/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

/*
 * Copyright (C) 2015 ScyllaDB
 *
 * Modified by ScyllaDB
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <seastar/core/metrics.hh>

#include "cql3/query_processor.hh"
#include "cql3/CqlParser.hpp"
#include "cql3/error_collector.hh"
#include "cql3/statements/batch_statement.hh"
#include "cql3/util.hh"

#include "transport/messages/result_message.hh"

#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
#include <cryptopp/md5.h>

namespace cql3 {

using namespace statements;
using namespace transport::messages;

logging::logger log("query_processor");

distributed<query_processor> _the_query_processor;

const sstring query_processor::CQL_VERSION = "3.3.1";

class query_processor::internal_state {
    service::query_state _qs;
public:
    internal_state()
        : _qs(service::client_state{service::client_state::internal_tag()})
    { }
    operator service::query_state&() {
        return _qs;
    }
    operator const service::query_state&() const {
        return _qs;
    }
    operator service::client_state&() {
        return _qs.get_client_state();
    }
    operator const service::client_state&() const {
        return _qs.get_client_state();
    }
    api::timestamp_type next_timestamp() {
        return _qs.get_client_state().get_timestamp();
    }
};

api::timestamp_type query_processor::next_timestamp() {
    return _internal_state->next_timestamp();
}

query_processor::query_processor(distributed<service::storage_proxy>& proxy,
                                 distributed<database>& db)
    : _migration_subscriber{std::make_unique<migration_subscriber>(this)}
    , _proxy(proxy)
    , _db(db)
    , _internal_state(new internal_state())
{
    namespace sm = seastar::metrics;

    _metrics.add_group("query_processor", {
        sm::make_derive("statements_prepared", _stats.prepare_invocations,
                        sm::description("Counts a total number of parsed CQL requests.")),
    });

    _metrics.add_group("cql", {
        sm::make_derive("reads", _cql_stats.reads,
                        sm::description("Counts a total number of CQL read requests.")),

        sm::make_derive("inserts", _cql_stats.inserts,
                        sm::description("Counts a total number of CQL INSERT requests.")),

        sm::make_derive("updates", _cql_stats.updates,
                        sm::description("Counts a total number of CQL UPDATE requests.")),

        sm::make_derive("deletes", _cql_stats.deletes,
                        sm::description("Counts a total number of CQL DELETE requests.")),

        sm::make_derive("batches", _cql_stats.batches,
                        sm::description("Counts a total number of CQL BATCH requests.")),

        sm::make_derive("statements_in_batches", _cql_stats.statements_in_batches,
                        sm::description("Counts a total number of sub-statements in CQL BATCH requests.")),

        sm::make_derive("batches_pure_logged", _cql_stats.batches_pure_logged,
                        sm::description("Counts a total number of LOGGED batches that were executed as LOGGED batches.")),

        sm::make_derive("batches_pure_unlogged", _cql_stats.batches_pure_unlogged,
                        sm::description("Counts a total number of UNLOGGED batches that were executed as UNLOGGED batches.")),

        sm::make_derive("batches_unlogged_from_logged", _cql_stats.batches_unlogged_from_logged,
                        sm::description("Counts a total number of LOGGED batches that were executed as UNLOGGED batches.")),
    });

    service::get_local_migration_manager().register_listener(_migration_subscriber.get());
}

query_processor::~query_processor()
{}

future<> query_processor::stop()
{
    service::get_local_migration_manager().unregister_listener(_migration_subscriber.get());
    return make_ready_future<>();
}

future<::shared_ptr<result_message>>
query_processor::process(const sstring_view& query_string, service::query_state& query_state, query_options& options)
{
    log.trace("process: \"{}\"", query_string);
    tracing::trace(query_state.get_trace_state(), "Parsing a statement");
    auto p = get_statement(query_string, query_state.get_client_state());
    options.prepare(p->bound_names);
    auto cql_statement = p->statement;
    if (cql_statement->get_bound_terms() != options.get_values_count()) {
        throw exceptions::invalid_request_exception("Invalid amount of bind variables");
    }

    warn(unimplemented::cause::METRICS);
#if 0
        if (!queryState.getClientState().isInternal)
            metrics.regularStatementsExecuted.inc();
#endif
    tracing::trace(query_state.get_trace_state(), "Processing a statement");
    return process_statement(std::move(cql_statement), query_state, options);
}

future<::shared_ptr<result_message>>
query_processor::process_statement(::shared_ptr<cql_statement> statement,
                                   service::query_state& query_state,
                                   const query_options& options)
{
#if 0
        logger.trace("Process {} @CL.{}", statement, options.getConsistency());
#endif

    return statement->check_access(query_state.get_client_state()).then([this, statement, &query_state, &options]() {
        auto& client_state = query_state.get_client_state();

        statement->validate(_proxy, client_state);

        auto fut = make_ready_future<::shared_ptr<transport::messages::result_message>>();
        if (client_state.is_internal()) {
            fut = statement->execute_internal(_proxy, query_state, options);
        } else  {
            fut = statement->execute(_proxy, query_state, options);
        }

        return fut.then([statement] (auto msg) {
            if (msg) {
                return make_ready_future<::shared_ptr<result_message>>(std::move(msg));
            }
            return make_ready_future<::shared_ptr<result_message>>(
                ::make_shared<result_message::void_message>());
        });
    });
}

future<::shared_ptr<transport::messages::result_message::prepared>>
query_processor::prepare(const std::experimental::string_view& query_string, service::query_state& query_state)
{
    auto& client_state = query_state.get_client_state();
    return prepare(query_string, client_state, client_state.is_thrift());
}

future<::shared_ptr<transport::messages::result_message::prepared>>
query_processor::prepare(const std::experimental::string_view& query_string,
                         const service::client_state& client_state,
                         bool for_thrift)
{
    auto existing = get_stored_prepared_statement(query_string, client_state.get_raw_keyspace(), for_thrift);
    if (existing) {
        return make_ready_future<::shared_ptr<transport::messages::result_message::prepared>>(existing);
    }

    return futurize<::shared_ptr<transport::messages::result_message::prepared>>::apply([this, &query_string, &client_state, for_thrift] {
        auto prepared = get_statement(query_string, client_state);
        auto bound_terms = prepared->statement->get_bound_terms();
        if (bound_terms > std::numeric_limits<uint16_t>::max()) {
            throw exceptions::invalid_request_exception(sprint("Too many markers(?). %d markers exceed the allowed maximum of %d", bound_terms, std::numeric_limits<uint16_t>::max()));
        }
        assert(bound_terms == prepared->bound_names.size());
        return store_prepared_statement(query_string, client_state.get_raw_keyspace(), std::move(prepared), for_thrift);
    });
}

::shared_ptr<transport::messages::result_message::prepared>
query_processor::get_stored_prepared_statement(const std::experimental::string_view& query_string,
                                               const sstring& keyspace,
                                               bool for_thrift)
{
    if (for_thrift) {
        auto statement_id = compute_thrift_id(query_string, keyspace);
        auto it = _thrift_prepared_statements.find(statement_id);
        if (it == _thrift_prepared_statements.end()) {
            return ::shared_ptr<result_message::prepared>();
        }
        return ::make_shared<result_message::prepared::thrift>(statement_id, it->second->checked_weak_from_this());
    } else {
        auto statement_id = compute_id(query_string, keyspace);
        auto it = _prepared_statements.find(statement_id);
        if (it == _prepared_statements.end()) {
            return ::shared_ptr<result_message::prepared>();
        }
        return ::make_shared<result_message::prepared::cql>(statement_id, it->second->checked_weak_from_this());
    }
}

future<::shared_ptr<transport::messages::result_message::prepared>>
query_processor::store_prepared_statement(const std::experimental::string_view& query_string,
                                          const sstring& keyspace,
                                          std::unique_ptr<statements::prepared_statement> prepared,
                                          bool for_thrift)
{
#if 0
    // Concatenate the current keyspace so we don't mix prepared statements between keyspace (#5352).
    // (if the keyspace is null, queryString has to have a fully-qualified keyspace so it's fine.
    long statementSize = measure(prepared.statement);
    // don't execute the statement if it's bigger than the allowed threshold
    if (statementSize > MAX_CACHE_PREPARED_MEMORY)
        throw new InvalidRequestException(String.format("Prepared statement of size %d bytes is larger than allowed maximum of %d bytes.",
                                                        statementSize,
                                                        MAX_CACHE_PREPARED_MEMORY));
#endif
    prepared->raw_cql_statement = query_string.data();
    if (for_thrift) {
        auto statement_id = compute_thrift_id(query_string, keyspace);
        auto msg = ::make_shared<result_message::prepared::thrift>(statement_id, prepared->checked_weak_from_this());
        _thrift_prepared_statements.emplace(statement_id, std::move(prepared));
        return make_ready_future<::shared_ptr<result_message::prepared>>(std::move(msg));
    } else {
        auto statement_id = compute_id(query_string, keyspace);
        auto msg = ::make_shared<result_message::prepared::cql>(statement_id, prepared->checked_weak_from_this());
        _prepared_statements.emplace(statement_id, std::move(prepared));
        return make_ready_future<::shared_ptr<result_message::prepared>>(std::move(msg));
    }
}

static bytes md5_calculate(const std::experimental::string_view& s)
{
    constexpr size_t size = CryptoPP::Weak1::MD5::DIGESTSIZE;
    CryptoPP::Weak::MD5 hash;
    unsigned char digest[size];
    hash.CalculateDigest(digest, reinterpret_cast<const unsigned char*>(s.data()), s.size());
    return std::move(bytes{reinterpret_cast<const int8_t*>(digest), size});
}

static sstring hash_target(const std::experimental::string_view& query_string, const sstring& keyspace) {
    return keyspace + query_string.to_string();
}

bytes query_processor::compute_id(const std::experimental::string_view& query_string, const sstring& keyspace)
{
    return md5_calculate(hash_target(query_string, keyspace));
}

int32_t query_processor::compute_thrift_id(const std::experimental::string_view& query_string, const sstring& keyspace)
{
    auto target = hash_target(query_string, keyspace);
    uint32_t h = 0;
    for (auto&& c : hash_target(query_string, keyspace)) {
        h = 31*h + c;
    }
    return static_cast<int32_t>(h);
}

std::unique_ptr<prepared_statement>
query_processor::get_statement(const sstring_view& query, const service::client_state& client_state)
{
#if 0
        Tracing.trace("Parsing {}", queryStr);
#endif
    ::shared_ptr<raw::parsed_statement> statement = parse_statement(query);

    // Set keyspace for statement that require login
    auto cf_stmt = dynamic_pointer_cast<raw::cf_statement>(statement);
    if (cf_stmt) {
        cf_stmt->prepare_keyspace(client_state);
    }
#if 0
        Tracing.trace("Preparing statement");
#endif
    ++_stats.prepare_invocations;
    return statement->prepare(_db.local(), _cql_stats);
}

::shared_ptr<raw::parsed_statement>
query_processor::parse_statement(const sstring_view& query)
{
    try {
        auto statement = util::do_with_parser(query,  std::mem_fn(&cql3_parser::CqlParser::query));
        if (!statement) {
            throw exceptions::syntax_exception("Parsing failed");
        }
        return statement;
    } catch (const exceptions::recognition_exception& e) {
        throw exceptions::syntax_exception(sprint("Invalid or malformed CQL query string: %s", e.what()));
    } catch (const exceptions::cassandra_exception& e) {
        throw;
    } catch (const std::exception& e) {
        log.error("The statement: {} could not be parsed: {}", query, e.what());
        throw exceptions::syntax_exception(sprint("Failed parsing statement: [%s] reason: %s", query, e.what()));
    }
}

query_options query_processor::make_internal_options(const statements::prepared_statement::checked_weak_ptr& p,
                                                     const std::initializer_list<data_value>& values,
                                                     db::consistency_level cl)
{
    if (p->bound_names.size() != values.size()) {
        throw std::invalid_argument(sprint("Invalid number of values. Expecting %d but got %d", p->bound_names.size(), values.size()));
    }
    auto ni = p->bound_names.begin();
    std::vector<cql3::raw_value> bound_values;
    for (auto& v : values) {
        auto& n = *ni++;
        if (v.type() == bytes_type) {
            bound_values.push_back(cql3::raw_value::make_value(value_cast<bytes>(v)));
        } else if (v.is_null()) {
            bound_values.push_back(cql3::raw_value::make_null());
        } else {
            bound_values.push_back(cql3::raw_value::make_value(n->type->decompose(v)));
        }
    }
    return query_options(cl, bound_values);
}

statements::prepared_statement::checked_weak_ptr query_processor::prepare_internal(const sstring& query_string)
{
    auto& p = _internal_statements[query_string];
    if (p == nullptr) {
        auto np = parse_statement(query_string)->prepare(_db.local(), _cql_stats);
        np->statement->validate(_proxy, *_internal_state);
        p = std::move(np); // inserts it into map
    }
    return p->checked_weak_from_this();
}

future<::shared_ptr<untyped_result_set>>
query_processor::execute_internal(const sstring& query_string,
                                  const std::initializer_list<data_value>& values)
{
    if (log.is_enabled(logging::log_level::trace)) {
        log.trace("execute_internal: \"{}\" ({})", query_string, ::join(", ", values));
    }
    return execute_internal(prepare_internal(query_string), values);
}

future<::shared_ptr<untyped_result_set>>
query_processor::execute_internal(statements::prepared_statement::checked_weak_ptr p,
                                  const std::initializer_list<data_value>& values)
{
    auto opts = make_internal_options(p, values);
    return do_with(std::move(opts), [this, p = std::move(p)](auto& opts) {
        return p->statement->execute_internal(_proxy, *_internal_state, opts).then([stmt = p->statement](auto msg) {
            return make_ready_future<::shared_ptr<untyped_result_set>>(::make_shared<untyped_result_set>(msg));
        });
    });
}

future<::shared_ptr<untyped_result_set>>
query_processor::process(const sstring& query_string,
                         db::consistency_level cl,
                         const std::initializer_list<data_value>& values,
                         bool cache)
{
    if (cache) {
        return process(prepare_internal(query_string), cl, values);
    } else {
        auto p = parse_statement(query_string)->prepare(_db.local(), _cql_stats);
        p->statement->validate(_proxy, *_internal_state);
        auto checked_weak_ptr = p->checked_weak_from_this();
        return process(std::move(checked_weak_ptr), cl, values).finally([p = std::move(p)] {});
    }
}

future<::shared_ptr<untyped_result_set>>
query_processor::process(statements::prepared_statement::checked_weak_ptr p,
                         db::consistency_level cl,
                         const std::initializer_list<data_value>& values)
{
    auto opts = make_internal_options(p, values, cl);
    return do_with(std::move(opts), [this, p = std::move(p)](auto & opts) {
        return p->statement->execute(_proxy, *_internal_state, opts).then([](auto msg) {
            return make_ready_future<::shared_ptr<untyped_result_set>>(::make_shared<untyped_result_set>(msg));
        });
    });
}

future<::shared_ptr<transport::messages::result_message>>
query_processor::process_batch(::shared_ptr<statements::batch_statement> batch,
                               service::query_state& query_state,
                               query_options& options)
{
    return batch->check_access(query_state.get_client_state()).then([this, &query_state, &options, batch] {
        batch->validate();
        batch->validate(_proxy, query_state.get_client_state());
        return batch->execute(_proxy, query_state, options);
    });
}

query_processor::migration_subscriber::migration_subscriber(query_processor* qp)
    : _qp{qp}
{
}

void query_processor::migration_subscriber::on_create_keyspace(const sstring& ks_name)
{
}

void query_processor::migration_subscriber::on_create_column_family(const sstring& ks_name, const sstring& cf_name)
{
}

void query_processor::migration_subscriber::on_create_user_type(const sstring& ks_name, const sstring& type_name)
{
}

void query_processor::migration_subscriber::on_create_function(const sstring& ks_name, const sstring& function_name)
{
    log.warn("{} event ignored", __func__);
}

void query_processor::migration_subscriber::on_create_aggregate(const sstring& ks_name, const sstring& aggregate_name)
{
    log.warn("{} event ignored", __func__);
}

void query_processor::migration_subscriber::on_create_view(const sstring& ks_name, const sstring& view_name)
{
}

void query_processor::migration_subscriber::on_update_keyspace(const sstring& ks_name)
{
}

void query_processor::migration_subscriber::on_update_column_family(const sstring& ks_name, const sstring& cf_name, bool columns_changed)
{
    // #1255: Ignoring columns_changed deliberately.
    log.info("Column definitions for {}.{} changed, invalidating related prepared statements", ks_name, cf_name);
    remove_invalid_prepared_statements(ks_name, cf_name);
}

void query_processor::migration_subscriber::on_update_user_type(const sstring& ks_name, const sstring& type_name)
{
}

void query_processor::migration_subscriber::on_update_function(const sstring& ks_name, const sstring& function_name)
{
}

void query_processor::migration_subscriber::on_update_aggregate(const sstring& ks_name, const sstring& aggregate_name)
{
}

void query_processor::migration_subscriber::on_update_view(const sstring& ks_name, const sstring& view_name, bool columns_changed)
{
}

void query_processor::migration_subscriber::on_drop_keyspace(const sstring& ks_name)
{
    remove_invalid_prepared_statements(ks_name, std::experimental::nullopt);
}

void query_processor::migration_subscriber::on_drop_column_family(const sstring& ks_name, const sstring& cf_name)
{
    remove_invalid_prepared_statements(ks_name, cf_name);
}

void query_processor::migration_subscriber::on_drop_user_type(const sstring& ks_name, const sstring& type_name)
{
}

void query_processor::migration_subscriber::on_drop_function(const sstring& ks_name, const sstring& function_name)
{
    log.warn("{} event ignored", __func__);
}

void query_processor::migration_subscriber::on_drop_aggregate(const sstring& ks_name, const sstring& aggregate_name)
{
    log.warn("{} event ignored", __func__);
}

void query_processor::migration_subscriber::on_drop_view(const sstring& ks_name, const sstring& view_name)
{
}

void query_processor::migration_subscriber::remove_invalid_prepared_statements(sstring ks_name, std::experimental::optional<sstring> cf_name)
{
    _qp->invalidate_prepared_statements([&] (::shared_ptr<cql_statement> stmt) {
        return this->should_invalidate(ks_name, cf_name, stmt);
    });
}

bool query_processor::migration_subscriber::should_invalidate(sstring ks_name, std::experimental::optional<sstring> cf_name, ::shared_ptr<cql_statement> statement)
{
    return statement->depends_on_keyspace(ks_name) && (!cf_name || statement->depends_on_column_family(*cf_name));
}

}