graphql.annotations.processor.util.DataFetcherConstructor Maven / Gradle / Ivy

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/**
 * Copyright 2016 Yurii Rashkovskii
 *
 * Licensed 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
 */
package graphql.annotations.processor.util;

import graphql.annotations.annotationTypes.GraphQLDataFetcher;
import graphql.annotations.processor.exceptions.GraphQLAnnotationsException;
import graphql.schema.DataFetcher;
import org.osgi.service.component.annotations.Component;

import java.lang.reflect.Constructor;
import java.util.stream.Stream;

import static graphql.annotations.processor.util.ReflectionKit.constructNewInstance;
import static graphql.annotations.processor.util.ReflectionKit.newInstance;
import static java.util.Arrays.stream;

@Component(service = DataFetcherConstructor.class)
public class DataFetcherConstructor {
    public DataFetcher constructDataFetcher(String fieldName, GraphQLDataFetcher annotatedDataFetcher) {
        final String[] args;
        if (annotatedDataFetcher.firstArgIsTargetName()) {
            args = Stream.concat(Stream.of(fieldName), stream(annotatedDataFetcher.args())).toArray(String[]::new);
        } else {
            args = annotatedDataFetcher.args();
        }
        if (args.length == 0) {
            return newInstance(annotatedDataFetcher.value());
        } else {
            return Stream.of(annotatedDataFetcher.value().getConstructors())
                    // filter only constructor that have the same args as the annotation args
                    // or that get String[], String... args
                    .filter(x -> (x.getParameterCount() == args.length) ||
                            (x.getParameterTypes().length == 1 && x.getParameterTypes()[0] == String[].class))
                    .map(x -> {
                        try {
                            Constructor constructor;
                            if (x.getParameterTypes().length == 1 && x.getParameterTypes()[0] == String[].class) {
                                constructor = annotatedDataFetcher.value().getDeclaredConstructor(String[].class);
                                return constructNewInstance(constructor, new Object[]{args});
                            }

                            constructor = annotatedDataFetcher.value().getDeclaredConstructor(
                                    stream(args).map(v -> String.class).toArray(Class[]::new));
                            return constructNewInstance(constructor, (Object[]) args);
                        } catch (NoSuchMethodException e) {
                            throw new GraphQLAnnotationsException("Unable to instantiate DataFetcher via constructor for: " + fieldName, e);
                        }
                    })
                    .findFirst()
                    .orElseThrow(NoArgsConstructorException::new);
        }
    }

    public static class NoArgsConstructorException extends RuntimeException {
    }
}