/******************************************************************************
* Copyright (c) 2020, Hobu Inc. (info@hobu.co)
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*       with the distribution.
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*       names of its contributors may be used to endorse or promote
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****************************************************************************/

#pragma once

#include <list>
#include <memory>
#include <mutex>
#include <condition_variable>

#include <nlohmann/json.hpp>

#include <pdal/util/ThreadPool.hpp>

namespace pdal
{
namespace i3s
{

using Page = NL::json;
using PagePtr = std::shared_ptr<NL::json>;
using FetchFunction = std::function<std::string(std::string)>;

class PageManager
{
    struct PageEntry
    {
        int index;
        PagePtr page;
    };

public:
    PageManager(int cacheSize, int threads, int indexFactor, FetchFunction fetch);

    void fetchPage(int index);
    PagePtr getPage(int index);

private:
    ThreadPool m_pool;
    size_t m_cacheSize;
    int m_indexFactor;
    FetchFunction m_fetch;
    std::list<PageEntry> m_cache;
    std::mutex m_mutex;
    std::condition_variable m_cv;

    PagePtr getPageLocked(int index);
    void evict();
};

} //namespace i3s
} // namespace pdal
