/**
 * Copyright 2005-2016 The Kuali Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
 *
 * 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.kuali.rice.krad.uif.component;

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

import org.kuali.rice.krad.datadictionary.parse.BeanTag;
import org.kuali.rice.krad.datadictionary.parse.BeanTagAttribute;
import org.kuali.rice.krad.datadictionary.parse.BeanTags;
import org.kuali.rice.krad.datadictionary.uif.UifDictionaryBeanBase;
import org.kuali.rice.krad.datadictionary.validator.ValidationTrace;
import org.kuali.rice.krad.datadictionary.validator.Validator;

/**
 * Configuration for replacing a property value based on a condition
 *
 * <p>
 * A <code>Component</code> may be configured with one or more <code>PropertyReplacer</code> instances. Each defines
 * a condition to evaluate during the apply model phase, and if that condition succeeds the property on the component
 * given by {@link #getPropertyName()}, will be replaced with the value given by {@link #getReplacement()}. Conditions
 * are defined using an expression language and may reference any variables available in the component's context.
 * </p>
 *
 * <p>
 * Property replacers can be used to change out an entire Component or List/Map of Components. For example, based on a
 * condition you might want to display a <code>TextControl</code> or <code>RadioControl</code> for an
 * <code>InputField</code>. You can define the field with a text control, then include a property replacer as
 * follows:
 * <pre>
 * <bean parent="PropertyReplacer" p:propertyName="control"
 * p:condition="field1 eq '10985'" p:replacement-ref="RadioControl"/>
 *
 * </pre>
 *
 * Note <code>Component</code> contains a <code>List</code> or property replacers which will be evaluated in the order
 * contained within the list. So in the above example if we wanted to now add a further condition which sets the
 * control
 * to a checkbox, we would just add another property replacer bean.
 * <pre>
 *   <property name="propertyReplacers">
 * <list>
 * <bean parent="PropertyReplacer" p:propertyName="control"
 * p:condition="field1 eq '10985'" p:replacement-ref="RadioControl"/>
 * <bean parent="PropertyReplacer" p:propertyName="control"
 * p:condition="field1 eq '11456'" p:replacement-ref="CheckboxControl"/>
 *     </list>
 *   </property>
 * </pre>
 *
 * Property replacers may be used to substitute primitive properties as well, such as Strings
 * </p>
 *
 * @author Kuali Rice Team (rice.collab@kuali.org)
 */
@BeanTag(name = "propertyReplacer", parent = "Uif-ConditionalBeanPropertyReplacer")
public class PropertyReplacer extends UifDictionaryBeanBase {
    private static final long serialVersionUID = -8405429643299461398L;

    private String propertyName;

    @KeepExpression
    private String condition;
    private Object replacement;

    public PropertyReplacer() {
        super();
    }

    /**
     * Returns a list of nested components
     *
     * <p>
     * All nested components will be returned in the list. Current assumption is that
     * <code>PropertyReplacer</code> can only contain a <code>Component</code>, <code>List</code> or
     * <code>Map</code> for nested components
     * </p>
     *
     * @return nested components
     */
    public List<Component> getNestedComponents() {
        ArrayList<Component> nestedComponents = new ArrayList<Component>();

        if (replacement instanceof Component) {
            nestedComponents.add(((Component) replacement));
        } else if (replacement instanceof List) {
            for (Object replacementItem : (List<?>) replacement) {
                if (replacementItem instanceof Component) {
                    nestedComponents.add((Component) replacementItem);
                }
            }
        } else if (replacement instanceof Map) {
            for (Object replacementItem : ((Map<?, ?>) replacement).values()) {
                if (replacementItem instanceof Component) {
                    nestedComponents.add((Component) replacementItem);
                }
            }
        }

        return nestedComponents;
    }

    /**
     * Name of the property on the Component the property replacer is associated with that
     * will be set when the condition for the replacer succeeds
     *
     * <p>
     * Note the property name must be readable/writable on the component. The property name may
     * be nested, and include Map or List references.
     * </p>
     *
     * @return property name to set
     */
    @BeanTagAttribute
    public String getPropertyName() {
        return this.propertyName;
    }

    /**
     * Setter for the property name that will be set
     *
     * @param propertyName
     */
    public void setPropertyName(String propertyName) {
        this.propertyName = propertyName;
    }

    /**
     * Gives the expression that should be evaluated to determine whether or not
     * the property replacement should be made
     *
     * <p>
     * Expression follows SPEL and may access any model data along with any variables
     * available in the context for the Component. The expression should evaluate to
     * a boolean. If the resulting boolean is true, the object given by {@link #getReplacement()}
     * will be set as the value for the associated property on the component. If the resulting
     * boolean is false, no action will take place
     * </p>
     *
     * <p>
     * Note the value does not need to contain the expression placeholder @{}
     * </p>
     *
     * @return expression that should be evaluated
     * @see org.kuali.rice.krad.uif.view.ExpressionEvaluator
     * @see org.kuali.rice.krad.uif.UifConstants.ContextVariableNames
     */
    @BeanTagAttribute
    public String getCondition() {
        return this.condition;
    }

    /**
     * Setter for the replacement condition
     *
     * @param condition
     */
    public void setCondition(String condition) {
        this.condition = condition;
    }

    /**
     * Gives the Object that should be used to set the property value if the replacers condition
     * evaluates to true
     *
     * <p>
     * Note the configured Object must be valid for the type given by the property on the Component. Standard
     * property editors will be used for setting the property value
     * </p>
     *
     * @return instance to set
     */
    @BeanTagAttribute
    public Object getReplacement() {
        return this.replacement;
    }

    /**
     * Setter for the replacement Object
     *
     * @param replacement
     */
    public void setReplacement(Object replacement) {
        this.replacement = replacement;
    }

    /**
     * Validates different requirements of component compiling a series of reports detailing information on errors
     * found in the component.  Used by the RiceDictionaryValidator.
     *
     * @param tracer record of component's location
     */
    public void completeValidation(ValidationTrace tracer) {
        tracer.addBean("PropertyReplacer", getPropertyName());

        // Checking that required fields are set
        if (getPropertyName() == null || getCondition() == null || getReplacement() == null) {
            String currentValues[] = {"propertyName =" + getPropertyName(), "condition =" + getCondition(),
                    "replacement =" + getReplacement()};
            tracer.createWarning("PropertyName, condition and replacement should be set", currentValues);
        }

        // Validating Spring EL in condition
        if (!Validator.validateSpringEL(getCondition())) {
            String currentValues[] = {"condition =" + getCondition()};
            tracer.createError("Invalid Spring Expression Language", currentValues);
        }
    }
}
