////////////////////////////////////////////////////////////////////////////
//
// Copyright 2016 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////

#ifndef REALM_SYNC_CONFIG_HPP
#define REALM_SYNC_CONFIG_HPP

#include <realm/db.hpp>
#include <realm/util/assert.hpp>
#include <realm/util/optional.hpp>

#include <functional>
#include <memory>
#include <string>
#include <map>
#include <system_error>
#include <unordered_map>

namespace realm {

class SyncUser;
class SyncSession;

namespace bson {
class Bson;
}

enum class SimplifiedProtocolError {
    ConnectionIssue,
    UnexpectedInternalIssue,
    SessionIssue,
    BadAuthentication,
    PermissionDenied,
    ClientResetRequested,
};

namespace sync {
using port_type = std::uint_fast16_t;
enum class ProtocolError;
}

SimplifiedProtocolError get_simplified_error(sync::ProtocolError err);

struct SyncError {

    std::error_code error_code;
    std::string message;
    bool is_fatal;
    std::unordered_map<std::string, std::string> user_info;
    /// The sync server may send down an error that the client does not recognize,
    /// whether because of a version mismatch or an oversight. It is still valuable
    /// to expose these errors so that users can do something about them.
    bool is_unrecognized_by_client = false;

    SyncError(std::error_code error_code, std::string message, bool is_fatal)
        : error_code(std::move(error_code))
        , message(std::move(message))
        , is_fatal(is_fatal)
    {
    }

    static constexpr const char c_original_file_path_key[] = "ORIGINAL_FILE_PATH";
    static constexpr const char c_recovery_file_path_key[] = "RECOVERY_FILE_PATH";

    /// The error is a client error, which applies to the client and all its sessions.
    bool is_client_error() const;

    /// The error is a protocol error, which may either be connection-level or session-level.
    bool is_connection_level_protocol_error() const;

    /// The error is a connection-level protocol error.
    bool is_session_level_protocol_error() const;

    /// The error indicates a client reset situation.
    bool is_client_reset_requested() const;
};

using SyncSessionErrorHandler = void(std::shared_ptr<SyncSession>, SyncError);

enum class ClientResyncMode : unsigned char {
    // Fire a client reset error
    Manual,
    // Discard local changes, without disrupting accessors or closing the Realm
    SeamlessLoss,
};

enum class ReconnectMode {
    /// This is the mode that should always be used in production. In this
    /// mode the client uses a scheme for determining a reconnect delay that
    /// prevents it from creating too many connection requests in a short
    /// amount of time (i.e., a server hammering protection mechanism).
    normal,

    /// For testing purposes only.
    ///
    /// Never reconnect automatically after the connection is closed due to
    /// an error. Allow immediate reconnect if the connection was closed
    /// voluntarily (e.g., due to sessions being abandoned).
    ///
    /// In this mode, Client::cancel_reconnect_delay() and
    /// Session::cancel_reconnect_delay() can still be used to trigger
    /// another reconnection attempt (with no delay) after an error has
    /// caused the connection to be closed.
    testing
};

enum class SyncSessionStopPolicy {
    Immediately,          // Immediately stop the session as soon as all Realms/Sessions go out of scope.
    LiveIndefinitely,     // Never stop the session.
    AfterChangesUploaded, // Once all Realms/Sessions go out of scope, wait for uploads to complete and stop.
};

struct SyncConfig {
    struct ProxyConfig {
        using port_type = sync::port_type;
        enum class Type { HTTP, HTTPS } type;
        std::string address;
        port_type port;
    };
    using SSLVerifyCallback = bool(const std::string& server_address, ProxyConfig::port_type server_port,
                                   const char* pem_data, size_t pem_size, int preverify_ok, int depth);

    std::shared_ptr<SyncUser> user;
    std::string partition_value;
    SyncSessionStopPolicy stop_policy = SyncSessionStopPolicy::AfterChangesUploaded;
    std::function<SyncSessionErrorHandler> error_handler;
    bool client_validate_ssl = true;
    util::Optional<std::string> ssl_trust_certificate_path;
    std::function<SSLVerifyCallback> ssl_verify_callback;
    util::Optional<ProxyConfig> proxy_config;

    // If true, upload/download waits are canceled on any sync error and not just fatal ones
    bool cancel_waits_on_nonfatal_error = false;

    util::Optional<std::string> authorization_header_name;
    std::map<std::string, std::string> custom_http_headers;

    // The name of the directory which Realms should be backed up to following
    // a client reset in ClientResyncMode::Manual mode
    util::Optional<std::string> recovery_directory;
    ClientResyncMode client_resync_mode = ClientResyncMode::Manual;
    std::function<void(TransactionRef local, TransactionRef remote)> notify_before_client_reset;
    std::function<void(TransactionRef local)> notify_after_client_reset;
    std::function<void(const std::string&, std::function<void(DBRef, util::Optional<std::string>)>)>
        get_fresh_realm_for_path;

    explicit SyncConfig(std::shared_ptr<SyncUser> user, bson::Bson partition);
    explicit SyncConfig(std::shared_ptr<SyncUser> user, std::string partition);
    explicit SyncConfig(std::shared_ptr<SyncUser> user, const char* partition);
};

} // namespace realm

#endif // REALM_SYNC_CONFIG_HPP