/*
    * 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.maven.shared.filtering;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.file.Files;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Properties;
  
  import org.slf4j.Logger;
  
  import static org.apache.maven.shared.filtering.FilteringUtils.isEmpty;
  
  /**
   * @author <a href="mailto:kenney@neonics.com">Kenney Westerhof</a>
   * @author William Ferguson
   */
  public final class PropertyUtils {
      /**
       * Private empty constructor to prevent instantiation.
       */
      private PropertyUtils() {
          // prevent instantiation
      }
  
      /**
       * Reads a property file, resolving all internal variables, using the supplied base properties.
       * <p>
       * The properties are resolved iteratively, so if the value of property A refers to property B, then after
       * resolution the value of property B will contain the value of property B.
       * </p>
       *
       * @param propFile The property file to load.
       * @param baseProps Properties containing the initial values to substitute into the properties file.
       * @return Properties object containing the properties in the file with their values fully resolved.
       * @throws IOException if profile does not exist, or cannot be read.
       */
      public static Properties loadPropertyFile(File propFile, Properties baseProps) throws IOException {
          return loadPropertyFile(propFile, baseProps, null);
      }
  
      /**
       * Reads a property file, resolving all internal variables, using the supplied base properties.
       * <p>
       * The properties are resolved iteratively, so if the value of property A refers to property B, then after
       * resolution the value of property B will contain the value of property B.
       * </p>
       *
       * @param propFile The property file to load.
       * @param baseProps Properties containing the initial values to substitute into the properties file.
       * @param logger Logger instance
       * @return Properties object containing the properties in the file with their values fully resolved.
       * @throws IOException if profile does not exist, or cannot be read.
       *
       * @since 3.1.2
       */
      public static Properties loadPropertyFile(File propFile, Properties baseProps, Logger logger) throws IOException {
          if (!propFile.exists()) {
              throw new FileNotFoundException(propFile.toString());
          }
  
          final Properties fileProps = new Properties();
  
          try (InputStream inStream = Files.newInputStream(propFile.toPath())) {
              fileProps.load(inStream);
          }
  
          final Properties combinedProps = new Properties();
          combinedProps.putAll(baseProps == null ? new Properties() : baseProps);
          combinedProps.putAll(fileProps);
  
          // The algorithm iterates only over the fileProps which is all that is required to resolve
          // the properties defined within the file. This is slightly different to current, however
          // I suspect that this was the actual original intent.
          //
          // The difference is that #loadPropertyFile(File, boolean, boolean) also resolves System properties
          // whose values contain expressions. I believe this is unexpected and is not validated by the test cases,
          // as can be verified by replacing the implementation of #loadPropertyFile(File, boolean, boolean)
          // with the commented variant I have provided that reuses this method.
 
         for (Object o : fileProps.keySet()) {
             final String k = (String) o;
             final String propValue = getPropertyValue(k, combinedProps, logger);
             fileProps.setProperty(k, propValue);
         }
 
         return fileProps;
     }
 
     /**
      * Reads a property file, resolving all internal variables.
      *
      * @param propfile The property file to load
      * @param fail whether to throw an exception when the file cannot be loaded or to return null
      * @param useSystemProps whether to incorporate System.getProperties settings into the returned Properties object.
      * @return the loaded and fully resolved Properties object
      * @throws IOException if profile does not exist, or cannot be read.
      */
     public static Properties loadPropertyFile(File propfile, boolean fail, boolean useSystemProps) throws IOException {
         return loadPropertyFile(propfile, fail, useSystemProps, null);
     }
 
     /**
      * Reads a property file, resolving all internal variables.
      *
      * @param propfile The property file to load
      * @param fail whether to throw an exception when the file cannot be loaded or to return null
      * @param useSystemProps whether to incorporate System.getProperties settings into the returned Properties object.
      * @param logger Logger instance
      * @return the loaded and fully resolved Properties object
      * @throws IOException if profile does not exist, or cannot be read.
      *
      * @since 3.1.2
      */
     public static Properties loadPropertyFile(File propfile, boolean fail, boolean useSystemProps, Logger logger)
             throws IOException {
 
         final Properties baseProps = new Properties();
 
         if (useSystemProps) {
             baseProps.putAll(System.getProperties());
         }
 
         final Properties resolvedProps = new Properties();
         try {
             resolvedProps.putAll(loadPropertyFile(propfile, baseProps, logger));
         } catch (FileNotFoundException e) {
             if (fail) {
                 throw new FileNotFoundException(propfile.toString());
             }
         }
 
         if (useSystemProps) {
             resolvedProps.putAll(baseProps);
         }
 
         return resolvedProps;
     }
 
     /**
      * Retrieves a property value, replacing values like ${token} using the Properties to look them up. It will leave
      * unresolved properties alone, trying for System properties, and implements reparsing (in the case that the value
      * of a property contains a key), and will not loop endlessly on a pair like test = ${test}.
      *
      * @param k
      * @param p
      * @param logger Logger instance
      * @return The filtered property value.
      */
     private static String getPropertyValue(String k, Properties p, Logger logger) {
         // This can also be done using InterpolationFilterReader,
         // but it requires reparsing the file over and over until
         // it doesn't change.
 
         // for cycle detection
         List<String> valueChain = new LinkedList<>();
         valueChain.add(k);
 
         String v = p.getProperty(k);
         String defaultValue = v;
         StringBuilder ret = new StringBuilder();
         int idx, idx2;
 
         while ((idx = v.indexOf("${")) >= 0) {
             // append prefix to result
             ret.append(v, 0, idx);
 
             // strip prefix from original
             v = v.substring(idx + 2);
 
             // if no matching } then bail
             idx2 = v.indexOf('}');
             if (idx2 < 0) {
                 break;
             }
 
             // strip out the key and resolve it
             // resolve the key/value for the ${statement}
             String nk = v.substring(0, idx2);
             v = v.substring(idx2 + 1);
             String nv = p.getProperty(nk);
 
             if (valueChain.contains(nk)) {
                 if (logger != null) {
                     logCircularDetection(valueChain, nk, logger);
                 }
                 return defaultValue;
             } else {
                 valueChain.add(nk);
 
                 // try global environment..
                 if (nv == null && !isEmpty(nk)) {
                     nv = System.getProperty(nk);
                 }
 
                 // if the key cannot be resolved,
                 // leave it alone ( and don't parse again )
                 // else prefix the original string with the
                 // resolved property ( so it can be parsed further )
                 // taking recursion into account.
                 if (nv == null || k.equals(nk)) {
                     ret.append("${").append(nk).append("}");
                 } else {
                     v = nv + v.replace("${" + nk + "}", nv);
                 }
             }
         }
 
         return ret + v;
     }
 
     /**
      * Logs the detected cycle in properties resolution
      * @param valueChain the sequence of properties resolved so far
      * @param nk the key the closes the cycle
      * @param logger Logger instance
      */
     private static void logCircularDetection(List<String> valueChain, String nk, Logger logger) {
         StringBuilder sb = new StringBuilder("Circular reference between properties detected: ");
         for (String key : valueChain) {
             sb.append(key).append(" => ");
         }
         sb.append(nk);
         logger.warn(sb.toString());
     }
 }