package org.davidmoten.rx.jdbc;
   
   import java.util.Collection;
   import java.util.List;
   
   import com.github.davidmoten.guavamini.Lists;
   
   /**
    * Encapsulates a query parameter.
   */
  public final class Parameter {
      
      static final Parameter NULL = new Parameter(null);
  
      private final String name;
      /**
       * Actual query parameter value to be encapsulated.
       */
      private final Object value;
  
      /**
       * Constructor.
       * 
       * @param parameter
       */
      Parameter(Object value) {
          this(null, value);
      }
  
      Parameter(String name, Object value) {
          this.name = name;
          this.value = value;
      }
  
      /**
       * Returns the parameter value.
       * 
       * @return
       */
      Object value() {
          return value;
      }
  
      boolean isCollection() {
          return value != null && (value instanceof Collection);
      }
  
      int size() {
          // TODO cache all these calcs when constructed
          if (value != null) {
              if (value instanceof Collection) {
                  return ((Collection<?>) value).size();
              } else {
                  return 1;
              }
          } else {
              return 1;
          }
      }
  
      boolean hasName() {
          return name != null;
      }
  
      String name() {
          return name;
      }
  
      public static ParameterListBuilder named(String name, String value) {
          return new ParameterListBuilder(Lists.newArrayList()).named(name, value);
      }
  
      public static class ParameterListBuilder {
          private final List<Parameter> list;
          private String lastName;
  
          ParameterListBuilder(List<Parameter> list) {
              this.list = list;
          }
  
          public ParameterListBuilder named(String name, String value) {
              list.add(new Parameter(name, value));
              lastName = name;
              return this;
          }
  
          public ParameterListBuilder value(String value) {
              return named(lastName, value);
          }
  
          public List<Parameter> list() {
              return list;
          }
      }
  
      @Override
      public String toString() {
          StringBuilder b = new StringBuilder();
          b.append("Parameter[");
         b.append("name=");
         b.append(name);
         b.append(", value=");
         b.append(String.valueOf(value));
         b.append("]");
         return b.toString();
     }
 
     public static Parameter create(String name, Object value) {
         return new Parameter(name, value);
     }
 
 }