//
   //  ========================================================================
   //  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.security.authentication;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.Locale;
  import javax.servlet.RequestDispatcher;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletRequestWrapper;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpServletResponseWrapper;
  import javax.servlet.http.HttpSession;
  
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpHeaderValue;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.HttpVersion;
  import org.eclipse.jetty.http.MimeTypes;
  import org.eclipse.jetty.security.ServerAuthException;
  import org.eclipse.jetty.security.UserAuthentication;
  import org.eclipse.jetty.server.Authentication;
  import org.eclipse.jetty.server.Authentication.User;
  import org.eclipse.jetty.server.HttpChannel;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.Response;
  import org.eclipse.jetty.server.UserIdentity;
  import org.eclipse.jetty.util.MultiMap;
  import org.eclipse.jetty.util.StringUtil;
  import org.eclipse.jetty.util.URIUtil;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.security.Constraint;
  
  /**
   * FORM Authenticator.
   *
   * <p>This authenticator implements form authentication will use dispatchers to
   * the login page if the {@link #__FORM_DISPATCH} init parameter is set to true.
   * Otherwise it will redirect.</p>
   *
   * <p>The form authenticator redirects unauthenticated requests to a log page
   * which should use a form to gather username/password from the user and send them
   * to the /j_security_check URI within the context.  FormAuthentication uses
   * {@link SessionAuthentication} to wrap Authentication results so that they
   * are  associated with the session.</p>
   *
   *
   */
  public class FormAuthenticator extends LoginAuthenticator
  {
      private static final Logger LOG = Log.getLogger(FormAuthenticator.class);
  
      public final static String __FORM_LOGIN_PAGE="org.eclipse.jetty.security.form_login_page";
      public final static String __FORM_ERROR_PAGE="org.eclipse.jetty.security.form_error_page";
      public final static String __FORM_DISPATCH="org.eclipse.jetty.security.dispatch";
      public final static String __J_URI = "org.eclipse.jetty.security.form_URI";
      public final static String __J_POST = "org.eclipse.jetty.security.form_POST";
      public final static String __J_METHOD = "org.eclipse.jetty.security.form_METHOD";
      public final static String __J_SECURITY_CHECK = "/j_security_check";
      public final static String __J_USERNAME = "j_username";
      public final static String __J_PASSWORD = "j_password";
  
      private String _formErrorPage;
      private String _formErrorPath;
      private String _formLoginPage;
      private String _formLoginPath;
      private boolean _dispatch;
      private boolean _alwaysSaveUri;
  
      public FormAuthenticator()
      {
      }
  
      /* ------------------------------------------------------------ */
      public FormAuthenticator(String login,String error,boolean dispatch)
      {
          this();
          if (login!=null)
             setLoginPage(login);
         if (error!=null)
             setErrorPage(error);
         _dispatch=dispatch;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * If true, uris that cause a redirect to a login page will always
      * be remembered. If false, only the first uri that leads to a login
      * page redirect is remembered.
      * See https://bugs.eclipse.org/bugs/show_bug.cgi?id=379909
      * @param alwaysSave
      */
     public void setAlwaysSaveUri (boolean alwaysSave)
     {
         _alwaysSaveUri = alwaysSave;
     }
 
 
     /* ------------------------------------------------------------ */
     public boolean getAlwaysSaveUri ()
     {
         return _alwaysSaveUri;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see org.eclipse.jetty.security.authentication.LoginAuthenticator#setConfiguration(org.eclipse.jetty.security.Authenticator.AuthConfiguration)
      */
     @Override
     public void setConfiguration(AuthConfiguration configuration)
     {
         super.setConfiguration(configuration);
         String login=configuration.getInitParameter(FormAuthenticator.__FORM_LOGIN_PAGE);
         if (login!=null)
             setLoginPage(login);
         String error=configuration.getInitParameter(FormAuthenticator.__FORM_ERROR_PAGE);
         if (error!=null)
             setErrorPage(error);
         String dispatch=configuration.getInitParameter(FormAuthenticator.__FORM_DISPATCH);
         _dispatch = dispatch==null?_dispatch:Boolean.valueOf(dispatch);
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public String getAuthMethod()
     {
         return Constraint.__FORM_AUTH;
     }
 
     /* ------------------------------------------------------------ */
     private void setLoginPage(String path)
     {
         if (!path.startsWith("/"))
         {
             LOG.warn("form-login-page must start with /");
             path = "/" + path;
         }
         _formLoginPage = path;
         _formLoginPath = path;
         if (_formLoginPath.indexOf('?') > 0)
             _formLoginPath = _formLoginPath.substring(0, _formLoginPath.indexOf('?'));
     }
 
     /* ------------------------------------------------------------ */
     private void setErrorPage(String path)
     {
         if (path == null || path.trim().length() == 0)
         {
             _formErrorPath = null;
             _formErrorPage = null;
         }
         else
         {
             if (!path.startsWith("/"))
             {
                 LOG.warn("form-error-page must start with /");
                 path = "/" + path;
             }
             _formErrorPage = path;
             _formErrorPath = path;
 
             if (_formErrorPath.indexOf('?') > 0)
                 _formErrorPath = _formErrorPath.substring(0, _formErrorPath.indexOf('?'));
         }
     }
     
     
     /* ------------------------------------------------------------ */
     @Override
     public UserIdentity login(String username, Object password, ServletRequest request)
     {
         
         UserIdentity user = super.login(username,password,request);
         if (user!=null)
         {
             HttpSession session = ((HttpServletRequest)request).getSession(true);
             Authentication cached=new SessionAuthentication(getAuthMethod(),user,password);
             session.setAttribute(SessionAuthentication.__J_AUTHENTICATED, cached);
         }
         return user;
     }
     
     
     /* ------------------------------------------------------------ */
     @Override
     public void prepareRequest(ServletRequest request)
     {
         //if this is a request resulting from a redirect after auth is complete
         //(ie its from a redirect to the original request uri) then due to 
         //browser handling of 302 redirects, the method may not be the same as
         //that of the original request. Replace the method and original post
         //params (if it was a post).
         //
         //See Servlet Spec 3.1 sec 13.6.3
         HttpServletRequest httpRequest = (HttpServletRequest)request;
         HttpSession session = httpRequest.getSession(false);
         if (session == null || session.getAttribute(SessionAuthentication.__J_AUTHENTICATED) == null)
             return; //not authenticated yet
         
         String juri = (String)session.getAttribute(__J_URI);
         if (juri == null || juri.length() == 0)
             return; //no original uri saved
         
         String method = (String)session.getAttribute(__J_METHOD);
         if (method == null || method.length() == 0)
             return; //didn't save original request method
        
         StringBuffer buf = httpRequest.getRequestURL();
         if (httpRequest.getQueryString() != null)
             buf.append("?").append(httpRequest.getQueryString());
         
         if (!juri.equals(buf.toString()))
             return; //this request is not for the same url as the original
         
         //restore the original request's method on this request
         if (LOG.isDebugEnabled()) LOG.debug("Restoring original method {} for {} with method {}", method, juri,httpRequest.getMethod());
         Request base_request = HttpChannel.getCurrentHttpChannel().getRequest();
         HttpMethod m = HttpMethod.fromString(method);
         base_request.setMethod(m,m.asString());
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public Authentication validateRequest(ServletRequest req, ServletResponse res, boolean mandatory) throws ServerAuthException
     {
         HttpServletRequest request = (HttpServletRequest)req;
         HttpServletResponse response = (HttpServletResponse)res;
         String uri = request.getRequestURI();
         if (uri==null)
             uri=URIUtil.SLASH;
 
         mandatory|=isJSecurityCheck(uri);
         if (!mandatory)
             return new DeferredAuthentication(this);
 
         if (isLoginOrErrorPage(URIUtil.addPaths(request.getServletPath(),request.getPathInfo())) &&!DeferredAuthentication.isDeferred(response))
             return new DeferredAuthentication(this);
 
         HttpSession session = request.getSession(true);
 
         try
         {
             // Handle a request for authentication.
             if (isJSecurityCheck(uri))
             {
                 final String username = request.getParameter(__J_USERNAME);
                 final String password = request.getParameter(__J_PASSWORD);
 
                 UserIdentity user = login(username, password, request);
                 LOG.debug("jsecuritycheck {} {}",username,user);
                 session = request.getSession(true);
                 if (user!=null)
                 {                    
                     // Redirect to original request
                     String nuri;
                     FormAuthentication form_auth;
                     synchronized(session)
                     {
                         nuri = (String) session.getAttribute(__J_URI);
 
                         if (nuri == null || nuri.length() == 0)
                         {
                             nuri = request.getContextPath();
                             if (nuri.length() == 0)
                                 nuri = URIUtil.SLASH;
                         }
                         form_auth = new FormAuthentication(getAuthMethod(),user);
                     }
                     LOG.debug("authenticated {}->{}",form_auth,nuri);
 
                     response.setContentLength(0);
                     Response base_response = HttpChannel.getCurrentHttpChannel().getResponse();
                     Request base_request = HttpChannel.getCurrentHttpChannel().getRequest();
                     int redirectCode = (base_request.getHttpVersion().getVersion() < HttpVersion.HTTP_1_1.getVersion() ? HttpServletResponse.SC_MOVED_TEMPORARILY : HttpServletResponse.SC_SEE_OTHER);
                     base_response.sendRedirect(redirectCode, response.encodeRedirectURL(nuri));
                     return form_auth;
                 }
 
                 // not authenticated
                 if (LOG.isDebugEnabled())
                     LOG.debug("Form authentication FAILED for " + StringUtil.printable(username));
                 if (_formErrorPage == null)
                 {
                     LOG.debug("auth failed {}->403",username);
                     if (response != null)
                         response.sendError(HttpServletResponse.SC_FORBIDDEN);
                 }
                 else if (_dispatch)
                 {
                     LOG.debug("auth failed {}=={}",username,_formErrorPage);
                     RequestDispatcher dispatcher = request.getRequestDispatcher(_formErrorPage);
                     response.setHeader(HttpHeader.CACHE_CONTROL.asString(),HttpHeaderValue.NO_CACHE.asString());
                     response.setDateHeader(HttpHeader.EXPIRES.asString(),1);
                     dispatcher.forward(new FormRequest(request), new FormResponse(response));
                 }
                 else
                 {
                     LOG.debug("auth failed {}->{}",username,_formErrorPage);
                     Response base_response = HttpChannel.getCurrentHttpChannel().getResponse();
                     Request base_request = HttpChannel.getCurrentHttpChannel().getRequest();
                     int redirectCode = (base_request.getHttpVersion().getVersion() < HttpVersion.HTTP_1_1.getVersion() ? HttpServletResponse.SC_MOVED_TEMPORARILY : HttpServletResponse.SC_SEE_OTHER);
                     base_response.sendRedirect(redirectCode, response.encodeRedirectURL(URIUtil.addPaths(request.getContextPath(),_formErrorPage)));
                 }
 
                 return Authentication.SEND_FAILURE;
             }
 
             // Look for cached authentication
             Authentication authentication = (Authentication) session.getAttribute(SessionAuthentication.__J_AUTHENTICATED);
             if (authentication != null)
             {
                 // Has authentication been revoked?
                 if (authentication instanceof Authentication.User &&
                     _loginService!=null &&
                     !_loginService.validate(((Authentication.User)authentication).getUserIdentity()))
                 {
                     LOG.debug("auth revoked {}",authentication);
                     session.removeAttribute(SessionAuthentication.__J_AUTHENTICATED);
                 }
                 else
                 {
                     synchronized (session)
                     {
                         String j_uri=(String)session.getAttribute(__J_URI);
                         if (j_uri!=null)
                         {
                             //check if the request is for the same url as the original and restore
                             //params if it was a post
                             LOG.debug("auth retry {}->{}",authentication,j_uri);
                             StringBuffer buf = request.getRequestURL();
                             if (request.getQueryString() != null)
                                 buf.append("?").append(request.getQueryString());
 
                             if (j_uri.equals(buf.toString()))
                             {
                                 MultiMap<String> j_post = (MultiMap<String>)session.getAttribute(__J_POST);
                                 if (j_post!=null)
                                 {
                                     LOG.debug("auth rePOST {}->{}",authentication,j_uri);
                                     Request base_request = HttpChannel.getCurrentHttpChannel().getRequest();
                                     base_request.setContentParameters(j_post);
                                 }
                                 session.removeAttribute(__J_URI);
                                 session.removeAttribute(__J_METHOD);
                                 session.removeAttribute(__J_POST);
                             }
                         }
                     }
                     LOG.debug("auth {}",authentication);
                     return authentication;
                 }
             }
 
             // if we can't send challenge
             if (DeferredAuthentication.isDeferred(response))
             {
                 LOG.debug("auth deferred {}",session.getId());
                 return Authentication.UNAUTHENTICATED;
             }
 
             // remember the current URI
             synchronized (session)
             {
                 // But only if it is not set already, or we save every uri that leads to a login form redirect
                 if (session.getAttribute(__J_URI)==null || _alwaysSaveUri)
                 {
                     StringBuffer buf = request.getRequestURL();
                     if (request.getQueryString() != null)
                         buf.append("?").append(request.getQueryString());
                     session.setAttribute(__J_URI, buf.toString());
                     session.setAttribute(__J_METHOD, request.getMethod());
 
                     if (MimeTypes.Type.FORM_ENCODED.is(req.getContentType()) && HttpMethod.POST.is(request.getMethod()))
                     {
                         Request base_request = (req instanceof Request)?(Request)req:HttpChannel.getCurrentHttpChannel().getRequest();
                         MultiMap<String> formParameters = new MultiMap<>();
                         base_request.extractFormParameters(formParameters);
                         session.setAttribute(__J_POST, formParameters);
                     }
                 }
             }
 
             // send the the challenge
             if (_dispatch)
             {
                 LOG.debug("challenge {}=={}",session.getId(),_formLoginPage);
                 RequestDispatcher dispatcher = request.getRequestDispatcher(_formLoginPage);
                 response.setHeader(HttpHeader.CACHE_CONTROL.asString(),HttpHeaderValue.NO_CACHE.asString());
                 response.setDateHeader(HttpHeader.EXPIRES.asString(),1);
                 dispatcher.forward(new FormRequest(request), new FormResponse(response));
             }
             else
             {
                 LOG.debug("challenge {}->{}",session.getId(),_formLoginPage);
                 Response base_response = HttpChannel.getCurrentHttpChannel().getResponse();
                 Request base_request = HttpChannel.getCurrentHttpChannel().getRequest();
                 int redirectCode = (base_request.getHttpVersion().getVersion() < HttpVersion.HTTP_1_1.getVersion() ? HttpServletResponse.SC_MOVED_TEMPORARILY : HttpServletResponse.SC_SEE_OTHER);
                 base_response.sendRedirect(redirectCode, response.encodeRedirectURL(URIUtil.addPaths(request.getContextPath(),_formLoginPage)));
             }
             return Authentication.SEND_CONTINUE;
         }
         catch (IOException | ServletException e)
         {
             throw new ServerAuthException(e);
         }
     }
 
     /* ------------------------------------------------------------ */
     public boolean isJSecurityCheck(String uri)
     {
         int jsc = uri.indexOf(__J_SECURITY_CHECK);
 
         if (jsc<0)
             return false;
         int e=jsc+__J_SECURITY_CHECK.length();
         if (e==uri.length())
             return true;
         char c = uri.charAt(e);
         return c==';'||c=='#'||c=='/'||c=='?';
     }
 
     /* ------------------------------------------------------------ */
     public boolean isLoginOrErrorPage(String pathInContext)
     {
         return pathInContext != null && (pathInContext.equals(_formErrorPath) || pathInContext.equals(_formLoginPath));
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public boolean secureResponse(ServletRequest req, ServletResponse res, boolean mandatory, User validatedUser) throws ServerAuthException
     {
         return true;
     }
 
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     protected static class FormRequest extends HttpServletRequestWrapper
     {
         public FormRequest(HttpServletRequest request)
         {
             super(request);
         }
 
         @Override
         public long getDateHeader(String name)
         {
             if (name.toLowerCase(Locale.ENGLISH).startsWith("if-"))
                 return -1;
             return super.getDateHeader(name);
         }
 
         @Override
         public String getHeader(String name)
         {
             if (name.toLowerCase(Locale.ENGLISH).startsWith("if-"))
                 return null;
             return super.getHeader(name);
         }
 
         @Override
         public Enumeration<String> getHeaderNames()
         {
             return Collections.enumeration(Collections.list(super.getHeaderNames()));
         }
 
         @Override
         public Enumeration<String> getHeaders(String name)
         {
             if (name.toLowerCase(Locale.ENGLISH).startsWith("if-"))
                 return Collections.<String>enumeration(Collections.<String>emptyList());
             return super.getHeaders(name);
         }
     }
 
     /* ------------------------------------------------------------ */
     /* ------------------------------------------------------------ */
     protected static class FormResponse extends HttpServletResponseWrapper
     {
         public FormResponse(HttpServletResponse response)
         {
             super(response);
         }
 
         @Override
         public void addDateHeader(String name, long date)
         {
             if (notIgnored(name))
                 super.addDateHeader(name,date);
         }
 
         @Override
         public void addHeader(String name, String value)
         {
             if (notIgnored(name))
                 super.addHeader(name,value);
         }
 
         @Override
         public void setDateHeader(String name, long date)
         {
             if (notIgnored(name))
                 super.setDateHeader(name,date);
         }
 
         @Override
         public void setHeader(String name, String value)
         {
             if (notIgnored(name))
                 super.setHeader(name,value);
         }
 
         private boolean notIgnored(String name)
         {
             if (HttpHeader.CACHE_CONTROL.is(name) ||
                 HttpHeader.PRAGMA.is(name) ||
                 HttpHeader.ETAG.is(name) ||
                 HttpHeader.EXPIRES.is(name) ||
                 HttpHeader.LAST_MODIFIED.is(name) ||
                 HttpHeader.AGE.is(name))
                 return false;
             return true;
         }
     }
 
     /* ------------------------------------------------------------ */
     /** This Authentication represents a just completed Form authentication.
      * Subsequent requests from the same user are authenticated by the presents
      * of a {@link SessionAuthentication} instance in their session.
      */
     public static class FormAuthentication extends UserAuthentication implements Authentication.ResponseSent
     {
         public FormAuthentication(String method, UserIdentity userIdentity)
         {
             super(method,userIdentity);
         }
 
         @Override
         public String toString()
         {
             return "Form"+super.toString();
         }
     }
 }