/*
    * ====================================================================
    * 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.net;
  
  import java.net.InetAddress;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.net.UnknownHostException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  import org.apache.hc.core5.http.HttpHost;
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.http.message.BasicNameValuePair;
  import org.apache.hc.core5.util.TextUtils;
  
  /**
   * Builder for {@link URI} instances.
   *
   * @since 5.0
   */
  public class URIBuilder {
  
      /**
       * Creates a new builder for the host {@link InetAddress#getLocalHost()}.
       *
       * @return a new builder.
       * @throws UnknownHostException if the local host name could not be resolved into an address.
       */
      public static URIBuilder localhost() throws UnknownHostException {
          return new URIBuilder().setHost(InetAddress.getLocalHost());
      }
  
      /**
       * Creates a new builder for the host {@link InetAddress#getLoopbackAddress()}.
       */
      public static URIBuilder loopbackAddress() {
          return new URIBuilder().setHost(InetAddress.getLoopbackAddress());
      }
  
      private String scheme;
      private String encodedSchemeSpecificPart;
      private String encodedAuthority;
      private String userInfo;
      private String encodedUserInfo;
      private String host;
      private int port;
      private String encodedPath;
      private List<String> pathSegments;
      private String encodedQuery;
      private List<NameValuePair> queryParams;
      private String query;
      private Charset charset;
      private String fragment;
      private String encodedFragment;
  
      /**
       * Constructs an empty instance.
       */
      public URIBuilder() {
          super();
          this.port = -1;
      }
  
      /**
       * Construct an instance from the string which must be a valid URI.
       *
       * @param string a valid URI in string form
       * @throws URISyntaxException if the input is not a valid URI
       */
     public URIBuilder(final String string) throws URISyntaxException {
         this(new URI(string), null);
     }
 
     /**
      * Construct an instance from the provided URI.
      * @param uri
      */
     public URIBuilder(final URI uri) {
         this(uri, null);
     }
 
     /**
      * Construct an instance from the string which must be a valid URI.
      *
      * @param string a valid URI in string form
      * @throws URISyntaxException if the input is not a valid URI
      */
     public URIBuilder(final String string, final Charset charset) throws URISyntaxException {
         this(new URI(string), charset);
     }
 
     /**
      * Construct an instance from the provided URI.
      * @param uri
      */
     public URIBuilder(final URI uri, final Charset charset) {
         super();
         setCharset(charset);
         digestURI(uri);
     }
 
     public URIBuilder setCharset(final Charset charset) {
         this.charset = charset;
         return this;
     }
 
     public Charset getCharset() {
         return charset;
     }
 
     private List <NameValuePair> parseQuery(final String query, final Charset charset) {
         if (query != null && !query.isEmpty()) {
             return URLEncodedUtils.parse(query, charset);
         }
         return null;
     }
 
     private List <String> parsePath(final String path, final Charset charset) {
         if (path != null && !path.isEmpty()) {
             return URLEncodedUtils.parsePathSegments(path, charset);
         }
         return null;
     }
 
     /**
      * Builds a {@link URI} instance.
      */
     public URI build() throws URISyntaxException {
         return new URI(buildString());
     }
 
     private String buildString() {
         final StringBuilder sb = new StringBuilder();
         if (this.scheme != null) {
             sb.append(this.scheme).append(':');
         }
         if (this.encodedSchemeSpecificPart != null) {
             sb.append(this.encodedSchemeSpecificPart);
         } else {
             if (this.encodedAuthority != null) {
                 sb.append("//").append(this.encodedAuthority);
             } else if (this.host != null) {
                 sb.append("//");
                 if (this.encodedUserInfo != null) {
                     sb.append(this.encodedUserInfo).append("@");
                 } else if (this.userInfo != null) {
                     encodeUserInfo(sb, this.userInfo);
                     sb.append("@");
                 }
                 if (InetAddressUtils.isIPv6Address(this.host)) {
                     sb.append("[").append(this.host).append("]");
                 } else {
                     sb.append(this.host);
                 }
                 if (this.port >= 0) {
                     sb.append(":").append(this.port);
                 }
             }
             if (this.encodedPath != null) {
                 sb.append(normalizePath(this.encodedPath, sb.length() == 0));
             } else if (this.pathSegments != null) {
                 encodePath(sb, this.pathSegments);
             }
             if (this.encodedQuery != null) {
                 sb.append("?").append(this.encodedQuery);
             } else if (this.queryParams != null && !this.queryParams.isEmpty()) {
                 sb.append("?");
                 encodeUrlForm(sb, this.queryParams);
             } else if (this.query != null) {
                 sb.append("?");
                 encodeUric(sb, this.query);
             }
         }
         if (this.encodedFragment != null) {
             sb.append("#").append(this.encodedFragment);
         } else if (this.fragment != null) {
             sb.append("#");
             encodeUric(sb, this.fragment);
         }
         return sb.toString();
     }
 
     private static String normalizePath(final String path, final boolean relative) {
         String s = path;
         if (TextUtils.isBlank(s)) {
             return "";
         }
         if (!relative && !s.startsWith("/")) {
             s = "/" + s;
         }
         return s;
     }
 
     private void digestURI(final URI uri) {
         this.scheme = uri.getScheme();
         this.encodedSchemeSpecificPart = uri.getRawSchemeSpecificPart();
         this.encodedAuthority = uri.getRawAuthority();
         this.host = uri.getHost();
         this.port = uri.getPort();
         this.encodedUserInfo = uri.getRawUserInfo();
         this.userInfo = uri.getUserInfo();
         this.encodedPath = uri.getRawPath();
         this.pathSegments = parsePath(uri.getRawPath(), this.charset != null ? this.charset : StandardCharsets.UTF_8);
         this.encodedQuery = uri.getRawQuery();
         this.queryParams = parseQuery(uri.getRawQuery(), this.charset != null ? this.charset : StandardCharsets.UTF_8);
         this.encodedFragment = uri.getRawFragment();
         this.fragment = uri.getFragment();
     }
 
     private void encodeUserInfo(final StringBuilder buf, final String userInfo) {
         URLEncodedUtils.encUserInfo(buf, userInfo, this.charset != null ? this.charset : StandardCharsets.UTF_8);
     }
 
     private void encodePath(final StringBuilder buf, final List<String> pathSegments) {
         URLEncodedUtils.formatSegments(buf, pathSegments, this.charset != null ? this.charset : StandardCharsets.UTF_8);
     }
 
     private void encodeUrlForm(final StringBuilder buf, final List<NameValuePair> params) {
         URLEncodedUtils.formatParameters(buf, params, this.charset != null ? this.charset : StandardCharsets.UTF_8);
     }
 
     private void encodeUric(final StringBuilder buf, final String fragment) {
         URLEncodedUtils.encUric(buf, fragment, this.charset != null ? this.charset : StandardCharsets.UTF_8);
     }
 
     /**
      * Sets URI scheme.
      *
      * @return this.
      */
     public URIBuilder setScheme(final String scheme) {
         this.scheme = !TextUtils.isBlank(scheme) ? scheme : null;
         return this;
     }
 
     /**
      * Sets URI user info. The value is expected to be unescaped and may contain non ASCII
      * characters.
      *
      * @return this.
      */
     public URIBuilder setUserInfo(final String userInfo) {
         this.userInfo = !TextUtils.isBlank(userInfo) ? userInfo : null;
         this.encodedSchemeSpecificPart = null;
         this.encodedAuthority = null;
         this.encodedUserInfo = null;
         return this;
     }
 
     /**
      * Sets URI user info as a combination of username and password. These values are expected to
      * be unescaped and may contain non ASCII characters.
      *
      * @return this.
      */
     public URIBuilder setUserInfo(final String username, final String password) {
         return setUserInfo(username + ':' + password);
     }
 
     /**
      * Sets URI host.
      *
      * @return this.
      */
     public URIBuilder setHost(final InetAddress host) {
         this.host = host != null ? host.getHostAddress() : null;
         this.encodedSchemeSpecificPart = null;
         this.encodedAuthority = null;
         return this;
     }
 
     /**
      * Sets URI host.
      *
      * @return this.
      */
     public URIBuilder setHost(final String host) {
         this.host = !TextUtils.isBlank(host) ? host : null;
         this.encodedSchemeSpecificPart = null;
         this.encodedAuthority = null;
         return this;
     }
 
     /**
      * Sets the scheme, host name, and port.
      *
      * @param httpHost the scheme, host name, and port.
      * @return this.
      */
     public URIBuilder setHttpHost(final HttpHost httpHost ) {
         setScheme(httpHost.getSchemeName());
         setHost(httpHost.getHostName());
         setPort(httpHost.getPort());
         return this;
     }
 
     /**
      * Sets URI port.
      *
      * @return this.
      */
     public URIBuilder setPort(final int port) {
         this.port = port < 0 ? -1 : port;
         this.encodedSchemeSpecificPart = null;
         this.encodedAuthority = null;
         return this;
     }
 
     /**
      * Sets URI path. The value is expected to be unescaped and may contain non ASCII characters.
      *
      * @return this.
      */
     public URIBuilder setPath(final String path) {
         return setPathSegments(path != null ? URLEncodedUtils.splitPathSegments(path) : null);
     }
 
     /**
      * Sets URI path. The value is expected to be unescaped and may contain non ASCII characters.
      *
      * @return this.
      */
     public URIBuilder setPathSegments(final String... pathSegments) {
         this.pathSegments = pathSegments.length > 0 ? Arrays.asList(pathSegments) : null;
         this.encodedSchemeSpecificPart = null;
         this.encodedPath = null;
         return this;
     }
 
     /**
      * Sets URI path. The value is expected to be unescaped and may contain non ASCII characters.
      *
      * @return this.
      */
     public URIBuilder setPathSegments(final List<String> pathSegments) {
         this.pathSegments = pathSegments != null && pathSegments.size() > 0 ? new ArrayList<>(pathSegments) : null;
         this.encodedSchemeSpecificPart = null;
         this.encodedPath = null;
         return this;
     }
 
     /**
      * Removes URI query.
      *
      * @return this.
      */
     public URIBuilder removeQuery() {
         this.queryParams = null;
         this.query = null;
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         return this;
     }
 
     /**
      * Sets URI query parameters. The parameter name / values are expected to be unescaped
      * and may contain non ASCII characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove custom query if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder setParameters(final List <NameValuePair> nvps) {
         if (this.queryParams == null) {
             this.queryParams = new ArrayList<>();
         } else {
             this.queryParams.clear();
         }
         this.queryParams.addAll(nvps);
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.query = null;
         return this;
     }
 
     /**
      * Adds URI query parameters. The parameter name / values are expected to be unescaped
      * and may contain non ASCII characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove custom query if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder addParameters(final List <NameValuePair> nvps) {
         if (this.queryParams == null) {
             this.queryParams = new ArrayList<>();
         }
         this.queryParams.addAll(nvps);
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.query = null;
         return this;
     }
 
     /**
      * Sets URI query parameters. The parameter name / values are expected to be unescaped
      * and may contain non ASCII characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove custom query if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder setParameters(final NameValuePair... nvps) {
         if (this.queryParams == null) {
             this.queryParams = new ArrayList<>();
         } else {
             this.queryParams.clear();
         }
         Collections.addAll(this.queryParams, nvps);
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.query = null;
         return this;
     }
 
     /**
      * Adds parameter to URI query. The parameter name and value are expected to be unescaped
      * and may contain non ASCII characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove custom query if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder addParameter(final String param, final String value) {
         if (this.queryParams == null) {
             this.queryParams = new ArrayList<>();
         }
         this.queryParams.add(new BasicNameValuePair(param, value));
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.query = null;
         return this;
     }
 
     /**
      * Sets parameter of URI query overriding existing value if set. The parameter name and value
      * are expected to be unescaped and may contain non ASCII characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove custom query if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder setParameter(final String param, final String value) {
         if (this.queryParams == null) {
             this.queryParams = new ArrayList<>();
         }
         if (!this.queryParams.isEmpty()) {
             for (final Iterator<NameValuePair> it = this.queryParams.iterator(); it.hasNext(); ) {
                 final NameValuePair nvp = it.next();
                 if (nvp.getName().equals(param)) {
                     it.remove();
                 }
             }
         }
         this.queryParams.add(new BasicNameValuePair(param, value));
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.query = null;
         return this;
     }
 
     /**
      * Clears URI query parameters.
      *
      * @return this.
      */
     public URIBuilder clearParameters() {
         this.queryParams = null;
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         return this;
     }
 
     /**
      * Sets custom URI query. The value is expected to be unescaped and may contain non ASCII
      * characters.
      * <p>
      * Please note query parameters and custom query component are mutually exclusive. This method
      * will remove query parameters if present.
      * </p>
      *
      * @return this.
      */
     public URIBuilder setCustomQuery(final String query) {
         this.query = !TextUtils.isBlank(query) ? query : null;
         this.encodedQuery = null;
         this.encodedSchemeSpecificPart = null;
         this.queryParams = null;
         return this;
     }
 
     /**
      * Sets URI fragment. The value is expected to be unescaped and may contain non ASCII
      * characters.
      *
      * @return this.
      */
     public URIBuilder setFragment(final String fragment) {
         this.fragment = !TextUtils.isBlank(fragment) ? fragment : null;
         this.encodedFragment = null;
         return this;
     }
 
     public boolean isAbsolute() {
         return this.scheme != null;
     }
 
     public boolean isOpaque() {
         return this.pathSegments == null && this.encodedPath == null;
     }
 
     public String getScheme() {
         return this.scheme;
     }
 
     public String getUserInfo() {
         return this.userInfo;
     }
 
     public String getHost() {
         return this.host;
     }
 
     public int getPort() {
         return this.port;
     }
 
     public boolean isPathEmpty() {
         return (this.pathSegments == null || this.pathSegments.isEmpty()) &&
                 (this.encodedPath == null || this.encodedPath.isEmpty());
     }
 
     public List<String> getPathSegments() {
         return this.pathSegments != null ? new ArrayList<>(this.pathSegments) : Collections.<String>emptyList();
     }
 
     public String getPath() {
         if (this.pathSegments == null) {
             return null;
         }
         final StringBuilder result = new StringBuilder();
         for (final String segment : this.pathSegments) {
             result.append('/').append(segment);
         }
         return result.toString();
     }
 
     public boolean isQueryEmpty() {
         return (this.queryParams == null || this.queryParams.isEmpty()) && this.encodedQuery == null;
     }
 
     public List<NameValuePair> getQueryParams() {
         return this.queryParams != null ? new ArrayList<>(this.queryParams) : Collections.<NameValuePair>emptyList();
     }
 
     public String getFragment() {
         return this.fragment;
     }
 
     @Override
     public String toString() {
         return buildString();
     }
 
 }