package com.cornetdesign;

import junit.framework.TestCase;

import java.lang.reflect.Field;

public class BeanTestCase extends TestCase {

    private static final String TEST_STRING_VAL1 = "Some Value";
    private static final String TEST_STRING_VAL2 = "Some Other Value";

    public static void assertMeetsEqualsContract(Class classUnderTest) {
        Object o1;
        Object o2;
        try {
            //Get Instances
            o1 = classUnderTest.newInstance();
            o2 = classUnderTest.newInstance();

            assertTrue("Instances with default constructor not equal (o1.equals(o2))", o1.equals(o2));
            assertTrue("Instances with default constructor not equal (o2.equals(o1))", o2.equals(o1));

            Field[] fields = classUnderTest.getDeclaredFields();
            for(int i = 0; i < fields.length; i++) {

                //Reset the instances
                o1 = classUnderTest.newInstance();
                o2 = classUnderTest.newInstance();

                Field field = fields[i];
                field.setAccessible(true);
                if(field.getType() == String.class) {
                    field.set(o1, TEST_STRING_VAL1);
                }  else if(field.getType() == boolean.class) {
                    field.setBoolean(o1, true);
                }   else if(field.getType() == short.class) {
                    field.setShort(o1, (short)1);
                }   else if(field.getType() == long.class) {
                    field.setLong(o1, (long)1);
                }   else if(field.getType() == float.class) {
                    field.setFloat(o1, (float)1);
                }   else if(field.getType() == int.class) {
                    field.setInt(o1, 1);
                }   else if(field.getType() == byte.class) {
                    field.setByte(o1, (byte)1);
                }   else if(field.getType() == char.class) {
                    field.setChar(o1, (char)1);
                }   else if(field.getType() == double.class) {
                    field.setDouble(o1, (double)1);
                }   else if(field.getType().isEnum()) {
                    field.set(o1, field.getType().getEnumConstants()[0]);
                } else if(Object.class.isAssignableFrom(field.getType())) {
                    field.set(o1, field.getType().newInstance());
                }   else {
                    fail("Don't know how to set a " + field.getType().getName());
                }

                assertFalse("Instances with o1 having " + field.getName() + " set and o2 having it not set are equal", o1.equals(o2));


                field.set(o2, field.get(o1));

                assertTrue("After setting o2 with the value of the object in o1, the two objects in the field are not equal"
                        , field.get(o1).equals(field.get(o2)));

                assertTrue("Instances with o1 having "
                        + field.getName()
                        + " set and o2 having it set to the same object of type "
                        + field.get(o2).getClass().getName()
                        + " are not equal", o1.equals(o2));
                
                if(field.getType() == String.class) {
                    field.set(o2, TEST_STRING_VAL2);
                }  else if(field.getType() == boolean.class) {
                    field.setBoolean(o2, false);
                }   else if(field.getType() == short.class) {
                    field.setShort(o2, (short)0);
                }   else if(field.getType() == long.class) {
                    field.setLong(o2, (long)0);
                }   else if(field.getType() == float.class) {
                    field.setFloat(o2, (float)0);
                }   else if(field.getType() == int.class) {
                    field.setInt(o2, 0);
                }   else if(field.getType() == byte.class) {
                    field.setByte(o2, (byte)0);
                }   else if(field.getType() == char.class) {
                    field.setChar(o2, (char)0);
                }   else if(field.getType() == double.class) {
                    field.setDouble(o2, (double)1);
                }   else if(field.getType().isEnum()) {
                    field.set(o2, field.getType().getEnumConstants()[1]);
                } else if(Object.class.isAssignableFrom(field.getType())) {
                    field.set(o2, field.getType().newInstance());
                }   else {
                    fail("Don't know how to set a " + field.getType().getName());
                }
                if(field.get(o1).equals(field.get(o2)))  {
                    //Even though we have different instances, they are equal. Let's walk one of them
                    //to see if we can find a field to set
                    Field[] paramFields = field.get(o1).getClass().getDeclaredFields();
                    for(int j=0; j < paramFields.length; j++) {
                        paramFields[j].setAccessible(true);
                        if(paramFields[j].getType() == String.class) {
                            paramFields[j].set(field.get(o1), TEST_STRING_VAL1);
                        }
                    }
                }

                assertFalse("After setting o2 with a different object than what is in o1, the two objects in the field are equal. "
                        + "This is after an attempt to walk the fields to make them different"
                        , field.get(o1).equals(field.get(o2)));
                assertFalse("Instances with o1 having " + field.getName() + " set and o2 having it set to a different object are equal", o1.equals(o2));
            }

        } catch (InstantiationException e) {
            e.printStackTrace();
            throw new AssertionError("Unable to construct an instance of the class under test");
        } catch (IllegalAccessException e) {
            e.printStackTrace();
            throw new AssertionError("Unable to construct an instance of the class under test");
        }
    }

    public void testEqualsContractMet() {
        assertMeetsEqualsContract(FakeObject.class);
    }

    public static void assertMeetsHashCodeContract(Class classUnderTest) {
        try {
            Field[] fields = classUnderTest.getDeclaredFields();
            for(int i = 0; i < fields.length; i++) {
                Object o1 = classUnderTest.newInstance();
                int initialHashCode = o1.hashCode();

                Field field = fields[i];
                field.setAccessible(true);
                if(field.getType() == String.class) {
                    field.set(o1, TEST_STRING_VAL1);
                }  else if(field.getType() == boolean.class) {
                    field.setBoolean(o1, true);
                }   else if(field.getType() == short.class) {
                    field.setShort(o1, (short)1);
                }   else if(field.getType() == long.class) {
                    field.setLong(o1, (long)1);
                }   else if(field.getType() == float.class) {
                    field.setFloat(o1, (float)1);
                }   else if(field.getType() == int.class) {
                    field.setInt(o1, 1);
                }   else if(field.getType() == byte.class) {
                    field.setByte(o1, (byte)1);
                }   else if(field.getType() == char.class) {
                    field.setChar(o1, (char)1);
                }   else if(field.getType() == double.class) {
                    field.setDouble(o1, (double)1);
                }   else if(field.getType().isEnum()) {
                    field.set(o1, field.getType().getEnumConstants()[0]);
                } else if(Object.class.isAssignableFrom(field.getType())) {
                    field.set(o1, field.getType().newInstance());
                }   else {
                    fail("Don't know how to set a " + field.getType().getName());
                }
                int updatedHashCode = o1.hashCode();
                assertFalse("The field " + field.getName() + " was not taken into account for the hashCode contract ", initialHashCode == updatedHashCode);
            }
        } catch (InstantiationException e) {
            e.printStackTrace();
            throw new AssertionError("Unable to construct an instance of the class under test");
        } catch (IllegalAccessException e) {
            e.printStackTrace();
            throw new AssertionError("Unable to construct an instance of the class under test");
        }
    }

    public void testHashCodeContractMet() {
        assertMeetsHashCodeContract(FakeObject.class);
    }

}