natch

#pragma once

#include "query.h"
#include "exceptions.h"

#include "columns/array.h"
#include "columns/date.h"
#include "columns/decimal.h"
#include "columns/enum.h"
#include "columns/geo.h"
#include "columns/ip4.h"
#include "columns/ip6.h"
#include "columns/lowcardinality.h"
#include "columns/nothing.h"
#include "columns/nullable.h"
#include "columns/numeric.h"
#include "columns/map.h"
#include "columns/string.h"
#include "columns/tuple.h"
#include "columns/uuid.h"

#include <chrono>
#include <cstdint>
#include <memory>
#include <ostream>
#include <string>
#include <optional>

typedef struct ssl_ctx_st SSL_CTX;

namespace clickhouse {

struct ServerInfo {
    std::string name;
    std::string timezone;
    std::string display_name;
    uint64_t    version_major;
    uint64_t    version_minor;
    uint64_t    version_patch;
    uint64_t    revision;
};

/// Methods of block compression.
enum class CompressionMethod : int8_t {
    None = -1,
    LZ4  = 1,
    ZSTD = 2,
};

struct Endpoint {
    std::string host;
    uint16_t port = 9000;
    inline bool operator==(const Endpoint& right) const {
        return host == right.host && port == right.port;
    }
};

enum class EndpointsIterationAlgorithm {
    RoundRobin = 0,
};

struct ClientOptions {
    // Setter goes first, so it is possible to apply 'deprecated' annotation safely.
#define DECLARE_FIELD(name, type, setter, default_value) \
    inline auto & setter(const type& value) { \
        name = value; \
        return *this; \
    } \
    type name = default_value

    /// Hostname of the server.
    DECLARE_FIELD(host, std::string, SetHost, std::string());
    /// Service port.
    DECLARE_FIELD(port, uint16_t, SetPort, 9000);

    /** Set endpoints (host+port), only one is used.
     * Client tries to connect to those endpoints one by one, on the round-robin basis:
     * first default enpoint (set via SetHost() + SetPort()), then each of endpoints, from begin() to end(),
     * the first one to establish connection is used for the rest of the session.
     * If port isn't specified, default(9000) value will be used.
     */
    DECLARE_FIELD(endpoints, std::vector<Endpoint>, SetEndpoints, {});

    /// Default database.
    DECLARE_FIELD(default_database, std::string, SetDefaultDatabase, "default");
    /// User name.
    DECLARE_FIELD(user, std::string, SetUser, "default");
    /// Access password.
    DECLARE_FIELD(password, std::string, SetPassword, std::string());

    /// By default all exceptions received during query execution will be
    /// passed to OnException handler.  Set rethrow_exceptions to true to
    /// enable throwing exceptions with standard c++ exception mechanism.
    DECLARE_FIELD(rethrow_exceptions, bool, SetRethrowException, true);

    /// Ping server every time before execute any query.
    DECLARE_FIELD(ping_before_query, bool, SetPingBeforeQuery, false);
    /// Count of retry to send request to server.
    DECLARE_FIELD(send_retries, unsigned int, SetSendRetries, 1);
    /// Amount of time to wait before next retry.
    DECLARE_FIELD(retry_timeout, std::chrono::seconds, SetRetryTimeout, std::chrono::seconds(5));

    /// Compression method.
    DECLARE_FIELD(compression_method, CompressionMethod, SetCompressionMethod, CompressionMethod::None);

    /// TCP Keep alive options
    DECLARE_FIELD(tcp_keepalive, bool, TcpKeepAlive, false);
    DECLARE_FIELD(tcp_keepalive_idle, std::chrono::seconds, SetTcpKeepAliveIdle, std::chrono::seconds(60));
    DECLARE_FIELD(tcp_keepalive_intvl, std::chrono::seconds, SetTcpKeepAliveInterval, std::chrono::seconds(5));
    DECLARE_FIELD(tcp_keepalive_cnt, unsigned int, SetTcpKeepAliveCount, 3);

    // TCP options
    DECLARE_FIELD(tcp_nodelay, bool, TcpNoDelay, true);

    /// Connection socket connect timeout. If the timeout is negative then the connect operation will never timeout.
    DECLARE_FIELD(connection_connect_timeout, std::chrono::milliseconds, SetConnectionConnectTimeout, std::chrono::seconds(5));

    /// Connection socket timeout. If the timeout is set to zero then the operation will never timeout.
    DECLARE_FIELD(connection_recv_timeout, std::chrono::milliseconds, SetConnectionRecvTimeout, std::chrono::milliseconds(0));
    DECLARE_FIELD(connection_send_timeout, std::chrono::milliseconds, SetConnectionSendTimeout, std::chrono::milliseconds(0));

    /** It helps to ease migration of the old codebases, which can't afford to switch
    * to using ColumnLowCardinalityT or ColumnLowCardinality directly,
    * but still want to benefit from smaller on-wire LowCardinality bandwidth footprint.
    *
    * @see LowCardinalitySerializationAdaptor, CreateColumnByType
    */
    [[deprecated("Makes implementation of LC(X) harder and code uglier. Will be removed in next major release (3.0) ")]]
    DECLARE_FIELD(backward_compatibility_lowcardinality_as_wrapped_column, bool, SetBakcwardCompatibilityFeatureLowCardinalityAsWrappedColumn, false);

    /** Set max size data to compress if compression enabled.
     *
     *  Allows choosing tradeoff between RAM\CPU:
     *  - Lower value reduces RAM usage, but slightly increases CPU usage.
     *  - Higher value increases RAM usage but slightly decreases CPU usage.
     */
    DECLARE_FIELD(max_compression_chunk_size, unsigned int, SetMaxCompressionChunkSize, 65535);

    struct SSLOptions {
        /** There are two ways to configure an SSL connection:
         *  - provide a pre-configured SSL_CTX, which is not modified and not owned by the Client.
         *  - provide a set of options and allow the Client to create and configure SSL_CTX by itself.
         */

        /** Pre-configured SSL-context for SSL-connection.
         *  If NOT null client DONES NOT take ownership of context and it must be valid for client lifetime.
         *  If null client initlaizes OpenSSL and creates his own context, initializes it using
         *  other options, like path_to_ca_files, path_to_ca_directory, use_default_ca_locations, etc.
         *
         *  Either way context is used to create an SSL-connection, which is then configured with
         *  whatever was provided as `configuration`, `host_flags`, `skip_verification` and `use_sni`.
         */
        SSL_CTX * ssl_context = nullptr;
        auto & SetExternalSSLContext(SSL_CTX * new_ssl_context) {
            ssl_context = new_ssl_context;
            return *this;
        }

        /** Means to validate the server-supplied certificate against trusted Certificate Authority (CA).
         *  If no CAs are configured, the server's identity can't be validated, and the Client would err.
         *  See https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_default_verify_paths.html
        */
        /// Load default CA certificates from default locations.
        DECLARE_FIELD(use_default_ca_locations, bool, SetUseDefaultCALocations, true);
        /// Path to the CA files to verify server certificate, may be empty.
        DECLARE_FIELD(path_to_ca_files, std::vector<std::string>, SetPathToCAFiles, {});
        /// Path to the directory with CA files used to validate server certificate, may be empty.
        DECLARE_FIELD(path_to_ca_directory, std::string, SetPathToCADirectory, "");

        /** Min and max protocol versions to use, set with SSL_CTX_set_min_proto_version and SSL_CTX_set_max_proto_version
         *  for details see https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_min_proto_version.html
         */
        DECLARE_FIELD(min_protocol_version, int, SetMinProtocolVersion, DEFAULT_VALUE);
        DECLARE_FIELD(max_protocol_version, int, SetMaxProtocolVersion, DEFAULT_VALUE);

        /** Options to be set with SSL_CTX_set_options,
         * for details see https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_options.html
        */
        DECLARE_FIELD(context_options, int, SetContextOptions, DEFAULT_VALUE);

        /** Use SNI at ClientHello
         */
        DECLARE_FIELD(use_sni, bool, SetUseSNI, true);

        /** Skip SSL session verification (server's certificate, etc).
         *
         *  WARNING: settig to true will bypass all SSL session checks, which
         *  is dangerous, but can be used against self-signed certificates, e.g. for testing purposes.
         */
        DECLARE_FIELD(skip_verification, bool, SetSkipVerification, false);

        /** Mode of verifying host ssl certificate against name of the host, set with SSL_set_hostflags.
         *  For details see https://www.openssl.org/docs/man1.1.1/man3/SSL_set_hostflags.html
         */
        DECLARE_FIELD(host_flags, int, SetHostVerifyFlags, DEFAULT_VALUE);

        struct CommandAndValue {
            std::string command;
            std::optional<std::string> value = std::nullopt;
        };
        /** Extra configuration options, set with SSL_CONF_cmd.
         *  For deatils see https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html
         *
         *  Takes multiple pairs of command-value strings, all commands are supported,
         *  and prefix is empty.
         *  i.e. pass `sigalgs` or `SignatureAlgorithms` instead of `-sigalgs`.
         *
         *  Rewrites any other options/flags if set in other ways.
         */
        DECLARE_FIELD(configuration, std::vector<CommandAndValue>, SetConfiguration, {});

        static const int DEFAULT_VALUE = -1;
    };

    // By default SSL is turned off.
    std::optional<SSLOptions> ssl_options = std::nullopt;

    // Will throw an exception if client was built without SSL support.
    ClientOptions& SetSSLOptions(SSLOptions options);

#undef DECLARE_FIELD
};

std::ostream& operator<<(std::ostream& os, const ClientOptions& options);
std::ostream& operator<<(std::ostream& os, const Endpoint& options);

class SocketFactory;

struct ExternalTable {
  const std::string_view name;
  const Block& data;
};

using ExternalTables = std::vector<ExternalTable>;

/**
 *
 */
class Client {
public:
     Client(const ClientOptions& opts);
     Client(const ClientOptions& opts,
            std::unique_ptr<SocketFactory> socket_factory);
    ~Client();

    /// Intends for execute arbitrary queries.
    void Execute(const Query& query);

    /// Intends for execute select queries.  Data will be returned with
    /// one or more call of \p cb.
    void Select(const std::string& query, SelectCallback cb);
    void Select(const std::string& query, const std::string& query_id, SelectCallback cb);

    /// Executes a select query which can be canceled by returning false from
    /// the data handler function \p cb.
    void SelectCancelable(const std::string& query, SelectCancelableCallback cb);
    void SelectCancelable(const std::string& query, const std::string& query_id, SelectCancelableCallback cb);

    // The same as Select but with an external data
    // required for the query, see https://clickhouse.com/docs/engines/table-engines/special/external-data
    void SelectWithExternalData(const std::string& query, const ExternalTables& external_tables, SelectCallback cb);
    void SelectWithExternalData(const std::string& query, const std::string& query_id, const ExternalTables& external_tables, SelectCallback cb);

    // The same as SelectWithExternalData but can be canceled by returning false from
    // the data handler function \p cb.
    void SelectWithExternalDataCancelable(const std::string& query, const ExternalTables& external_tables, SelectCancelableCallback cb);
    void SelectWithExternalDataCancelable(const std::string& query, const std::string& query_id, const ExternalTables& external_tables, SelectCancelableCallback cb);

    /// Alias for Execute.
    void Select(const Query& query);

    /// Intends for insert block of data into a table \p table_name.
    void Insert(const std::string& table_name, const Block& block);
    void Insert(const std::string& table_name, const std::string& query_id, const Block& block);

    /// Ping server for aliveness.
    void Ping();

    /// Reset connection with initial params.
    void ResetConnection();

    const ServerInfo& GetServerInfo() const;

    /// Get current connected endpoint.
    /// In case when client is not connected to any endpoint, nullopt will returned.
    const std::optional<Endpoint>& GetCurrentEndpoint() const;

    // Try to connect to different endpoints one by one only one time. If it doesn't work, throw an exception.
    void ResetConnectionEndpoint();

    struct Version
    {
        uint16_t major;
        uint16_t minor;
        uint16_t patch;
        uint16_t build;
        const char * extra;
    };

    static Version GetVersion();

private:
    const ClientOptions options_;

    class Impl;
    std::unique_ptr<Impl> impl_;
};

}