/*******************************************************************************
 * Copyright (c) 2012, Directors of the Tyndale STEP Project
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met:
 * 
 * Redistributions of source code must retain the above copyright 
 * notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the following disclaimer in 
 * the documentation and/or other materials provided with the 
 * distribution.
 * Neither the name of the Tyndale House, Cambridge (www.TyndaleHouse.com)  
 * nor the names of its contributors may be used to endorse or promote 
 * products derived from this software without specific prior written 
 * permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 
 * THE POSSIBILITY OF SUCH DAMAGE.
 ******************************************************************************/
package com.tyndalehouse.step.core.utils;

import java.io.IOException;
import java.io.InputStream;
import java.util.Map.Entry;
import java.util.Properties;

import com.google.inject.AbstractModule;
import com.google.inject.name.Names;

/**
 * A colletion of utilities to read property files
 * 
 * @author chrisburrell
 */
public abstract class AbstractStepGuiceModule extends AbstractModule {
    private final String propertyFileUrl;
    private Properties moduleProperties;

    /**
     * Sets up the module to have properties in it
     * 
     * @param propertyFileUrl the classpath URL to the property file
     */
    public AbstractStepGuiceModule(final String propertyFileUrl) {
        this.propertyFileUrl = propertyFileUrl;
    }

    @Override
    protected final void configure() {
        readProperties();
        doConfigure();
    }

    /**
     * reads the core properties from the file
     * 
     * @return a list of properties read from file
     */
    private Properties readProperties() {
        InputStream stream = null;
        try {
            stream = AbstractStepGuiceModule.class.getResourceAsStream(this.propertyFileUrl);
            this.moduleProperties = new Properties();
            this.moduleProperties.load(stream);
            applySystemPropertiesOverride();

            Names.bindProperties(super.binder(), this.moduleProperties);
        } catch (final IOException e) {
            // This is the preferred way to tell Guice something went wrong
            super.addError(e);
        } finally {
            IOUtils.closeQuietly(stream);
        }
        return this.moduleProperties;
    }

    /**
     * Overrides with anything that has been specified in system properties
     */
    private void applySystemPropertiesOverride() {
        final Properties sys = System.getProperties();
        for (final Entry<Object, Object> p : sys.entrySet()) {
            if (this.moduleProperties.containsKey(p.getKey())) {
                this.moduleProperties.setProperty((String) p.getKey(), (String) p.getValue());
            }
        }
    }

    /**
     * @return the moduleProperties
     */
    public Properties getModuleProperties() {
        return this.moduleProperties;
    }

    /**
     * a place to do specific module configuration
     */
    protected abstract void doConfigure();
}