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/*
 * Copyright (C) 2015 fuwjax.org ([email protected])
 *
 * 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
 * limitations under the License.
 */
package org.fuwjax.oss.inject;

import org.fuwjax.oss.generic.GenericMember;
import org.fuwjax.oss.generic.Spec;
import org.fuwjax.oss.util.RunWrapException;

import javax.inject.Inject;
import java.lang.reflect.Type;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static org.fuwjax.oss.generic.GenericMember.MemberType.CONSTRUCTOR;
import static org.fuwjax.oss.generic.GenericMember.TargetType.INSTANCE;
import static org.fuwjax.oss.util.function.Functions.function;

public class InjectSpec {
    private static ConcurrentMap specs = new ConcurrentHashMap<>();

    public static InjectSpec of(final Type type) throws ReflectiveOperationException {
        try {
            return specs.computeIfAbsent(type, function(InjectSpec::new));
        } catch (RunWrapException e) {
            throw e.throwIf(ReflectiveOperationException.class);
        }
    }

    private final GenericMember constructor;
    private final List members;

    private InjectSpec(final Type type) throws ReflectiveOperationException {
        Spec spec = Spec.of(type);
        constructor = constructor(spec);
        members = spec.members().filter(INSTANCE.and(InjectSpec::isInject)).collect(Collectors.toList());
    }

    private static GenericMember constructor(final Spec type) throws ReflectiveOperationException {
        final List constructors = type.members().filter(CONSTRUCTOR).collect(Collectors.toList());
        if (constructors.size() == 0) {
            return null;
        }
        if (constructors.size() == 1) {
            return constructors.get(0);
        }
        final List injects = constructors.stream().filter(InjectSpec::isInject).collect(Collectors.toList());
        if (injects.isEmpty()) {
            return constructors.stream().filter(m -> m.paramTypes().length == 0).findAny().orElse(null);
        }
        if (injects.size() == 1) {
            return injects.get(0);
        }
        return null;
    }

    private static boolean isInject(final GenericMember member) {
        return member.source().isAnnotationPresent(Inject.class);
    }

    public Stream members() {
        return members.stream();
    }

    public GenericMember constructor() {
        if (constructor == null) {
            throw new IllegalArgumentException("Inject specifications require a single @Inject constructor");
        }
        return constructor;
    }
}