nz.co.senanque.rules.RuleProxyField Maven / Gradle / Ivy

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This is a plugin to Madura Objects. It provides a rules/constraint engine to assist with validation, deriving new values from user inputs (eg total of invoices entered on this customer) an manipulating metadata (eg because the amount is above X we make some field readonly). Note that the Java that is using the monitored objects is quite unaware of the rules layer implemented here. That means you can change rules without having to go back to your Java code, and it also means you don't have to wonder if everything implemented the same rules. Anything using that Java object has the rules (unless you turn them all off).
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/*******************************************************************************
 * Copyright (c)2014 Prometheus Consulting
 *
 * 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 nz.co.senanque.rules;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import nz.co.senanque.validationengine.ListeningArray;
import nz.co.senanque.validationengine.ObjectMetadata;
import nz.co.senanque.validationengine.ProxyField;
import nz.co.senanque.validationengine.ValidationUtils;
import nz.co.senanque.validationengine.metadata.PropertyMetadata;

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

/**
 * 
 * This describes the settings on a particular field.
 * 
 * @author Roger Parkinson
 * @version $Revision: 1.3 $
 */
public class RuleProxyField implements Serializable
{
	private static final long serialVersionUID = 1L;

	protected enum Required {
        TRUE, TEMP, FALSE
    }

    private final transient ProxyField m_proxyField;
    private transient List m_inputRules = null;
    private transient List m_outputRules = null;
    private transient Rule m_sourceRule = null;
    private static final Logger log = LoggerFactory.getLogger(RuleProxyField.class);
    private final transient Indenter m_indenter;
    private final transient RuleSessionImpl m_ruleSession;
    private transient boolean m_needsReset;

    protected RuleProxyField(final ProxyField proxyField, final Indenter indenter, final RuleSessionImpl ruleSession)
    {
        m_proxyField = proxyField;
        m_indenter = indenter;
        m_ruleSession = ruleSession;
    }

    protected String getPath()
    {
        return m_proxyField.getPath();
    }

    protected PropertyMetadata getPropertyMetadata()
    {
        return m_proxyField.getPropertyMetadata();
    }

    protected boolean isReadOnly()
    {
        return m_proxyField.isReadOnly();
    }

    protected void setReadOnly(final boolean readOnly)
    {
        m_proxyField.setReadOnly(readOnly);
    }

    protected void setInActive(final boolean readOnly)
    {
        m_proxyField.setInActive(readOnly);
    }

    protected boolean isInActive()
    {
        return m_proxyField.isInActive();
    }

    public List getInputRules()
    {
        if (m_inputRules == null)
        {
            m_inputRules = new ArrayList();
        }
        return m_inputRules;
    }

    private List getOutputRules()
    {
        if (m_outputRules == null)
        {
            m_outputRules = new ArrayList();
        }
        return m_outputRules;
    }
    protected void addOutputRule(final RuleContext ruleContext)
    {
        final List rules = getOutputRules();
        if (!rules.contains(ruleContext))
        {
            rules.add(ruleContext);     
        }
    }
    protected void addInputRule(final RuleContext ruleContext)
    {
        final List rules = getInputRules();
        if (!rules.contains(ruleContext))
        {
            rules.add(ruleContext);     
        }
    }
    protected void removeInputRule(final RuleContext ruleContext)
    {
        final List rules = getInputRules();
        if (!rules.contains(ruleContext))
        {
            rules.remove(ruleContext);     
        }
    }
    public void reset()
    {
        log.debug("{}resetting {}",m_indenter,this);
        m_sourceRule = null;
        setNeedsReset(true);
        // if this field is annotated unknown then remember it for later.
        if (m_proxyField.getPropertyMetadata().isUnknown())
        {
        	m_ruleSession.addUnknownField(m_proxyField);
        }
        Object currentValue=null;
		try {
			currentValue = getValue();
		} catch (UnKnownFieldValueException e1) {
			// ignore
		}
        m_ruleSession.clearEvaluating();
        m_ruleSession.addAssignedField(m_proxyField);
        if (currentValue != null && !(currentValue instanceof ListeningArray))
        {
            m_proxyField.reset();
        }
        m_ruleSession.addToReviewList(this);
        for (RuleContext rc: getInputRules())
        {
            if (m_ruleSession.alreadyResettingRule(rc))
            {
                continue;
            }
            try
            {
                rc.reset();
            }
            catch (InferenceException e)
            {
                log.error("{}attempting to reset rule: {}",new Object[]{m_indenter,rc},e);
            }
        }
    }

    public void setValue(final Object newValue)
    {
        if (m_sourceRule != null)
        {
        	String message = m_ruleSession.getMessage("nz.co.senanque.rules.cannot.force.value", new Object[]{ this.toString(),m_sourceRule.getRuleName() });
            throw new InferenceException(message);
        }
        if (!(newValue instanceof DummyValue))
        {
            m_proxyField.setValue(newValue);
        }
    }
    protected void setValue(final Object value, final Rule rule)
    {
        log.debug("{}Setting field: {} rule: {}",new Object[]{m_indenter,this,rule});
        m_sourceRule = rule;
        if (!(value instanceof DummyValue))
        {
            m_proxyField.setValue(value);
        }
    }

	/**
	 * Find the first unfilled field needed to supply this field and return it.
	 * @return proxyfield describing the unfilled field
	 */
	public RuleProxyField backChain() {
		ObjectMetadata objectMetadata = m_proxyField.getObjectMetadata();
		// loop through the rules that output this field
        for (RuleContext rc: getOutputRules())
        {
        	// loop through the fields needed by this rule to fire
            for (FieldReference fr :rc.getRule().listeners())
            {
            	RuleProxyField rpf = m_ruleSession.getRuleProxyField(objectMetadata.getProxyField(fr.getFieldName()));
        		// if this rpf has no value yet then look for an rpf that can deliver it.
        		// if none is found then return this rpf, else return the one we found.
            	if (rpf.askFor())
            	{
            		RuleProxyField rpf1 = rpf.backChain();
            		if (rpf1 == null)
            		{
            			return rpf;
            		}
            		else
            		{
            			return rpf1;
            		}
            	}
            }
        }
		return null;
	}
	private boolean askFor()
	{
		ProxyField proxy = getProxyField();
		if (proxy.isNotKnown())
		{
			// this means we asked for it and they said they did not know
			// so we don't ask again
	    	log.debug("{} NotKnown {} UnKnown {} FALSE",new Object[]{proxy.getFieldName(),proxy.isNotKnown(),proxy.isUnknown()});
			return false;
		}
		if (proxy.isUnknown())
		{
	    	log.debug("{} NotKnown {} UnKnown {} TRUE",new Object[]{proxy.getFieldName(),proxy.isNotKnown(),proxy.isUnknown()});
			return true;
		}
    	log.debug("{} NotKnown {} UnKnown {} FALSE",new Object[]{proxy.getFieldName(),proxy.isNotKnown(),proxy.isUnknown()});
		return false;
	}
    public Object getValue()
    {
    	if (m_proxyField == null)
    	{
    		log.debug("no proxyfield found");
    		return null;
    	}
    	if (m_proxyField.isUnknown() || m_proxyField.isNotKnown())
    	{
    		throw new UnKnownFieldValueException(this);
    	}
        Object ret = m_proxyField.getValue();
        return ret;
    }
    public void assign(final Object a)
    {
    	if (m_proxyField != null)
    	{
    		m_proxyField.assign(a);
    	}
    }

	/**
     * Get the current value without running the backchainer
     * @return the internal value
     */
    public Object getInternalValue()
    {
       return m_proxyField.getValue();
    }

    public String toString()
    {
        return getPath();
    }

    public boolean isRequired()
    {
        return m_proxyField.isRequired();
    }

    public boolean isDerived()
    {
        return m_proxyField.isDerived();
    }

    public void setDerived(final boolean derived)
    {
        m_proxyField.setDerived(derived);
    }

    public boolean needsReset()
    {
        return m_needsReset;
    }

    public void setNeedsReset(final boolean needsReset)
    {
        m_needsReset = needsReset;
    }

    public boolean isDifferent(final Object value)
    {
        return !ValidationUtils.equals(getInternalValue(),value);
    }

    public void setRequired(final boolean required)
    {
        m_proxyField.setRequired(required);        
    }

	public ProxyField getProxyField() {
		return m_proxyField;
	}


}