// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_
#define COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_

#include <memory>

#include "base/feature_list.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/threading/thread_checker.h"
#include "components/enterprise/buildflags/buildflags.h"
#include "components/prefs/pref_change_registrar.h"
#include "components/proxy_config/pref_proxy_config_tracker.h"
#include "components/proxy_config/proxy_config_dictionary.h"
#include "net/proxy_resolution/proxy_config_service.h"
#include "net/proxy_resolution/proxy_config_with_annotation.h"

#if BUILDFLAG(ENTERPRISE_PROXY)
#include "base/scoped_observation.h"
#include "components/enterprise/net/core/enterprise_proxy_service.h"
#endif  // BUILDFLAG(ENTERPRISE_PROXY)

class PrefService;
class PrefRegistrySimple;

namespace base {
class SingleThreadTaskRunner;
}

namespace policy {
class PolicyService;
}

// Killswitch for the rules set by the "ProxyOverrideRules" policy.
PROXY_CONFIG_EXPORT BASE_DECLARE_FEATURE(kEnableProxyOverrideRules);

// Killswitch for preserving explicit proxy rules when system proxy is unset.
PROXY_CONFIG_EXPORT BASE_DECLARE_FEATURE(
    kProxyOverrideRulesFixUnsetSystemProxy);

// A net::ProxyConfigService implementation that applies preference proxy
// settings (pushed from PrefProxyConfigTrackerImpl) as overrides to the proxy
// configuration determined by a baseline delegate ProxyConfigService on
// non-ChromeOS platforms. ChromeOS has its own implementation of overrides in
// ash::ProxyConfigServiceImpl.
class ProxyConfigServiceImpl : public net::ProxyConfigService,
                               public net::ProxyConfigService::Observer {
 public:
  ProxyConfigServiceImpl(std::unique_ptr<net::ProxyConfigService> base_service,
                         ProxyPrefs::ConfigState initial_config_state,
                         const net::ProxyConfigWithAnnotation& initial_config);

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

  ~ProxyConfigServiceImpl() override;

  // ProxyConfigService implementation:
  void AddObserver(net::ProxyConfigService::Observer* observer) override;
  void RemoveObserver(net::ProxyConfigService::Observer* observer) override;
  ConfigAvailability GetLatestProxyConfig(
      net::ProxyConfigWithAnnotation* config) override;
  void OnLazyPoll() override;
  bool UsesPolling() override;

  // Method on IO thread that receives the preference proxy settings pushed from
  // PrefProxyConfigTrackerImpl.
  void UpdateProxyConfig(ProxyPrefs::ConfigState config_state,
                         const net::ProxyConfigWithAnnotation& config);

  base::WeakPtr<ProxyConfigServiceImpl> AsWeakPtr();

 private:
  // ProxyConfigService::Observer implementation:
  void OnProxyConfigChanged(const net::ProxyConfigWithAnnotation& config,
                            ConfigAvailability availability) override;

  // Makes sure that the observer registration with the base service is set up.
  void RegisterObserver();

  std::unique_ptr<net::ProxyConfigService> base_service_;
  base::ObserverList<net::ProxyConfigService::Observer, true>::Unchecked
      observers_;

  // Tracks configuration state of |pref_config_|. |pref_config_| is valid only
  // if |pref_config_state_| is not CONFIG_UNSET.
  ProxyPrefs::ConfigState pref_config_state_;

  // Configuration as defined by prefs.
  net::ProxyConfigWithAnnotation pref_config_;

  // Indicates whether the base service registration is done.
  bool registered_observer_;

  base::ThreadChecker thread_checker_;

  base::WeakPtrFactory<ProxyConfigServiceImpl> weak_ptr_factory_{this};
};

// A class that tracks proxy preferences. It translates the configuration
// to net::ProxyConfig and pushes the result over to
// ProxyConfigServiceImpl::UpdateProxyConfig.
class PROXY_CONFIG_EXPORT PrefProxyConfigTrackerImpl
    : public PrefProxyConfigTracker
#if BUILDFLAG(ENTERPRISE_PROXY)
    ,
      public enterprise_net::EnterpriseProxyService::Observer
#endif  // BUILDFLAG(ENTERPRISE_PROXY)
{
 public:
  // |proxy_config_service_task_runner| is the thread the ProxyConfigService
  // will live on. Use nullptr if it lives on the current thread.
  // |policy_service| is required to check the affiliation over the user, but
  // can be null if its usage is not applicable to the caller.
  PrefProxyConfigTrackerImpl(PrefService* pref_service,
                             scoped_refptr<base::SingleThreadTaskRunner>
                                 proxy_config_service_task_runner,
                             policy::PolicyService* policy_service = nullptr);

#if BUILDFLAG(ENTERPRISE_PROXY)
  PrefProxyConfigTrackerImpl(
      PrefService* pref_service,
      scoped_refptr<base::SingleThreadTaskRunner>
          proxy_config_service_task_runner,
      policy::PolicyService* policy_service,
      enterprise_net::EnterpriseProxyService* enterprise_proxy_service);
#endif  // BUILDFLAG(ENTERPRISE_PROXY)

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

  ~PrefProxyConfigTrackerImpl() override;

  // PrefProxyConfigTracker implementation:
  std::unique_ptr<net::ProxyConfigService> CreateTrackingProxyConfigService(
      std::unique_ptr<net::ProxyConfigService> base_service) override;

  // Notifies the tracker that the pref service passed upon construction is
  // about to go away. This must be called from the UI thread.
  void DetachFromPrefService() override;

  // Determines if |config_state| takes precedence regardless, which happens if
  // config is from policy or extension or other-precede.
  static bool PrefPrecedes(ProxyPrefs::ConfigState config_state);

  // Determines the proxy configuration that should take effect in the network
  // layer, based on prefs and system configurations.
  // |pref_state| refers to state of |pref_config|.
  // |system_availability| refers to availability of |system_config|.
  // |ignore_fallback_config| indicates if fallback config from prefs should
  // be ignored.
  // Returns effective |effective_config| and its state in
  // |effective_config_source|.
  static net::ProxyConfigService::ConfigAvailability GetEffectiveProxyConfig(
      ProxyPrefs::ConfigState pref_state,
      const net::ProxyConfigWithAnnotation& pref_config,
      net::ProxyConfigService::ConfigAvailability system_availability,
      const net::ProxyConfigWithAnnotation& system_config,
      bool ignore_fallback_config,
      ProxyPrefs::ConfigState* effective_config_state,
      net::ProxyConfigWithAnnotation* effective_config);

  // Converts a ProxyConfigDictionary to net::ProxyConfig representation.
  // Returns true if the data from in the dictionary is valid, false otherwise.
  static bool PrefConfigToNetConfig(const ProxyConfigDictionary& proxy_dict,
                                    net::ProxyConfigWithAnnotation* config);

  // Registers the proxy preferences. These are actually registered
  // the same way in local state and in user prefs.
  static void RegisterPrefs(PrefRegistrySimple* registry);
  static void RegisterProfilePrefs(PrefRegistrySimple* registry);

  // Creates a proxy configuration from proxy-related preferences of
  // |pref_service|. Configuration is stored in |config|, return value indicates
  // whether the configuration is valid. |policy_service| is required to check
  // the affiliation over the user, but can be null if its usage is not
  // applicable to the caller.
  static ProxyPrefs::ConfigState ReadPrefConfig(
      const PrefService* pref_service,
      net::ProxyConfigWithAnnotation* config,
      policy::PolicyService* policy_service);

#if BUILDFLAG(ENTERPRISE_PROXY)
  // enterprise_net::EnterpriseProxyService::Observer implementation:
  void OnDynamicProxyConfigsStatusChanged() override;
  void OnEnterpriseProxyServiceDestroyed() override;
#endif  // BUILDFLAG(ENTERPRISE_PROXY)

 protected:
  // Get the proxy configuration currently defined by preferences.
  // Status is indicated in the return value.
  // Writes the configuration to |config| unless the return value is
  // CONFIG_UNSET, in which case |config| and |config_source| are not touched.
  ProxyPrefs::ConfigState GetProxyConfig(
      net::ProxyConfigWithAnnotation* config);

  // Called when there's a change in prefs proxy config.
  // Subclasses can extend it for changes in other sources of proxy config.
  // Checks new config against old config, and if there was no change, does
  // nothing.
  virtual void OnProxyConfigChanged(
      ProxyPrefs::ConfigState config_state,
      const net::ProxyConfigWithAnnotation& config);

  void OnProxyPrefChanged();

  const PrefService* prefs() const { return pref_service_; }

 private:
  // Tracks configuration state. |pref_config_| is valid only if |config_state_|
  // is not CONFIG_UNSET.
  ProxyPrefs::ConfigState pref_config_state_;

  // Configuration as defined by prefs.
  net::ProxyConfigWithAnnotation pref_config_;

  raw_ptr<PrefService> pref_service_;
  raw_ptr<policy::PolicyService> policy_service_ = nullptr;
  base::WeakPtr<ProxyConfigServiceImpl> proxy_config_service_impl_;
  PrefChangeRegistrar proxy_prefs_;

  // State of |active_config_|.  |active_config_| is only valid if
  // |active_config_state_| is not ProxyPrefs::CONFIG_UNSET.
  ProxyPrefs::ConfigState active_config_state_;

  // Active proxy configuration, last received from OnProxyConfigChanged.
  net::ProxyConfigWithAnnotation active_config_;

  scoped_refptr<base::SingleThreadTaskRunner> proxy_config_service_task_runner_;

  base::ThreadChecker thread_checker_;

#if BUILDFLAG(ENTERPRISE_PROXY)
  base::ScopedObservation<enterprise_net::EnterpriseProxyService,
                          enterprise_net::EnterpriseProxyService::Observer>
      enterprise_proxy_observation_{this};
#endif  // BUILDFLAG(ENTERPRISE_PROXY)
  // Caches the active PvD dynamic routing rules so that dynamic routing updates
  // persist across preference changes.
  net::ProxyConfig::DynamicRoutingConfig active_dynamic_routing_config_;
};

#endif  // COMPONENTS_PROXY_CONFIG_PREF_PROXY_CONFIG_TRACKER_IMPL_H_