#ifndef LIBPKG_DATA_STORAGE_PRIVATE_H
#define LIBPKG_DATA_STORAGE_PRIVATE_H

#include "./package.h"

#include "../lmdb-safe/lmdb-reflective.hh"
#include "../lmdb-safe/lmdb-safe.hh"
#include "../lmdb-safe/lmdb-typed.hh"

#include <boost/multi_index/hashed_index.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/sequenced_index.hpp>
#include <boost/multi_index_container.hpp>

#include <memory>
#include <mutex>

namespace LibPkg {

using StorageID = std::uint32_t;

template <typename StorageType, typename EntryType> struct StorageCacheRef {
    using Storage = StorageType;
    explicit StorageCacheRef(const StorageType &relatedStorage, const std::shared_ptr<EntryType> &entry);
    explicit StorageCacheRef(const StorageType &relatedStorage, const std::string &entryName);
    bool operator==(const StorageCacheRef &other) const;
    const StorageType *relatedStorage = nullptr;
    const std::string *entryName;
};

template <typename StorageType, typename EntryType>
inline StorageCacheRef<StorageType, EntryType>::StorageCacheRef(const StorageType &relatedStorage, const std::shared_ptr<EntryType> &entry)
    : relatedStorage(&relatedStorage)
    , entryName(&entry->name)
{
}

template <typename StorageType, typename EntryType>
inline StorageCacheRef<StorageType, EntryType>::StorageCacheRef(const StorageType &relatedStorage, const std::string &entryName)
    : relatedStorage(&relatedStorage)
    , entryName(&entryName)
{
}

template <typename StorageType, typename EntryType>
inline bool StorageCacheRef<StorageType, EntryType>::operator==(const StorageCacheRef<StorageType, EntryType> &other) const
{
    return relatedStorage == other.relatedStorage && *entryName == *other.entryName;
}

template <typename StorageRefType, typename EntryType> struct StorageCacheEntry {
    using Ref = StorageRefType;
    using Entry = EntryType;
    using Storage = typename Ref::Storage;
    explicit StorageCacheEntry(const StorageRefType &ref);
    StorageRefType ref;
    StorageID id;
    std::shared_ptr<EntryType> entry;
};

template <typename StorageRefType, typename EntryType>
inline StorageCacheEntry<StorageRefType, EntryType>::StorageCacheEntry(const StorageRefType &ref)
    : ref(ref)
    , id(0)
{
}

template <typename StorageEntryType> class StorageCacheEntries {
public:
    using Ref = typename StorageEntryType::Ref;
    using Entry = typename StorageEntryType::Entry;
    using Storage = typename StorageEntryType::Storage;
    using StorageEntry = StorageEntryType;
    using EntryList = boost::multi_index::multi_index_container<StorageEntry,
        boost::multi_index::indexed_by<boost::multi_index::sequenced<>,
            boost::multi_index::hashed_unique<boost::multi_index::tag<Ref>, BOOST_MULTI_INDEX_MEMBER(StorageEntryType, Ref, ref)>>>;
    using iterator = typename EntryList::iterator;

    explicit StorageCacheEntries(std::size_t limit = 1000);

    StorageEntry &findOrCreate(const Ref &ref);
    void undo();
    std::size_t erase(const Ref &ref);
    std::size_t clear(const Storage &storage);
    iterator begin();
    iterator end();

private:
    EntryList m_entries;
    std::size_t m_limit;
};

template <typename StorageEntryType>
inline StorageCacheEntries<StorageEntryType>::StorageCacheEntries(std::size_t limit)
    : m_limit(limit)
{
}

template <typename StorageEntryType> inline void StorageCacheEntries<StorageEntryType>::undo()
{
    m_entries.pop_front();
}

template <typename StorageEntryType> inline std::size_t StorageCacheEntries<StorageEntryType>::erase(const Ref &ref)
{
    return m_entries.template get<typename StorageEntryType::Ref>().erase(ref);
}

template <typename StorageEntryType> inline auto StorageCacheEntries<StorageEntryType>::begin() -> iterator
{
    return m_entries.begin();
}

template <typename StorageEntryType> inline auto StorageCacheEntries<StorageEntryType>::end() -> iterator
{
    return m_entries.end();
}

template <typename StorageEntriesType, typename TransactionType, typename SpecType> struct StorageCache {
    using Entries = StorageEntriesType;
    using Entry = typename Entries::Entry;
    using Txn = TransactionType;
    using Storage = typename Entries::Storage;
    struct StoreResult {
        StorageID id = 0;
        bool updated = false;
        std::shared_ptr<typename Entries::Entry> oldEntry;
    };

    SpecType retrieve(Storage &storage, const std::string &entryName);
    StoreResult store(Storage &storage, const std::shared_ptr<Entry> &entry, bool force);
    StoreResult store(Storage &storage, Txn &txn, const std::shared_ptr<Entry> &entry);
    bool invalidate(Storage &storage, const std::string &entryName);
    void clear(Storage &storage);
    void clearCacheOnly(Storage &storage);

private:
    Entries m_entries;
    std::mutex m_mutex;
};

using PackageStorage = LMDBSafe::TypedDBI<Package, LMDBSafe::index_on<Package, std::string, &Package::name>>;
using DependencyStorage = LMDBSafe::TypedDBI<DatabaseDependency, LMDBSafe::index_on<Dependency, std::string, &DatabaseDependency::name>>;
using LibraryDependencyStorage
    = LMDBSafe::TypedDBI<DatabaseLibraryDependency, LMDBSafe::index_on<DatabaseLibraryDependency, std::string, &DatabaseLibraryDependency::name>>;
using PackageCacheRef = StorageCacheRef<DatabaseStorage, Package>;
using PackageCacheEntry = StorageCacheEntry<PackageCacheRef, Package>;
using PackageCacheEntries = StorageCacheEntries<PackageCacheEntry>;
using PackageCache = StorageCache<PackageCacheEntries, PackageStorage::RWTransaction, PackageSpec>;

extern template struct StorageCacheRef<DatabaseStorage, Package>;
extern template struct StorageCacheEntry<PackageCacheRef, Package>;
extern template class StorageCacheEntries<PackageCacheEntry>;
extern template struct StorageCache<PackageCacheEntries, PackageStorage::RWTransaction, PackageSpec>;

struct StorageDistribution {
    explicit StorageDistribution(const char *path, std::uint32_t maxDbs);

    std::unique_ptr<DatabaseStorage> forDatabase(std::string_view uniqueDatabaseName);

private:
    std::shared_ptr<LMDBSafe::MDBEnv> m_env;
    PackageCache m_packageCache;
};

inline std::unique_ptr<DatabaseStorage> StorageDistribution::forDatabase(std::string_view uniqueDatabaseName)
{
    return std::make_unique<DatabaseStorage>(m_env, m_packageCache, uniqueDatabaseName);
}

struct DatabaseStorage {
    explicit DatabaseStorage(const std::shared_ptr<LMDBSafe::MDBEnv> &env, PackageCache &packageCache, std::string_view uniqueDatabaseName);
    PackageCache &packageCache;
    PackageStorage packages;
    DependencyStorage providedDeps;
    DependencyStorage requiredDeps;
    LibraryDependencyStorage providedLibs;
    LibraryDependencyStorage requiredLibs;

private:
    std::shared_ptr<LMDBSafe::MDBEnv> m_env;
};

std::size_t hash_value(const PackageCacheRef &ref);

} // namespace LibPkg

#endif // LIBPKG_DATA_STORAGE_PRIVATE_H