/*
 * 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.config.event;

import static org.apache.juneau.commons.utils.StringUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;
import static org.apache.juneau.config.event.ConfigEventType.*;

import java.util.*;

/**
 * Represents a change to a config.
 */
public class ConfigEvent {

   /**
    * Removes a value from a configuration.
    *
    * @param config
    *    The configuration name.
    * @param section
    *    The section name.
    *    <br>Must not be <jk>null</jk>.
    * @param key
    *    The entry name.
    *    <br>Must not be <jk>null</jk>.
    * @return
    *    A new {@link ConfigEvent} object.
    */
   public static ConfigEvent removeEntry(String config, String section, String key) {
      return new ConfigEvent(REMOVE_ENTRY, config, section, key, null, null, null, null);
   }

   /**
    * Removes a section from the config.
    *
    * @param config
    *    The configuration name.
    * @param section
    *    The section name.
    * @return
    *    A new {@link ConfigEvent} object.
    */
   public static ConfigEvent removeSection(String config, String section) {
      return new ConfigEvent(REMOVE_SECTION, config, section, null, null, null, null, null);
   }

   /**
    * Sets or replaces a value in a configuration.
    *
    * @param config
    *    The configuration name.
    * @param section
    *    The section name.
    *    <br>Must not be <jk>null</jk>.
    * @param key
    *    The entry name.
    *    <br>Must not be <jk>null</jk>.
    * @param value
    *    The entry value.
    *    <br>Can be <jk>null</jk> to remove an entry.
    * @param comment
    *    Optional comment string to add on the same line as the entry.
    * @param modifiers
    *    Optional entry modifiers.
    * @param prelines
    *    Comment lines that occur before this entry.
    *    <br>Must not be <jk>null</jk>.
    * @return
    *    A new {@link ConfigEvent} object.
    */
   public static ConfigEvent setEntry(String config, String section, String key, String value, String modifiers, String comment, List<String> prelines) {
      return new ConfigEvent(SET_ENTRY, config, section, key, value, modifiers, comment, prelines);
   }

   /**
    * Adds a new empty section to the config.
    *
    * @param config
    *    The configuration name.
    * @param section
    *    The section name.
    * @param prelines
    *    Comment lines that occur before this section.
    *    <br>Must not be <jk>null</jk>.
    * @return
    *    A new {@link ConfigEvent} object.
    */
   public static ConfigEvent setSection(String config, String section, List<String> prelines) {
      return new ConfigEvent(SET_SECTION, config, section, null, null, null, null, prelines);
   }

   private final ConfigEventType type;
   private final String config, section, key, value, comment;

   private final List<String> preLines;

   private final String modifiers;

   /**
    * Constructor.
    * @param type - The event type.
    * @param config - The configuration name.
    * @param section - The section name.
    * @param key - The entry name.
    * @param value - The entry value.
    * @param modifiers - The entry modifiers.
    * @param comment - Optional comment string to add on the same line as the entry.
    * @param preLines - Optional comment lines that occur before this entry.
    */
   protected ConfigEvent(ConfigEventType type, String config, String section, String key, String value, String modifiers, String comment, List<String> preLines) {
      this.type = type;
      this.config = config;
      this.section = section;
      this.key = key;
      this.value = value;
      this.comment = comment;
      this.preLines = preLines;
      this.modifiers = modifiers;
   }

   /**
    * Returns the entry comment.
    *
    * @return The entry comment.
    */
   public String getComment() { return comment; }

   /**
    * Returns the configuration name.
    *
    * @return The configuration name.
    */
   public String getConfig() { return config; }

   /**
    * Returns the entry name.
    *
    * @return The entry name.
    */
   public String getKey() { return key; }

   /**
    * Returns the modifiers on this entry.
    *
    * @return
    *    The modifier characters.
    *    <br>Never <jk>null</jk>.
    */
   public String getModifiers() { return modifiers; }

   /**
    * Returns the section or entry lines.
    *
    * @return The section or entry lines.
    */
   public List<String> getPreLines() { return preLines; }

   /**
    * Returns the section name.
    *
    * @return The section name.
    */
   public String getSection() { return section; }

   /**
    * Returns the event type.
    *
    * @return The event type.
    */
   public ConfigEventType getType() { return type; }

   /**
    * Returns the entry value.
    *
    * @return The entry value.
    */
   public String getValue() { return value; }

   @Override /* Overridden from Object */
   public String toString() {
      return switch (type) {
         case REMOVE_SECTION -> "REMOVE_SECTION(" + section + ")";
         case REMOVE_ENTRY -> "REMOVE_ENTRY(" + section + (section.isEmpty() ? "" : "/") + key + ")";
         case SET_SECTION -> "SET_SECTION(" + section + ", preLines=" + join(preLines, '|') + ")";
         case SET_ENTRY -> {
            var out = new StringBuilder("SET(");
            out.append(section + (section.isEmpty() ? "" : "/") + key);
            if (nn(modifiers))
               out.append(modifiers);
            out.append(" = ");
            var val = value == null ? "null" : value;
            if (val.indexOf('\n') != -1)
               val = val.replaceAll("(\\r?\\n)", "$1\t");
            if (val.indexOf('#') != -1)
               val = val.replace("#", "\\#");
            out.append(val);
            if (ne(comment))
               out.append(" # ").append(comment);
            out.append(')');
            yield out.toString();
         }
         default -> null; // NOSONAR - Intentional.
      };
   }
}