// 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.

#pragma once

#include <butil/macros.h>

#include <glog/logging.h>

#include <stddef.h>

#include <stdint.h>

#include <atomic>

#include <memory>

#include <roaring/roaring.hh>

#include <string>

#include "common/config.h"

#include "common/status.h"

#include "io/fs/file_system.h"

#include "io/fs/path.h"

#include "runtime/exec_env.h"

#include "runtime/memory/lru_cache_policy.h"

#include "runtime/memory/mem_tracker.h"

#include "util/lru_cache.h"

#include "util/slice.h"

#include "util/time.h"

namespace doris::segment_v2 {

class ConditionCacheHandle;

class ConditionCache : public LRUCachePolicy {

public:

    using LRUCachePolicy::insert;

    // The cache key or segment lru cache

    struct CacheKey {

        CacheKey(RowsetId rowset_id_, int64_t segment_id_, uint64_t digest_)

                : rowset_id(rowset_id_), segment_id(segment_id_), digest(digest_) {}

        RowsetId rowset_id;

        int64_t segment_id;

        uint64_t digest;

        // Encode to a flat binary which can be used as LRUCache's key

        [[nodiscard]] std::string encode() const {

            char buf[16];

            memcpy(buf, &segment_id, 8);

            memcpy(buf + 8, &digest, 8);

            return rowset_id.to_string() + std::string(buf, 16);

        }

    };

    class CacheValue : public LRUCacheValueBase {

    public:

        std::shared_ptr<std::vector<bool>> filter_result;

    };

    // Create global instance of this class

    static ConditionCache* create_global_cache(size_t capacity, uint32_t num_shards = 16) {

        auto* res = new ConditionCache(capacity, num_shards);

        return res;

    }

    // Return global instance.

    // Client should call create_global_cache before.

    static ConditionCache* instance() { return ExecEnv::GetInstance()->get_condition_cache(); }

    ConditionCache() = delete;

    ConditionCache(size_t capacity, uint32_t num_shards)

            : LRUCachePolicy(CachePolicy::CacheType::CONDITION_CACHE, capacity, LRUCacheType::SIZE,

                             config::inverted_index_cache_stale_sweep_time_sec, num_shards,

                             /*element_count_capacity*/ 0, /*enable_prune*/ true,

                             /*is_lru_k*/ true) {}

    bool lookup(const CacheKey& key, ConditionCacheHandle* handle);

    void insert(const CacheKey& key, std::shared_ptr<std::vector<bool>> filter_result);

};

class ConditionCacheHandle {

public:

    ConditionCacheHandle() = default;

    ConditionCacheHandle(LRUCachePolicy* cache, Cache::Handle* handle)

            : _cache(cache), _handle(handle) {}

    ~ConditionCacheHandle() {

        if (_handle != nullptr) {

            _cache->release(_handle);

        }

    }

    ConditionCacheHandle(ConditionCacheHandle&& other) noexcept {

        // we can use std::exchange if we switch c++14 on

        std::swap(_cache, other._cache);

        std::swap(_handle, other._handle);

    }

    ConditionCacheHandle& operator=(ConditionCacheHandle&& other) noexcept {

        std::swap(_cache, other._cache);

        std::swap(_handle, other._handle);

        return *this;

    }

    LRUCachePolicy* cache() const { return _cache; }

    std::shared_ptr<std::vector<bool>> get_filter_result() const {

        if (!_cache) {

            return nullptr;

        }

        return ((ConditionCache::CacheValue*)_cache->value(_handle))->filter_result;

    }

private:

    LRUCachePolicy* _cache = nullptr;

    Cache::Handle* _handle = nullptr;

    // Don't allow copy and assign

    DISALLOW_COPY_AND_ASSIGN(ConditionCacheHandle);

};

} // namespace doris::segment_v2