#ifndef OSRM_STORAGE_SHARED_DATA_INDEX_HPP
#define OSRM_STORAGE_SHARED_DATA_INDEX_HPP

#include "storage/shared_datatype.hpp"

#include <boost/iterator/function_output_iterator.hpp>

#include <type_traits>
#include <unordered_map>

namespace osrm::storage
{

// This class wraps one or more shared memory regions with the associated data layout
// to abstract away in which region a block of memory is stored.
class SharedDataIndex
{
  public:
    struct AllocatedRegion
    {
        void *memory_ptr;
        std::unique_ptr<BaseDataLayout> layout;
    };

    SharedDataIndex() = default;
    SharedDataIndex(std::vector<AllocatedRegion> regions_) : regions(std::move(regions_))
    {
        // Build mapping from block name to region
        for (auto index : util::irange<std::uint32_t>(0, regions.size()))
        {
            regions[index].layout->List("",
                                        boost::make_function_output_iterator([&](const auto &name) {
                                            block_to_region[name] = index;
                                        }));
        }
    }

    template <typename OutIter> void List(const std::string &name_prefix, OutIter out) const
    {
        for (const auto &region : regions)
        {
            region.layout->List(name_prefix, out);
        }
    }

    template <typename T> auto GetBlockPtr(const std::string &name) const
    {
#if !defined(__GNUC__) || (__GNUC__ > 4)
        // is_tivially_copyable only exists in GCC >=5
        static_assert(std::is_trivially_copyable<T>::value,
                      "Block-based data must be a trivially copyable type");
        static_assert(sizeof(T) % alignof(T) == 0, "aligned T* can't be used as an array pointer");
#endif
        const auto &region = GetBlockRegion(name);
        return reinterpret_cast<T *>(region.layout->GetBlockPtr(region.memory_ptr, name));
    }

    template <typename T> auto GetBlockPtr(const std::string &name)
    {
#if !defined(__GNUC__) || (__GNUC__ > 4)
        // is_tivially_copyable only exists in GCC >=5
        static_assert(std::is_trivially_copyable<T>::value,
                      "Block-based data must be a trivially copyable type");
        static_assert(sizeof(T) % alignof(T) == 0, "aligned T* can't be used as an array pointer");
#endif
        const auto &region = GetBlockRegion(name);
        return reinterpret_cast<T *>(region.layout->GetBlockPtr(region.memory_ptr, name));
    }

    std::size_t GetBlockEntries(const std::string &name) const
    {
        const auto &region = GetBlockRegion(name);
        return region.layout->GetBlockEntries(name);
    }

    std::size_t GetBlockSize(const std::string &name) const
    {
        const auto &region = GetBlockRegion(name);
        return region.layout->GetBlockSize(name);
    }

  private:
    const AllocatedRegion &GetBlockRegion(const std::string &name) const
    {
        const auto index_iter = block_to_region.find(name);
        if (index_iter == block_to_region.end())
        {
            throw util::exception("data block " + name + " not found " + SOURCE_REF);
        }
        return regions[index_iter->second];
    }

    std::vector<AllocatedRegion> regions;
    std::unordered_map<std::string, std::uint32_t> block_to_region;
};
} // namespace osrm::storage

#endif
