package org.codehaus.plexus.components.secdispatcher;
   
   import java.util.Collection;
   import java.util.List;
   import java.util.Optional;
   
   import static java.util.Objects.requireNonNull;
   
   /**
   * Meta description of dispatcher.
   */
  public interface DispatcherMeta {
      final class Field {
          private final String key;
          private final boolean optional;
          private final String defaultValue;
          private final String description;
          private final List<Field> options;
  
          private Field(String key, boolean optional, String defaultValue, String description, List<Field> options) {
              this.key = requireNonNull(key);
              this.optional = optional;
              this.defaultValue = defaultValue;
              this.description = requireNonNull(description);
              this.options = options;
          }
  
          /**
           * The key to be used in configuration map for field.
           */
          public String getKey() {
              return key;
          }
  
          /**
           * Is configuration optional?
           */
          public boolean isOptional() {
              return optional;
          }
  
          /**
           * Optional default value of the configuration.
           */
          public Optional<String> getDefaultValue() {
              return Optional.ofNullable(defaultValue);
          }
  
          /**
           * The human description of the configuration.
           */
          public String getDescription() {
              return description;
          }
  
          /**
           * Optional list of options, if this configuration accepts limited values. Each option is represented
           * as field, where {@link #getKey()} represents the value to be used, and {@link #displayName()} represents
           * the description of option. The {@link #getDefaultValue()}, if present represents the value to be used
           * instead of {@link #getKey()}.
           */
          public Optional<List<Field>> getOptions() {
              return Optional.ofNullable(options);
          }
  
          public static Builder builder(String key) {
              return new Builder(key);
          }
  
          public static final class Builder {
              private final String key;
              private boolean optional;
              private String defaultValue;
              private String description;
              private List<Field> options;
  
              private Builder(String key) {
                  this.key = requireNonNull(key);
              }
  
              public Builder optional(boolean optional) {
                  this.optional = optional;
                  return this;
              }
  
              public Builder defaultValue(String defaultValue) {
                  this.defaultValue = defaultValue;
                  return this;
              }
  
              public Builder description(String description) {
                  this.description = requireNonNull(description);
                  return this;
              }
  
              public Builder options(List<Field> options) {
                  this.options = requireNonNull(options);
                  return this;
              }
 
             public Field build() {
                 return new Field(key, optional, defaultValue, description, options);
             }
         }
     }
 
     /**
      * Option to hide this instance from users, like for migration or legacy purposes.
      */
     default boolean isHidden() {
         return false;
     }
 
     /**
      * The name of the dispatcher.
      */
     String name();
 
     /**
      * Returns the display (human) name of the dispatcher.
      */
     String displayName();
 
     /**
      * Returns the configuration fields of the dispatcher.
      */
     Collection<Field> fields();
 }