/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.joran.action;

import java.util.Map;

import org.xml.sax.Attributes;

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.boolex.EventEvaluator;
import ch.qos.logback.core.joran.spi.InterpretationContext;
import ch.qos.logback.core.spi.LifeCycle;
import ch.qos.logback.core.util.OptionHelper;

abstract public class AbstractEventEvaluatorAction extends Action {

    EventEvaluator<?> evaluator;
    boolean inError = false;

    /**
     * Instantiates an evaluator of the given class and sets its name.
     */
    public void begin(InterpretationContext ec, String name, Attributes attributes) {
        // Let us forget about previous errors (in this instance)
        inError = false;
        evaluator = null;

        String className = attributes.getValue(CLASS_ATTRIBUTE);
        if (OptionHelper.isEmpty(className)) {
            className = defaultClassName();
            addInfo("Assuming default evaluator class [" + className + "]");
        }

        if (OptionHelper.isEmpty(className)) {
            className = defaultClassName();
            inError = true;
            addError("Mandatory \"" + CLASS_ATTRIBUTE + "\" attribute not set for <evaluator>");
            return;
        }

        String evaluatorName = attributes.getValue(Action.NAME_ATTRIBUTE);
        if (OptionHelper.isEmpty(evaluatorName)) {
            inError = true;
            addError("Mandatory \"" + NAME_ATTRIBUTE + "\" attribute not set for <evaluator>");
            return;
        }
        try {
            evaluator = (EventEvaluator<?>) OptionHelper.instantiateByClassName(className, ch.qos.logback.core.boolex.EventEvaluator.class, context);

            evaluator.setContext(this.context);
            evaluator.setName(evaluatorName);

            ec.pushObject(evaluator);
            addInfo("Adding evaluator named [" + evaluatorName + "] to the object stack");

        } catch (Exception oops) {
            inError = true;
            addError("Could not create evaluator of type " + className + "].", oops);
        }
    }

    /**
     * Returns a default class name in case the class attribute is not specified
     * 
     * @return
     */
    abstract protected String defaultClassName();

    /**
     * Once the children elements are also parsed, now is the time to activate the
     * evaluator options.
     */
    @SuppressWarnings("unchecked")
    public void end(InterpretationContext ec, String e) {
        if (inError) {
            return;
        }

        if (evaluator instanceof LifeCycle) {
            ((LifeCycle) evaluator).start();
            addInfo("Starting evaluator named [" + evaluator.getName() + "]");
        }

        Object o = ec.peekObject();

        if (o != evaluator) {
            addWarn("The object on the top the of the stack is not the evaluator pushed earlier.");
        } else {
            ec.popObject();

            try {
                Map<String, EventEvaluator<?>> evaluatorMap = (Map<String, EventEvaluator<?>>) context.getObject(CoreConstants.EVALUATOR_MAP);
                if (evaluatorMap == null) {
                    addError("Could not find EvaluatorMap");
                } else {
                    evaluatorMap.put(evaluator.getName(), evaluator);
                }
            } catch (Exception ex) {
                addError("Could not set evaluator named [" + evaluator + "].", ex);
            }
        }
    }

    public void finish(InterpretationContext ec) {
    }
}