Copyright 2014 Netflix, Inc.
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.
/**
 * Copyright 2014 Netflix, Inc.
 *
 * 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.
 */
package com.netflix.config;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Maps;

public abstract class DynamicMapProperty<TKEY, TVAL> extends DynamicStringListProperty {
    private static final Logger logger = LoggerFactory.getLogger(DynamicMapProperty.class);
    
    private Map<TKEY,TVAL> defaultValuesMap;

    private volatile Map<TKEY,TVAL> values;
    
    public DynamicMapProperty(String propName, String defaultValue, String mapEntryDelimiterRegex) {
        super(propName, defaultValue, mapEntryDelimiterRegex);
        defaultValuesMap = parseMapFromStringList(getDefaultValue());
    }
    
    public DynamicMapProperty(String propName, String defaultValue) {
        super(propName, defaultValue);
        defaultValuesMap = parseMapFromStringList(getDefaultValue());
    }

    public DynamicMapProperty(String propName, Map<TKEY, TVAL> defaultValue, String mapEntryDelimiterRegex) {
        this(propName, (String) null, mapEntryDelimiterRegex);
        // Make a defensive copy of the default value. Would prefer to use an ImmutableMap, but that
        // does not allow for null values in the Map.
        defaultValuesMap = (defaultValue == null ? null : Collections.unmodifiableMap(Maps.newLinkedHashMap(defaultValue)));
        
        // The values will be initialized as an empty map in the super constructor
        if (defaultValuesMap != null && values.isEmpty()) {
            values = defaultValuesMap;
        }
    }

    public DynamicMapProperty(String propName, Map<TKEY, TVAL> defaultValue) {
        this(propName, defaultValue, DynamicStringListProperty.DEFAULT_DELIMITER);
    }

    public Map<TKEY,TVAL> getMap() {
        return values;
    }
    
    public Map<TKEY,TVAL> getDefaultValueMap() {
        return defaultValuesMap;
    }

    protected void load() {
        super.load();
        values = parseMapFromStringList(super.get());
    }
    
    protected Map<TKEY,TVAL> parseMapFromStringList(List<String> strings) {
        if (strings == null || strings.isEmpty()) {
            return Collections.emptyMap();
        }
        
        Map<TKEY,TVAL> map = new LinkedHashMap<TKEY,TVAL>(strings.size());
        for (String s : strings) {
            String kv[] = getKeyValue(s);
            if (kv.length == 2) {
                map.put(getKey(kv[0]), getValue(kv[1]));
            } else {
                logger.warn("Ignoring illegal key value pair: " + s);
            }
        }
        return Collections.unmodifiableMap(map);
    }
    
    protected String[] getKeyValue(String keyValue) {
        return keyValue.split("=");    
    }
    
    protected abstract TKEY getKey(String key);
    
    protected abstract TVAL getValue(String value);    
}