/*
 * 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.
 */
package org.apache.juneau;

import static org.apache.juneau.common.utils.StringUtils.*;
import static org.apache.juneau.common.utils.ThrowableUtils.*;

import org.apache.juneau.annotation.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.common.utils.*;
import org.apache.juneau.json.*;
import org.apache.juneau.parser.*;

/**
 * Represents a URL broken into authority/context-root/servlet-path/path-info parts.
 *
 * <p>
 * A typical request against a URL takes the following form:
 * <p class='bcode'>
 *    http://host:port/context-root/servlet-path/path-info
 *    |   authority   |  context   |  resource  |  path  |
 *    +--------------------------------------------------+
 * </p>
 *
 * <p>
 * This class allows you to convert URL strings to absolute (e.g. <js>"http://host:port/foo/bar"</js>) or root-relative
 * (e.g. <js>"/foo/bar"</js>) URLs.
 *
 * <h5 class='section'>See Also:</h5><ul>
 * </ul>
 */
@Bean
public class UriContext {

   /**
    * Default URI context.
    *
    * <p>
    * No information about authority, servlet-root, context-root, or path-info is known.
    */
   public static final UriContext DEFAULT = new UriContext();

   @SuppressWarnings("javadoc")
   public final String authority, contextRoot, servletPath, pathInfo, parentPath;

   // Lazy-initialized fields.
   private String aContextRoot, rContextRoot, aServletPath, rResource, aPathInfo, rPath;

   /**
    * Static creator.
    *
    * @param authority
    *    The authority portion of URL (e.g. <js>"http://hostname:port"</js>)
    * @param contextRoot
    *    The context root of the application (e.g. <js>"/context-root"</js>, or <js>"context-root"</js>)
    * @param servletPath
    *    The servlet path (e.g. <js>"/servlet-path"</js>, or <js>"servlet-path"</js>)
    * @param pathInfo
    *    The path info (e.g. <js>"/path-info"</js>, or <js>"path-info"</js>)
    * @return A new {@link UriContext} object.
    */
   public static UriContext of(String authority, String contextRoot, String servletPath, String pathInfo) {
      return new UriContext(authority, contextRoot, servletPath, pathInfo);
   }

   /**
    * Static creator.
    *
    * @param s
    *    The input string.
    *    <br>Example: <js>{authority:'http://localhost:10000',contextRoot:'/myContext',servletPath:'/myServlet',pathInfo:'/foo'}</js>
    * @return A new {@link UriContext} object.
    */
   public static UriContext of(String s) {
      try {
         return new UriContext(s);
      } catch (ParseException e) {
         throw asRuntimeException(e);
      }
   }

   /**
    * Constructor.
    *
    * <p>
    * Leading and trailing slashes are trimmed of all parameters.
    *
    * <p>
    * Any parameter can be <jk>null</jk>.  Blanks and nulls are equivalent.
    *
    * @param authority
    *    The authority portion of URL (e.g. <js>"http://hostname:port"</js>)
    * @param contextRoot
    *    The context root of the application (e.g. <js>"/context-root"</js>, or <js>"context-root"</js>)
    * @param servletPath
    *    The servlet path (e.g. <js>"/servlet-path"</js>, or <js>"servlet-path"</js>)
    * @param pathInfo
    *    The path info (e.g. <js>"/path-info"</js>, or <js>"path-info"</js>)
    */
   @Beanc
   public UriContext(@Name("authority") String authority, @Name("contextRoot") String contextRoot, @Name("servletPath") String servletPath, @Name("pathInfo") String pathInfo) {
      this.authority = Utils.nullIfEmpty3(trimSlashes(authority));
      this.contextRoot = Utils.nullIfEmpty3(trimSlashes(contextRoot));
      this.servletPath = Utils.nullIfEmpty3(trimSlashes(servletPath));
      this.pathInfo = Utils.nullIfEmpty3(trimSlashes(pathInfo));
      this.parentPath = this.pathInfo == null || this.pathInfo.indexOf('/') == -1 ? null
         : this.pathInfo.substring(0, this.pathInfo.lastIndexOf('/'));
   }

   /**
    * Default constructor.
    *
    * <p>
    * All <jk>null</jk> values.
    */
   public UriContext() {
      this(null, null, null, null);
   }

   /**
    * String constructor.
    *
    * <p>
    * Input string is a JSON object with the following format:
    * <js>{authority:'xxx',contextRoot:'xxx',servletPath:'xxx',pathInfo:'xxx'}</js>
    *
    * @param s
    *    The input string.
    *    <br>Example: <js>{authority:'http://localhost:10000',contextRoot:'/myContext',servletPath:'/myServlet',pathInfo:'/foo'}</js>
    * @throws ParseException
    *    If input string is not a valid JSON object.
    */
   public UriContext(String s) throws ParseException {
      JsonMap m = JsonMap.ofJson(s);
      this.authority = Utils.nullIfEmpty3(trimSlashes(m.getString("authority")));
      this.contextRoot = Utils.nullIfEmpty3(trimSlashes(m.getString("contextRoot")));
      this.servletPath = Utils.nullIfEmpty3(trimSlashes(m.getString("servletPath")));
      this.pathInfo = Utils.nullIfEmpty3(trimSlashes(m.getString("pathInfo")));
      this.parentPath = this.pathInfo == null || this.pathInfo.indexOf('/') == -1 ? null
         : this.pathInfo.substring(0, this.pathInfo.lastIndexOf('/'));
   }

   /**
    * Returns the absolute URI of just the authority portion of this URI context.
    *
    * <p>
    * Example:  <js>"http://hostname:port"</js>
    *
    * <p>
    * If the authority is null/empty, returns <js>"/"</js>.
    *
    * @return
    *    The absolute URI of just the authority portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getAbsoluteAuthority() {
      return authority == null ? "/" : authority;
   }

   /**
    * Returns the absolute URI of the context-root portion of this URI context.
    *
    * <p>
    * Example:  <js>"http://hostname:port/context-root"</js>
    *
    * @return
    *    The absolute URI of the context-root portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getAbsoluteContextRoot() {
      if (aContextRoot == null) {
         if (authority == null)
            aContextRoot = getRootRelativeContextRoot();
         else
            aContextRoot = (
               contextRoot == null
               ? authority
               : (authority + '/' + contextRoot)
            );
      }
      return aContextRoot;
   }

   /**
    * Returns the root-relative URI of the context portion of this URI context.
    *
    * <p>
    * Example:  <js>"/context-root"</js>
    *
    * @return
    *    The root-relative URI of the context portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getRootRelativeContextRoot() {
      if (rContextRoot == null)
         rContextRoot = contextRoot == null ? "/" : ('/' + contextRoot);
      return rContextRoot;
   }

   /**
    * Returns the absolute URI of the resource portion of this URI context.
    *
    * <p>
    * Example:  <js>"http://hostname:port/context-root/servlet-path"</js>
    *
    * @return
    *    The absolute URI of the resource portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getAbsoluteServletPath() {
      if (aServletPath == null) {
         if (authority == null)
            aServletPath = getRootRelativeServletPath();
         else {
            if (contextRoot == null)
               aServletPath = (
                  servletPath == null
                  ? authority
                  : authority + '/' + servletPath
               );
            else
               aServletPath = (
                  servletPath == null
                  ? (authority + '/' + contextRoot)
                  : (authority + '/' + contextRoot + '/' + servletPath)
               );
         }
      }
      return aServletPath;
   }

   /**
    * Returns the root-relative URI of the resource portion of this URI context.
    *
    * <p>
    * Example:  <js>"/context-root/servlet-path"</js>
    *
    * @return
    *    The root-relative URI of the resource portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getRootRelativeServletPath() {
      if (rResource == null) {
         if (contextRoot == null)
            rResource = (
               servletPath == null
               ? "/"
               : ('/' + servletPath)
            );
         else
            rResource = (
               servletPath == null
               ? ('/' + contextRoot)
               : ('/' + contextRoot + '/' + servletPath)
            );
      }
      return rResource;
   }

   /**
    * Returns the parent of the URL returned by {@link #getAbsoluteServletPath()}.
    *
    * @return The parent of the URL returned by {@link #getAbsoluteServletPath()}.
    */
   public String getAbsoluteServletPathParent() {
      return getParent(getAbsoluteServletPath());
   }

   /**
    * Returns the parent of the URL returned by {@link #getRootRelativeServletPath()}.
    *
    * @return The parent of the URL returned by {@link #getRootRelativeServletPath()}.
    */
   public String getRootRelativeServletPathParent() {
      return getParent(getRootRelativeServletPath());
   }

   /**
    * Returns the absolute URI of the path portion of this URI context.
    *
    * <p>
    * Example:  <js>"http://hostname:port/context-root/servlet-path/path-info"</js>
    *
    * @return
    *    The absolute URI of the path portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getAbsolutePathInfo() {
      if (aPathInfo == null) {
         if (authority == null)
            aPathInfo = getRootRelativePathInfo();
         else {
            if (contextRoot == null) {
               if (servletPath == null)
                  aPathInfo = (
                     pathInfo == null
                     ? authority : (authority + '/' + pathInfo)
                  );
               else
                  aPathInfo = (
                     pathInfo == null
                     ? (authority + '/' + servletPath)
                     : (authority + '/' + servletPath + '/' + pathInfo)
                  );
            } else {
               if (servletPath == null)
                  aPathInfo = (
                     pathInfo == null
                     ? authority + '/' + contextRoot
                     : (authority + '/' + contextRoot + '/' + pathInfo)
                  );
               else
                  aPathInfo = (
                     pathInfo == null
                     ? (authority + '/' + contextRoot + '/' + servletPath)
                     : (authority + '/' + contextRoot + '/' + servletPath + '/' + pathInfo)
                  );
            }
         }
      }
      return aPathInfo;
   }

   /**
    * Returns the root-relative URI of the path portion of this URI context.
    *
    * <p>
    * Example:  <js>"/context-root/servlet-path/path-info"</js>
    *
    * @return
    *    The root-relative URI of the path portion of this URI context.
    *    Never <jk>null</jk>.
    */
   public String getRootRelativePathInfo() {
      if (rPath == null) {
         if (contextRoot == null) {
            if (servletPath == null)
               rPath = (
                  pathInfo == null
                  ? "/"
                  : ('/' + pathInfo)
               );
            else
               rPath = (
                  pathInfo == null
                  ? ('/' + servletPath)
                  : ('/' + servletPath + '/' + pathInfo)
               );
         } else {
            if (servletPath == null)
               rPath = (
                  pathInfo == null
                  ? ('/' + contextRoot)
                  : ('/' + contextRoot + '/' + pathInfo)
               );
            else
               rPath = (
                  pathInfo == null
                  ? ('/' + contextRoot + '/' + servletPath)
                  : ('/' + contextRoot + '/' + servletPath + '/' + pathInfo)
               );
         }
      }
      return rPath;
   }

   /**
    * Returns the parent of the URL returned by {@link #getAbsolutePathInfo()}.
    *
    * @return The parent of the URL returned by {@link #getAbsolutePathInfo()}.
    */
   public String getAbsolutePathInfoParent() {
      return getParent(getAbsolutePathInfo());
   }

   /**
    * Returns the parent of the URL returned by {@link #getRootRelativePathInfo()}.
    *
    * @return The parent of the URL returned by {@link #getRootRelativePathInfo()}.
    */
   public String getRootRelativePathInfoParent() {
      return getParent(getRootRelativePathInfo());
   }

   private static String getParent(String uri) {
      int i = uri.lastIndexOf('/');
      if (i <= 1)
         return "/";
      return uri.substring(0, i);
   }

   @Override /* Object */
   public String toString() {
      return Json5Serializer.DEFAULT.toString(this);
   }
}