/*
 * Copyright 2014-2015 Groupon, Inc
 * Copyright 2014-2015 The Billing Project, LLC
 *
 * The Billing Project 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.
 */

package org.killbill.billing.util.cache;

import java.util.List;

import javax.inject.Inject;
import javax.inject.Singleton;

import org.killbill.billing.callcontext.InternalTenantContext;
import org.killbill.billing.tenant.api.TenantInternalApi;
import org.killbill.billing.util.cache.Cachable.CacheType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Singleton
public class TenantKVCacheLoader extends BaseCacheLoader {

    private static final Logger logger = LoggerFactory.getLogger(TenantKVCacheLoader.class);
    private final TenantInternalApi tenantApi;

    @Inject
    public TenantKVCacheLoader(final TenantInternalApi tenantApi) {
        super();
        this.tenantApi = tenantApi;
    }

    @Override
    public CacheType getCacheType() {
        return CacheType.TENANT_KV;
    }

    @Override
    public Object load(final Object key, final Object argument) {

        checkCacheLoaderStatus();

        if (!(key instanceof String)) {
            throw new IllegalArgumentException("Unexpected key type of " + key.getClass().getName());
        }
        if (!(argument instanceof CacheLoaderArgument)) {
            throw new IllegalArgumentException("Unexpected key type of " + argument.getClass().getName());
        }
        final String[] parts = ((String) key).split(CacheControllerDispatcher.CACHE_KEY_SEPARATOR);
        final String rawKey = parts[0];
        final String tenantRecordId = parts[1];

        final InternalTenantContext internalTenantContext = new InternalTenantContext(Long.valueOf(tenantRecordId));
        final List<String> valuesForKey = tenantApi.getTenantValuesForKey(rawKey, internalTenantContext);
        if (valuesForKey == null || valuesForKey.size() == 0) {
            return null;
        }
        if (valuesForKey.size() > 1) {
            throw new IllegalStateException("TenantKVCacheLoader expecting no more than one value for key " + key);
        }
        return valuesForKey.get(0);
    }
}
