/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *   Copyright 2020-Present Couchbase, 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.
 */

#pragma once

#include <couchbase/codec/tao_json_serializer.hxx>
#include <couchbase/common_options.hxx>
#include <couchbase/mutation_state.hxx>
#include <couchbase/query_error_context.hxx>
#include <couchbase/query_profile.hxx>
#include <couchbase/query_result.hxx>
#include <couchbase/query_scan_consistency.hxx>

#include <chrono>
#include <functional>
#include <memory>
#include <optional>

namespace couchbase
{
/**
 * Options for cluster#query() and scope#query().
 *
 * @since 1.0.0
 * @committed
 */
struct query_options : public common_options<query_options> {
    /**
     * Immutable value object representing consistent options.
     *
     * @since 1.0.0
     * @internal
     */
    struct built : public common_options<query_options>::built {
        const bool adhoc;
        const bool metrics;
        const bool readonly;
        const bool flex_index;
        const bool preserve_expiry;
        std::optional<bool> use_replica;
        std::optional<std::uint64_t> max_parallelism;
        std::optional<std::uint64_t> scan_cap;
        std::optional<std::chrono::milliseconds> scan_wait;
        std::optional<std::uint64_t> pipeline_batch;
        std::optional<std::uint64_t> pipeline_cap;
        std::optional<std::string> client_context_id;
        std::optional<query_scan_consistency> scan_consistency;
        std::vector<mutation_token> mutation_state;
        const query_profile profile;
        std::vector<codec::binary> positional_parameters;
        std::map<std::string, codec::binary, std::less<>> named_parameters;
        std::map<std::string, codec::binary, std::less<>> raw;
    };

    /**
     * Validates options and returns them as an immutable value.
     *
     * @return consistent options as an immutable value
     *
     * @exception std::system_error with code errc::common::invalid_argument if the options are not valid
     *
     * @since 1.0.0
     * @internal
     */
    [[nodiscard]] auto build() const -> built
    {
        return {
            build_common_options(),
            adhoc_,
            metrics_,
            readonly_,
            flex_index_,
            preserve_expiry_,
            use_replica_,
            max_parallelism_,
            scan_cap_,
            scan_wait_,
            pipeline_batch_,
            pipeline_cap_,
            client_context_id_,
            scan_consistency_,
            mutation_state_,
            profile_,
            positional_parameters_,
            named_parameters_,
            raw_,
        };
    }

    /**
     * Allows turning this request into a prepared statement query.
     *
     * If set to `false`, the SDK will transparently perform "prepare and execute" logic the first time this
     * query is seen and then subsequently reuse the prepared statement name when sending it to the server. If a query
     * is executed frequently, this is a good way to speed it up since it will save the server the task of re-parsing
     * and analyzing the query.
     *
     * If you are using prepared statements, make sure that if certain parts of the query string change you are using
     * #named_parameters() or #positional_parameters(). If the statement string itself changes it cannot be cached.
     *
     * @param adhoc if set to false this query will be turned into a prepared statement query.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto adhoc(bool adhoc) -> query_options&
    {
        adhoc_ = adhoc;
        return self();
    }

    /**
     * Enables per-request metrics in the trailing section of the query.
     *
     * If this method is set to true, the server will send metrics back to the client which are available through the
     * {@link query_meta_data#metrics()} section. As opposed to {@link #profile(query_profile)}, returning metrics is rather
     * cheap and can also be enabled in production if needed.
     *
     * @param metrics set to true if the server should return simple query metrics.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto metrics(bool metrics) -> query_options&
    {
        metrics_ = metrics;
        return self();
    }

    /**
     * Customizes the server profiling level for this query.
     *
     * @note that you only want to tune this if you want to gather profiling/performance metrics for debugging. Turning
     * this on in production (depending on the level) will likely have performance impact on the server query engine
     * as a whole and on this query in particular!
     *
     * This is an Enterprise Edition feature. On Community Edition the parameter will be accepted, but no profiling
     * information returned.
     *
     * @param profile the custom query profile level for this query.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto profile(query_profile profile) -> query_options&
    {
        profile_ = profile;
        return self();
    }

    /**
     * Allows explicitly marking a query as being readonly and not mutating and documents on the server side.
     *
     * In addition to providing some security in that you are not accidentally modifying data, setting this flag to true also helps the
     * client to more proactively retry and re-dispatch a query since then it can be sure it is idempotent. As a result, if your query is
     * readonly then it is a good idea to set this flag.
     *
     * If set to true, then (at least) the following statements are not allowed:
     * <ol>
     *  <li>CREATE INDEX</li>
     *  <li>DROP INDEX</li>
     *  <li>INSERT</li>
     *  <li>MERGE</li>
     *  <li>UPDATE</li>
     *  <li>UPSERT</li>
     *  <li>DELETE</li>
     * </ol>
     *
     * @param readonly true if readonly should be set, false is the default and will use the server side default.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto readonly(bool readonly) -> query_options&
    {
        readonly_ = readonly;
        return self();
    }

    /**
     * Tells the query engine to use a flex index (utilizing the search service).
     *
     * @param flex_index if a flex index should be used, false is the default.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto flex_index(bool flex_index) -> query_options&
    {
        flex_index_ = flex_index;
        return self();
    }

    /**
     * Tells the query engine to preserve expiration values set on any documents modified by this query.
     *
     * This feature works from Couchbase Server 7.1.0 onwards.
     *
     * @param preserve_expiry whether expiration values should be preserved, the default is false.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto preserve_expiry(bool preserve_expiry) -> query_options&
    {
        preserve_expiry_ = preserve_expiry;
        return self();
    }

    /**
     * Specifies that the query engine should use replica nodes for KV fetches if the active node is down.
     *
     * @param use_replica whether replica nodes should be used if the active node is down. If not provided, the server default will be used.
     * @return the options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto use_replica(bool use_replica) -> query_options&
    {
        use_replica_ = use_replica;
        return self();
    }

    /**
     * Allows overriding the default maximum parallelism for the query execution on the server side.
     *
     * If 0 value is set, the parallelism is disabled. If not provided, the server default will be used.
     *
     * @param max_parallelism the maximum parallelism for this query, 0 value disable it.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto max_parallelism(std::uint64_t max_parallelism) -> query_options&
    {
        max_parallelism_ = max_parallelism;
        return self();
    }

    /**
     * Supports customizing the maximum buffered channel size between the indexer and the query service.
     *
     * This is an advanced API and should only be tuned with care. Use 0 to disable.
     *
     * @param scan_cap the scan cap size, use 0 value to disable.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto scan_cap(std::uint64_t scan_cap) -> query_options&
    {
        scan_cap_ = scan_cap;
        return self();
    }

    /**
     * Allows customizing how long the query engine is willing to wait until the index catches up to whatever scan
     * consistency is asked for in this query.
     *
     * @note that if {@link query_scan_consistency::not_bounded} is used, this method doesn't do anything at all. If no value is provided to
     * this method, the server default is used.
     *
     * @param wait the maximum duration the query engine is willing to wait before failing.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto scan_wait(std::chrono::milliseconds wait) -> query_options&
    {
        if (scan_consistency_ == query_scan_consistency::not_bounded) {
            scan_wait_.reset();
        } else {
            scan_wait_ = wait;
        }
        return self();
    }

    /**
     * Supports customizing the number of items execution operators can batch for fetch from the KV layer on the server.
     *
     * This is an advanced API and should only be tuned with care.
     *
     * @param pipeline_batch the pipeline batch size.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto pipeline_batch(std::uint64_t pipeline_batch) -> query_options&
    {
        pipeline_batch_ = pipeline_batch;
        return self();
    }

    /**
     *
     * Allows customizing the maximum number of items each execution operator can buffer between various operators on the server.
     *
     * This is an advanced API and should only be tuned with care.
     *
     * @param pipeline_cap the pipeline cap size.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto pipeline_cap(std::uint64_t pipeline_cap) -> query_options&
    {
        pipeline_cap_ = pipeline_cap;
        return self();
    }

    /**
     * Supports providing a custom client context ID for this query.
     *
     * If no client context ID is provided by the user, a UUID is generated and sent automatically so by default it is always possible to
     * identify a query when debugging.
     *
     * @param client_context_id the client context ID
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto client_context_id(std::string client_context_id) -> query_options&
    {
        if (client_context_id.empty()) {
            client_context_id_.reset();
        } else {
            client_context_id_ = std::move(client_context_id);
        }
        return self();
    }

    /**
     * Customizes the consistency guarantees for this query.
     *
     * Tuning the scan consistency allows to trade data "freshness" for latency and vice versa. By default
     * {@link query_scan_consistency::not_bounded} is used, which means that the server returns the data it has in the index right away.
     * This is fast, but might not include the most recent mutations. If you want to include all the mutations up to the point of the query,
     * use {@link query_scan_consistency::request_plus}.
     *
     * Note that you cannot use this method and {@link #consistent_with(const mutation_state&)} at the same time, since they are mutually
     * exclusive. As a rule of thumb, if you only care to be consistent with the mutation you just wrote on the same thread/app, use
     * {@link #consistent_with(const mutation_state&)}. If you need "global" scan consistency, use
     * {@link query_scan_consistency::request_plus} on this method.
     *
     * @param scan_consistency the index scan consistency to be used for this query
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto scan_consistency(query_scan_consistency scan_consistency) -> query_options&
    {
        scan_consistency_ = scan_consistency;
        mutation_state_.clear();
        return self();
    }

    /**
     * Sets the {@link mutation_token}s this query should be consistent with.
     *
     * These mutation tokens are returned from mutations (i.e. as part of a {@link mutation_result}) and if you want your
     * N1QL query to include those you need to pass the mutation tokens into a {@link mutation_state}.
     *
     * Note that you cannot use this method and {@link #scan_consistency(query_scan_consistency)} at the same time, since
     * they are mutually exclusive. As a rule of thumb, if you only care to be consistent with the mutation you just wrote
     * on the same thread/app, use this method. If you need "global" scan consistency, use
     * {@link query_scan_consistency#request_plus} on {@link #scan_consistency(query_scan_consistency)}.
     *
     * @param state the mutation state containing the mutation tokens.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    auto consistent_with(const mutation_state& state) -> query_options&
    {
        mutation_state_ = state.tokens();
        scan_consistency_.reset();
        return self();
    }

    /**
     *
     * @tparam Value
     * @param name
     * @param value
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    template<typename Value>
    auto raw(std::string name, const Value& value) -> query_options&
    {
        raw_[std::move(name)] = std::move(codec::tao_json_serializer::serialize(value));
        return self();
    }

    /**
     * Set list of positional parameters for a query.
     *
     * @tparam Parameters types for the parameters
     * @param parameters the sequence of positional parameters. Each entry will be encoded into JSON.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    template<typename... Parameters>
    auto positional_parameters(const Parameters&... parameters) -> query_options&
    {
        named_parameters_.clear();
        positional_parameters_.clear();
        encode_positional_parameters(parameters...);
        return self();
    }

    /**
     * Set list of named parameters for a query.
     *
     * @tparam Parameters types for the parameter pairs
     * @param parameters the sequence of name-value pairs. Each value will be encoded into JSON.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @committed
     */
    template<typename... Parameters>
    auto named_parameters(const Parameters&... parameters) -> query_options&
    {
        named_parameters_.clear();
        positional_parameters_.clear();
        encode_named_parameters(parameters...);
        return self();
    }

    /**
     * Set map of raw options for a query.
     *
     * This function expects that all parameters encoded into pairs containing mapping names of the parameter to valid JSON values encoded
     * as string.
     *
     * @note This function is low-level, and instead @ref raw() should be considered.
     *
     * @param options mapping of pairs, where each entry contains string with valid JSON value.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @uncommitted
     */
    auto encoded_raw_options(std::map<std::string, codec::binary, std::less<>> options) -> query_options&
    {
        raw_ = std::move(options);
        return self();
    }

    /**
     * Set list of positional parameters for a query.
     *
     * This function expects that all parameters encoded into byte strings containing valid JSON values.
     *
     * @note This function is low-level, and instead @ref positional_parameters() should be considered.
     *
     * @param parameters vector of binaries, where each entry contains string with valid JSON value.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @uncommitted
     */
    auto encoded_positional_parameters(std::vector<codec::binary> parameters) -> query_options&
    {
        named_parameters_.clear();
        positional_parameters_ = std::move(parameters);
        return self();
    }

    /**
     * Set map of named parameters for a query.
     *
     * This function expects that all parameters encoded into pairs containing mapping names of the parameter to valid JSON values encoded
     * as string.
     *
     * @note This function is low-level, and instead @ref named_parameters() should be considered.
     *
     * @param parameters mapping of pairs, where each entry contains string with valid JSON value.
     * @return this options builder for chaining purposes.
     *
     * @since 1.0.0
     * @uncommitted
     */
    auto encoded_named_parameters(std::map<std::string, codec::binary, std::less<>> parameters) -> query_options&
    {
        named_parameters_ = std::move(parameters);
        positional_parameters_.clear();
        return self();
    }

  private:
    template<typename Parameter, typename... Rest>
    void encode_positional_parameters(const Parameter& parameter, Rest... args)
    {
        positional_parameters_.emplace_back(std::move(codec::tao_json_serializer::serialize(parameter)));
        if constexpr (sizeof...(args) > 0) {
            encode_positional_parameters(args...);
        }
    }

    template<typename Name, typename Parameter, typename... Rest>
    void encode_named_parameters(const std::pair<Name, Parameter>& parameter, Rest... args)
    {
        named_parameters_[parameter.first] = std::move(codec::tao_json_serializer::serialize(parameter.second));
        if constexpr (sizeof...(args) > 0) {
            encode_named_parameters(args...);
        }
    }

    bool adhoc_{ true };
    bool metrics_{ false };
    bool readonly_{ false };
    bool flex_index_{ false };
    bool preserve_expiry_{ false };
    std::optional<bool> use_replica_{};
    std::optional<std::uint64_t> max_parallelism_{};
    std::optional<std::uint64_t> scan_cap_{};
    std::optional<std::uint64_t> pipeline_batch_{};
    std::optional<std::uint64_t> pipeline_cap_{};
    std::optional<std::string> client_context_id_{};
    std::optional<std::chrono::milliseconds> scan_wait_{};
    std::optional<query_scan_consistency> scan_consistency_{};
    std::vector<mutation_token> mutation_state_{};
    query_profile profile_{ query_profile::off };
    std::vector<codec::binary> positional_parameters_{};
    std::map<std::string, codec::binary, std::less<>> raw_{};
    std::map<std::string, codec::binary, std::less<>> named_parameters_{};
};

/**
 * The signature for the handler of the @ref cluster#query() and @ref scope#query() operations
 *
 * @since 1.0.0
 * @uncommitted
 */
using query_handler = std::function<void(couchbase::query_error_context, query_result)>;

#ifndef COUCHBASE_CXX_CLIENT_DOXYGEN
namespace core
{
class cluster;
namespace impl
{

/**
 * @since 1.0.0
 * @internal
 */
void
initiate_query_operation(std::shared_ptr<couchbase::core::cluster> core,
                         std::string statement,
                         std::optional<std::string> query_context,
                         query_options::built options,
                         query_handler&& handler);
#endif
} // namespace impl
} // namespace core
} // namespace couchbase
