/*
 * Copyright (C) 2015-present ScyllaDB
 */

/*
 * SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
 */

#pragma once

#include "replica/database.hh"
#include <seastar/json/json_elements.hh>
#include <any>
#include "api/api_init.hh"

namespace api {

void set_column_family(http_context& ctx, httpd::routes& r, sharded<replica::database>& db);
void unset_column_family(http_context& ctx, httpd::routes& r);

table_info parse_table_info(const sstring& name, const replica::database& db);

template<class Mapper, class I, class Reducer>
future<I> map_reduce_cf_raw(sharded<replica::database>& db, const sstring& name, I init,
        Mapper mapper, Reducer reducer) {
    auto uuid = parse_table_info(name, db.local()).id;
    using mapper_type = std::function<future<std::unique_ptr<std::any>>(replica::database&)>;
    using reducer_type = std::function<std::unique_ptr<std::any>(std::unique_ptr<std::any>, std::unique_ptr<std::any>)>;
    return db.map_reduce0(mapper_type([mapper, uuid](replica::database& db) {
        return futurize_invoke([mapper, &db, uuid] {
            return mapper(db.find_column_family(uuid));
        }).then([] (auto result) {
            return std::make_unique<std::any>(I(std::move(result)));
        });
    }), std::make_unique<std::any>(std::move(init)), reducer_type([reducer = std::move(reducer)] (std::unique_ptr<std::any> a, std::unique_ptr<std::any> b) mutable {
        return std::make_unique<std::any>(I(reducer(std::any_cast<I>(std::move(*a)), std::any_cast<I>(std::move(*b)))));
    })).then([] (std::unique_ptr<std::any> r) {
        return std::any_cast<I>(std::move(*r));
    });
}


template<class Mapper, class I, class Reducer>
future<json::json_return_type> map_reduce_cf(sharded<replica::database>& db, const sstring& name, I init,
        Mapper mapper, Reducer reducer) {
    return map_reduce_cf_raw(db, name, init, mapper, reducer).then([](const I& res) {
        return make_ready_future<json::json_return_type>(res);
    });
}

template<class Mapper, class I, class Reducer, class Result>
future<json::json_return_type> map_reduce_cf(sharded<replica::database>& db, const sstring& name, I init,
        Mapper mapper, Reducer reducer, Result result) {
    return map_reduce_cf_raw(db, name, init, mapper, reducer).then([result](const I& res) mutable {
        result = res;
        return make_ready_future<json::json_return_type>(result);
    });
}

struct map_reduce_column_families_locally {
    std::any init;
    std::function<future<std::unique_ptr<std::any>>(replica::column_family&)> mapper;
    std::function<std::unique_ptr<std::any>(std::unique_ptr<std::any>, std::unique_ptr<std::any>)> reducer;
    future<std::unique_ptr<std::any>> operator()(replica::database& db) const {
        auto res = seastar::make_lw_shared<std::unique_ptr<std::any>>(std::make_unique<std::any>(init));
        return db.get_tables_metadata().for_each_table_gently([res, this] (table_id, seastar::lw_shared_ptr<replica::table> table) -> future<> {
            *res = reducer(std::move(*res), co_await mapper(*table.get()));
        }).then([res] () {
            return std::move(*res);
        });
    }
};

template<class Mapper, class I, class Reducer>
future<I> map_reduce_cf_raw(sharded<replica::database>& db, I init,
        Mapper mapper, Reducer reducer) {
    using mapper_type = std::function<future<std::unique_ptr<std::any>>(replica::column_family&)>;
    using reducer_type = std::function<std::unique_ptr<std::any>(std::unique_ptr<std::any>, std::unique_ptr<std::any>)>;
    auto wrapped_mapper = mapper_type([mapper = std::move(mapper)] (replica::column_family& cf) mutable {
        return futurize_invoke([&cf, mapper] {
            return mapper(cf);
        }).then([] (auto result) {
            return std::make_unique<std::any>(I(std::move(result)));
        });
    });
    auto wrapped_reducer = reducer_type([reducer = std::move(reducer)] (std::unique_ptr<std::any> a, std::unique_ptr<std::any> b) mutable {
        return std::make_unique<std::any>(I(reducer(std::any_cast<I>(std::move(*a)), std::any_cast<I>(std::move(*b)))));
    });
    return db.map_reduce0(map_reduce_column_families_locally{init,
            std::move(wrapped_mapper), wrapped_reducer}, std::make_unique<std::any>(init), wrapped_reducer).then([] (std::unique_ptr<std::any> res) {
        return std::any_cast<I>(std::move(*res));
    });
}


template<class Mapper, class I, class Reducer>
future<json::json_return_type> map_reduce_cf(sharded<replica::database>& db, I init,
        Mapper mapper, Reducer reducer) {
    return map_reduce_cf_raw(db, init, mapper, reducer).then([](const I& res) {
        return make_ready_future<json::json_return_type>(res);
    });
}

std::tuple<sstring, sstring> parse_fully_qualified_cf_name(sstring name);

}