package org.apache.http.impl.auth;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthOption;
import org.apache.http.auth.AuthProtocolState;
import org.apache.http.auth.AuthScheme;
import org.apache.http.auth.AuthState;
import org.apache.http.auth.AuthenticationException;
import org.apache.http.auth.ContextAwareAuthScheme;
import org.apache.http.auth.Credentials;
import org.apache.http.auth.MalformedChallengeException;
import org.apache.http.client.AuthenticationStrategy;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Asserts;
import java.io.IOException;
import java.util.Locale;
import java.util.Map;
import java.util.Queue;

public class HttpAuthenticator {
   private final Log log;

   public HttpAuthenticator(Log log) {
      this.log = log != null ? log : LogFactory.getLog(this.getClass());
   }

   public HttpAuthenticator() {
      this((Log)null);
   }

   public boolean isAuthenticationRequested(HttpHost host, HttpResponse response, AuthenticationStrategy authStrategy, AuthState authState, HttpContext context) {
      if (authStrategy.isAuthenticationRequested(host, response, context)) {
         this.log.debug("Authentication required");
         if (authState.getState() == AuthProtocolState.SUCCESS) {
            authStrategy.authFailed(host, authState.getAuthScheme(), context);
         }

         return true;
      } else {
         switch (authState.getState()) {
            case CHALLENGED:
            case HANDSHAKE:
               this.log.debug("Authentication succeeded");
               authState.setState(AuthProtocolState.SUCCESS);
               authStrategy.authSucceeded(host, authState.getAuthScheme(), context);
            case SUCCESS:
               break;
            default:
               authState.setState(AuthProtocolState.UNCHALLENGED);
         }

         return false;
      }
   }

   public boolean handleAuthChallenge(HttpHost host, HttpResponse response, AuthenticationStrategy authStrategy, AuthState authState, HttpContext context) {
      try {
         if (this.log.isDebugEnabled()) {
            this.log.debug(host.toHostString() + " requested authentication");
         }

         Map<String, Header> challenges = authStrategy.getChallenges(host, response, context);
         if (challenges.isEmpty()) {
            this.log.debug("Response contains no authentication challenges");
            return false;
         } else {
            AuthScheme authScheme = authState.getAuthScheme();
            switch (authState.getState()) {
               case CHALLENGED:
               case HANDSHAKE:
                  if (authScheme == null) {
                     this.log.debug("Auth scheme is null");
                     authStrategy.authFailed(host, (AuthScheme)null, context);
                     authState.reset();
                     authState.setState(AuthProtocolState.FAILURE);
                     return false;
                  }
               case UNCHALLENGED:
                  if (authScheme != null) {
                     String id = authScheme.getSchemeName();
                     Header challenge = (Header)challenges.get(id.toLowerCase(Locale.ROOT));
                     if (challenge != null) {
                        this.log.debug("Authorization challenge processed");
                        authScheme.processChallenge(challenge);
                        if (authScheme.isComplete()) {
                           this.log.debug("Authentication failed");
                           authStrategy.authFailed(host, authState.getAuthScheme(), context);
                           authState.reset();
                           authState.setState(AuthProtocolState.FAILURE);
                           return false;
                        }

                        authState.setState(AuthProtocolState.HANDSHAKE);
                        return true;
                     }

                     authState.reset();
                  }
                  break;
               case SUCCESS:
                  authState.reset();
                  break;
               case FAILURE:
                  return false;
            }

            Queue<AuthOption> authOptions = authStrategy.select(challenges, host, response, context);
            if (authOptions != null && !authOptions.isEmpty()) {
               if (this.log.isDebugEnabled()) {
                  this.log.debug("Selected authentication options: " + authOptions);
               }

               authState.setState(AuthProtocolState.CHALLENGED);
               authState.update(authOptions);
               return true;
            } else {
               return false;
            }
         }
      } catch (MalformedChallengeException ex) {
         if (this.log.isWarnEnabled()) {
            this.log.warn("Malformed challenge: " + ex.getMessage());
         }

         authState.reset();
         return false;
      }
   }

   public void generateAuthResponse(HttpRequest request, AuthState authState, HttpContext context) throws HttpException, IOException {
      AuthScheme authScheme = authState.getAuthScheme();
      Credentials creds = authState.getCredentials();
      switch (authState.getState()) {
         case CHALLENGED:
            Queue<AuthOption> authOptions = authState.getAuthOptions();
            if (authOptions != null) {
               while(!authOptions.isEmpty()) {
                  AuthOption authOption = (AuthOption)authOptions.remove();
                  authScheme = authOption.getAuthScheme();
                  creds = authOption.getCredentials();
                  authState.update(authScheme, creds);
                  if (this.log.isDebugEnabled()) {
                     this.log.debug("Generating response to an authentication challenge using " + authScheme.getSchemeName() + " scheme");
                  }

                  try {
                     Header header = this.doAuth(authScheme, creds, request, context);
                     request.addHeader(header);
                     break;
                  } catch (AuthenticationException ex) {
                     if (this.log.isWarnEnabled()) {
                        this.log.warn(authScheme + " authentication error: " + ex.getMessage());
                     }
                  }
               }

               return;
            }

            this.ensureAuthScheme(authScheme);
         case HANDSHAKE:
         default:
            break;
         case SUCCESS:
            this.ensureAuthScheme(authScheme);
            if (authScheme.isConnectionBased()) {
               return;
            }
            break;
         case FAILURE:
            return;
      }

      if (authScheme != null) {
         try {
            Header header = this.doAuth(authScheme, creds, request, context);
            request.addHeader(header);
         } catch (AuthenticationException ex) {
            if (this.log.isErrorEnabled()) {
               this.log.error(authScheme + " authentication error: " + ex.getMessage());
            }
         }
      }

   }

   private void ensureAuthScheme(AuthScheme authScheme) {
      Asserts.notNull(authScheme, "Auth scheme");
   }

   private Header doAuth(AuthScheme authScheme, Credentials creds, HttpRequest request, HttpContext context) throws AuthenticationException {
      return authScheme instanceof ContextAwareAuthScheme ? ((ContextAwareAuthScheme)authScheme).authenticate(creds, request, context) : authScheme.authenticate(creds, request);
   }
}
