/*
 * Copyright (C) 2016 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/>.
 */

/*
 * 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.
 */

#include <vector>
#include <chrono>

#include "sstables.hh"
#include "compaction.hh"
#include "database.hh"
#include "compaction_strategy.hh"
#include "compaction_strategy_impl.hh"
#include "schema.hh"
#include "sstable_set.hh"
#include "compatible_ring_position.hh"
#include <boost/range/algorithm/find.hpp>
#include <boost/range/adaptors.hpp>
#include <boost/icl/interval_map.hpp>
#include <boost/algorithm/cxx11/any_of.hpp>
#include "size_tiered_compaction_strategy.hh"
#include "date_tiered_compaction_strategy.hh"
#include "leveled_compaction_strategy.hh"
#include "time_window_compaction_strategy.hh"

logging::logger date_tiered_manifest::logger = logging::logger("DateTieredCompactionStrategy");
logging::logger leveled_manifest::logger("LeveledManifest");

namespace sstables {

extern logging::logger clogger;

class incremental_selector_impl {
public:
    virtual ~incremental_selector_impl() {}
    virtual std::tuple<dht::token_range, std::vector<shared_sstable>, dht::token> select(const dht::token& token) = 0;
};

class sstable_set_impl {
public:
    virtual ~sstable_set_impl() {}
    virtual std::unique_ptr<sstable_set_impl> clone() const = 0;
    virtual std::vector<shared_sstable> select(const dht::partition_range& range) const = 0;
    virtual void insert(shared_sstable sst) = 0;
    virtual void erase(shared_sstable sst) = 0;
    virtual std::unique_ptr<incremental_selector_impl> make_incremental_selector() const = 0;
};

sstable_set::sstable_set(std::unique_ptr<sstable_set_impl> impl, lw_shared_ptr<sstable_list> all)
        : _impl(std::move(impl))
        , _all(std::move(all)) {
}

sstable_set::sstable_set(const sstable_set& x)
        : _impl(x._impl->clone())
        , _all(make_lw_shared(sstable_list(*x._all))) {
}

sstable_set::sstable_set(sstable_set&&) noexcept = default;

sstable_set&
sstable_set::operator=(const sstable_set& x) {
    if (this != &x) {
        auto tmp = sstable_set(x);
        *this = std::move(tmp);
    }
    return *this;
}

sstable_set&
sstable_set::operator=(sstable_set&&) noexcept = default;

std::vector<shared_sstable>
sstable_set::select(const dht::partition_range& range) const {
    return _impl->select(range);
}

void
sstable_set::insert(shared_sstable sst) {
    _impl->insert(sst);
    try {
        _all->insert(sst);
    } catch (...) {
        _impl->erase(sst);
        throw;
    }
}

void
sstable_set::erase(shared_sstable sst) {
    _impl->erase(sst);
    _all->erase(sst);
}

sstable_set::~sstable_set() = default;

sstable_set::incremental_selector::incremental_selector(std::unique_ptr<incremental_selector_impl> impl)
    : _impl(std::move(impl)) {
}

sstable_set::incremental_selector::~incremental_selector() = default;

sstable_set::incremental_selector::incremental_selector(sstable_set::incremental_selector&&) noexcept = default;

sstable_set::incremental_selector::selection
sstable_set::incremental_selector::select(const dht::token& t) const {
    if (!_current_token_range || !_current_token_range->contains(t, dht::token_comparator())) {
        std::tie(_current_token_range, _current_sstables, _current_next_token) = _impl->select(t);
    }
    return {_current_sstables, _current_next_token};
}

sstable_set::incremental_selector
sstable_set::make_incremental_selector() const {
    return incremental_selector(_impl->make_incremental_selector());
}

// default sstable_set, not specialized for anything
class bag_sstable_set : public sstable_set_impl {
    // erasing is slow, but select() is fast
    std::vector<shared_sstable> _sstables;
public:
    virtual std::unique_ptr<sstable_set_impl> clone() const override {
        return std::make_unique<bag_sstable_set>(*this);
    }
    virtual std::vector<shared_sstable> select(const dht::partition_range& range = query::full_partition_range) const override {
        return _sstables;
    }
    virtual void insert(shared_sstable sst) override {
        _sstables.push_back(std::move(sst));
    }
    virtual void erase(shared_sstable sst) override {
        _sstables.erase(boost::find(_sstables, sst));
    }
    virtual std::unique_ptr<incremental_selector_impl> make_incremental_selector() const override;
    class incremental_selector;
};

class bag_sstable_set::incremental_selector : public incremental_selector_impl {
    const std::vector<shared_sstable>& _sstables;
public:
    incremental_selector(const std::vector<shared_sstable>& sstables)
        : _sstables(sstables) {
    }
    virtual std::tuple<dht::token_range, std::vector<shared_sstable>, dht::token> select(const dht::token& token) override {
        return std::make_tuple(dht::token_range::make_open_ended_both_sides(), _sstables, dht::maximum_token());
    }
};

std::unique_ptr<incremental_selector_impl> bag_sstable_set::make_incremental_selector() const {
    return std::make_unique<incremental_selector>(_sstables);
}

// specialized when sstables are partitioned in the token range space
// e.g. leveled compaction strategy
class partitioned_sstable_set : public sstable_set_impl {
    using value_set = std::unordered_set<shared_sstable>;
    using interval_map_type = boost::icl::interval_map<compatible_ring_position, value_set>;
    using interval_type = interval_map_type::interval_type;
    using map_iterator = interval_map_type::const_iterator;
private:
    schema_ptr _schema;
    std::vector<shared_sstable> _unleveled_sstables;
    interval_map_type _leveled_sstables;
private:
    static interval_type make_interval(const schema& s, const dht::partition_range& range) {
        return interval_type::closed(
                compatible_ring_position(s, range.start()->value()),
                compatible_ring_position(s, range.end()->value()));
    }
    interval_type make_interval(const dht::partition_range& range) const {
        return make_interval(*_schema, range);
    }
    interval_type singular(const dht::ring_position& rp) const {
        auto crp = compatible_ring_position(*_schema, rp);
        return interval_type::closed(crp, crp);
    }
    std::pair<map_iterator, map_iterator> query(const dht::partition_range& range) const {
        if (range.start() && range.end()) {
            return _leveled_sstables.equal_range(make_interval(range));
        }
        else if (range.start() && !range.end()) {
            auto start = singular(range.start()->value());
            return { _leveled_sstables.lower_bound(start), _leveled_sstables.end() };
        } else if (!range.start() && range.end()) {
            auto end = singular(range.end()->value());
            return { _leveled_sstables.begin(), _leveled_sstables.upper_bound(end) };
        } else {
            return { _leveled_sstables.begin(), _leveled_sstables.end() };
        }
    }
public:
    explicit partitioned_sstable_set(schema_ptr schema)
            : _schema(std::move(schema)) {
    }
    virtual std::unique_ptr<sstable_set_impl> clone() const override {
        return std::make_unique<partitioned_sstable_set>(*this);
    }
    virtual std::vector<shared_sstable> select(const dht::partition_range& range) const override {
        auto ipair = query(range);
        auto b = std::move(ipair.first);
        auto e = std::move(ipair.second);
        value_set result;
        while (b != e) {
            boost::copy(b++->second, std::inserter(result, result.end()));
        }
        auto r = _unleveled_sstables;
        r.insert(r.end(), result.begin(), result.end());
        return r;
    }
    virtual void insert(shared_sstable sst) override {
        if (sst->get_sstable_level() == 0) {
            _unleveled_sstables.push_back(std::move(sst));
        } else {
            auto first = sst->get_first_decorated_key().token();
            auto last = sst->get_last_decorated_key().token();
            using bound = dht::partition_range::bound;
            _leveled_sstables.add({
                    make_interval(
                            dht::partition_range(
                                    bound(dht::ring_position::starting_at(first)),
                                    bound(dht::ring_position::ending_at(last)))),
                    value_set({sst})});
        }
    }
    virtual void erase(shared_sstable sst) override {
        if (sst->get_sstable_level() == 0) {
            _unleveled_sstables.erase(std::remove(_unleveled_sstables.begin(), _unleveled_sstables.end(), sst), _unleveled_sstables.end());
        } else {
            auto first = sst->get_first_decorated_key().token();
            auto last = sst->get_last_decorated_key().token();
            using bound = dht::partition_range::bound;
            _leveled_sstables.subtract({
                    make_interval(
                            dht::partition_range(
                                    bound(dht::ring_position::starting_at(first)),
                                    bound(dht::ring_position::ending_at(last)))),
                    value_set({sst})});
        }
    }
    virtual std::unique_ptr<incremental_selector_impl> make_incremental_selector() const override;
    class incremental_selector;
};

class partitioned_sstable_set::incremental_selector : public incremental_selector_impl {
    schema_ptr _schema;
    const std::vector<shared_sstable>& _unleveled_sstables;
    map_iterator _it;
    const map_iterator _end;
private:
    static dht::token_range to_token_range(const interval_type& i) {
        return dht::token_range::make({i.lower().token(), boost::icl::is_left_closed(i.bounds())},
            {i.upper().token(), boost::icl::is_right_closed(i.bounds())});
    }
public:
    incremental_selector(schema_ptr schema, const std::vector<shared_sstable>& unleveled_sstables, const interval_map_type& leveled_sstables)
        : _schema(std::move(schema))
        , _unleveled_sstables(unleveled_sstables)
        , _it(leveled_sstables.begin())
        , _end(leveled_sstables.end()) {
    }
    virtual std::tuple<dht::token_range, std::vector<shared_sstable>, dht::token> select(const dht::token& token) override {
        auto pr = dht::partition_range::make(dht::ring_position::starting_at(token), dht::ring_position::ending_at(token));
        auto interval = make_interval(*_schema, std::move(pr));
        auto ssts = _unleveled_sstables;

        const auto next_token =  [&] {
            const auto next = std::next(_it);
            return next == _end ? dht::maximum_token() : next->first.lower().token();
        };

        const auto current_token =  [&] {
            return _it == _end ? dht::maximum_token() : _it->first.lower().token();
        };

        while (_it != _end) {
            if (boost::icl::contains(_it->first, interval)) {
                ssts.insert(ssts.end(), _it->second.begin(), _it->second.end());
                return std::make_tuple(to_token_range(_it->first), std::move(ssts), next_token());
            }
            // we don't want to skip current interval if token lies before it.
            if (boost::icl::lower_less(interval, _it->first)) {
                return std::make_tuple(dht::token_range::make({token, true}, {_it->first.lower().token(), false}),
                    std::move(ssts),
                    current_token());
            }
            _it++;
        }
        return std::make_tuple(dht::token_range::make_open_ended_both_sides(), std::move(ssts), dht::maximum_token());
    }
};

std::unique_ptr<incremental_selector_impl> partitioned_sstable_set::make_incremental_selector() const {
    return std::make_unique<incremental_selector>(_schema, _unleveled_sstables, _leveled_sstables);
}

std::unique_ptr<sstable_set_impl> compaction_strategy_impl::make_sstable_set(schema_ptr schema) const {
    return std::make_unique<bag_sstable_set>();
}

std::unique_ptr<sstable_set_impl> leveled_compaction_strategy::make_sstable_set(schema_ptr schema) const {
    return std::make_unique<partitioned_sstable_set>(std::move(schema));
}

std::vector<resharding_descriptor>
compaction_strategy_impl::get_resharding_jobs(column_family& cf, std::vector<sstables::shared_sstable> candidates) {
    std::vector<resharding_descriptor> jobs;
    shard_id reshard_at_current = 0;

    clogger.debug("Trying to get resharding jobs for {}.{}...", cf.schema()->ks_name(), cf.schema()->cf_name());
    for (auto& candidate : candidates) {
        auto level = candidate->get_sstable_level();
        jobs.push_back(resharding_descriptor{{std::move(candidate)}, std::numeric_limits<uint64_t>::max(), reshard_at_current++ % smp::count, level});
    }
    return jobs;
}

//
// Null compaction strategy is the default compaction strategy.
// As the name implies, it does nothing.
//
class null_compaction_strategy : public compaction_strategy_impl {
public:
    virtual compaction_descriptor get_sstables_for_compaction(column_family& cfs, std::vector<sstables::shared_sstable> candidates) override {
        return sstables::compaction_descriptor();
    }

    virtual int64_t estimated_pending_compactions(column_family& cf) const override {
        return 0;
    }

    virtual compaction_strategy_type type() const {
        return compaction_strategy_type::null;
    }
};

//
// Major compaction strategy is about compacting all available sstables into one.
//
class major_compaction_strategy : public compaction_strategy_impl {
    static constexpr size_t min_compact_threshold = 2;
public:
    virtual compaction_descriptor get_sstables_for_compaction(column_family& cfs, std::vector<sstables::shared_sstable> candidates) override {
        // At least, two sstables must be available for compaction to take place.
        if (cfs.sstables_count() < min_compact_threshold) {
            return sstables::compaction_descriptor();
        }
        return sstables::compaction_descriptor(std::move(candidates));
    }

    virtual int64_t estimated_pending_compactions(column_family& cf) const override {
        return (cf.sstables_count() < min_compact_threshold) ? 0 : 1;
    }

    virtual compaction_strategy_type type() const {
        return compaction_strategy_type::major;
    }
};

compaction_strategy::compaction_strategy(::shared_ptr<compaction_strategy_impl> impl)
    : _compaction_strategy_impl(std::move(impl)) {}
compaction_strategy::compaction_strategy() = default;
compaction_strategy::~compaction_strategy() = default;
compaction_strategy::compaction_strategy(const compaction_strategy&) = default;
compaction_strategy::compaction_strategy(compaction_strategy&&) = default;
compaction_strategy& compaction_strategy::operator=(compaction_strategy&&) = default;

compaction_strategy_type compaction_strategy::type() const {
    return _compaction_strategy_impl->type();
}

compaction_descriptor compaction_strategy::get_sstables_for_compaction(column_family& cfs, std::vector<sstables::shared_sstable> candidates) {
    return _compaction_strategy_impl->get_sstables_for_compaction(cfs, std::move(candidates));
}

std::vector<resharding_descriptor> compaction_strategy::get_resharding_jobs(column_family& cf, std::vector<sstables::shared_sstable> candidates) {
    return _compaction_strategy_impl->get_resharding_jobs(cf, std::move(candidates));
}

void compaction_strategy::notify_completion(const std::vector<shared_sstable>& removed, const std::vector<shared_sstable>& added) {
    _compaction_strategy_impl->notify_completion(removed, added);
}

bool compaction_strategy::parallel_compaction() const {
    return _compaction_strategy_impl->parallel_compaction();
}

int64_t compaction_strategy::estimated_pending_compactions(column_family& cf) const {
    return _compaction_strategy_impl->estimated_pending_compactions(cf);
}

bool compaction_strategy::use_clustering_key_filter() const {
    return _compaction_strategy_impl->use_clustering_key_filter();
}

sstable_set
compaction_strategy::make_sstable_set(schema_ptr schema) const {
    return sstable_set(
            _compaction_strategy_impl->make_sstable_set(std::move(schema)),
            make_lw_shared<sstable_list>());
}

compaction_strategy make_compaction_strategy(compaction_strategy_type strategy, const std::map<sstring, sstring>& options) {
    ::shared_ptr<compaction_strategy_impl> impl;

    switch(strategy) {
    case compaction_strategy_type::null:
        impl = make_shared<null_compaction_strategy>(null_compaction_strategy());
        break;
    case compaction_strategy_type::major:
        impl = make_shared<major_compaction_strategy>(major_compaction_strategy());
        break;
    case compaction_strategy_type::size_tiered:
        impl = make_shared<size_tiered_compaction_strategy>(size_tiered_compaction_strategy(options));
        break;
    case compaction_strategy_type::leveled:
        impl = make_shared<leveled_compaction_strategy>(leveled_compaction_strategy(options));
        break;
    case compaction_strategy_type::date_tiered:
        impl = make_shared<date_tiered_compaction_strategy>(date_tiered_compaction_strategy(options));
        break;
    case compaction_strategy_type::time_window:
        impl = make_shared<time_window_compaction_strategy>(time_window_compaction_strategy(options));
        break;
    default:
        throw std::runtime_error("strategy not supported");
    }

    return compaction_strategy(std::move(impl));
}

}