/*
    * Copyright (C) 2003-2012 eXo Platform SAS.
    *
    * This program is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Affero General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
    * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU Affero General Public License for more details.
   *
   * You should have received a copy of the GNU Affero General Public License
   * along with this program. If not, see <http://www.gnu.org/licenses/>.
   */
  package org.exoplatform.social.common.router;
  
  import java.io.UnsupportedEncodingException;
  import java.net.URLEncoder;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.regex.Pattern;
  
  import org.exoplatform.services.log.ExoLogger;
  import org.exoplatform.services.log.Log;
  import org.exoplatform.social.common.router.regex.ExoMatcher;
  import org.exoplatform.social.common.router.regex.ExoPattern;
  import org.picocontainer.Startable;
  
  public class ExoRouter implements Startable {
  
    /**
     * The Logger.
     */
    private static final Log LOG = ExoLogger.getLogger(ExoRouter.class);
    
    static ExoPattern defaultRoutePattern = ExoPattern.compile("^({path}.*/[^\\s]*)\\s+({action}[^\\s(]+)({params}.+)?(\\s*)$");
  
    /**
     * All the loaded routes.
     */
    public static List<Route> routes = new CopyOnWriteArrayList<Route>();
  
    public static void reset() {
      routes.clear();
    }
    
    public ExoRouter() {}
  
    public void addRoutes(ExoRouterConfig routerConfig) {
      Map<String, String> routeMapping = routerConfig.getRouteMapping();
      
      for(Map.Entry<String, String> entry : routeMapping.entrySet()) {
        addRoute(entry.getValue(), entry.getKey());
      }
    }
    
    /**
     * Add new route which loaded from route configuration file.
     * 
     * @param path /{pageID}/ForumService
     * @param action the action which appends to patch after "ForumService"
     *          string.
     */
    public static void addRoute(String path, String action) {
      addRoute(path, action, null);
    }
  
    /**
     * Add new route which loaded from route configuration file.
     * 
     * @param path /{pageID}/ForumService
     * @param action /{pageID}/ForumService
     * @param params the action which appends to patch after "ForumService" string
     *          ex: {@literal /{pageID}/{ForumService|}/{action} =>/{pageID}/ForumService/{}}
     */
    public static void addRoute(String path, String action, String params) {
      appendRoute(path, action, params);
    }
  
    public static void appendRoute(String path, String action, String params) {
      int position = routes.size();
      routes.add(position, getRoute(path, action, params));
    }
  
    public static Route getRoute(String path, String action, String params) {
      return getRoute(path, action, params, null, 0);
    }
  
    public static Route getRoute(String path, String action) {
      return getRoute(path, action, null, null, 0);
    }
  
    public static Route getRoute(String path, String action, String params, String sourceFile, int line) {
      Route route = new Route();
     route.path = path.replace("//", "/");
     route.action = action;
     route.routesFile = sourceFile;
     route.routesFileLine = line;
     route.addParams(params);
     route.compute();
     return route;
   }
 
   /**
    * Add a new route at the beginning of the route list
    */
   public static void prependRoute(String path, String action, String params) {
     routes.add(0, getRoute(path, action, params));
   }
 
   /**
    * Add a new route at the beginning of the route list
    */
   public static void prependRoute(String path, String action) {
     routes.add(0, getRoute(path, action));
   }
 
   public static Route route(String path) {
     for (Route route : routes) {
       Map<String, String> args = route.matches(path);
       if (args != null) {
         route.localArgs = args;
         return route;
       }
     }
 
     return null;
   }
 
   /**
    * Generates ActionBuilder base on the action name and arguments list.
    * Example: invokes {@code reverse("show.topic", new HashMap<String, Object>{topicId, "topicId321"})} method.
    *           
    * @param action
    * @param args
    * @return
    */
   public static ActionBuilder reverse(String action, Map<String, Object> args) {
     Map<String, Object> argsbackup = new HashMap<String, Object>(args);
     // Add routeArgs
     for (Route route : routes) {
       if (route.actionPattern != null) {
         ExoMatcher matcher = route.actionPattern.matcher(action);
         if (matcher.matches()) {
           for (String group : route.actionArgs) {
             String v = matcher.group(group);
             if (v == null) {
               continue;
             }
             args.put(group, v.toLowerCase());
           }
           List<String> inPathArgs = new ArrayList<String>(16);
           boolean allRequiredArgsAreHere = true;
 
           for (Route.ParamArg arg : route.args) {
             inPathArgs.add(arg.name);
             Object value = args.get(arg.name);
             if (value != null) {
               if (!value.toString().startsWith(":") && !arg.constraint.matches(value.toString())) {
                 allRequiredArgsAreHere = false;
                 break;
               }
             }
           }
           if (allRequiredArgsAreHere) {
             StringBuilder queryString = new StringBuilder();
             String path = route.path;
             if (path.endsWith("/?")) {
               path = path.substring(0, path.length() - 2);
             }
             for (Map.Entry<String, Object> entry : args.entrySet()) {
               String key = entry.getKey();
               Object value = entry.getValue();
               if (inPathArgs.contains(key) && value != null) {
                 path = path.replaceAll("\\{(<[^>]+>)?" + key + "\\}", value.toString().replace("$", "\\$").replace("%3A", ":").replace("%40", "@"));
               } else if (value != null) {
                 try {
                   queryString.append(URLEncoder.encode(key, "UTF-8"));
                   queryString.append("=");
                   if (value.toString().startsWith(":")) {
                     queryString.append(value.toString());
                   } else {
                     queryString.append(URLEncoder.encode(value.toString() + "", "UTF-8"));
                   }
                   queryString.append("&");
                 } catch (UnsupportedEncodingException ex) {
                   LOG.debug("Unsupported encoding error: " + ex);
                 }
 
               }
             }
             String qs = queryString.toString();
             if (qs.endsWith("&")) {
               qs = qs.substring(0, qs.length() - 1);
             }
             ActionBuilder actionDefinition = new ActionBuilder();
             actionDefinition.url = qs.length() == 0 ? path : path + "?" + qs;
             actionDefinition.action = action;
             actionDefinition.args = argsbackup;
             return actionDefinition;
           }
         }
       }
     }
     return null;
   }
 
   public static class ActionBuilder {
     public String url;
 
     /**
      * TODO - what is this? does it include the class and package?
      */
     public String action;
 
     /**
      * TODO - are these the required args in the routing file, or the query
      *       string in a request?
      */
     public Map<String, Object> args;
 
     public ActionBuilder add(String key, Object value) {
       args.put(key, value);
       return reverse(action, args);
     }
 
     public ActionBuilder remove(String key) {
       args.remove(key);
       return reverse(action, args);
     }
 
     public ActionBuilder addRef(String fragment) {
       url += "#" + fragment;
       return this;
     }
 
     @Override
     public String toString() {
       return url;
     }
 
   }
   
   /**
    * Route class which contains path, action and argument list.
    * 
    * @author thanhvc
    *
    */
   public static class Route {
 
     public String path;
 
     public String action;
 
     ExoPattern actionPattern;
 
     List<String> actionArgs = new ArrayList<String>(3);
 
     ExoPattern pattern;
 
     public String routesFile;
 
     List<ParamArg> args = new ArrayList<ParamArg>(3);
 
     Map<String, String> staticArgs = new HashMap<String, String>(3);
 
     public Map<String, String> localArgs = null;
 
     public int routesFileLine;
 
     static ExoPattern customRegexPattern =  ExoPattern.compile("\\{([a-zA-Z_][a-zA-Z_0-9]*)\\}");
 
     static ExoPattern argsPattern = ExoPattern.compile("\\{<([^>]+)>([a-zA-Z_0-9]+)\\}");
 
     static ExoPattern paramPattern = ExoPattern.compile("([a-zA-Z_0-9]+):'(.*)'");
 
     public void compute() {
       String patternString = this.path;
       patternString = customRegexPattern.matcher(patternString).replaceAll("\\{<[^/]+>$1\\}");
       ExoMatcher matcher = argsPattern.matcher(patternString);
       while (matcher.find()) {
         ParamArg arg = new ParamArg();
         arg.name = matcher.group(2);
         arg.constraint = ExoPattern.compile(matcher.group(1));
         args.add(arg);
       }
 
       patternString = argsPattern.matcher(patternString).replaceAll("({$2}$1)");
       this.pattern = ExoPattern.compile(patternString);
       // Action pattern
       patternString = action;
       patternString = patternString.replace(".", "[.]");
       for (ParamArg arg : args) {
         if (patternString.contains("{" + arg.name + "}")) {
           patternString = patternString.replace("{" + arg.name + "}", "({" + arg.name + "}" + arg.constraint.toString() + ")");
           actionArgs.add(arg.name);
         }
       }
       actionPattern = ExoPattern.compile(patternString, Pattern.CASE_INSENSITIVE);
     }
 
     public void addParams(String params) {
       if (params == null || params.length() < 1) {
         return;
       }
       params = params.substring(1, params.length() - 1);
       for (String param : params.split(",")) {
         ExoMatcher matcher = paramPattern.matcher(param);
         if (matcher.matches()) {
           staticArgs.put(matcher.group(1), matcher.group(2));
         } else {
           LOG.warn("Ignoring %s (static params must be specified as key:'value',...)");
         }
       }
     }
     /**
      * Base on defined Pattern, when provided URI path, 
      * this method will extract all of parameters path value 
      * in given path which reflects in defined Pattern
      * 
      * Example: 
      * defined Pattern = "/{pageID}/topic/{topicID}"
      * invokes:: matches("1256/topic/topic544343");
      * result: {@code Map<String, String> = {"pageID" -> "1256"}, {"topicID" -> "topic544343"}}
      * 
      * @param path : given URI path
      * @return
      */
     public Map<String, String> matches(String path) {
       ExoMatcher matcher = pattern.matcher(path);
       if (matcher.matches()) {
         Map<String, String> localArgs = new HashMap<String, String>();
         for (ParamArg arg : args) {
           if (arg.defaultValue == null) {
             localArgs.put(arg.name, matcher.group(arg.name));
           }
         }
         return localArgs;
       }
 
       return null;
     }
 
     static class ParamArg {
       String name;
 
       ExoPattern constraint;
 
       String defaultValue;
     }
   }
 
   @Override
   public void start() {
     
   }
 
   @Override
   public void stop() {
     
   }
 
 }