package com.esri.solutions.jitk.common.gazetteer;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.ByteArrayRequestEntity;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import com.esri.solutions.jitk.common.gazetteer.IGazetteerService.SearchMethod;

import org.apache.log4j.Logger;

import org.apache.xerces.parsers.SAXParser;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import java.text.StringCharacterIterator;


/**
 * Class that will interact with the WFS-G service via HTTP.
 */
public class WFSGClient {
	
	
    /**
     * {@link Logger} used to log messages for this class.
     */
    private static final Logger _logger = Logger.getLogger(WFSGClient.class);

    /**
     * URL of the WFS-G service.
     */
    private String m_serviceUrl = null;

    /**
     * {@link String} representation of the WFS-G get features
     * request.
     */
    private String m_getFeaturesRequest = null;

    /**
     * {@link String} representation of the WFS-G get features
     * response.
     */
    private String m_getFeaturesResponse = null;

    /**
     * Reference to the {@link WFSCapabilities} object.
     */
    private WFSCapabilities m_capabilities = null;

    /**
     * Constructor that initializes the instance with the URL
     * to the WFS-G service.  Also makes a get capabilities call
     * to the WFS-G service to retrieve the capabilities document via
     * {@link #getCapabilities()}.
     *
     * @param url {@link String} Url to the WFS-G service.
     */
    public WFSGClient(String url) {
        m_serviceUrl = url;

        m_capabilities = getCapabilities();
    }

    /**
     * Gets the Url to the WFS-G service.
     *
     * @return {@link String} Url to the WFS-G service.
     */
    public String getServiceUrl() {
        return m_serviceUrl;
    }

    /**
     * Sets the Url to the WFS-G service.
     *
     * @param url {@link String} Url to the WFS-G service.
     */
    public void setServiceUrl(String url) {
        m_serviceUrl = url;
    }

    /**
     * Gets the {@link String} representation of the WFS get
     * features request generated by {@link #createGetFeaturesRequest(String, int)}.
     *
     * @return {@link String} representation of the WFS get features request.
     */
    public String getGetFeaturesRequest() {
        return m_getFeaturesRequest;
    }

    /**
     * Gets the {@link String} representation of the WFS get
     * features response generated by {@link #submitGetFeatureRequest(String)}.
     *
     * @return {@link String} representation of the WFS get features response.
     */
    public String getGetFeaturesResponse() {
        return m_getFeaturesResponse;
    }

    /**
     * Creates a WFS get feature request with the given <code>placeName</code>
     * and <code>numFeatures</code> arguments.  The output of this method can be
     * retrieved via {@link #getGetFeaturesRequest()}.
     *
     * @param placeName {@link String} feature name for searching.
     * @param numFeatures Max number of requested features returned.
     */
    public void createGetFeaturesRequest(String placeName, int numFeatures, 
    		       SearchMethod searchMethod) {
        String strXML = "";

        if (placeName.length() > 0) {
            strXML = "<?xml version='1.0' ?>";
            strXML += ("<wfs:GetFeature service='WFS' version=\"1.1.0\" outputFormat=\"GML3\" maxFeatures=\"" +
            numFeatures + "\" ");
            strXML += "xmlns:iso19112=\"http://www.opengis.net/iso19112\" ";
            strXML += "xmlns:xs=\"http://www.w3.org/2001/XMLSchema\" ";
            strXML += "xmlns:gml=\"http://www.opengis.net/gml\" ";
            strXML += "xmlns:wfs=\"http://www.opengis.net/wfs\" ";
            strXML += "xmlns:ogc=\"http://www.opengis.net/ogc\" ";
            strXML += "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" ";
            strXML += "xsi:schemaLocation=\"http://www.opengis.net/wfs../wfs/1.0.0/WFS-basic.xsd\">";
            strXML += "  <wfs:Query typeName=\"iso19112:SI_LOCATIONINSTANCE\">";
            strXML += "    <ogc:Filter>";
            strXML += "      <ogc:PropertyIsLike wildCard=\"*\" singleChar=\"?\" escapeChar=\"!\">";
            strXML += "        <ogc:PropertyName>geographicIdentifier</ogc:PropertyName>";
            if (searchMethod.equals(SearchMethod.CONTAINS))
            	strXML += ("        <ogc:Literal>%" + placeName + "*</ogc:Literal>");
            else if (searchMethod.equals(SearchMethod.BEGINS_WITH))
            	strXML += ("        <ogc:Literal>" + placeName + "*</ogc:Literal>");
            strXML += "      </ogc:PropertyIsLike>";
            strXML += "    </ogc:Filter>";
            strXML += "  </wfs:Query>";
            strXML += "</wfs:GetFeature>";
        }

        _logger.debug(strXML);

        m_getFeaturesRequest = strXML;
    }

    /**
     * Submits a WFS get feature request to the WFS service using HTTP. The
     * output of this method can be retrieved via {@link #getGetFeaturesResponse()}.
     *
     * @param theRequest {@link String} representation of the WFS get feature request.
     */
    public void submitGetFeatureRequest(String theRequest) {
        HttpClient httpClient = null;
        PostMethod method = null;
        ByteArrayRequestEntity requestEntity = null;
        BufferedReader rd = null;
        String line = null;
        StringBuilder sb = null;

        try {
            httpClient = new HttpClient();
            method = new PostMethod(m_capabilities.getGetFeatureUrlPost());
            requestEntity = new ByteArrayRequestEntity(theRequest.getBytes(),
                    "text/xml");

            method.setRequestEntity(requestEntity);

            httpClient.executeMethod(method);

            // Get the response
            rd = new BufferedReader(new InputStreamReader(
                        method.getResponseBodyAsStream()));

            sb = new StringBuilder();
            sb.append("<?xml version='1.0' ?>");

            while ((line = rd.readLine()) != null) {
                StringCharacterIterator iterator = new StringCharacterIterator(line);
                char character = iterator.current();

                while (character != StringCharacterIterator.DONE) {
                    //					if (character == '<') {
                    //						sb.append("&lt;");
                    //					} else if (character == '>') {
                    //						sb.append("&gt;");
                    //					} else if (character == '\"') {
                    //						sb.append("&quot;");
                    //					} else if (character == '\'') {
                    //						sb.append("&#039;");
                    //					} else if (character == '\\') {
                    //						sb.append("&#092;");
                    //					} else if (character == '&') {
                    //						sb.append("&amp;");
                    //					} else {
                    sb.append(character);
                    //					}
                    character = iterator.next();
                }
            }

            rd.close();

            m_getFeaturesResponse = sb.toString();
        } catch (Exception ex) {
            _logger.warn("Error submitting request", ex);
        } finally {
            if (method != null) {
                method.releaseConnection();
            }
        }
    }

    /**
     * Submits a WFS get capabilities request to the WFS service using HTTP.
     * The response is then parsed using the Simple API for XML (SAX).
     *
     * @return Reference to the {@link WFSCapabilities} object.
     */
    private WFSCapabilities getCapabilities() {
        WFSCapabilities capabilities = null;
        String capabilitiesUrl = null;
        HttpClient httpClient = null;
        GetMethod method = null;

        CapabilitiesHandler handler = null;
        SAXParser parser = null;

        if (m_serviceUrl.charAt(m_serviceUrl.length() - 1) != '?') {
            capabilitiesUrl = m_serviceUrl + "?";
        } else {
            capabilitiesUrl = m_serviceUrl;
        }

        capabilitiesUrl += "request=GetCapabilities&service=WFS&version=1.1.0";

        try {
            httpClient = new HttpClient();
            method = new GetMethod(capabilitiesUrl);

            httpClient.executeMethod(method);

            handler = new CapabilitiesHandler();
            parser = new SAXParser();
            parser.setContentHandler(handler);
            parser.parse(new InputSource(method.getResponseBodyAsStream()));

            capabilities = handler.getWFSCapabilities();
        } catch (IOException ex) {
            _logger.warn("IOException occurred getting WFS capabilities.", ex);
        } catch (SAXException ex) {
            _logger.warn("SAXException occurred parsing WFS capabilities document.",
                ex);
        } finally {
            if (method != null) {
                method.releaseConnection();
            }
        }

        return capabilities;
    }

    /**
     * SAX content handler class for parsing the XML capabilities document
     * of a WFS service.  Extends {@link DefaultHandler}.
     */
    private class CapabilitiesHandler extends DefaultHandler {
        /**
             * Reference to the {@link WFSCapabilities} object.
             */
        WFSCapabilities capabilities = new WFSCapabilities();

        /**
         * Flag used when parsing the XML capabilities document.
         */
        boolean isGetFeatureOperation = Boolean.FALSE;

        /**
         * Gets the parsed {@link WFSCapabilities} document.
         *
         * @return Parsed {@link WFSCapabilities} object.
         */
        public WFSCapabilities getWFSCapabilities() {
            return capabilities;
        }

        /*
         * (non-Javadoc)
         * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
         */
        public void endElement(String uri, String localName, String rawName)
            throws SAXException {
            if (localName.equalsIgnoreCase("Operation") &&
                    isGetFeatureOperation) {
                isGetFeatureOperation = Boolean.FALSE;
            }
        }

        /*
         * (non-Javadoc)
         * @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
         */
        public void startElement(String uri, String localName, String rawName,
            Attributes attributes) throws SAXException {
            if (localName.equalsIgnoreCase("Operation")) {
                if (attributes.getValue("name").equalsIgnoreCase("GetFeature")) {
                    isGetFeatureOperation = Boolean.TRUE;
                }
            }

            if (isGetFeatureOperation && localName.equalsIgnoreCase("Post")) {
                capabilities.setGetFeatureUrlPost(attributes.getValue(
                        "xlink:href"));
            }
        }
    }
}