/*
 * 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.internal;

import static org.apache.juneau.commons.utils.Shorts.*;
import static org.apache.juneau.commons.utils.StringUtils.*;

import java.io.*;
import java.util.*;

import org.apache.juneau.commons.lang.*;

/**
 * Represents a single entry in a configuration.
 *
 * This is a read-only object.
 *
 * @param rawLine The raw line this entry was parsed from, or <jk>null</jk> if the entry was created programmatically.
 * @param key The name of this entry.
 * @param value The raw value of this entry.
 * @param comment The same-line comment of this entry, or <jk>null</jk> if it has no comment.
 * @param modifiers The modifiers for this entry, or <jk>null</jk> if it has no modifiers.
 * @param preLines The pre-lines of this entry as an unmodifiable list.
 */
public record ConfigMapEntry(String rawLine, String key, String value, String comment, String modifiers, List<String> preLines) {

   static final ConfigMapEntry NULL = new ConfigMapEntry(null, null, null, null, null, null);
   private static final AsciiSet REPLACE_CHARS = AsciiSet.of("\\#");

   /**
    * Canonical constructor.
    *
    * <p>
    * Normalizes {@code preLines} to an unmodifiable copy (empty when <jk>null</jk>) so this record is truly immutable.
    */
   public ConfigMapEntry {
      preLines = preLines == null ? Collections.emptyList() : u(cp(preLines));
   }

   /**
    * Constructor for a programmatically-created entry (no raw line).
    *
    * @param key The name of this entry.
    * @param value The raw value of this entry.
    * @param modifiers The modifiers for this entry, or <jk>null</jk> if it has no modifiers.
    * @param comment The same-line comment of this entry, or <jk>null</jk> if it has no comment.
    * @param preLines The pre-lines of this entry.  Can be <jk>null</jk> (treated as an empty list).
    */
   ConfigMapEntry(String key, String value, String modifiers, String comment, List<String> preLines) {
      this(null, key, value, comment, modifiers, preLines);
   }

   /**
    * Parses a raw config line into an entry.
    *
    * @param line The raw line to parse.
    * @param preLines The pre-lines preceding this entry.
    * @return A new immutable entry.
    */
   static ConfigMapEntry parse(String line, List<String> preLines) {
      var i = line.indexOf('=');
      var key2 = line.substring(0, i).trim();

      var m1 = key2.indexOf('<');
      var m2 = key2.indexOf('>');

      var modifiers = nie((m1 > -1 && m2 > m1) ? key2.substring(m1 + 1, m2) : null);
      var key = m1 == -1 ? key2 : key2.substring(0, m1);

      var rest = line.substring(i + 1);

      String comment = null;
      if (rest.indexOf('#') != -1) {
         var l2 = splita(rest, '#', 2);
         rest = l2[0];
         if (l2.length == 2)
            comment = l2[1].trim();
      }

      var value = replaceUnicodeSequences(rest.trim());

      return new ConfigMapEntry(line, key, value, comment, modifiers, preLines);
   }

   /**
    * Returns the same-line comment of this entry.
    *
    * @return The same-line comment of this entry, or <jk>null</jk> if it has no comment.
    */
   public String getComment() { return comment; }

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

   /**
    * Returns the modifiers for this entry.
    *
    * @return The modifiers for this entry, or <jk>null</jk> if it has no modifiers.
    */
   public String getModifiers() { return modifiers; }

   /**
    * Returns the pre-lines of this entry.
    *
    * @return The pre-lines of this entry as an unmodifiable list.
    */
   public List<String> getPreLines() { return preLines; }

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

   @SuppressWarnings({
      "java:S3776" // Cognitive complexity acceptable for config entry writer
   })
   Writer writeTo(Writer w) throws IOException {
      if (value == null)
         return w;
      for (var pl : preLines)
         w.append(pl).append('\n');
      if (nn(rawLine)) {
         for (var i = 0; i < rawLine.length(); i++) {
            var c = rawLine.charAt(i);
            if (c == '\n')
               w.append('\n').append('\t');
            else if (c != '\r') // HTT - '\r' in raw line requires OS-level carriage return in stored config content
               w.append(c);
         }
         w.append('\n');
      } else {
         w.append(key);
         if (nn(modifiers))
            w.append('<').append(modifiers).append('>');
         w.append(" = ");

         var val = value;
         for (var i = 0; i < val.length(); i++) {
            var c = val.charAt(i);
            if (c == '\n')
               w.append('\n').append('\t');
            else if (c != '\r') { // HTT - '\r' in value requires OS-level carriage return injection
               if (REPLACE_CHARS.contains(c) || (Character.isISOControl(c) && c != '\t')) { // c is already known to be neither '\n' nor '\r' here
                  w.append(unicodeSequence(c));
               } else {
                  w.append(c);
               }
            }
         }

         if (ine(comment))
            w.append(" # ").append(comment);

         w.append('\n');
      }
      return w;
   }
}