package util;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;

import org.apache.http.HttpResponse;
import org.apache.http.ParseException;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;
import org.apache.log4j.Logger;
import org.openslx.bwlp.thrift.iface.AuthenticationError;
import org.openslx.bwlp.thrift.iface.TAuthenticationException;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonSyntaxException;

import edu.kit.scc.dei.ecplean.ECPAuthenticationException;
import edu.kit.scc.dei.ecplean.ECPAuthenticator;

public class ShibbolethECP {

	/**
	 * Logger instance for this class
	 */
	private final static Logger LOGGER = Logger.getLogger(ShibbolethECP.class);

	/**
	 * Static gson object for (de)serialization
	 */
	private static final Gson GSON = new GsonBuilder().create();
	
	/**
	 * ServiceProviderResponse Object representing the last response we received
	 */
	private static ServiceProviderResponse lastResponse = null;
	/**
	 * URL for bwLehrpool registration  
	 */
	private static URL registrationUrl = null;
	/**
	 * Return codes
	 */
	public static enum ReturnCode {
		NO_ERROR(0, "Authentication against the identity provider and request of the service provider resource worked."),
	  IDP_ERROR(1, "Authentication against the identity provider failed."),
	  UNREG_ERROR(2, "User not registered to use bwLehrpool."),
	  ERROR_SP(3, "Invalid resource of the service provider."),
	  ERROR_URL(4, "Invalid URL received from master server."),
		ERROR_OTHER(5, "Internal error.");

	  private final int id;
	  private final String msg;

	  ReturnCode(int id, String msg) {
	    this.id = id;
	    this.msg = msg;
	  }

	  public int getId() {
	    return this.id;
	  }

	  public String getMsg() {
	    return this.msg;
	  }
	}
	
	/**
	 * Static URI to the SP.
	 */
	private final static URI BWLP_SP;
	static {
		URI tmp;
		try {
			tmp = new URI("https://bwlp-masterserver.ruf.uni-freiburg.de/webif/shib/api.php");
		} catch (URISyntaxException e) {
			// should never happen!
			LOGGER.error("Bad URI syntax of the service provider, see trace: ", e);
			tmp = null;
		}
		BWLP_SP = tmp;
	}

	public static ServiceProviderResponse getResponse() {
		return lastResponse;
	}
	/**
	 * Fetches the resource
	 *
	 * @param idpUrl
	 *            URL of the identity provider to authenticate against, as String.
	 * @param user
	 *            Username as String.
	 * @param pass
	 *            Password as String.
	 * @return
	 * 						true if login worked, false otherwise.
	 * @throws TAuthenticationException
	 */
	public static ReturnCode doLogin(final String idpUrl, final String user, final String pass)
			throws TAuthenticationException, URISyntaxException, ClientProtocolException, IOException,
			ParseException, JsonSyntaxException, MalformedURLException {

		// first lets do some sanity checks
		if (BWLP_SP == null) {
			LOGGER.error("URI to service provider is not set. Check the initialization of 'BWLP_SP'.");
			return ReturnCode.ERROR_OTHER;
		}
		if (idpUrl == null) {
			LOGGER.error("Identity provider is not set, did you initialize this class correctly?");
			return ReturnCode.ERROR_OTHER;
		}
		if (user == null) {
			LOGGER.error("No username given, aborting...");
			return ReturnCode.ERROR_OTHER;
		}
		if (pass == null) {
			LOGGER.error("No password given, aborting...");
			return ReturnCode.ERROR_OTHER;
		}

		// now init the authenticator for that idp and our static sp
		final ECPAuthenticator auth = new ECPAuthenticator(user, pass, new URI(idpUrl), BWLP_SP);
		
    try {
			auth.authenticate();
    } catch (ECPAuthenticationException e) {
			LOGGER.error("ECP Authentication Exception, see trace: ", e);
			throw new TAuthenticationException(AuthenticationError.GENERIC_ERROR, e.getMessage());
    }
    // here test again for the SP's URL
    final HttpGet testSp = new HttpGet(BWLP_SP);
    final HttpResponse response = auth.getHttpClient().execute(testSp);

    LOGGER.debug("SP request returned: " + response.getStatusLine());
    final String responseBody = EntityUtils.toString(response.getEntity());
    
    lastResponse = GSON.fromJson(responseBody, ServiceProviderResponse.class);

    // TODO: here we will need to parse the answer accordingly.
    // no errors, meaning everything worked fine.
    if (lastResponse.status.equals("unregistered")) {
			registrationUrl = new URL(lastResponse.url);
			return ReturnCode.UNREG_ERROR;
    }
    // TODO the rest of the cases...
    if (lastResponse.status.equals("error")) {
    	LOGGER.error("Server side error: " + lastResponse.error);
    	return ReturnCode.ERROR_OTHER;
    }
    if (lastResponse.status.equals("anonymous")) {
    	LOGGER.error("IdP did not forward user account information to SP. Contact developper.");
    	return ReturnCode.ERROR_OTHER;
    }
    if (lastResponse.status.equals("ok")) {
    	return ReturnCode.NO_ERROR;
    }
    // still here? then something else went wrong
    return ReturnCode.ERROR_OTHER;
	}
	/**
	 * @return Registration URL given by the SP.
	 */
	public static URL getRegistrationUrl() {
		return registrationUrl;
	}
}