package org.openslx.bwlp.sat.web;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Map;

import org.apache.commons.io.output.ByteArrayOutputStream;
import org.apache.log4j.Logger;
import org.openslx.bwlp.sat.database.mappers.DbLecture;
import org.openslx.bwlp.sat.fileserv.FileServer;
import org.openslx.bwlp.thrift.iface.LectureRead;
import org.openslx.bwlp.thrift.iface.NetRule;
import org.openslx.bwlp.thrift.iface.TNotFoundException;
import org.openslx.util.Json;
import org.openslx.util.vm.VmMetaData;
import org.simpleframework.xml.Serializer;
import org.simpleframework.xml.core.Persister;

import fi.iki.elonen.NanoHTTPD;

public class WebServer extends NanoHTTPD {

	private static final Logger LOGGER = Logger.getLogger(WebServer.class);

	private static final Serializer serializer = new Persister();

	public WebServer(int port) {
		super("127.0.0.1", port);
		super.maxRequestSize = 65535;
	}

	/**
	 * Extract request source ip address. Honors the x-forwarded-for header.
	 * 
	 * @param headers
	 *            map of headers as supplied by nanohttpd
	 * @return IP address, or empty string if unknown
	 */
	private String extractIp(Map<String, String> headers) {
		String ip;
		ip = headers.get("remote-addr");
		if (ip != null && !ip.equals("127.0.0.1"))
			return ip;
		if (headers == null || headers.isEmpty())
			return "";
		ip = headers.get("x-forwarded-for");
		if (ip == null || ip.isEmpty())
			return "";
		final int i = ip.lastIndexOf(',');
		if (i == -1)
			return ip.trim();
		return ip.substring(i + 1).trim();
	}

	@Override
	public Response serve(IHTTPSession session) {
		String uri = session.getUri();

		if (uri == null || uri.length() == 0) {
			return internalServerError();
		}

		// Sanitize
		if (uri.contains("//")) {
			uri = uri.replaceAll("//+", "/");
		}

		try {
			return handle(session, uri);
		} catch (Throwable t) {
			LOGGER.debug("Could not handle request", t);
			return internalServerError();
		}
	}

	private Response handle(IHTTPSession session, String uri) {
		// Our special stuff
		String[] parts = uri.replaceFirst("^/+", "").split("/+");
		// /vmchooser/*
		if (parts.length > 1 && parts[0].equals("vmchooser")) {
			if (parts[1].equals("list")) {
				try {
					return serveVmChooserList(session.getParms());
				} catch (Exception e) {
					LOGGER.debug("problem while retrieving the vmChooserList", e);
					return internalServerError();
				}
			}
			if (parts[1].equals("lecture")) {
				if (parts.length < 3)
					return badRequest("Bad Request");
				if (parts.length < 4 || parts[3].equals("vmx"))
					return serveLectureStart(parts[2]);
				if (parts[3].equals("netrules"))
					return serveLectureNetRules(parts[2]);
				if (parts[3].equals("runscript"))
					return serveLectureScript(parts[2]);
			}
			return notFound();
		}
		if (uri.startsWith("/status/fileserver")) {
			return serveStatus();
		}
		if (session.getMethod() == Method.POST && uri.startsWith("/do/")) {
			try {
				session.parseBody(null);
			} catch (IOException | ResponseException e) {
				LOGGER.debug("could not parse request body", e);
				return internalServerError();
			}
			return WebRpc.handle(uri.substring(4), session.getParms());
		}

		return notFound();
	}

	private Response serveStatus() {
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.OK, "application/json; charset=utf-8",
				Json.serialize(FileServer.instance().getStatus()));
	}

	/**
	 * Return meta data (eg. *.vmx) required to start the given lecture.
	 * 
	 * @param lectureId
	 * @return
	 */
	private Response serveLectureStart(String lectureId) {
		VmMetaData meta;
		try {
			meta = DbLecture.getClientLaunchData(lectureId);
		} catch (TNotFoundException e) {
			return notFound();
		} catch (SQLException e) {
			return internalServerError();
		}
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.OK, "text/plain; charset=utf-8",
				new ByteArrayInputStream(meta.getFilteredDefinitionArray()));
	}

	private Response serveLectureNetRules(String lectureId) {
		LectureRead lecture;
		try {
			lecture = DbLecture.getLectureDetails(null, lectureId);
		} catch (TNotFoundException e) {
			return notFound();
		} catch (SQLException e) {
			return internalServerError();
		}
		StringBuilder sb = new StringBuilder();
		if (lecture.networkExceptions != null) {
			for (NetRule rule : lecture.networkExceptions) {
				sb.append(rule.direction.name());
				sb.append(' ');
				sb.append(rule.host);
				sb.append(' ');
				sb.append(rule.port);
				sb.append(' ');
				sb.append(lecture.hasInternetAccess ? "REJECT" : "ACCEPT");
				sb.append('\n');
			}
		}
		if (lecture.hasInternetAccess) {
			sb.append("IN * 0 ACCEPT\n");
			sb.append("OUT * 0 ACCEPT\n");
		} else {
			sb.append("IN * 0 REJECT\n");
			sb.append("OUT * 0 REJECT\n");
		}
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.OK, "text/plain; charset=utf-8",
				sb.toString());
	}
	
	private Response serveLectureScript(String lectureId) {
		LectureRead lecture;
		try {
			lecture = DbLecture.getLectureDetails(null, lectureId);
		} catch (TNotFoundException e) {
			return notFound();
		} catch (SQLException e) {
			return internalServerError();
		}
		if (lecture.runscript == null) {
			lecture.runscript = "";
		}
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.OK, "text/plain; charset=utf-8",
				lecture.runscript);
	}

	/**
	 * Return full list of lectures matching given location(s).
	 * 
	 * @return
	 * @throws Exception
	 */
	private Response serveVmChooserList(Map<String, String> params) throws Exception {
		String locations = params.get("locations");
		boolean exams = params.containsKey("exams");

		VmChooserListXml listXml = DbLecture.getUsableListXml(exams, locations);
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		serializer.write(listXml, baos);
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.OK, "text/xml; charset=utf-8",
				new ByteArrayInputStream(baos.toByteArray()));
	}

	/**
	 * Helper for returning "Internal Server Error" Status
	 */
	public static Response internalServerError() {
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.INTERNAL_ERROR, "text/plain",
				"Internal Server Error");
	}

	/**
	 * Helper for returning "404 Not Found" Status
	 */
	public static Response notFound() {
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.NOT_FOUND, "text/plain", "Nicht gefunden!");
	}

	/**
	 * Helper for returning "Bad Request" Status
	 */
	public static Response badRequest(String message) {
		if (message == null) {
			message = "Schlechte Anfrage!";
		}
		return new NanoHTTPD.Response(NanoHTTPD.Response.Status.BAD_REQUEST, "text/plain", message);
	}

}