#include <Interpreters/Cluster.h>
#include <Common/DNSCache.h>
#include <Common/escapeForFileName.h>
#include <Common/isLocalAddress.h>
#include <Common/SimpleCache.h>
#include <Common/StringUtils/StringUtils.h>
#include <Common/parseAddress.h>
#include <IO/HexWriteBuffer.h>
#include <IO/WriteHelpers.h>
#include <IO/ReadHelpers.h>
#include <Poco/Util/AbstractConfiguration.h>
#include <Poco/Util/Application.h>
#include <openssl/sha.h>

namespace DB
{

namespace ErrorCodes
{
    extern const int UNKNOWN_ELEMENT_IN_CONFIG;
    extern const int EXCESSIVE_ELEMENT_IN_CONFIG;
    extern const int LOGICAL_ERROR;
    extern const int SHARD_HAS_NO_CONNECTIONS;
    extern const int SYNTAX_ERROR;
}

namespace
{

/// Default shard weight.
static constexpr UInt32 default_weight = 1;

inline bool isLocal(const Cluster::Address & address, UInt16 clickhouse_port)
{
    ///    If there is replica, for which:
    /// - its port is the same that the server is listening;
    /// - its host is resolved to set of addresses, one of which is the same as one of addresses of network interfaces of the server machine*;
    /// then we must go to this shard without any inter-process communication.
    ///
    /// * - this criteria is somewhat approximate.
    ///
    /// Also, replica is considered non-local, if it has default database set
    ///  (only reason is to avoid query rewrite).

    return address.default_database.empty() && isLocalAddress(address.resolved_address, clickhouse_port);
}


Poco::Net::SocketAddress resolveSocketAddress(const String & host, UInt16 port)
{
    return Poco::Net::SocketAddress(DNSCache::instance().resolveHost(host), port);
}

}

/// Implementation of Cluster::Address class

Cluster::Address::Address(Poco::Util::AbstractConfiguration & config, const String & config_prefix)
{
    UInt16 clickhouse_port = config.getInt("tcp_port", 0);

    host_name = config.getString(config_prefix + ".host");
    port = static_cast<UInt16>(config.getInt(config_prefix + ".port"));
    resolved_address = resolveSocketAddress(host_name, port);
    user = config.getString(config_prefix + ".user", "default");
    password = config.getString(config_prefix + ".password", "");
    default_database = config.getString(config_prefix + ".default_database", "");
    is_local = isLocal(*this, clickhouse_port);
}


Cluster::Address::Address(const String & host_port_, const String & user_, const String & password_, UInt16 clickhouse_port)
    : user(user_), password(password_)
{
    auto parsed_host_port = parseAddress(host_port_, clickhouse_port);

    resolved_address = resolveSocketAddress(parsed_host_port.first, parsed_host_port.second);
    host_name = parsed_host_port.first;
    port = parsed_host_port.second;
    is_local = isLocal(*this, clickhouse_port);
}


String Cluster::Address::toString() const
{
    return toString(host_name, port);
}

String Cluster::Address::toString(const String & host_name, UInt16 port)
{
    return escapeForFileName(host_name) + ':' + DB::toString(port);
}

String Cluster::Address::readableString() const
{
    return host_name + ':' + DB::toString(port);
}

void Cluster::Address::fromString(const String & host_port_string, String & host_name, UInt16 & port)
{
    auto pos = host_port_string.find_last_of(':');
    if (pos == std::string::npos)
        throw Exception("Incorrect <host>:<port> format " + host_port_string, ErrorCodes::SYNTAX_ERROR);

    host_name = unescapeForFileName(host_port_string.substr(0, pos));
    port = parse<UInt16>(host_port_string.substr(pos + 1));
}


String Cluster::Address::toStringFull() const
{
    return
        escapeForFileName(user) +
        (password.empty() ? "" : (':' + escapeForFileName(password))) + '@' +
        escapeForFileName(resolved_address.host().toString()) + ':' +
        std::to_string(resolved_address.port()) +
        (default_database.empty() ? "" : ('#' + escapeForFileName(default_database)));
}


/// Implementation of Clusters class

Clusters::Clusters(Poco::Util::AbstractConfiguration & config, const Settings & settings, const String & config_name)
{
    Poco::Util::AbstractConfiguration::Keys config_keys;
    config.keys(config_name, config_keys);

    for (const auto & key : config_keys)
        impl.emplace(key, std::make_shared<Cluster>(config, settings, config_name + "." + key));
}


ClusterPtr Clusters::getCluster(const std::string & cluster_name) const
{
    std::lock_guard lock(mutex);

    auto it = impl.find(cluster_name);
    return (it != impl.end()) ? it->second : nullptr;
}


void Clusters::setCluster(const String & cluster_name, const std::shared_ptr<Cluster> & cluster)
{
    std::lock_guard lock(mutex);
    impl[cluster_name] = cluster;
}


void Clusters::updateClusters(Poco::Util::AbstractConfiguration & config, const Settings & settings, const String & config_name)
{
    Poco::Util::AbstractConfiguration::Keys config_keys;
    config.keys(config_name, config_keys);

    std::lock_guard lock(mutex);

    for (const auto & key : config_keys)
    {
        auto it = impl.find(key);
        auto new_cluster = std::make_shared<Cluster>(config, settings, config_name + "." + key);

        if (it == impl.end())
            impl.emplace(key, std::move(new_cluster));
        else
        {
            //TODO: Check that cluster update is necessarily
            it->second = std::move(new_cluster);
        }
    }
}

Clusters::Impl Clusters::getContainer() const
{
    std::lock_guard lock(mutex);
    /// The following line copies container of shared_ptrs to return value under lock
    return impl;
}


/// Implementation of `Cluster` class

Cluster::Cluster(Poco::Util::AbstractConfiguration & config, const Settings & settings, const String & cluster_name)
{
    Poco::Util::AbstractConfiguration::Keys config_keys;
    config.keys(cluster_name, config_keys);

    if (config_keys.empty())
        throw Exception("No cluster elements (shard, node) specified in config at path " + cluster_name, ErrorCodes::SHARD_HAS_NO_CONNECTIONS);

    const auto & config_prefix = cluster_name + ".";

    UInt32 current_shard_num = 1;

    for (const auto & key : config_keys)
    {
        if (startsWith(key, "node"))
        {
            /// Shard without replicas.

            Addresses addresses;

            const auto & prefix = config_prefix + key;
            const auto weight = config.getInt(prefix + ".weight", default_weight);

            addresses.emplace_back(config, prefix);
            addresses.back().replica_num = 1;
            const auto & address = addresses.back();

            ShardInfo info;
            info.shard_num = current_shard_num;
            info.weight = weight;

            if (address.is_local)
                info.local_addresses.push_back(address);
            else
            {
                ConnectionPoolPtrs pools;
                pools.push_back(std::make_shared<ConnectionPool>(
                    settings.distributed_connections_pool_size,
                    address.host_name, address.port, address.resolved_address,
                    address.default_database, address.user, address.password,
                    ConnectionTimeouts::getTCPTimeouts(settings).getSaturated(settings.limits.max_execution_time),
                    "server", Protocol::Compression::Enable, Protocol::Encryption::Disable));

                info.pool = std::make_shared<ConnectionPoolWithFailover>(
                        std::move(pools), settings.load_balancing, settings.connections_with_failover_max_tries);
            }

            if (weight)
                slot_to_shard.insert(std::end(slot_to_shard), weight, shards_info.size());

            shards_info.push_back(info);
            addresses_with_failover.push_back(addresses);
        }
        else if (startsWith(key, "shard"))
        {
            /// Shard with replicas.

            Poco::Util::AbstractConfiguration::Keys replica_keys;
            config.keys(config_prefix + key, replica_keys);

            addresses_with_failover.emplace_back();
            Addresses & replica_addresses = addresses_with_failover.back();
            UInt32 current_replica_num = 1;

            const auto & partial_prefix = config_prefix + key + ".";
            const auto weight = config.getUInt(partial_prefix + ".weight", default_weight);

            bool internal_replication = config.getBool(partial_prefix + ".internal_replication", false);

            /// in case of internal_replication we will be appending names to dir_name_for_internal_replication
            std::string dir_name_for_internal_replication;

            auto first = true;
            for (const auto & replica_key : replica_keys)
            {
                if (startsWith(replica_key, "weight") || startsWith(replica_key, "internal_replication"))
                    continue;

                if (startsWith(replica_key, "replica"))
                {
                    replica_addresses.emplace_back(config, partial_prefix + replica_key);
                    replica_addresses.back().replica_num = current_replica_num;
                    ++current_replica_num;

                    if (!replica_addresses.back().is_local)
                    {
                        if (internal_replication)
                        {
                            auto dir_name = replica_addresses.back().toStringFull();
                            if (first)
                                dir_name_for_internal_replication = dir_name;
                            else
                                dir_name_for_internal_replication += "," + dir_name;
                        }

                        if (first) first = false;
                    }
                }
                else
                    throw Exception("Unknown element in config: " + replica_key, ErrorCodes::UNKNOWN_ELEMENT_IN_CONFIG);
            }

            Addresses shard_local_addresses;

            ConnectionPoolPtrs replicas;
            replicas.reserve(replica_addresses.size());

            for (const auto & replica : replica_addresses)
            {
                if (replica.is_local)
                    shard_local_addresses.push_back(replica);
                else
                {
                    replicas.emplace_back(std::make_shared<ConnectionPool>(
                        settings.distributed_connections_pool_size,
                        replica.host_name, replica.port, replica.resolved_address,
                        replica.default_database, replica.user, replica.password,
                        ConnectionTimeouts::getTCPTimeouts(settings).getSaturated(settings.limits.max_execution_time),
                        "server", Protocol::Compression::Enable, Protocol::Encryption::Disable));
                }
            }

            ConnectionPoolWithFailoverPtr shard_pool;
            if (!replicas.empty())
                shard_pool = std::make_shared<ConnectionPoolWithFailover>(
                        std::move(replicas), settings.load_balancing, settings.connections_with_failover_max_tries);

            if (weight)
                slot_to_shard.insert(std::end(slot_to_shard), weight, shards_info.size());

            shards_info.push_back({std::move(dir_name_for_internal_replication), current_shard_num, weight,
                shard_local_addresses, shard_pool, internal_replication});
        }
        else
            throw Exception("Unknown element in config: " + key, ErrorCodes::UNKNOWN_ELEMENT_IN_CONFIG);

        ++current_shard_num;
    }

    if (addresses_with_failover.empty())
        throw Exception("There must be either 'node' or 'shard' elements in config", ErrorCodes::EXCESSIVE_ELEMENT_IN_CONFIG);

    initMisc();
}


Cluster::Cluster(const Settings & settings, const std::vector<std::vector<String>> & names,
                 const String & username, const String & password, UInt16 clickhouse_port, bool treat_local_as_shared)
{
    UInt32 current_shard_num = 1;

    for (const auto & shard : names)
    {
        Addresses current;
        for (auto & replica : shard)
            current.emplace_back(replica, username, password, clickhouse_port);

        addresses_with_failover.emplace_back(current);

        ConnectionPoolPtrs replicas;
        replicas.reserve(current.size());

        Addresses shard_local_addresses;

        for (const auto & replica : current)
        {
            if (replica.is_local && !treat_local_as_shared)
                shard_local_addresses.push_back(replica);
            else
            {
                replicas.emplace_back(std::make_shared<ConnectionPool>(
                        settings.distributed_connections_pool_size,
                        replica.host_name, replica.port, replica.resolved_address,
                        replica.default_database, replica.user, replica.password,
                        ConnectionTimeouts::getHTTPTimeouts(settings).getSaturated(settings.limits.max_execution_time),
                        "server", Protocol::Compression::Enable, Protocol::Encryption::Disable));
            }
        }

        ConnectionPoolWithFailoverPtr shard_pool = std::make_shared<ConnectionPoolWithFailover>(
                std::move(replicas), settings.load_balancing, settings.connections_with_failover_max_tries);

        slot_to_shard.insert(std::end(slot_to_shard), default_weight, shards_info.size());
        shards_info.push_back({{}, current_shard_num, default_weight, std::move(shard_local_addresses), shard_pool, false});
        ++current_shard_num;
    }

    initMisc();
}


Poco::Timespan Cluster::saturate(const Poco::Timespan & v, const Poco::Timespan & limit)
{
    if (limit.totalMicroseconds() == 0)
        return v;
    else
        return (v > limit) ? limit : v;
}


void Cluster::initMisc()
{
    for (const auto & shard_info : shards_info)
    {
        if (!shard_info.isLocal() && !shard_info.hasRemoteConnections())
            throw Exception("Found shard without any specified connection",
                ErrorCodes::SHARD_HAS_NO_CONNECTIONS);
    }

    for (const auto & shard_info : shards_info)
    {
        if (shard_info.isLocal())
            ++local_shard_count;
        else
            ++remote_shard_count;
    }

    for (auto & shard_info : shards_info)
    {
        if (!shard_info.isLocal())
        {
            any_remote_shard_info = &shard_info;
            break;
        }
    }
}


std::unique_ptr<Cluster> Cluster::getClusterWithSingleShard(size_t index) const
{
    return std::unique_ptr<Cluster>{ new Cluster(*this, index) };
}

Cluster::Cluster(const Cluster & from, size_t index)
    : shards_info{from.shards_info[index]}
{
    if (!from.addresses_with_failover.empty())
        addresses_with_failover.emplace_back(from.addresses_with_failover[index]);

    initMisc();
}

}