/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.client.methods;

import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.HttpState;
import org.apache.commons.httpclient.HttpConnection;
import org.apache.commons.httpclient.HttpMethodBase;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.jackrabbit.webdav.DavConstants;
import org.apache.jackrabbit.webdav.DavException;
import org.apache.jackrabbit.webdav.DavServletResponse;
import org.apache.jackrabbit.webdav.MultiStatus;
import org.apache.jackrabbit.webdav.header.Header;
import org.apache.jackrabbit.webdav.xml.XmlSerializable;
import org.apache.jackrabbit.webdav.xml.DomUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.io.InputStream;

/**
 * <code>DavMethodBase</code>...
 */
public abstract class DavMethodBase extends EntityEnclosingMethod implements DavMethod, DavConstants {

    private static Logger log = LoggerFactory.getLogger(DavMethodBase.class);

    private boolean success;
    private Document responseDocument;
    private MultiStatus multiStatus;

    public DavMethodBase(String uri) {
        super(uri);
    }

    //---------------------------------------------------------< HttpMethod >---
    /**
     * Reset method to 'abstract' in order to force subclasses to change the
     * name (inherited value is {@link GetMethod#getName()}).
     *
     * @return Name of the method.
     * @see HttpMethod#getName()
     */
    @Override
    public abstract String getName();

    //----------------------------------------------------------< DavMethod >---
    /**
     * @see DavMethod#addRequestHeader(Header)
     */
    public void addRequestHeader(Header header) {
        addRequestHeader(header.getHeaderName(), header.getHeaderValue());
    }

    /**
     * @see DavMethod#setRequestHeader(Header)
     */
    public void setRequestHeader(Header header) {
        setRequestHeader(header.getHeaderName(), header.getHeaderValue());
    }

    /**
     * @see DavMethod#getResponseBodyAsMultiStatus()
     */
    public MultiStatus getResponseBodyAsMultiStatus() throws IOException, DavException {
        checkUsed();
        if (multiStatus != null) {
            return multiStatus;
        } else {
            DavException dx = getResponseException();
            if (dx != null) {
                throw dx;
            } else {
                throw new DavException(getStatusCode(), getName() + " resulted with unexpected status: " + getStatusLine());
            }
        }
    }

    /**
     * @see DavMethod#getResponseBodyAsDocument()
     */
    public Document getResponseBodyAsDocument() throws IOException {
        if (responseDocument != null) {
            // response has already been read
            return responseDocument;
        }

        InputStream in = getResponseBodyAsStream();
        if (in != null) {
            // read response and try to build a xml document
            try {
                return DomUtil.parseDocument(in);
            } catch (ParserConfigurationException e) {
                IOException exception =
                    new IOException("XML parser configuration error");
                exception.initCause(e);
                throw exception;
            } catch (SAXException e) {
                IOException exception = new IOException("XML parsing error");
                exception.initCause(e);
                throw exception;
            } finally {
                in.close();
            }
        }
        // no body or no parseable.
        return null;
    }

    /**
     *
     * @return
     * @throws IOException
     */
    Element getRootElement() throws IOException {
        Document document = getResponseBodyAsDocument();
        if (document != null) {
            return document.getDocumentElement();
        }
        return null;
    }

    /**
     * @see DavMethod#getResponseException()
     */
    public DavException getResponseException() throws IOException {
        checkUsed();
        if (success) {
            String msg = "Cannot retrieve exception from successful response.";
            log.warn(msg);
            throw new IllegalStateException(msg);
        }

        Element responseRoot = null;
        try  {
            responseRoot = getRootElement();
        } catch (IOException e) {
            // unparsable body -> use null element
        }
        if (responseRoot != null) {
            return new DavException(getStatusCode(), getStatusText(), null, responseRoot);
        } else {
            // fallback: no or unparsable response body
            return new DavException(getStatusCode(), getStatusText());
        }
    }

    /**
     * @see DavMethod#checkSuccess()
     */
    public void checkSuccess() throws DavException, IOException {
        if (!succeeded()) {
            throw getResponseException();
        }
    }

    /**
     * @see DavMethod#succeeded()
     */
    public boolean succeeded() {
        checkUsed();
        return success;
    }

    //--------------------------------------------------------------------------
    /**
     *
     * @param requestBody
     * @throws IOException
     */
    public void setRequestBody(Document requestBody) throws IOException {
        setRequestEntity(new XmlRequestEntity(requestBody));
    }

    /**
     *
     * @param requestBody
     * @throws IOException
     */
    public void setRequestBody(XmlSerializable requestBody) throws IOException {
        try {
            Document doc = DomUtil.createDocument();
            doc.appendChild(requestBody.toXml(doc));
            setRequestBody(doc);
        } catch (ParserConfigurationException e) {
            IOException exception =
                new IOException("XML parser configuration error");
            exception.initCause(e);
            throw exception;
        }
    }

    /**
     *
     * @param statusCode
     * @return true if the specified status code corresponds to a successfully
     * completed request.
     */
    abstract protected boolean isSuccess(int statusCode);

    /**
     *
     * @param success
     */
    protected void setSuccess(boolean success) {
        this.success = success;
    }

    /**
     * @return true if this method was successfully executed; false otherwise.
     */
    protected boolean getSuccess() {
        return success;
    }

    /**
     * This method is invoked during the {@link #processResponseBody(HttpState, HttpConnection)},
     * which in this implementation parses the response body into a <code>MultiStatus</code>
     * object if the status code indicates 207 (MultiStatus).<br>
     * Subclasses may want to override this method in order to apply specific
     * validation of the multi-status.
     * <P>
     * This implementation does nothing.
     *
     * @param multiStatus
     * @param httpState
     * @param httpConnection
     * @see #processResponseBody(HttpState, HttpConnection)
     */
    protected void processMultiStatusBody(MultiStatus multiStatus, HttpState httpState, HttpConnection httpConnection) {
        // does nothing
    }

    //-----------------------------------------------------< HttpMethodBase >---
    /**
     *
     * @param httpState
     * @param httpConnection
     */
    @Override
    protected void processStatusLine(HttpState httpState, HttpConnection httpConnection) {
        super.processStatusLine(httpState, httpConnection);
        int code = getStatusCode();
        // sub classes define if status code indicates success.
        success = isSuccess(code);
    }

    /**
     * In case of a MultiStatus response code, this method parses the response
     * body and resets the 'success' flag depending on the multistatus content,
     * which could indicate method failure as well.
     *
     * @param httpState
     * @param httpConnection
     * @see HttpMethodBase#processResponseBody(HttpState, HttpConnection)
     */
    @Override
    protected void processResponseBody(HttpState httpState, HttpConnection httpConnection) {
        // in case of multi-status response
        if (getStatusCode() == DavServletResponse.SC_MULTI_STATUS) {
            try {
                multiStatus = MultiStatus.createFromXml(getRootElement());
                // sub-class processing/validation of the multiStatus
                processMultiStatusBody(multiStatus, httpState, httpConnection);
            } catch (IOException e) {
                log.error("Error while parsing multistatus response: " + e);
                success = false;
            }
        }
    }
}
