package com.guinetik.hexafun.examples.counter;
   
   import com.guinetik.hexafun.fun.Result;
   import com.guinetik.hexafun.examples.counter.CounterInputs.*;
   
   /**
    * Validation functions for counter operations.
    *
    * <p>Each validator is a pure function: Input -> Result&lt;Input&gt;
   * Can be composed/chained in the DSL.
   */
  public final class CounterValidators {
  
      private CounterValidators() {}
  
      /**
       * Validates that the counter in IncrementInput is not null.
       */
      public static Result<IncrementInput> validateIncrement(IncrementInput input) {
          if (input == null) {
              return Result.fail("Input cannot be null");
          }
          if (input.counter() == null) {
              return Result.fail("Counter cannot be null");
          }
          return Result.ok(input);
      }
  
      /**
       * Validates that the counter in DecrementInput is not null.
       */
      public static Result<DecrementInput> validateDecrement(DecrementInput input) {
          if (input == null) {
              return Result.fail("Input cannot be null");
          }
          if (input.counter() == null) {
              return Result.fail("Counter cannot be null");
          }
          return Result.ok(input);
      }
  
      /**
       * Validates that the counter in AddInput is not null.
       */
      public static Result<AddInput> validateAddCounter(AddInput input) {
          if (input == null) {
              return Result.fail("Input cannot be null");
          }
          if (input.counter() == null) {
              return Result.fail("Counter cannot be null");
          }
          return Result.ok(input);
      }
  
      /**
       * Validates that the amount in AddInput is within bounds [-100, 100].
       */
      public static Result<AddInput> validateAddAmount(AddInput input) {
          if (input.amount() < -100 || input.amount() > 100) {
              return Result.fail("Amount must be between -100 and 100");
          }
          return Result.ok(input);
      }
  }