// Copyright (c) 2012 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.

#ifndef CHROME_BROWSER_INTRANET_REDIRECT_DETECTOR_H_
#define CHROME_BROWSER_INTRANET_REDIRECT_DETECTOR_H_

#include <map>
#include <memory>
#include <string>
#include <vector>

#include "base/memory/weak_ptr.h"
#include "build/build_config.h"
#include "components/pref_registry/pref_registry_syncable.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "services/network/public/cpp/network_connection_tracker.h"
#include "services/network/public/mojom/host_resolver.mojom.h"
#include "url/gurl.h"

namespace network {
class SimpleURLLoader;
}

class PrefRegistrySimple;

#if !(BUILDFLAG(IS_MAC) || BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX) || \
      BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_FUCHSIA))
#error "IntranetRedirectDetector should only be built on Desktop platforms."
#endif

// This object is responsible for determining whether the user is on a network
// that redirects requests for intranet hostnames to another site, and if so,
// tracking what that site is (including across restarts via a pref).  For
// example, the user's ISP might convert a request for "http://query/" into a
// 302 redirect to "http://isp.domain.com/search?q=query" in order to display
// custom pages on typos, nonexistent sites, etc.
//
// We use this information in the OmniboxNavigationObserver to avoid displaying
// infobars for these cases.  Our infobars are designed to allow users to get at
// intranet sites when they were erroneously taken to a search result page.  In
// these cases, however, users would be shown a confusing and useless infobar
// when they really did mean to do a search.
//
// Consumers should call RedirectOrigin(), which is guaranteed to synchronously
// return a value at all times (even during startup or in unittest mode).  If no
// redirection is in place, the returned GURL will be empty.
class IntranetRedirectDetector
    : public network::NetworkConnectionTracker::NetworkConnectionObserver,
      public network::mojom::DnsConfigChangeManagerClient {
 public:
  // Only the main browser process loop should call this, when setting up
  // g_browser_process->intranet_redirect_detector_.  No code other than the
  // IntranetRedirectDetector itself should actually use
  // g_browser_process->intranet_redirect_detector() (which shouldn't be hard,
  // since there aren't useful public functions on this object for consumers to
  // access anyway).
  IntranetRedirectDetector();

  IntranetRedirectDetector(const IntranetRedirectDetector&) = delete;
  IntranetRedirectDetector& operator=(const IntranetRedirectDetector&) = delete;

  ~IntranetRedirectDetector() override;

  // Returns the current redirect origin.  This will be empty if no redirection
  // is in place.
  static GURL RedirectOrigin();

  static void RegisterPrefs(PrefRegistrySimple* registry);

 private:
  // Called on connection or config change to ensure detector runs again (after
  // a delay).
  void Restart();

  // Called when the startup or restart sleep has finished.  Runs any pending
  // fetch.
  void FinishSleep();

  // Invoked from SimpleURLLoader after download is complete.
  void OnSimpleLoaderComplete(network::SimpleURLLoader* source,
                              std::unique_ptr<std::string> response_body);

  // NetworkConnectionTracker::NetworkConnectionObserver
  void OnConnectionChanged(network::mojom::ConnectionType type) override;

  // network::mojom::DnsConfigChangeManagerClient
  void OnDnsConfigChanged() override;

  void SetupDnsConfigClient();
  void OnDnsConfigClientConnectionError();

  // Whether the IntranetRedirectDetector is enabled by policy. Disabled by
  // default.
  bool IsEnabledByPolicy();

  GURL redirect_origin_;
  std::map<network::SimpleURLLoader*, std::unique_ptr<network::SimpleURLLoader>>
      simple_loaders_;
  std::vector<GURL> resulting_origins_;
  bool in_sleep_ = true;  // True if we're in the seven-second "no fetching"
                          // period that begins at browser start, or the
                          // one-second "no fetching" period that begins after
                          // network switches.
  mojo::Receiver<network::mojom::DnsConfigChangeManagerClient>
      dns_config_client_receiver_{this};
  base::WeakPtrFactory<IntranetRedirectDetector> weak_ptr_factory_{this};
};

#endif  // CHROME_BROWSER_INTRANET_REDIRECT_DETECTOR_H_