// Copyright 2014 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_SYNC_TEST_FAKE_SERVER_H_
#define COMPONENTS_SYNC_TEST_FAKE_SERVER_H_

#include <stdint.h>

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

#include "base/files/file_path.h"
#include "base/location.h"
#include "base/observer_list.h"
#include "base/observer_list_types.h"
#include "base/threading/thread_checker.h"
#include "base/values.h"
#include "components/sync/base/collaboration_id.h"
#include "components/sync/base/data_type.h"
#include "components/sync/engine/loopback_server/loopback_server.h"
#include "components/sync/engine/loopback_server/loopback_server_entity.h"
#include "components/sync/engine/loopback_server/persistent_bookmark_entity.h"
#include "components/sync/engine/loopback_server/persistent_tombstone_entity.h"
#include "components/sync/engine/loopback_server/persistent_unique_client_entity.h"
#include "components/sync/protocol/client_commands.pb.h"
#include "components/sync/protocol/deletion_origin.pb.h"
#include "components/sync/protocol/sync.pb.h"
#include "net/http/http_status_code.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace switches {

inline constexpr char kDisableFakeServerFailureOutput[] =
    "disable-fake-server-failure-output";

}  // namespace switches

namespace sync_pb {
class EntitySpecifics;
class DataTypeProgressMarker;
class SyncEntity;
enum SyncEnums_ErrorType : int;
}  // namespace sync_pb

namespace fake_server {

// A fake version of the Sync server used for testing. This class is not thread
// safe.
// `switches::kDisableFakeServerFailureOutput` can be passed to the command line
// to avoid debug logs upon test failure.
class FakeServer : public syncer::LoopbackServer::ObserverForTests {
 public:
  class Observer : public base::CheckedObserver {
   public:
    ~Observer() override = default;

    // Called whenever a commit command is received by FakeServer. Note that
    // Commit command may fail and hence it's not guaranteed that OnCommit()
    // will be called. However, before any OnCommit() call there will be a
    // corresponding OnWillCommit() call.
    virtual void OnWillCommit() {}

    // Called after FakeServer has processed a successful commit. The types
    // updated as part of the commit are passed in `committed_data_types`.
    virtual void OnCommit(syncer::DataTypeSet committed_data_types) {}

    // Called whenever a get updates request is received by FakeServer.
    virtual void OnWillGetUpdates(
        const sync_pb::ClientToServerMessage& message) {}

    // Called after FakeServer has processed a successful get updates request.
    virtual void OnSuccessfulGetUpdates() {}
  };

  // Persists the server state to `loopback_server_dir` (useful for PRE_ tests).
  explicit FakeServer(const base::FilePath& loopback_server_dir);

  // Convenience version of the above which uses a new temporary directory.
  FakeServer();

  ~FakeServer() override;

  // Handles a /command POST (with the given `request`) to the server.
  // `response` must not be null.
  net::HttpStatusCode HandleCommand(const std::string& request,
                                    std::string* response);

  // Handles a /chrome-sync/event request.
  void HandleEvent(const sync_pb::EventRequest& request);

  // Helpers for fetching the last Commit or GetUpdates messages, respectively.
  // Returns true if the specified message existed, and false if no message has
  // been received.
  bool GetLastCommitMessage(sync_pb::ClientToServerMessage* message);
  bool GetLastGetUpdatesMessage(sync_pb::ClientToServerMessage* message);

  // Creates a `base::DictValue` representation of all entities present in the
  // server. The dictionary keys are the strings generated by
  // DataTypeToDebugString and the values are base::ListValues containing
  // StringValue versions of entity names.
  base::DictValue GetEntitiesAsDictForTesting();

  // Returns all entities stored by the server of the given `data_type`.
  // This method returns SyncEntity protocol buffer objects (instead of
  // LoopbackServerEntity) so that callers can inspect datatype-specific data
  // (e.g., the URL of a session tab). Permanent entities are excluded.
  std::vector<sync_pb::SyncEntity> GetSyncEntitiesByDataType(
      syncer::DataType data_type);

  // Returns all permanent entities stored by the server of the given
  // `data_type`. This method returns SyncEntity protocol buffer objects
  // (instead of LoopbackServerEntity) so that callers can inspect
  // datatype-specific data (e.g., the URL of a session tab).
  std::vector<sync_pb::SyncEntity> GetPermanentSyncEntitiesByDataType(
      syncer::DataType data_type);

  // Returns all keystore keys from the server.
  const std::vector<std::vector<uint8_t>>& GetKeystoreKeys() const;

  // Triggers the keystore key rotation events on the server side: generating
  // new keystore key and touching the Nigori node.
  void TriggerKeystoreKeyRotation();

  // Adds `entity` to the server's collection of entities. This method makes no
  // guarantees that the added entity will result in successful server
  // operations.
  void InjectEntity(std::unique_ptr<syncer::LoopbackServerEntity> entity);

  // Modifies the entity on the server with the given `id`. The entity's
  // EntitySpecifics are replaced with `updated_specifics` and its version is
  // updated. If the given `id` does not exist or the DataType of
  // `updated_specifics` does not match the entity, false is returned.
  // Otherwise, true is returned to represent a successful modification.
  //
  // This method sometimes updates entity data beyond EntitySpecifics. For
  // example, in the case of a bookmark, changing the BookmarkSpecifics title
  // field will modify the top-level entity's name field.
  bool ModifyEntitySpecifics(const std::string& id,
                             const sync_pb::EntitySpecifics& updated_specifics);

  bool ModifyBookmarkEntity(const std::string& id,
                            const std::string& parent_id,
                            const sync_pb::EntitySpecifics& updated_specifics);

  // Clears server data simulating a "dashboard stop and clear" and sets a new
  // store birthday.
  void ClearServerData();

  // Deletes all `data_type` entities from the server without creating
  // tombstones.
  void DeleteAllEntitiesForDataType(syncer::DataType data_type);

  // Causes future calls to HandleCommand() fail with the given response code.
  void SetHttpError(net::HttpStatusCode http_status_code);

  // Undoes previous calls to SetHttpError().
  void ClearHttpError();

  // Returns the current HTTP error status code, or std::nullopt if none.
  std::optional<net::HttpStatusCode> GetHttpError() const;

  // Sets the provided `client_command` in all subsequent successful requests.
  void SetClientCommand(const sync_pb::ClientCommand& client_command);

  // Force the server to return `error_type` in the error_code field of
  // ClientToServerResponse on all subsequent commit requests. If any of errors
  // triggerings currently configured it must be called only with
  // sync_pb::SyncEnums::SUCCESS.
  void TriggerCommitError(const sync_pb::SyncEnums_ErrorType& error_type);

  // Force the server to return `error_type` in the error_code field of
  // ClientToServerResponse on all subsequent sync requests. If any of errors
  // triggerings currently configured it must be called only with
  // sync_pb::SyncEnums::SUCCESS.
  void TriggerError(const sync_pb::SyncEnums_ErrorType& error_type);

  // Force the server to return the given data as part of the error field of
  // ClientToServerResponse on all subsequent sync requests. Must not be called
  // if any of errors triggerings currently configured.
  void TriggerActionableProtocolError(
      const sync_pb::SyncEnums_ErrorType& error_type,
      const std::string& description,
      const std::string& url,
      const sync_pb::SyncEnums::Action& action);

  void ClearActionableProtocolError();

  // Instructs the server to send triggered errors on every other request
  // (starting with the first one after this call). This feature can be used to
  // test the resiliency of the client when communicating with a problematic
  // server or flaky network connection. This method should only be called
  // after a call to TriggerError or TriggerActionableProtocolError. Returns
  // true if triggered error alternating was successful.
  bool EnableAlternatingTriggeredErrors();

  // Simulates the state where a client's progress markers for `data_type` are
  // too old and will be rejected by the server. Instead, the server will *once*
  // respond with a full update along with a "clear all" GC directive. After the
  // server has returned the GC directive, this automatically gets reset, so
  // future GetUpdates requests will be treated normally again.
  void SetRejectOldProgressMarkerForType(syncer::DataType data_type);

  using UpdateMode = syncer::LoopbackServer::UpdateMode;

  // Configures the update mode for `data_type`. When set to
  // `UpdateMode::kFull`, the server will respond with a full update and a GC
  // directive whenever there are new or updated entities for `data_type`.
  void SetUpdateMode(syncer::DataType data_type, UpdateMode update_mode);

  // If called, all subsequent GetUpdatesResponses won't contain
  // encryption_keys.
  void DisallowSendingEncryptionKeys();

  // Mimics throttling of datatypes.
  void SetThrottledTypes(syncer::DataTypeSet types);

  // Adds `observer` to FakeServer's observer list. This should be called
  // before the Profile associated with `observer` is connected to the server.
  void AddObserver(Observer* observer);

  // Removes `observer` from the FakeServer's observer list. This method
  // must be called if AddObserver was ever called with `observer`.
  void RemoveObserver(Observer* observer);

  // Enables strong consistency model (i.e. server detects conflicts).
  void EnableStrongConsistencyWithConflictDetectionModel();

  // Sets a maximum batch size for GetUpdates requests.
  void SetMaxGetUpdatesBatchSize(int batch_size);

  // Sets the bag of chips returned by the server.
  void SetBagOfChips(const sync_pb::ChipBag& bag_of_chips);

  void TriggerMigrationDoneError(syncer::DataTypeSet types);

  void EnableGcDirectiveForMigration();

  int GetMigrationVersion(syncer::DataType type) const;

  static int GetProgressMarkerMigrationVersion(
      const sync_pb::DataTypeProgressMarker& progress_marker);

  // Add the user to the collaboration for the shared data types. No-op if the
  // user is already in this collaboration.
  void AddCollaboration(syncer::CollaborationId collaboration_id);

  // Removes the user from the collaboration. Does not clean up related entities
  // from the server.
  void RemoveCollaboration(const syncer::CollaborationId& collaboration_id);

  // Implement LoopbackServer::ObserverForTests:
  void OnCommit(syncer::DataTypeSet committed_data_types) override;
  void OnCommittedDeletionOrigin(
      syncer::DataType type,
      const sync_pb::DeletionOrigin& deletion_origin) override;

  // Returns all DeletionOrigin protos committed to the server for `type`.
  const std::vector<sync_pb::DeletionOrigin>& GetCommittedDeletionOrigins(
      syncer::DataType type) const;

  std::string GetStoreBirthday() const;

  // Returns the current FakeServer as a WeakPtr.
  base::WeakPtr<FakeServer> AsWeakPtr();

  // Use this callback to generate response types for entities. They will still
  // be "committed" and stored as normal, this only affects the response type
  // the client sees. This allows tests to still inspect what the client has
  // done, although not as useful of a mechanism for multi client tests. Care
  // should be taken when failing responses, as the client will go into
  // exponential backoff, which can cause tests to be slow or time out.
  void OverrideResponseType(
      syncer::LoopbackServer::ResponseTypeProvider response_type_override);

  // Performs any pending disk write immediately. This is useful on platforms
  // where shutdown isn't graceful, and this object may not be destructed
  // properly (otherwise, the destructor takes care of this automatically).
  void FlushToDisk();

 private:
  // Analogous to HandleCommand() but deals with parsed protos.
  net::HttpStatusCode HandleParsedCommand(
      const sync_pb::ClientToServerMessage& message,
      sync_pb::ClientToServerResponse* response);

  // Returns whether a triggered error should be sent for the request.
  bool ShouldSendTriggeredError() const;
  bool HasTriggeredError() const;
  net::HttpStatusCode SendToLoopbackServer(
      const sync_pb::ClientToServerMessage& message,
      sync_pb::ClientToServerResponse* response);

  // Logs a string that is meant to be shown in case the running test fails,
  // as long as `switches::kDisableFakeServerFailureOutput` hasn't been passed
  // to the command line.
  void LogForTestFailure(const base::Location& location,
                         const std::string& title,
                         const std::string& body);

  // Notifies observers about an ongoing commit.
  void OnWillCommit();

  // Writes some of the member variables to disk, for state to carry over after
  // PRE_ states.
  void LoadFakeStateFromDisk();
  void WriteFakeStateToDisk() const;

  const base::FilePath fake_state_file_path_;

  // List used to implement LogForTestFailure().
  std::vector<std::unique_ptr<testing::ScopedTrace>> gtest_scoped_traces_;

  // If set, the server will return HTTP errors.
  std::optional<net::HttpStatusCode> http_error_status_code_;

  // All committed deletion origins (optional part of committed tombstone).
  std::map<syncer::DataType, std::vector<sync_pb::DeletionOrigin>>
      committed_deletion_origins_;

  // Used as the error_code field of ClientToServerResponse on all commit
  // requests.
  sync_pb::SyncEnums_ErrorType commit_error_type_ = sync_pb::SyncEnums::SUCCESS;

  // Used as the error_code field of ClientToServerResponse on all responses.
  sync_pb::SyncEnums_ErrorType error_type_ = sync_pb::SyncEnums::SUCCESS;

  // Used as the error field of ClientToServerResponse when its pointer is not
  // null.
  std::unique_ptr<sync_pb::ClientToServerResponse_Error>
      triggered_actionable_error_;

  // These values are used in tandem to return a triggered error (either
  // `error_type_` or `triggered_actionable_error_`) on every other request.
  // `alternate_triggered_errors_` is set if this feature is enabled and
  // `request_counter_` is used to send triggered errors on odd-numbered
  // requests. Note that `request_counter_` can be reset and is not necessarily
  // indicative of the total number of requests handled during the object's
  // lifetime.
  bool alternate_triggered_errors_ = false;
  int request_counter_ = 0;

  syncer::DataTypeSet old_progress_marker_types_;

  // If set to true all `this` will clear `encryption_keys` in all
  // GetUpdateResponse's.
  bool disallow_sending_encryption_keys_ = false;

  // Client command to be included in every response.
  sync_pb::ClientCommand client_command_;

  // FakeServer's observers.
  base::ObserverList<Observer, true> observers_;

  // The last received client to server messages.
  sync_pb::ClientToServerMessage last_commit_message_;
  sync_pb::ClientToServerMessage last_getupdates_message_;

  // Used to verify that FakeServer is only used from one thread.
  base::ThreadChecker thread_checker_;

  std::unique_ptr<syncer::LoopbackServer> loopback_server_;

  // Collaborations the user is a member of, used for all shared types.
  std::set<syncer::CollaborationId> collaborations_;

  // Creates WeakPtr versions of the current FakeServer. This must be the last
  // data member!
  base::WeakPtrFactory<FakeServer> weak_ptr_factory_{this};
};

}  // namespace fake_server

#endif  // COMPONENTS_SYNC_TEST_FAKE_SERVER_H_