/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.http.impl.routing;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.function.BiFunction;
  import java.util.function.Function;
  import java.util.regex.Pattern;
  import java.util.stream.Collectors;
  
  final class UriPathRouter<P, T> implements Function<String, T> {
  
      private final BiFunction<String, List<PathRoute<P, T>>, T> pathRouter;
      private final List<PathRoute<P, T>> routes;
  
      UriPathRouter(final Function<String, P> compiler,
                    final BiFunction<String, List<PathRoute<P, T>>, T> pathRouter,
                    final List<PathRoute<String, T>> routes) {
          this.pathRouter = pathRouter;
          this.routes = Collections.unmodifiableList(routes.stream()
                  .map(e -> new PathRoute<>(compiler.apply(e.pattern), e.handler))
                  .collect(Collectors.toList()));
  
      }
  
      @Override
      public T apply(final String path) {
          return pathRouter.apply(path, routes);
      }
  
      @Override
      public String toString() {
          return routes.toString();
      }
  
      static <T> UriPathRouter<?, T> bestMatch(final List<PathRoute<String, T>> routes) {
          return new UriPathRouter<>(e -> e, new BestMatcher<>(), routes);
      }
  
      static <T> UriPathRouter<?, T> ordered(final List<PathRoute<String, T>> routes) {
          return new UriPathRouter<>(e -> e, new OrderedMatcher<>(), routes);
      }
  
      static <T> UriPathRouter<?, T> regEx(final List<PathRoute<String, T>> routes) {
          return new UriPathRouter<>(Pattern::compile, new RegexMatcher<>(), routes);
      }
  
      private static final PathPatternMatcher PATH_PATTERN_MATCHER = PathPatternMatcher.INSTANCE;
  
      /**
       * Finds a match for the given path from a collection of URI patterns.
       * <p>
       * Patterns may have three formats:
       * </p>
       * <ul>
       * <li>{@code *}</li>
       * <li>{@code *<uri-path>}</li>
       * <li>{@code <uri-path>*}</li>
       * </ul>
       */
      final static class BestMatcher<T> implements BiFunction<String, List<PathRoute<String, T>>, T> {
  
          @Override
          public T apply(final String path, final List<PathRoute<String, T>> routes) {
              PathRoute<String, T> bestMatch = null;
              for (final PathRoute<String, T> route : routes) {
                  if (route.pattern.equals(path)) {
                      return route.handler;
                  }
                  if (PATH_PATTERN_MATCHER.match(route.pattern, path)) {
                      // we have a match. is it any better?
                      if (bestMatch == null || PATH_PATTERN_MATCHER.isBetter(route.pattern, bestMatch.pattern)) {
                          bestMatch = route;
                     }
                 }
             }
             return bestMatch != null ? bestMatch.handler : null;
         }
 
     }
 
     /**
      * Finds a match for the given path from an ordered collection of URI patterns.
      * <p>
      * Patterns may have three formats:
      * </p>
      * <ul>
      * <li>{@code *}</li>
      * <li>{@code *<uri-path>}</li>
      * <li>{@code <uri-path>*}</li>
      * </ul>
      */
     final static class OrderedMatcher<T> implements BiFunction<String, List<PathRoute<String, T>>, T> {
 
         @Override
         public T apply(final String path, final List<PathRoute<String, T>> routes) {
             for (final PathRoute<String, T> route : routes) {
                 final String pattern = route.pattern;
                 if (path.equals(pattern)) {
                     return route.handler;
                 }
                 if (PATH_PATTERN_MATCHER.match(pattern, path)) {
                     return route.handler;
                 }
             }
             return null;
         }
     }
 
     /**
      * Finds a match for the given path from a collection of regular expressions.
      */
     final static class RegexMatcher<T> implements BiFunction<String, List<PathRoute<Pattern, T>>, T> {
 
         @Override
         public T apply(final String path, final List<PathRoute<Pattern, T>> routes) {
             for (final PathRoute<Pattern, T> route : routes) {
                 final Pattern pattern = route.pattern;
                 if (pattern.matcher(path).matches()) {
                     return route.handler;
                 }
             }
             return null;
         }
 
     }
 
 }