ch.squaredesk.nova.comm.rest.annotation.BeanExaminer Maven / Gradle / Ivy

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/*
 * Copyright (c) Squaredesk GmbH and Oliver Dotzauer.
 *
 * This program is distributed under the squaredesk open source license. See the LICENSE file
 * distributed with this work for additional information regarding copyright ownership. You may also
 * obtain a copy of the license at
 *
 *   https://squaredesk.ch/license/oss/LICENSE
 */

package ch.squaredesk.nova.comm.rest.annotation;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.function.Predicate;
import java.util.stream.Collectors;

import static java.util.Arrays.stream;
import static java.util.Objects.requireNonNull;

class BeanExaminer {
    private static final Predicate interestingAnnotation = anno -> anno instanceof OnRestRequest;

    private BeanExaminer() {
    }

    static RestEndpoint[] restEndpointsIn (Object bean) {
        requireNonNull(bean, "bean to examine must not be null");

        return stream(bean.getClass().getDeclaredMethods())
                .filter(method -> stream(method.getDeclaredAnnotations()).anyMatch(interestingAnnotation))
                .peek(method -> {
                    if (!Modifier.isPublic(method.getModifiers()))
                        throw new IllegalArgumentException(
                                "Method " + prettyPrint(bean, method) + ", annotated with @" +
                                OnRestRequest.class.getSimpleName() + " must be public");
                })
                .map(method -> {
                    OnRestRequest annotation = stream(method.getDeclaredAnnotations())
                            .filter(interestingAnnotation)
                            .findFirst()
                            .map(anno -> (OnRestRequest)anno)
                            .get();
                    return new RestEndpoint(
                            RestResourceDescriptor.from(annotation.value(),
                                annotation.requestMethod(),
                                annotation.produces(),
                                annotation.consumes()),
                            method);
                })
                .toArray(RestEndpoint[]::new);
    }

    private static String prettyPrint (Object bean, Method method) {
        StringBuilder sb = new StringBuilder(bean.getClass().getName())
            .append('.')
            .append(method.getName())
            .append('(')
            .append(stream(method.getParameterTypes())
                    .map(paramterClass -> paramterClass.getSimpleName())
                    .collect(Collectors.joining(", ")))
            .append(')');
        return sb.toString();
    }
}