/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.juneau.commons.function;
  
  import static org.apache.juneau.TestUtils.assertThrowsWithMessage;
  import static org.junit.jupiter.api.Assertions.*;
  
  import java.util.function.*;
  
  import org.apache.juneau.*;
  import org.junit.jupiter.api.*;
  
  class Function2_Test extends TestBase {
  
  	//------------------------------------------------------------------------------------------------------------------
  	// Basic tests.
  	//------------------------------------------------------------------------------------------------------------------
  	@Test void a01_basic() {
  		Function2<Integer,Integer,Integer> x = (a,b)->a+b;
  		assertEquals(3, x.apply(1,2));
  	}
  
  	@Test void a02_withNullValues() {
  		Function2<String,Integer,String> x = (a, b) -> a + b;
  		assertEquals("null42", x.apply(null, 42));
  		assertEquals("foonull", x.apply("foo", null));  // String concatenation: "foo" + null = "foonull"
  		assertEquals("nullnull", x.apply(null, null));
  	}
  
  	@Test void a03_returnsNull() {
  		Function2<String,Integer,String> x = (a, b) -> null;
  		assertNull(x.apply("foo", 42));
  	}
  
  	//------------------------------------------------------------------------------------------------------------------
  	// andThen tests.
  	//------------------------------------------------------------------------------------------------------------------
  	@Test void b01_andThen_basic() {
  		Function2<Integer,Integer,Integer> first = (a, b) -> a + b;
  		Function<Integer,String> after = x -> "result: " + x;
  		Function2<Integer,Integer,String> composed = first.andThen(after);
  
  		assertEquals("result: 3", composed.apply(1, 2));
  	}
  
  	@Test void b02_andThen_differentReturnType() {
  		Function2<String,Integer,Integer> first = (a, b) -> a.length() + b;
  		Function<Integer,Boolean> after = x -> x > 5;
  		Function2<String,Integer,Boolean> composed = first.andThen(after);
  
  		assertTrue(composed.apply("hello", 1));  // 5 + 1 = 6 > 5
  		assertFalse(composed.apply("hi", 1));    // 2 + 1 = 3 <= 5
  	}
  
  	@Test void b03_andThen_chaining() {
  		Function2<Integer,Integer,Integer> first = (a, b) -> a + b;
  		Function<Integer,Integer> second = x -> x * 2;
  		Function<Integer,String> third = x -> "value: " + x;
  		Function2<Integer,Integer,String> composed = first.andThen(second).andThen(third);
  
  		assertEquals("value: 6", composed.apply(1, 2));  // (1+2)*2 = 6
  	}
  
  	@Test void b04_andThen_withNullAfter() {
  		Function2<Integer,Integer,Integer> first = (a, b) -> a + b;
  		assertThrowsWithMessage(IllegalArgumentException.class, "Argument 'after' cannot be null", () -> {
  			first.andThen(null);
  		});
  	}
  
  	@Test void b05_andThen_afterReturnsNull() {
  		Function2<Integer,Integer,Integer> first = (a, b) -> a + b;
  		Function<Integer,String> after = x -> null;
  		Function2<Integer,Integer,String> composed = first.andThen(after);
  
  		assertNull(composed.apply(1, 2));
  	}
  }