/*-
 * ============LICENSE_START=======================================================
 * openECOMP : APP-C
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights
 * 						reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */

package org.openecomp.appc.workflow.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;

import org.openecomp.appc.dao.util.DBUtils;
import org.openecomp.appc.rankingframework.AbstractRankedAttributesResolverFactory;
import org.openecomp.appc.rankingframework.ConfigurationEntry;
import org.openecomp.appc.rankingframework.ConfigurationSet;
import org.openecomp.appc.rankingframework.RankedAttributesResolver;

class WorkflowResolverDataReader {

    private static final String QUERY_STMT = "SELECT action,api_version,vnf_type,vnf_version,dg_name,dg_version,dg_module FROM VNF_DG_MAPPING";

    private static final Collection<String> ATTRIBUTE_NAMES = Arrays.asList("action","api_version", "vnf_type", "vnf_version");

    private static class ConfigurationSetAdaptor implements ConfigurationSet<WorkflowKey> {

        private final ResultSet resultSet;

        private class ResultSetIterator implements Iterator<ConfigurationEntry<WorkflowKey>>, ConfigurationEntry<WorkflowKey> {
            @Override
            public boolean hasNext() {
                try {
                    return resultSet.next();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public ConfigurationEntry<WorkflowKey> next() {
                return this;
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }

            @Override
            public Object getAttributeValue(String name) {
                try {
                    return resultSet.getObject(name);
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }

            @Override
            public WorkflowKey getResult() {
                try {
                    return new WorkflowKey(resultSet.getString("dg_name"), resultSet.getString("dg_version"), resultSet.getString("dg_module"));
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
        }

        ConfigurationSetAdaptor(ResultSet resultSet) {
            this.resultSet = resultSet;
        }

        @Override
        public Iterable<ConfigurationEntry<WorkflowKey>> getEntries() {
            return new Iterable<ConfigurationEntry<WorkflowKey>>() {

                @Override
                public Iterator<ConfigurationEntry<WorkflowKey>> iterator() {
                    return new ResultSetIterator();
                }
            };
        }

        @Override
        public Collection<String> getRankedAttributeNames() {
            return ATTRIBUTE_NAMES;
        }
    }

    RankedAttributesResolver<WorkflowKey> read() {
        try {
            try (Connection conn = DBUtils.getConnection("sdnctl")) {
                try (PreparedStatement stmt = conn.prepareStatement(QUERY_STMT)) {
                    try (ResultSet res = stmt.executeQuery()) {
                        if (res.next()) {
                            res.beforeFirst();
                            ConfigurationSet<WorkflowKey> resolverConfig = new ConfigurationSetAdaptor(res);
                            return AbstractRankedAttributesResolverFactory.getInstance().create(resolverConfig);
                        } else {
                            // TODO: Return empty object
                            throw new IllegalStateException();
                        }
                    }
                }
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}