package nabble.view.web.forum;

import fschmidt.util.java.IoUtils;
import fschmidt.util.servlet.AuthorizingServlet;
import fschmidt.util.servlet.JtpContext;
import fschmidt.util.servlet.CanonicalUrl;
import nabble.model.MailMessageFormat;
import nabble.model.Message;
import nabble.model.ModelHome;
import nabble.model.Node;
import nabble.model.Site;
import nabble.view.lib.Cache;
import nabble.view.lib.Jtp;
import nabble.view.lib.UrlMappable;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public final class AttachmentDownload extends HttpServlet implements UrlMappable, AuthorizingServlet, CanonicalUrl {
	private static final Pattern urlPtn = Pattern.compile("/attachment/(\\d+)/(\\d+)/(.*)$");

	private static String url(Site site,String postId,String attachmentId,String name) {
		return site.getBaseUrl()
				+ path(postId,attachmentId,name);
	}

	private static String path(String postId,String attachmentId,String name) {
		StringBuilder buf = new StringBuilder();
		buf.append( "/attachment/" );
		buf.append( postId );
		buf.append( "/" );
		buf.append( attachmentId );
		buf.append( "/" );
		buf.append( name );
		return buf.toString();
	}

	public String getCanonicalUrl(HttpServletRequest request) {
		Site site = Jtp.getSite(request);
		if( site == null )
			return null;
		String postId = request.getParameter("post");
		String attachmentId = request.getParameter("attachment");
		String name = request.getParameter("name");
		return url(site,postId,attachmentId,name);
	}

	public Map<String,String[]> getParameterMapFromUrl(HttpServletRequest request,String mappedUrl) {
		Matcher m = urlPtn.matcher(mappedUrl);
		if( !m.find() )
			throw new RuntimeException();
		Map<String,String[]> params = new HashMap<String,String[]>();
		String postId = m.group(1);
		params.put("post",new String[]{postId});
		String attachmentId = m.group(2);
		params.put("attachment",new String[]{attachmentId});
		String name = m.group(3);
		params.put("name",new String[]{name});
		return params;
	}

	public Pattern getUrlPattern() {
		return urlPtn;
	}

	public String getAuthorizationKey(HttpServletRequest request) throws ServletException {
		return Jtp.getReadAuthorizationKey( Jtp.getSiteNotNull(request).getNode(Jtp.getLong(request,"post")) );
	}

	public boolean authorize(String key,HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
		return Jtp.authorizeForRead(key,request,response); 
	}

	protected void service(HttpServletRequest request,HttpServletResponse response)
		throws ServletException, IOException
	{
		OutputStream out = response.getOutputStream();
		long postId = Long.parseLong( request.getParameter("post") );
		int attachmentId = Integer.parseInt( request.getParameter("attachment") );
		String name = request.getParameter("name");
		String contentType = FileDownload.getMimeByExtension(name);
		if (contentType==null /*|| !contentType.startsWith("image")*/) {
			contentType = "application/x-download";
			response.setHeader("content-disposition", "attachment; filename=\""+name+"\"");
		}
		response.setContentType(contentType);
		Node post = Jtp.getSiteNotNull(request).getNode(postId);
		if( post==null ) {
			response.sendError(HttpServletResponse.SC_GONE,"This post has been deleted.");
			return;
		}
		JtpContext jtpContext = (JtpContext)getServletContext().getAttribute(JtpContext.attrName);
		jtpContext.setEtag(request,response, Cache.nodeChangeEvent(post) );
		// If the user edits a mail message, we convert it into a HTML/TEXT format.
		// After this change all attachments are lost because we lose the RAW email where
		// the file was encoded. So we should return "404 Not Found" in such cases.
		Message.Format fmt = post.getMessage().getFormat();
		if (fmt instanceof MailMessageFormat) {
			InputStream in = ((MailMessageFormat) fmt).getAttachment(post,attachmentId);
			try {
				IoUtils.copyAll(in,out);
			} finally {
				in.close();
			}
		} else {
			response.sendError(HttpServletResponse.SC_NOT_FOUND, "File not found");
		}
	}

}