/*
    * 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.impl.model;
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  import java.util.function.BinaryOperator;
  import java.util.function.UnaryOperator;
  
  import org.apache.maven.api.annotations.Nullable;
  import org.apache.maven.api.di.Named;
  import org.apache.maven.api.di.Singleton;
  import org.apache.maven.api.services.Interpolator;
  import org.apache.maven.api.services.InterpolatorException;
  
  @Named
  @Singleton
  public class DefaultInterpolator implements Interpolator {
  
      private static final char ESCAPE_CHAR = '\\';
      private static final String DELIM_START = "${";
      private static final String DELIM_STOP = "}";
      private static final String MARKER = "$__";
  
      @Override
      public void interpolate(
              Map<String, String> map,
              UnaryOperator<String> callback,
              BinaryOperator<String> postprocessor,
              boolean defaultsToEmpty) {
          Map<String, String> org = new HashMap<>(map);
          for (String name : map.keySet()) {
              map.compute(
                      name,
                      (k, value) -> interpolate(
                              value,
                              name,
                              null,
                              v -> {
                                  String r = org.get(v);
                                  if (r == null && callback != null) {
                                      r = callback.apply(v);
                                  }
                                  return r;
                              },
                              postprocessor,
                              defaultsToEmpty));
          }
      }
  
      @Override
      public String interpolate(
              String val, UnaryOperator<String> callback, BinaryOperator<String> postprocessor, boolean defaultsToEmpty) {
          return interpolate(val, null, null, callback, postprocessor, defaultsToEmpty);
      }
  
      @Nullable
      public String interpolate(
              @Nullable String val,
              @Nullable String currentKey,
              @Nullable Set<String> cycleMap,
              @Nullable UnaryOperator<String> callback,
              @Nullable BinaryOperator<String> postprocessor,
              boolean defaultsToEmpty) {
          return substVars(val, currentKey, cycleMap, null, callback, postprocessor, defaultsToEmpty);
      }
  
      /**
       * Perform substitution on a property set
       *
       * @param properties the property set to perform substitution on
       * @param callback Callback for substitution
       */
      public void performSubstitution(Map<String, String> properties, UnaryOperator<String> callback) {
          performSubstitution(properties, callback, true);
      }
  
      /**
       * Perform substitution on a property set
       *
       * @param properties the property set to perform substitution on
      * @param callback the callback to obtain substitution values
      * @param defaultsToEmptyString sets an empty string if a replacement value is not found, leaves intact otherwise
      */
     public void performSubstitution(
             Map<String, String> properties, UnaryOperator<String> callback, boolean defaultsToEmptyString) {
         Map<String, String> org = new HashMap<>(properties);
         for (String name : properties.keySet()) {
             properties.compute(
                     name, (k, value) -> substVars(value, name, null, org, callback, null, defaultsToEmptyString));
         }
     }
 
     /**
      * <p>
      * This method performs property variable substitution on the
      * specified value. If the specified value contains the syntax
      * {@code ${&lt;prop-name&gt;}}, where {@code &lt;prop-name&gt;}
      * refers to either a configuration property or a system property,
      * then the corresponding property value is substituted for the variable
      * placeholder. Multiple variable placeholders may exist in the
      * specified value as well as nested variable placeholders, which
      * are substituted from innermost to outermost. Configuration
      * properties override system properties.
      * </p>
      *
      * @param val The string on which to perform property substitution.
      * @param currentKey The key of the property being evaluated used to
      *        detect cycles.
      * @param cycleMap Map of variable references used to detect nested cycles.
      * @param configProps Set of configuration properties.
      * @return The value of the specified string after system property substitution.
      * @throws InterpolatorException If there was a syntax error in the
      *         property placeholder syntax or a recursive variable reference.
      **/
     public String substVars(String val, String currentKey, Set<String> cycleMap, Map<String, String> configProps) {
         return substVars(val, currentKey, cycleMap, configProps, null);
     }
 
     /**
      * <p>
      * This method performs property variable substitution on the
      * specified value. If the specified value contains the syntax
      * {@code ${&lt;prop-name&gt;}}, where {@code &lt;prop-name&gt;}
      * refers to either a configuration property or a system property,
      * then the corresponding property value is substituted for the variable
      * placeholder. Multiple variable placeholders may exist in the
      * specified value as well as nested variable placeholders, which
      * are substituted from innermost to outermost. Configuration
      * properties override system properties.
      * </p>
      *
      * @param val The string on which to perform property substitution.
      * @param currentKey The key of the property being evaluated used to
      *        detect cycles.
      * @param cycleMap Map of variable references used to detect nested cycles.
      * @param configProps Set of configuration properties.
      * @param callback the callback to obtain substitution values
      * @return The value of the specified string after system property substitution.
      * @throws InterpolatorException If there was a syntax error in the
      *         property placeholder syntax or a recursive variable reference.
      **/
     public String substVars(
             String val,
             String currentKey,
             Set<String> cycleMap,
             Map<String, String> configProps,
             UnaryOperator<String> callback) {
         return substVars(val, currentKey, cycleMap, configProps, callback, null, false);
     }
 
     /**
      * <p>
      * This method performs property variable substitution on the
      * specified value. If the specified value contains the syntax
      * {@code ${&lt;prop-name&gt;}}, where {@code &lt;prop-name&gt;}
      * refers to either a configuration property or a system property,
      * then the corresponding property value is substituted for the variable
      * placeholder. Multiple variable placeholders may exist in the
      * specified value as well as nested variable placeholders, which
      * are substituted from innermost to outermost. Configuration
      * properties override system properties.
      * </p>
      *
      * @param val The string on which to perform property substitution.
      * @param currentKey The key of the property being evaluated used to
      *        detect cycles.
      * @param cycleMap Map of variable references used to detect nested cycles.
      * @param configProps Set of configuration properties.
      * @param callback the callback to obtain substitution values
      * @param defaultsToEmptyString sets an empty string if a replacement value is not found, leaves intact otherwise
      * @return The value of the specified string after system property substitution.
      * @throws IllegalArgumentException If there was a syntax error in the
      *         property placeholder syntax or a recursive variable reference.
      **/
     public static String substVars(
             String val,
             String currentKey,
             Set<String> cycleMap,
             Map<String, String> configProps,
             UnaryOperator<String> callback,
             BinaryOperator<String> postprocessor,
             boolean defaultsToEmptyString) {
         return unescape(
                 doSubstVars(val, currentKey, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString));
     }
 
     private static String doSubstVars(
             String val,
             String currentKey,
             Set<String> cycleMap,
             Map<String, String> configProps,
             UnaryOperator<String> callback,
             BinaryOperator<String> postprocessor,
             boolean defaultsToEmptyString) {
         if (val == null || val.isEmpty()) {
             return val;
         }
         if (cycleMap == null) {
             cycleMap = new HashSet<>();
         }
 
         // Put the current key in the cycle map.
         if (currentKey != null) {
             cycleMap.add(currentKey);
         }
 
         // Assume we have a value that is something like:
         // "leading ${foo.${bar}} middle ${baz} trailing"
 
         // Find the first ending '}' variable delimiter, which
         // will correspond to the first deepest nested variable
         // placeholder.
         int startDelim;
         int stopDelim = -1;
         do {
             stopDelim = val.indexOf(DELIM_STOP, stopDelim + 1);
             while (stopDelim > 0 && val.charAt(stopDelim - 1) == ESCAPE_CHAR) {
                 stopDelim = val.indexOf(DELIM_STOP, stopDelim + 1);
             }
 
             // Find the matching starting "${" variable delimiter
             // by looping until we find a start delimiter that is
             // greater than the stop delimiter we have found.
             startDelim = val.indexOf(DELIM_START);
             while (stopDelim >= 0) {
                 int idx = val.indexOf(DELIM_START, startDelim + DELIM_START.length());
                 if ((idx < 0) || (idx > stopDelim)) {
                     break;
                 } else if (idx < stopDelim) {
                     startDelim = idx;
                 }
             }
         } while (startDelim >= 0 && stopDelim >= 0 && stopDelim < startDelim + DELIM_START.length());
 
         // If we do not have a start or stop delimiter, then just
         // return the existing value.
         if ((startDelim < 0) || (stopDelim < 0)) {
             cycleMap.remove(currentKey);
             return val;
         }
 
         // At this point, we have found a variable placeholder so
         // we must perform a variable substitution on it.
         // Using the start and stop delimiter indices, extract
         // the first, deepest nested variable placeholder.
         String variable = val.substring(startDelim + DELIM_START.length(), stopDelim);
 
         String substValue =
                 processSubstitution(variable, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
 
         // Append the leading characters, the substituted value of
         // the variable, and the trailing characters to get the new
         // value.
         val = val.substring(0, startDelim) + substValue + val.substring(stopDelim + DELIM_STOP.length());
 
         // Now perform substitution again, since there could still
         // be substitutions to make.
         val = doSubstVars(val, currentKey, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
 
         cycleMap.remove(currentKey);
 
         // Return the value.
         return val;
     }
 
     private static String processSubstitution(
             String variable,
             Set<String> cycleMap,
             Map<String, String> configProps,
             UnaryOperator<String> callback,
             BinaryOperator<String> postprocessor,
             boolean defaultsToEmptyString) {
 
         // Process chained operators from left to right
         int startIdx = 0;
         String substValue = null;
 
         while (startIdx < variable.length()) {
             int idx1 = variable.indexOf(":-", startIdx);
             int idx2 = variable.indexOf(":+", startIdx);
             int idx = idx1 >= 0 ? idx2 >= 0 ? Math.min(idx1, idx2) : idx1 : idx2;
 
             if (idx < 0) {
                 // No more operators, process the final variable
                 if (substValue == null) {
                     String currentVar = variable.substring(startIdx);
                     substValue = resolveVariable(
                             currentVar, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
                 }
                 break;
             }
 
             // Get the current variable part before the operator
             String varPart = variable.substring(startIdx, idx);
             if (substValue == null) {
                 substValue =
                         resolveVariable(varPart, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
             }
 
             // Find the end of the current operator's value
             int nextIdx1 = variable.indexOf(":-", idx + 2);
             int nextIdx2 = variable.indexOf(":+", idx + 2);
             int nextIdx = nextIdx1 >= 0 ? nextIdx2 >= 0 ? Math.min(nextIdx1, nextIdx2) : nextIdx1 : nextIdx2;
 
             String op = variable.substring(idx, idx + 2);
             String opValue = variable.substring(idx + 2, nextIdx >= 0 ? nextIdx : variable.length());
 
             // Process the operator value through substitution if it contains variables
             String processedOpValue = doSubstVars(
                     opValue, variable, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
 
             // Apply the operator
             if (":+".equals(op)) {
                 if (substValue != null && !substValue.isEmpty()) {
                     substValue = processedOpValue;
                     // Skip any remaining operators since we've made a decision
                     break;
                 }
             } else if (":-".equals(op)) {
                 if (substValue == null || substValue.isEmpty()) {
                     substValue = processedOpValue;
                     // Skip any remaining operators since we've made a decision
                     break;
                 }
             } else {
                 throw new InterpolatorException("Bad substitution operator in: ${" + variable + "}");
             }
 
             startIdx = nextIdx >= 0 ? nextIdx : variable.length();
         }
 
         if (substValue == null) {
             if (defaultsToEmptyString) {
                 substValue = "";
             } else {
                 substValue = MARKER + "{" + variable + "}";
             }
         }
 
         return substValue;
     }
 
     private static String resolveVariable(
             String variable,
             Set<String> cycleMap,
             Map<String, String> configProps,
             UnaryOperator<String> callback,
             BinaryOperator<String> postprocessor,
             boolean defaultsToEmptyString) {
 
         // Verify that this is not a recursive variable reference
         if (!cycleMap.add(variable)) {
             throw new InterpolatorException("recursive variable reference: " + variable);
         }
 
         String substValue = null;
         // Try configuration properties first
         if (configProps != null) {
             substValue = configProps.get(variable);
         }
         if (substValue == null && !variable.isEmpty() && callback != null) {
             String s1 = callback.apply(variable);
             String s2 =
                     doSubstVars(s1, variable, cycleMap, configProps, callback, postprocessor, defaultsToEmptyString);
             substValue = postprocessor != null ? postprocessor.apply(variable, s2) : s2;
         }
 
         // Remove the variable from cycle map
         cycleMap.remove(variable);
         return substValue;
     }
 
     /**
      * Escapes special characters in the given string to prevent unwanted interpolation.
      *
      * @param val The string to be escaped.
      * @return The escaped string.
      */
     @Nullable
     public static String escape(@Nullable String val) {
         if (val == null || val.isEmpty()) {
             return val;
         }
         return val.replace("$", MARKER);
     }
 
     /**
      * Unescapes previously escaped characters in the given string.
      *
      * @param val The string to be unescaped.
      * @return The unescaped string.
      */
     @Nullable
     public static String unescape(@Nullable String val) {
         if (val == null || val.isEmpty()) {
             return val;
         }
         val = val.replace(MARKER, "$");
         int escape = val.indexOf(ESCAPE_CHAR);
         while (escape >= 0 && escape < val.length() - 1) {
             char c = val.charAt(escape + 1);
             if (c == '{' || c == '}') {
                 val = val.substring(0, escape) + val.substring(escape + 1);
             }
             escape = val.indexOf(ESCAPE_CHAR, escape + 1);
         }
         return val;
     }
 }