mcarleio / sciurus

import io.mcarle.sciurus.Sciurus;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;

public enum CacheRegister {

    INSTANCE;

    private final CacheSupplier DEFAULT_SUPPLIER = () -> ExpiringMapCache.INSTANCE;

    private final Map<String, CacheSupplier> CACHE_REGISTER = Collections.synchronizedMap(new HashMap<String, CacheSupplier>() {

        {

            put(Sciurus.CACHE_GLOBAL, DEFAULT_SUPPLIER);

            put(Sciurus.CACHE_MAP, DEFAULT_SUPPLIER);

        }

    });

    public void register(String cacheName, CustomCache cache) {

        if (cache == null) throw new IllegalArgumentException("missing cache");

        register(cacheName, new SimpleCacheSupplier(cache));

    }

    public boolean deregister(String cacheName) {

        CacheSupplier cacheSupplier = deregisterCache(cacheName);

        if (cacheSupplier != null) {

            cacheSupplier.postDeregister();

        }

        return cacheSupplier != null;

    }

    CustomCache getCache(String cacheName) throws CacheException {

        CacheSupplier cacheSupplier = CACHE_REGISTER.get(cacheName);

        if (cacheSupplier == null) throw new CacheException.UnknownCache();

        CustomCache cache;

        try {

            cache = cacheSupplier.get();

        } catch (Throwable t) {

            throw new CacheException.CacheSupplierThrewException(t);

        }

        if (cache == null) throw new CacheException.CacheSupplierReturnedNull();

        return cache;

    }

    private CacheSupplier deregisterCache(String cacheName) {

        if (Sciurus.CACHE_GLOBAL.equals(cacheName) || Sciurus.CACHE_MAP.equals(cacheName)) {

            return CACHE_REGISTER.put(cacheName, DEFAULT_SUPPLIER);

        } else {

            return CACHE_REGISTER.remove(cacheName);

        }

    }

}