/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.cloudstack.spring.module.factory;

import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.cloudstack.spring.module.model.ModuleDefinition;
import org.apache.cloudstack.spring.module.model.ModuleDefinitionSet;
import org.apache.cloudstack.spring.module.model.impl.DefaultModuleDefinitionSet;

public class ModuleBasedContextFactory {

    public ModuleDefinitionSet loadModules(Collection<ModuleDefinition> defs, String root) throws IOException {

        Map<String, ModuleDefinition> modules = wireUpModules(root, defs);

        DefaultModuleDefinitionSet moduleSet = new DefaultModuleDefinitionSet(modules, root);
        moduleSet.load();

        return moduleSet;
    }

    protected Map<String, ModuleDefinition> wireUpModules(String root, Collection<ModuleDefinition> defs) throws IOException {
        Map<String, ModuleDefinition> modules = new HashMap<String, ModuleDefinition>();

        for (ModuleDefinition def : defs) {
            modules.put(def.getName(), def);
        }

        ModuleDefinition rootDef = null;
        Map<String, ModuleDefinition> result = new HashMap<String, ModuleDefinition>();

        for (ModuleDefinition def : modules.values()) {
            if (def.getName().equals(root)) {
                rootDef = def;
            }

            if (def.getParentName() != null) {
                ModuleDefinition parentDef = modules.get(def.getParentName());

                if (parentDef != null)
                    parentDef.addChild(def);
            }
        }

        return traverse(rootDef, result);
    }

    protected Map<String, ModuleDefinition> traverse(ModuleDefinition base, Map<String, ModuleDefinition> result) {
        if (base == null)
            return result;

        if (result.containsKey(base.getName())) {
            throw new RuntimeException("Circular dependency to [" + base.getName() + "] from current set " + result.keySet());
        }

        result.put(base.getName(), base);

        for (ModuleDefinition childDef : base.getChildren())
            traverse(childDef, result);

        return result;
    }
}