luanpotter/validum

package xyz.luan.validum;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

import xyz.luan.reflection.tclass.TypedClass;

public final class ValidationHelper {

    private ValidationHelper() {
        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
    }

    public static boolean isValidationAnnotation(Annotation ann) {
        return ann.annotationType().getAnnotation(Validation.class) != null;
    }

    public static List<Annotation> getValidationAnnotations(Class<?> clazz) {
        return getValidationAnnotations(clazz.getAnnotations());
    }

    public static List<Annotation> getValidationAnnotations(Annotation[] annotations) {
        return Arrays.stream(annotations).filter(ann -> isValidationAnnotation(ann)).collect(Collectors.toList());
    }

    public static boolean isValidAnnotationType(Object value, Annotation annotation) {
        if (value == null) {
            return true;
        }

        List<Class<?>> validClasses = Validation.DefaultTypes.getClasses(annotation.annotationType().getAnnotation(Validation.class));
        for (Class<?> clazz : validClasses) {
            if (clazz.isAssignableFrom(value.getClass())) {
                return true;
            }
        }
        return false;
    }

    public static List<Annotation> getGlobals(TypedClass<?> c) {
        final List<Annotation> globalForField = getValidationAnnotations(c.asClass());
        c.getAnnotations().stream().filter(a -> isValidationAnnotation(a)).forEach(a -> globalForField.add(a));
        return globalForField;
    }

    public static Object getFieldValue(Object obj, Field f) {
        f.setAccessible(true);
        try {
            return f.get(obj);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            throw new AssertionError("Totally unexpected expection!", e);
        }
    }
}