/*
 * 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.commons.utils.CollectionUtils.*;
import static org.apache.juneau.commons.utils.StringUtils.*;
import static org.apache.juneau.commons.utils.ThrowableUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;

import java.util.function.Supplier;

import org.apache.juneau.annotation.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.commons.collections.*;
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.
 *
 */
@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();

   /**
    * 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 toRex(e);
      }
   }

   /**
    * 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);
   }

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

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

   // Memoized suppliers.
   private final Supplier<String> aContextRoot, rContextRoot, aServletPath, rResource, aPathInfo, rPath;

   /**
    * 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 {
      var m = JsonMap.ofJson(s);
      this.authority = nullIfEmpty(trimSlashes(m.getString("authority")));
      this.contextRoot = nullIfEmpty(trimSlashes(m.getString("contextRoot")));
      this.servletPath = nullIfEmpty(trimSlashes(m.getString("servletPath")));
      this.pathInfo = nullIfEmpty(trimSlashes(m.getString("pathInfo")));
      this.parentPath = this.pathInfo == null || this.pathInfo.indexOf('/') == -1 ? null : this.pathInfo.substring(0, this.pathInfo.lastIndexOf('/'));
      this.rContextRoot = mem(() -> findRContextRoot());
      this.rResource = mem(() -> findRResource());
      this.rPath = mem(() -> findRPath());
      this.aContextRoot = mem(() -> findAContextRoot());
      this.aServletPath = mem(() -> findAServletPath());
      this.aPathInfo = mem(() -> findAPathInfo());
   }

   /**
    * 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 = nullIfEmpty(trimSlashes(authority));
      this.contextRoot = nullIfEmpty(trimSlashes(contextRoot));
      this.servletPath = nullIfEmpty(trimSlashes(servletPath));
      this.pathInfo = nullIfEmpty(trimSlashes(pathInfo));
      this.parentPath = this.pathInfo == null || this.pathInfo.indexOf('/') == -1 ? null : this.pathInfo.substring(0, this.pathInfo.lastIndexOf('/'));
      this.rContextRoot = mem(() -> findRContextRoot());
      this.rResource = mem(() -> findRResource());
      this.rPath = mem(() -> findRPath());
      this.aContextRoot = mem(() -> findAContextRoot());
      this.aServletPath = mem(() -> findAServletPath());
      this.aPathInfo = mem(() -> findAPathInfo());
   }

   private String findRContextRoot() {
      return contextRoot == null ? "/" : ('/' + contextRoot);
   }

   private String findRResource() {
      // @formatter:off
      if (contextRoot == null)
         return (
            servletPath == null
            ? "/"
            : ('/' + servletPath)
         );
      return (
         servletPath == null
         ? ('/' + contextRoot)
         : ('/' + contextRoot + '/' + servletPath)
      );
      // @formatter:on
   }

   private String findRPath() {
      // @formatter:off
      if (contextRoot == null) {
         if (servletPath == null)
            return (
               pathInfo == null
               ? "/"
               : ('/' + pathInfo)
            );
         return (
            pathInfo == null
            ? ('/' + servletPath)
            : ('/' + servletPath + '/' + pathInfo)
         );
      }
      if (servletPath == null)
         return (
            pathInfo == null
            ? ('/' + contextRoot)
            : ('/' + contextRoot + '/' + pathInfo)
         );
      return (
         pathInfo == null
         ? ('/' + contextRoot + '/' + servletPath)
         : ('/' + contextRoot + '/' + servletPath + '/' + pathInfo)
      );
      // @formatter:on
   }

   private String findAContextRoot() {
      // @formatter:off
      if (authority == null)
         return rContextRoot.get();
      return (
         contextRoot == null
         ? authority
         : (authority + '/' + contextRoot)
      );
      // @formatter:on
   }

   private String findAServletPath() {
      // @formatter:off
      if (authority == null)
         return rResource.get();
      if (contextRoot == null)
         return (
            servletPath == null
            ? authority
            : authority + '/' + servletPath
         );
      return (
         servletPath == null
         ? (authority + '/' + contextRoot)
         : (authority + '/' + contextRoot + '/' + servletPath)
      );
      // @formatter:on
   }

   private String findAPathInfo() {
      // @formatter:off
      if (authority == null)
         return rPath.get();
      if (contextRoot == null) {
         if (servletPath == null)
            return (
               pathInfo == null
               ? authority : (authority + '/' + pathInfo)
            );
         return (
            pathInfo == null
            ? (authority + '/' + servletPath)
            : (authority + '/' + servletPath + '/' + pathInfo)
         );
      }
      if (servletPath == null)
         return (
            pathInfo == null
            ? authority + '/' + contextRoot
            : (authority + '/' + contextRoot + '/' + pathInfo)
         );
      return (
         pathInfo == null
         ? (authority + '/' + contextRoot + '/' + servletPath)
         : (authority + '/' + contextRoot + '/' + servletPath + '/' + pathInfo)
      );
      // @formatter:on
   }

   /**
    * 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() {
      return aContextRoot.get();
   }

   /**
    * 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() {
      return aPathInfo.get();
   }

   /**
    * 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 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() {
      return aServletPath.get();
   }

   /**
    * 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 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() {
      return rContextRoot.get();
   }

   /**
    * 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() {
      return rPath.get();
   }

   /**
    * 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()); }

   /**
    * 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() {
      return rResource.get();
   }

   /**
    * 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()); }

   protected FluentMap<String,Object> properties() {
      // @formatter:off
      return filteredBeanPropertyMap()
         .a("aContextRoot", aContextRoot.get())
         .a("aPathInfo", aPathInfo.get())
         .a("aServletPath", aServletPath.get())
         .a("authority", authority)
         .a("contextRoot", contextRoot)
         .a("parentPath", parentPath)
         .a("pathInfo", pathInfo)
         .a("rContextRoot", rContextRoot.get())
         .a("rResource", rResource.get())
         .a("servletPath", servletPath)
         .a("rPath", rPath.get());
      // @formatter:on
   }

   @Override /* Overridden from Object */
   public String toString() {
      return r(properties());
   }
}