content: /*
   * Copyright (C) 2009-2025 Lightbend Inc. <https://www.lightbend.com>
   */
  
  package akka.japi.pf;
  
  import scala.PartialFunction;
  import scala.Tuple2;
  import scala.runtime.BoxedUnit;
  
  /**
   * Builder used to create a partial function for {@link akka.actor.FSM#onTransition}.
   *
   * @param <S> the state type
   */
  public class FSMTransitionHandlerBuilder<S> {
  
    private final UnitPFBuilder<Tuple2<S, S>> builder = new UnitPFBuilder<Tuple2<S, S>>();
  
    /**
     * Add a case statement that matches on a from state and a to state.
     *
     * @param fromState the from state to match on, or null for any
     * @param toState the to state to match on, or null for any
     * @param apply an action to apply when the states match
     * @return the builder with the case statement added
     */
    public FSMTransitionHandlerBuilder<S> state(
        final S fromState, final S toState, final FI.UnitApplyVoid apply) {
      builder.match(
          Tuple2.class,
          new FI.TypedPredicate<Tuple2>() {
            @Override
            public boolean defined(Tuple2 t) {
              return (fromState == null || fromState.equals(t._1()))
                  && (toState == null || toState.equals(t._2()));
            }
          },
          new FI.UnitApply<Tuple2>() {
            @Override
            public void apply(Tuple2 t) throws Exception {
              apply.apply();
            }
          });
      return this;
    }
  
    /**
     * Add a case statement that matches on a from state and a to state.
     *
     * @param fromState the from state to match on, or null for any
     * @param toState the to state to match on, or null for any
     * @param apply an action to apply when the states match
     * @return the builder with the case statement added
     */
    public FSMTransitionHandlerBuilder<S> state(
        final S fromState, final S toState, final FI.UnitApply2<S, S> apply) {
      builder.match(
          Tuple2.class,
          new FI.TypedPredicate<Tuple2>() {
            @Override
            public boolean defined(Tuple2 t) {
              return (fromState == null || fromState.equals(t._1()))
                  && (toState == null || toState.equals(t._2()));
            }
          },
          new FI.UnitApply<Tuple2>() {
            @Override
            public void apply(Tuple2 t) throws Exception {
              @SuppressWarnings("unchecked")
              S sf = (S) t._1();
              @SuppressWarnings("unchecked")
              S st = (S) t._2();
              apply.apply(sf, st);
            }
          });
      return this;
    }
  
    /**
     * Build a {@link scala.PartialFunction} from this builder. After this call the builder will be
     * reset.
     *
     * @return a PartialFunction for this builder.
     */
    public PartialFunction<Tuple2<S, S>, BoxedUnit> build() {
      return builder.build();
    }
  }
  