/*
 * Copyright 2004-2005 The Apache Software Foundation or its licensors,
 *                     as applicable.
 *
 * 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 org.apache.jackrabbit.webdav.version.report;

import org.apache.jackrabbit.webdav.DavException;
import org.apache.jackrabbit.webdav.DavServletResponse;
import org.apache.jackrabbit.webdav.version.DeltaVConstants;
import org.apache.jackrabbit.webdav.version.DeltaVResource;
import org.apache.jackrabbit.webdav.xml.DomUtil;
import org.apache.jackrabbit.webdav.xml.Namespace;
import org.apache.jackrabbit.webdav.xml.XmlSerializable;
import org.apache.log4j.Logger;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import java.util.HashMap;

/**
 * <code>ReportType</code>...
 */
public class ReportType implements DeltaVConstants, XmlSerializable {

    private static Logger log = Logger.getLogger(ReportType.class);

    private static final HashMap types = new HashMap();

    public static final ReportType VERSION_TREE = register(XML_VERSION_TREE, NAMESPACE, VersionTreeReport.class);
    public static final ReportType EXPAND_PROPERTY = register(XML_EXPAND_PROPERTY, NAMESPACE, ExpandPropertyReport.class);
    public static final ReportType LOCATE_BY_HISTORY = register(XML_LOCATE_BY_HISTORY, NAMESPACE, LocateByHistoryReport.class);

    private final String key;
    private final String localName;
    private final Namespace namespace;
    private final Class reportClass;

    /**
     * Private constructor
     *
     * @see ReportType#register(String, org.apache.jackrabbit.webdav.xml.Namespace, Class)
     */
    private ReportType(String localName, Namespace namespace, String key, Class reportClass) {
        this.localName = localName;
        this.namespace = namespace;
        this.key = key;
        this.reportClass = reportClass;
    }

    /**
     * Creates a new {@link Report} with this type.
     *
     * @return
     * @throws DavException
     */
    public Report createReport(DeltaVResource resource, ReportInfo info) throws DavException {
        try {
            Report report = (Report) reportClass.getConstructor(new Class[0]).newInstance(new Object[0]);
            report.init(resource, info);
            return report;
        } catch (Exception e) {
            // should never occur
            throw new DavException(DavServletResponse.SC_INTERNAL_SERVER_ERROR, "Failed to register Report.");
        }
    }

    /**
     * Returns an Xml element representing this report type. It may be used to
     * build the body for a REPORT request.
     *
     * @param document
     * @return Xml representation
     * @see XmlSerializable#toXml(org.w3c.dom.Document)
     */
    public Element toXml(Document document) {
        return DomUtil.createElement(document, localName, namespace);
    }

    /**
     * Returns true if this <code>ReportType</code> is requested by the given
     * <code>ReportInfo</code>
     *
     * @param reqInfo
     * @return
     */
    public boolean isRequestedReportType(ReportInfo reqInfo) {
        if (reqInfo != null) {
            return getReportName().equals(reqInfo.getReportName());
        }
        return false;
    }

    /**
     * Return the qualified name of this <code>ReportType</code>.
     *
     * @return qualified name
     */
    public String getReportName() {
        return key;
            }

    /**
     *
     * @return
     */
    public String getLocalName() {
        return localName;
        }

    /**
     *
     * @return
     */
    public Namespace getNamespace() {
        return namespace;
    }

    /**
     * Register the report type with the given name, namespace and class, that can
     * run that report.
     *
     * @param localName
     * @param namespace
     * @param reportClass
     * @return
     * @throws IllegalArgumentException if either parameter is <code>null</code> or
     * if the given class does not implement the {@link Report} interface or if
     * it does not provide an empty constructor.
     */
    public static ReportType register(String localName, Namespace namespace, Class reportClass) {
        if (localName == null || namespace == null || reportClass == null) {
            throw new IllegalArgumentException("A ReportType cannot be registered with a null name, namespace or report class");
        }

        String key = DomUtil.getQualifiedName(localName, namespace);
        if (types.containsKey(key)) {
            return (ReportType) types.get(key);
        } else {
            // test if this report class has an empty constructor and implements Report interface
            boolean isValidClass = false;
            Class[] interfaces = reportClass.getInterfaces();
            for (int i = 0; i < interfaces.length && !isValidClass; i++) {
                isValidClass = (interfaces[i] == Report.class);
            }
            if (!isValidClass) {
                throw new IllegalArgumentException("The specified report class must implement the Report interface.");
            }

            try {
                reportClass.getConstructor(new Class[0]);
            } catch (NoSuchMethodException e) {
                throw new IllegalArgumentException("The specified report class must provide a default constructor.");
            }

            ReportType type = new ReportType(localName, namespace, key, reportClass);
            types.put(key, type);
            return type;
        }
    }

    /**
     * Return the <code>ReportType</code> requested by the given report info object.
     *
     * @param reportInfo
     * @return the requested <code>ReportType</code>
     * @throws IllegalArgumentException if the reportInfo is <code>null</code> or
     * if the requested report type has not been registered yet.
     */
    public static ReportType getType(ReportInfo reportInfo) {
        if (reportInfo == null) {
            throw new IllegalArgumentException("ReportInfo must not be null.");
        }
        String key = reportInfo.getReportName();
        if (types.containsKey(key)) {
            return (ReportType) types.get(key);
        } else {
            throw new IllegalArgumentException("The request report '"+key+"' has not been registered yet.");
        }
    }
}