package org.argeo.app.servlet.publish;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.net.URI;
import java.net.URL;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Map;
import java.util.Objects;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Templates;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.URIResolver;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.apache.fop.apps.FOPException;
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.FopFactory;
import org.apache.fop.apps.FopFactoryBuilder;
import org.apache.xalan.processor.TransformerFactoryImpl;
import org.apache.xmlgraphics.io.Resource;
import org.apache.xmlgraphics.io.ResourceResolver;
import org.argeo.api.acr.Content;
import org.argeo.api.acr.ContentRepository;
import org.argeo.api.acr.ContentSession;
import org.argeo.app.geo.GeoUtils;
import org.argeo.app.geo.GpxUtils;
import org.argeo.cms.auth.RemoteAuthUtils;
import org.argeo.cms.servlet.ServletHttpRequest;
import org.argeo.util.LangUtils;
import org.geotools.data.collection.ListFeatureCollection;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.opengis.feature.simple.SimpleFeature;

/**
 * A servlet transforming an XML view of the data to either FOP or PDF.
 */
public class FopServlet extends HttpServlet {
	private static final long serialVersionUID = 6906020513498289335L;

	private final static String PROP_ARGEO_FO_XSL = "argeo.fo.xsl";

	private ContentRepository contentRepository;

	private DocumentBuilderFactory documentBuilderFactory;
	private TransformerFactory transformerFactory;
	private Templates foTemplates;

	private URL xslUrl;

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String servletPath = req.getServletPath();
		String ext = servletPath.substring(servletPath.lastIndexOf('.'));
		servletPath = servletPath.substring(1, servletPath.lastIndexOf('.'));
		servletPath = servletPath.substring(servletPath.indexOf('/'), servletPath.length());
		String path = URLDecoder.decode(servletPath, StandardCharsets.UTF_8);

		boolean pdf = ".pdf".equals(ext);
		ContentSession session = RemoteAuthUtils.doAs(() -> contentRepository.get(), new ServletHttpRequest(req));
		Content content = session.get(path);
		Source xmlInput = content.adapt(Source.class);
		String systemId = req.getRequestURL().toString();
		xmlInput.setSystemId(systemId);

		// dev only
		final boolean DEV = true;
		if (DEV) {
			try (InputStream in = xslUrl.openStream()) {
				Source xslSource = new StreamSource(in);
				foTemplates = transformerFactory.newTemplates(xslSource);
				if (foTemplates == null)
					throw new IllegalStateException("Could not instantiate XSL " + xslUrl);
			} catch (TransformerConfigurationException | IOException e) {
				throw new IllegalStateException("Cannot instantiate XSL " + xslUrl, e);
			}
		}

		URIResolver uriResolver = (href, base) -> {
			try {
				URI url = URI.create(href);
				if (url.getScheme() != null) {
					if (url.getScheme().equals("file")) {
						InputStream in = Files.newInputStream(Paths.get(URI.create(url.toString())));
						return new StreamSource(in);
					}
					if (url.getScheme().equals("geo2svg")) {
						String includePath = path + url.getPath();
						String geoExt = includePath.substring(includePath.lastIndexOf('.'));
						Content geoContent = session.get(includePath);
						if (".gpx".equals(geoExt)) {
							try (InputStream in = geoContent.open(InputStream.class)) {
								SimpleFeature field = GpxUtils.parseGpxToPolygon(in);
								SimpleFeatureCollection features = new ListFeatureCollection(field.getType(), field);
								try (StringWriter writer = new StringWriter()) {
									GeoUtils.exportToSvg(features, writer, 100, 100);
									StreamSource res = new StreamSource(new StringReader(writer.toString()));
									return res;
								}
							} 
						} else {
							throw new UnsupportedOperationException(geoExt + " is not supported");
						}
					}
				}
			} catch (IOException e) {
				throw new RuntimeException("Cannot process " + href);
			}
			
			String p = href.startsWith("/")?href:path+'/'+href;
			Content subContent = session.get(p);
			return subContent.adapt(Source.class);
		};

		ResourceResolver resourceResolver = new ResourceResolver() {

			@Override
			public Resource getResource(URI uri) throws IOException {
				String subPath = uri.getPath();
				Content subContent = session.get(subPath);
				InputStream in = subContent.open(InputStream.class);
				return new Resource(in);
			}

			@Override
			public OutputStream getOutputStream(URI uri) throws IOException {
				return null;
			}
		};

		try {
			if (pdf) {
				FopFactoryBuilder builder = new FopFactoryBuilder(URI.create(req.getRequestURL().toString()),
						resourceResolver);
				FopFactory fopFactory = builder.build();
//				FopFactory fopFactory = FopFactory.newInstance(URI.create(req.getRequestURL().toString()));
				resp.setContentType("application/pdf");
				Fop fop = fopFactory.newFop("application/pdf", resp.getOutputStream());
				Transformer transformer = foTemplates.newTransformer();
				transformer.setURIResolver(uriResolver);
				Result fopResult = new SAXResult(fop.getDefaultHandler());
				transformer.transform(xmlInput, fopResult);

			} else {
				Result xmlOutput = new StreamResult(resp.getOutputStream());
				resp.setContentType("application/xml");
				Transformer transformer = foTemplates.newTransformer();
//				transformer = transformerFactory.newTransformer();// identity
				transformer.setURIResolver(uriResolver);
				transformer.transform(xmlInput, xmlOutput);
			}
		} catch (FOPException | IOException | TransformerException e) {
			throw new RuntimeException("Cannot process " + path, e);
		}

	}

	@Override
	public void init() throws ServletException {
//		for (Enumeration<String> it = getServletConfig().getInitParameterNames(); it.hasMoreElements();)
//			System.out.println(it.nextElement());
//		for (String str : getServletContext().getResourcePaths("/"))
//			System.out.println(str);
	}

	public void start(Map<String, Object> properties) {
		documentBuilderFactory = DocumentBuilderFactory.newInstance();
		documentBuilderFactory.setXIncludeAware(true);
		documentBuilderFactory.setNamespaceAware(true);

		// We must explicitly use the non-XSLTC transformer, as XSLTC is not working
		// with DocBook stylesheets
		transformerFactory = new TransformerFactoryImpl();
//		transformerFactory = TransformerFactory.newDefaultInstance();
		try {
			String xslStr = LangUtils.get(properties, PROP_ARGEO_FO_XSL);
			Objects.requireNonNull(xslStr);
			xslUrl = new URL(xslStr);
			try (InputStream in = xslUrl.openStream()) {
				Source xslSource = new StreamSource(in);
				foTemplates = transformerFactory.newTemplates(xslSource);
				if (foTemplates == null)
					throw new IllegalStateException("Could not instantiate XSL " + xslUrl);
			}

		} catch (TransformerConfigurationException | IOException e) {
			throw new IllegalStateException("Cannot instantiate XSL " + xslUrl, e);
		}
	}

	public void stop(Map<String, Object> properties) {

	}

	public void setContentRepository(ContentRepository contentRepository) {
		this.contentRepository = contentRepository;
	}

}