OpenEnergyMonitorGenericBindingProvider.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.openenergymonitor.internal;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.openhab.binding.openenergymonitor.OpenEnergyMonitorBindingProvider;
import org.openhab.core.binding.BindingConfig;
import org.openhab.core.items.Item;
import org.openhab.core.library.items.NumberItem;
import org.openhab.model.item.binding.AbstractGenericBindingProvider;
import org.openhab.model.item.binding.BindingConfigParseException;

/**
 * <p>
 * This class can parse information from the generic binding format and provides
 * Open Energy Monitor binding information from it.
 *
 * <p>
 * Examples for valid binding configuration strings:
 *
 * <ul>
 * <li><code>openenergymonitor="realPower"</code></li>
 * <li><code>openenergymonitor="phase1Current:JS(divideby100.js)"</code></li>
 * <li><code>openenergymonitor="phase1RealPower+phase2RealPower+phase3RealPower"</code></li>
 * <li><code>openenergymonitor="phase1Current+phase2Current+phase3Current:JS(divideby100.js)"</code></li>
 * <li><code>openenergymonitor="phase1RealPower+phase2RealPower+phase3RealPower"</code></li>
 * </ul>
 *
 * @author Pauli Anttila
 * @since 1.4.0
 */
public class OpenEnergyMonitorGenericBindingProvider extends AbstractGenericBindingProvider
        implements OpenEnergyMonitorBindingProvider {

    /** RegEx to extract a transformation string <code>'(.*?)\((.*)\)'</code> */
    private static final Pattern REGEX_EXTRACT_PATTERN = Pattern.compile("(.*?)\\((.*)\\)");

    /**
     * {@inheritDoc}
     */
    @Override
    public String getBindingType() {
        return "openenergymonitor";
    }

    /**
     * @{inheritDoc
     */
    @Override
    public void validateItemType(Item item, String bindingConfig) throws BindingConfigParseException {
        if (!(item instanceof NumberItem)) {
            throw new BindingConfigParseException(
                    "item '" + item.getName() + "' is of type '" + item.getClass().getSimpleName()
                            + "', only NumberItems are allowed - please check your *.items configuration");
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void processBindingConfiguration(String context, Item item, String bindingConfig)
            throws BindingConfigParseException {
        super.processBindingConfiguration(context, item, bindingConfig);

        OpenEnergyMonitorBindingConfig config = new OpenEnergyMonitorBindingConfig();

        String[] configParts = bindingConfig.trim().split(":");

        if (configParts.length > 2) {
            throw new BindingConfigParseException(
                    "Open Energy Monitor binding must contain 1-2 parts separated by ':'");
        }

        config.variable = configParts[0].trim();

        if (configParts.length == 2) {
            String[] parts = splitTransformationConfig(configParts[1].trim());
            config.transformationType = parts[0];
            config.transformationFunction = parts[1];
        } else {
            config.transformationType = null;
            config.transformationFunction = null;
        }

        addBindingConfig(item, config);
    }

    /**
     * Splits a transformation configuration string into its two parts - the
     * transformation type and the function/pattern to apply.
     * 
     * @param transformation
     *            the string to split
     * @return a string array with exactly two entries for the type and the
     *         function
     */
    protected String[] splitTransformationConfig(String transformation) {
        Matcher matcher = REGEX_EXTRACT_PATTERN.matcher(transformation);

        if (!matcher.matches()) {
            throw new IllegalArgumentException("given transformation function '" + transformation
                    + "' does not follow the expected pattern '<function>(<pattern>)'");
        }
        matcher.reset();

        matcher.find();
        String type = matcher.group(1);
        String pattern = matcher.group(2);

        return new String[] { type, pattern };
    }

    class OpenEnergyMonitorBindingConfig implements BindingConfig {
        public String variable = null;
        String transformationType = null;
        String transformationFunction = null;

        @Override
        public String toString() {
            return "OpenEnergyMonitorBindingConfigElement [" + "variable=" + variable + ", transformation type="
                    + transformationType + ", transformation function=" + transformationFunction + "]";
        }

    }

    @Override
    public String getVariable(String itemName) {
        OpenEnergyMonitorBindingConfig config = (OpenEnergyMonitorBindingConfig) bindingConfigs.get(itemName);
        return config != null ? config.variable : null;
    }

    @Override
    public String getTransformationType(String itemName) {
        OpenEnergyMonitorBindingConfig config = (OpenEnergyMonitorBindingConfig) bindingConfigs.get(itemName);
        return config != null ? config.transformationType : null;
    }

    @Override
    public String getTransformationFunction(String itemName) {
        OpenEnergyMonitorBindingConfig config = (OpenEnergyMonitorBindingConfig) bindingConfigs.get(itemName);
        return config != null ? config.transformationFunction : null;
    }

}