// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef REMOTING_HOST_IT2ME_IT2ME_HOST_H_
#define REMOTING_HOST_IT2ME_IT2ME_HOST_H_

#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "base/functional/callback_forward.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/values.h"
#include "remoting/base/errors.h"
#include "remoting/base/local_session_policies_provider.h"
#include "remoting/base/session_policies.h"
#include "remoting/host/chromeos/chromeos_enterprise_params.h"
#include "remoting/host/host_status_observer.h"
#include "remoting/host/it2me/it2me_confirmation_dialog.h"
#include "remoting/host/it2me/it2me_confirmation_dialog_proxy.h"
#include "remoting/host/it2me/it2me_constants.h"
#include "remoting/host/it2me/reconnect_params.h"
#include "remoting/host/register_support_host_request.h"
#include "remoting/protocol/errors.h"
#include "remoting/protocol/validating_authenticator.h"
#include "remoting/signaling/signal_strategy.h"

namespace remoting {

class ChromotingHost;
class ChromotingHostContext;
class CorpHostStatusLogger;
class DesktopEnvironmentFactory;
class FtlSignalingConnector;
class HostEventLogger;
class HostEventReporter;
class HostStatusMonitor;
class OAuthTokenGetter;
class RegisterSupportHostRequest;
class RsaKeyPair;

namespace protocol {
struct IceConfig;
}  // namespace protocol

// Internal implementation of the plugin's It2Me host function.
class It2MeHost : public base::RefCountedThreadSafe<It2MeHost>,
                  public HostStatusObserver {
 public:
  struct DeferredConnectContext {
    DeferredConnectContext();
    ~DeferredConnectContext();

    std::unique_ptr<RegisterSupportHostRequest> register_request;
    std::unique_ptr<SignalStrategy> signal_strategy;

    // `signaling_token_getter_` is used for signaling, which may require a
    // non-CRD token scope, while `api_token_getter_` is used for all other
    // services, which require a CRD token scope.
    // `signaling_token_getter` isn't really used by It2MeHost, since
    // `signal_strategy` already takes an `OAuthTokenGetter`. This is mostly for
    // testing purposes.
    std::unique_ptr<OAuthTokenGetter> signaling_token_getter;
    std::unique_ptr<OAuthTokenGetter> api_token_getter;

    // Only set when FTL signaling is being used.
    std::string ftl_device_id;

    // Use corp SessionAuthz auth instead of shared secret auth.
    // DEPRECATED: use `is_corp_user` instead.
    // TODO: crbug.com/417567187 - remove once corp IT2ME directory API is
    // rolled out.
    bool use_corp_session_authz = false;

    // Indicates whether the user is a corp user and corp flows need to be used
    // instead of the external ones.
    bool is_corp_user = false;
  };

  using CreateDeferredConnectContext =
      base::OnceCallback<std::unique_ptr<DeferredConnectContext>(
          ChromotingHostContext*)>;

  using HostEventReporterFactory =
      base::RepeatingCallback<std::unique_ptr<HostEventReporter>(
          scoped_refptr<HostStatusMonitor>)>;

  class Observer {
   public:
    virtual void OnClientAuthenticated(const std::string& client_username) = 0;
    virtual void OnStoreAccessCode(const std::string& access_code,
                                   base::TimeDelta access_code_lifetime) = 0;
    virtual void OnNatPoliciesChanged(bool nat_traversal_enabled,
                                      bool relay_connections_allowed) = 0;
    virtual void OnStateChanged(It2MeHostState state,
                                protocol::ErrorCode error_code) = 0;
  };

  It2MeHost();

  It2MeHost(const It2MeHost&) = delete;
  It2MeHost& operator=(const It2MeHost&) = delete;

  // Session parameters provided by the remote command infrastructure when the
  // session is started from the admin console for a managed Chrome OS device.
  void set_chrome_os_enterprise_params(ChromeOsEnterpriseParams params);
  // Callers should call is_enterprise_session() first to ensure the params are
  // present and retrievable.
  const ChromeOsEnterpriseParams& chrome_os_enterprise_params() const {
    return *chrome_os_enterprise_params_;
  }
  // Indicates whether this support session was initiated by the admin console
  // for a managed Chrome OS device.
  bool is_enterprise_session() const {
    return chrome_os_enterprise_params_.has_value();
  }

  // If set, only |authorized_helper| will be allowed to connect to this host.
  void set_authorized_helper(const std::string& authorized_helper);
  const std::string& authorized_helper() const { return authorized_helper_; }

  // If set, the host will use `reconnect_params` instead of registering with
  // the Directory service and generating new IDs and such.
  void set_reconnect_params(ReconnectParams reconnect_params);

  // Creates a new ReconnectParams struct if reconnections are allowed and the
  // remote client has connected, otherwise an empty optional is returned.
  virtual std::optional<ReconnectParams> CreateReconnectParams() const;

  // Creates It2Me host structures and starts the host.
  virtual void Connect(
      std::unique_ptr<ChromotingHostContext> context,
      base::Value::Dict policies,
      std::unique_ptr<It2MeConfirmationDialogFactory> dialog_factory,
      base::WeakPtr<It2MeHost::Observer> observer,
      CreateDeferredConnectContext create_context,
      const std::string& username,
      const protocol::IceConfig& ice_config);

  // Disconnects and shuts down the host.
  virtual void Disconnect();

  // HostStatusObserver implementation.
  void OnClientAccessDenied(const std::string& signaling_id) override;
  void OnClientConnected(const std::string& signaling_id) override;
  void OnClientDisconnected(const std::string& signaling_id) override;

  void SetStateForTesting(It2MeHostState state,
                          protocol::ErrorCode error_code) {
    SetState(state, error_code);
  }

  // Returns the callback used for validating the connection.  Do not run the
  // returned callback after this object has been destroyed.
  protocol::ValidatingAuthenticator::ValidationCallback
  GetValidationCallbackForTesting();

#if BUILDFLAG(IS_CHROMEOS)
  void SetHostEventReporterFactoryForTesting(HostEventReporterFactory factory);
#endif

  // Called when initial policies are read and when they change.
  void OnPolicyUpdate(base::Value::Dict policies);

 protected:
  friend class base::RefCountedThreadSafe<It2MeHost>;
  friend class It2MeNativeMessagingHostTest;

  ~It2MeHost() override;

  ChromotingHostContext* host_context() { return host_context_.get(); }
  base::WeakPtr<It2MeHost::Observer> observer() { return observer_; }

 private:
  friend class MockIt2MeHost;
  friend class It2MeHostTest;

  // Updates state of the host. Can be called only on the network thread.
  void SetState(It2MeHostState state, protocol::ErrorCode error_code);

  // Returns true if the host is in a post-starting, non-error state.
  bool IsRunning() const;

  // Processes the result of the confirmation dialog.
  void OnConfirmationResult(
      protocol::ValidatingAuthenticator::ResultCallback result_callback,
      It2MeConfirmationDialog::Result result);

  // Task posted to the network thread from Connect().
  void ConnectOnNetworkThread(const std::string& username,
                              const protocol::IceConfig& ice_config,
                              CreateDeferredConnectContext create_context);

  // Called when the support host registration completes.
  void OnReceivedSupportID(const std::string& support_id,
                           const base::TimeDelta& lifetime,
                           protocol::ErrorCode error_code);

  std::optional<ErrorCode> OnEffectiveSessionPoliciesReceived(
      const SessionPolicies& session_policies);

  // Reports the NAT policies to the observer. Will always report if no policies
  // have been reported, and will not report if the policies have not changed.
  void ReportNatPolicies(const SessionPolicies& session_policies);

  // Handlers for domain policies.
  void UpdateHostDomainListPolicy(std::vector<std::string> host_domain_list);
  void UpdateClientDomainListPolicy(
      std::vector<std::string> client_domain_list);
  void UpdateLocalSessionPolicies(const base::Value::Dict& platform_policies);

  void DisconnectOnNetworkThread(
      protocol::ErrorCode error_code = protocol::ErrorCode::OK);

  // Uses details of the connection and current policies to determine if the
  // connection should be accepted or rejected.
  void ValidateConnectionDetails(
      const std::string& remote_jid,
      protocol::ValidatingAuthenticator::ResultCallback result_callback);

  // Determines if remote support connections are allowed by policy.
  bool RemoteSupportConnectionsAllowed(const base::Value::Dict& policies);

  // Indicates whether the session allows a ChromeOS admin to reconnect.
  bool SessionSupportsReconnections() const;

  // Informs the client that the host is ready for reconnections. Sent over the
  // signaling channel.
  void SendReconnectSessionMessage() const;

  // Caller supplied fields.
  std::unique_ptr<ChromotingHostContext> host_context_;
  base::WeakPtr<It2MeHost::Observer> observer_;
  std::unique_ptr<SignalStrategy> signal_strategy_;
  std::unique_ptr<FtlSignalingConnector> ftl_signaling_connector_;
  std::unique_ptr<OAuthTokenGetter> api_token_getter_;

  It2MeHostState state_ = It2MeHostState::kDisconnected;

  std::optional<ReconnectParams> reconnect_params_;

  std::string support_id_;

  // This is empty if shared secret auth is not supported.
  std::string host_secret_;

  std::string ftl_device_id_;
  scoped_refptr<RsaKeyPair> host_key_pair_;
  std::unique_ptr<RegisterSupportHostRequest> register_request_;
  std::unique_ptr<DesktopEnvironmentFactory> desktop_environment_factory_;
  std::unique_ptr<HostEventLogger> host_event_logger_;
  std::unique_ptr<LocalSessionPoliciesProvider>
      local_session_policies_provider_;
#if BUILDFLAG(IS_CHROMEOS)
  std::unique_ptr<HostEventReporter> host_event_reporter_;
  HostEventReporterFactory host_event_reporter_factory_;
#endif  // BUILDFLAG(IS_CHROMEOS)

  bool use_corp_session_authz_ = false;

  // Only set if |use_corp_session_authz_| is true.
  std::unique_ptr<CorpHostStatusLogger> corp_host_status_logger_;

  std::unique_ptr<ChromotingHost> host_;
  int failed_login_attempts_ = 0;

  std::unique_ptr<It2MeConfirmationDialogFactory> confirmation_dialog_factory_;
  std::unique_ptr<It2MeConfirmationDialogProxy> confirmation_dialog_proxy_;

  // Indicates whether the session policies can still change. Once the session
  // has connected, any changes to the session policies will disconnect the
  // session.
  bool session_policies_finalized_ = false;

  // Stores the last nat traversal policy and relay connections allowed policy
  // values that have been reported to the observer. nullopt indicates that the
  // policy has not be reported.
  // Note: if these policies are not specified in SessionPolicies, they will be
  // `true` rather than nullopt.
  std::optional<bool> last_reported_nat_traversal_enabled_ = false;
  std::optional<bool> last_reported_relay_connections_allowed_ = false;

  // Set when the session was initiated for a managed Chrome OS device by an
  // admin using the admin console.
  std::optional<ChromeOsEnterpriseParams> chrome_os_enterprise_params_;

  // Only the username stored in |authorized_helper_| will be allowed to connect
  // to this host instance, if set. Note: setting this value does not override
  // any applicable Enterprise policies or other constraints.
  std::string authorized_helper_;

  // The client and host domain policy setting.
  std::vector<std::string> required_client_domain_list_;
  std::vector<std::string> required_host_domain_list_;

  // Stores the remote support connections allowed policy value.
  bool remote_support_connections_allowed_ = true;

  // Tracks the JID of the remote user when in a connecting state.
  std::string connecting_jid_;

  base::WeakPtrFactory<It2MeHost> weak_factory_{this};
};

// Having a factory interface makes it possible for the test to provide a mock
// implementation of the It2MeHost.
class It2MeHostFactory {
 public:
  It2MeHostFactory();

  It2MeHostFactory(const It2MeHostFactory&) = delete;
  It2MeHostFactory& operator=(const It2MeHostFactory&) = delete;

  virtual ~It2MeHostFactory();

  virtual std::unique_ptr<It2MeHostFactory> Clone() const;
  virtual scoped_refptr<It2MeHost> CreateIt2MeHost();
};

}  // namespace remoting

#endif  // REMOTING_HOST_IT2ME_IT2ME_HOST_H_