/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed 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 com.google.gson;

import java.lang.reflect.Field;
import java.util.Locale;

An enumeration that defines a few standard naming conventions for JSON field names. This enumeration should be used in conjunction with GsonBuilder to configure a Gson instance to properly translate Java field names into the desired JSON field names. 
Author:
Inderjeet Singh, Joel Leitch/**
 * An enumeration that defines a few standard naming conventions for JSON field names.
 * This enumeration should be used in conjunction with {@link com.google.gson.GsonBuilder}
 * to configure a {@link com.google.gson.Gson} instance to properly translate Java field
 * names into the desired JSON field names.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public enum FieldNamingPolicy implements FieldNamingStrategy {

  
Using this naming policy with Gson will ensure that the field name is
unchanged.
/**
   * Using this naming policy with Gson will ensure that the field name is
   * unchanged.
   */
  IDENTITY() {
    @Override public String translateName(Field f) {
      return f.getName();
    }
  },

  
Using this naming policy with Gson will ensure that the first "letter" of the Java
field name is capitalized when serialized to its JSON form.
Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

  
someFieldName ---> SomeFieldName
  
_someFieldName ---> _SomeFieldName

/**
   * Using this naming policy with Gson will ensure that the first "letter" of the Java
   * field name is capitalized when serialized to its JSON form.
   *
   * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p>
   * <ul>
   *   <li>someFieldName ---> SomeFieldName</li>
   *   <li>_someFieldName ---> _SomeFieldName</li>
   * </ul>
   */
  UPPER_CAMEL_CASE() {
    @Override public String translateName(Field f) {
      return upperCaseFirstLetter(f.getName());
    }
  },

  
Using this naming policy with Gson will ensure that the first "letter" of the Java
field name is capitalized when serialized to its JSON form and the words will be
separated by a space.
Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

  
someFieldName ---> Some Field Name
  
_someFieldName ---> _Some Field Name

Since:
1.4/**
   * Using this naming policy with Gson will ensure that the first "letter" of the Java
   * field name is capitalized when serialized to its JSON form and the words will be
   * separated by a space.
   *
   * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p>
   * <ul>
   *   <li>someFieldName ---> Some Field Name</li>
   *   <li>_someFieldName ---> _Some Field Name</li>
   * </ul>
   *
   * @since 1.4
   */
  UPPER_CAMEL_CASE_WITH_SPACES() {
    @Override public String translateName(Field f) {
      return upperCaseFirstLetter(separateCamelCase(f.getName(), " "));
    }
  },

  
Using this naming policy with Gson will modify the Java Field name from its camel cased
form to a lower case field name where each word is separated by an underscore (_).
Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

  
someFieldName ---> some_field_name
  
_someFieldName ---> _some_field_name
  
aStringField ---> a_string_field
  
aURL ---> a_u_r_l

/**
   * Using this naming policy with Gson will modify the Java Field name from its camel cased
   * form to a lower case field name where each word is separated by an underscore (_).
   *
   * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p>
   * <ul>
   *   <li>someFieldName ---> some_field_name</li>
   *   <li>_someFieldName ---> _some_field_name</li>
   *   <li>aStringField ---> a_string_field</li>
   *   <li>aURL ---> a_u_r_l</li>
   * </ul>
   */
  LOWER_CASE_WITH_UNDERSCORES() {
    @Override public String translateName(Field f) {
      return separateCamelCase(f.getName(), "_").toLowerCase(Locale.ENGLISH);
    }
  },

  
Using this naming policy with Gson will modify the Java Field name from its camel cased
form to a lower case field name where each word is separated by a dash (-).
Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

  
someFieldName ---> some-field-name
  
_someFieldName ---> _some-field-name
  
aStringField ---> a-string-field
  
aURL ---> a-u-r-l
 Using dashes in JavaScript is not recommended since dash is also used for a minus sign in expressions. This requires that a field named with dashes is always accessed as a quoted property like myobject['my-field']. Accessing it as an object field myobject.my-field will result in an unintended javascript expression. 
Since:
1.4/**
   * Using this naming policy with Gson will modify the Java Field name from its camel cased
   * form to a lower case field name where each word is separated by a dash (-).
   *
   * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p>
   * <ul>
   *   <li>someFieldName ---> some-field-name</li>
   *   <li>_someFieldName ---> _some-field-name</li>
   *   <li>aStringField ---> a-string-field</li>
   *   <li>aURL ---> a-u-r-l</li>
   * </ul>
   * Using dashes in JavaScript is not recommended since dash is also used for a minus sign in
   * expressions. This requires that a field named with dashes is always accessed as a quoted
   * property like {@code myobject['my-field']}. Accessing it as an object field
   * {@code myobject.my-field} will result in an unintended javascript expression.
   * @since 1.4
   */
  LOWER_CASE_WITH_DASHES() {
    @Override public String translateName(Field f) {
      return separateCamelCase(f.getName(), "-").toLowerCase(Locale.ENGLISH);
    }
  },

  
Using this naming policy with Gson will modify the Java Field name from its camel cased
form to a lower case field name where each word is separated by a dot (.).
Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

  
someFieldName ---> some.field.name
  
_someFieldName ---> _some.field.name
  
aStringField ---> a.string.field
  
aURL ---> a.u.r.l
 Using dots in JavaScript is not recommended since dot is also used for a member sign in expressions. This requires that a field named with dots is always accessed as a quoted property like myobject['my.field']. Accessing it as an object field myobject.my.field will result in an unintended javascript expression. 
Since:
2.8/**
   * Using this naming policy with Gson will modify the Java Field name from its camel cased
   * form to a lower case field name where each word is separated by a dot (.).
   *
   * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p>
   * <ul>
   *   <li>someFieldName ---> some.field.name</li>
   *   <li>_someFieldName ---> _some.field.name</li>
   *   <li>aStringField ---> a.string.field</li>
   *   <li>aURL ---> a.u.r.l</li>
   * </ul>
   * Using dots in JavaScript is not recommended since dot is also used for a member sign in
   * expressions. This requires that a field named with dots is always accessed as a quoted
   * property like {@code myobject['my.field']}. Accessing it as an object field
   * {@code myobject.my.field} will result in an unintended javascript expression.
   * @since 2.8
   */
  LOWER_CASE_WITH_DOTS() {
    @Override public String translateName(Field f) {
      return separateCamelCase(f.getName(), ".").toLowerCase(Locale.ENGLISH);
    }
  };

  
Converts the field name that uses camel-case define word separation into separate words that are separated by the provided separatorString. /**
   * Converts the field name that uses camel-case define word separation into
   * separate words that are separated by the provided {@code separatorString}.
   */
  static String separateCamelCase(String name, String separator) {
    StringBuilder translation = new StringBuilder();
    for (int i = 0, length = name.length(); i < length; i++) {
      char character = name.charAt(i);
      if (Character.isUpperCase(character) && translation.length() != 0) {
        translation.append(separator);
      }
      translation.append(character);
    }
    return translation.toString();
  }

  
Ensures the JSON field names begins with an upper case letter.
/**
   * Ensures the JSON field names begins with an upper case letter.
   */
  static String upperCaseFirstLetter(String name) {
    StringBuilder fieldNameBuilder = new StringBuilder();
    int index = 0;
    char firstCharacter = name.charAt(index);
    int length = name.length();

    while (index < length - 1) {
      if (Character.isLetter(firstCharacter)) {
        break;
      }

      fieldNameBuilder.append(firstCharacter);
      firstCharacter = name.charAt(++index);
    }

    if (!Character.isUpperCase(firstCharacter)) {
      String modifiedTarget = modifyString(Character.toUpperCase(firstCharacter), name, ++index);
      return fieldNameBuilder.append(modifiedTarget).toString();
    } else {
      return name;
    }
  }

  private static String modifyString(char firstCharacter, String srcString, int indexOfSubstring) {
    return (indexOfSubstring < srcString.length())
        ? firstCharacter + srcString.substring(indexOfSubstring)
        : String.valueOf(firstCharacter);
  }
}