThread::IOThread()
    : BrowserProcessSubThread(ChromeThread::IO),
      host_resolver_(NULL),
      prefetch_observer_(NULL),
      dns_master_(NULL) {}

IOThread::~IOThread() {
  // We cannot rely on our base class to stop the thread since we want our
  // CleanUp function to run.
  Stop();
}

net::HostResolver* IOThread::host_resolver() {
  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
  return host_resolver_;
}

void IOThread::InitDnsMaster(
    bool prefetching_enabled,
    base::TimeDelta max_queue_delay,
    size_t max_concurrent,
    const chrome_common_net::NameList& hostnames_to_prefetch,
    ListValue* referral_list) {
  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
  message_loop()->PostTask(
      FROM_HERE,
      NewRunnableMethod(
          this,
          &IOThread::InitDnsMasterOnIOThread,
          prefetching_enabled, max_queue_delay, max_concurrent,
          hostnames_to_prefetch, referral_list));
}

void IOThread::ChangedToOnTheRecord() {
  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
  message_loop()->PostTask(
      FROM_HERE,
      NewRunnableMethod(
          this,
          &IOThread::ChangedToOnTheRecordOnIOThread));
}

void IOThread::Init() {
  BrowserProcessSubThread::Init();

  DCHECK(!host_resolver_);
  host_resolver_ = CreateGlobalHostResolver();
  host_resolver_->AddRef();
}

void IOThread::CleanUp() {
  // Not initialized in Init().  May not be initialized.
  if (dns_master_) {
    DCHECK(prefetch_observer_);

    dns_master_->Shutdown();

    // TODO(willchan): Stop reference counting DnsMaster.  It's owned by
    // IOThread now.
    dns_master_->Release();
    dns_master_ = NULL;
    chrome_browser_net::FreeDnsPrefetchResources();
  }

  // Not initialized in Init().  May not be initialized.
  if (prefetch_observer_) {
    host_resolver_->RemoveObserver(prefetch_observer_);
    delete prefetch_observer_;
    prefetch_observer_ = NULL;
  }

  // TODO(eroman): temp hack for http://crbug.com/15513
  host_resolver_->Shutdown();

  // TODO(willchan): Stop reference counting HostResolver.  It's owned by
  // IOThread now.
  host_resolver_->Release();
  host_resolver_ = NULL;

  // URLFetcher and URLRequest instances must NOT outlive the IO thread.
  //
  // Strictly speaking, URLFetcher's CheckForLeaks() should be done on the
  // UI thread. However, since there _shouldn't_ be any instances left
  // at this point, it shouldn't be a race.
  //
  // We check URLFetcher first, since if it has leaked then an associated
  // URLRequest will also have leaked. However it is more useful to
  // crash showing the callstack of URLFetcher's allocation than its
  // URLRequest member.
  base::LeakTracker<URLFetcher>::CheckForLeaks();
  base::LeakTracker<URLRequest>::CheckForLeaks();

  BrowserProcessSubThread::CleanUp();
}

void IOThread::InitDnsMasterOnIOThread(
    bool prefetching_enabled,
    base::TimeDelta max_queue_delay,
    size_t max_concurrent,
    chrome_common_net::NameList hostnames_to_prefetch,
    ListValue* referral_list) {
  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
  CHECK(!dns_master_);

  chrome_browser_net::EnableDnsPrefetch(prefetching_enabled);

  dns_master_ = new chrome_browser_net::DnsMaster(
      host_resolver_, max_queue_delay, max_concurrent);
  dns_master_->AddRef();

  DCHECK(!prefetch_observer_);
  prefetch_observer_ = chrome_browser_net::CreatePrefetchObserver();
  host_resolver_->AddObserver(prefetch_observer_);

  FinalizeDnsPrefetchInitialization(
      dns_master_, prefetch_observer_, hostnames_to_prefetch, referral_list);
}

void IOThread::ChangedToOnTheRecordOnIOThread() {
  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));

  if (dns_master_) {
    // Destroy all evidence of our OTR session.
    dns_master_->DnsMaster::DiscardAllResults();
  }

  // Clear the host cache to avoid showing entries from the OTR session
  // in about:net-internals.
  net::HostCache* host_cache = host_resolver_->GetHostCache();
  if (host_cache)
    host_cache->clear();
}