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package com.google.inject.internal;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.ConfigurationException;
import com.google.inject.Inject;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.util.Classes;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.ConstructorBinding;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.InjectionPoint;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.Set;

import static com.google.common.base.Preconditions.checkState;
import static com.google.inject.internal.Annotations.findScopeAnnotation;

final class ConstructorBindingImpl extends BindingImpl
        implements ConstructorBinding, DelayedInitialize {

    private final Factory factory;

    private final InjectionPoint constructorInjectionPoint;

    private ConstructorBindingImpl(InjectorImpl injector,
                                   Key key,
                                   Object source,
                                   InternalFactory scopedFactory,
                                   Scoping scoping,
                                   Factory factory,
                                   InjectionPoint constructorInjectionPoint) {
        super(injector, key, source, scopedFactory, scoping);
        this.factory = factory;
        this.constructorInjectionPoint = constructorInjectionPoint;
    }

    public ConstructorBindingImpl(Key key, Object source, Scoping scoping,
                                  InjectionPoint constructorInjectionPoint, Set injectionPoints) {
        super(source, key, scoping);
        this.factory = new Factory(false, key);
        ConstructionProxy constructionProxy
                = new DefaultConstructionProxyFactory(constructorInjectionPoint).create();
        this.constructorInjectionPoint = constructorInjectionPoint;
        factory.constructorInjector = new ConstructorInjector(
                injectionPoints, constructionProxy, null, null);
    }

    /**
     * @param constructorInjector the constructor to use, or {@code null} to use the default.
     * @param failIfNotLinked     true if this ConstructorBindingImpl's InternalFactory should
     *                            only succeed if retrieved from a linked binding
     */
    static  ConstructorBindingImpl create(InjectorImpl injector, Key key,
                                                InjectionPoint constructorInjector,
                                                Object source,
                                                Scoping scoping,
                                                Errors errors,
                                                boolean failIfNotLinked, boolean failIfNotExplicit)
            throws ErrorsException {
        int numErrors = errors.size();

        @SuppressWarnings("unchecked") // constructorBinding guarantees type is consistent
                Class rawType = constructorInjector == null
                ? key.getTypeLiteral().getRawType()
                : (Class) constructorInjector.getDeclaringType().getRawType();

        // We can't inject abstract classes.
        if (Modifier.isAbstract(rawType.getModifiers())) {
            errors.missingImplementationWithHint(key, injector);
        }

        // Error: Inner class.
        if (Classes.isInnerClass(rawType)) {
            errors.cannotInjectInnerClass(rawType);
        }

        errors.throwIfNewErrors(numErrors);

        // Find a constructor annotated @Inject
        if (constructorInjector == null) {
            try {
                constructorInjector = InjectionPoint.forConstructorOf(key.getTypeLiteral());
                if (failIfNotExplicit && !hasAtInject((Constructor) constructorInjector.getMember())) {
                    errors.atInjectRequired(rawType);
                }
            } catch (ConfigurationException e) {
                throw errors.merge(e.getErrorMessages()).toException();
            }
        }

        // if no scope is specified, look for a scoping annotation on the concrete class
        if (!scoping.isExplicitlyScoped()) {
            Class annotatedType = constructorInjector.getMember().getDeclaringClass();
            Class scopeAnnotation = findScopeAnnotation(errors, annotatedType);
            if (scopeAnnotation != null) {
                scoping = Scoping.makeInjectable(Scoping.forAnnotation(scopeAnnotation),
                        injector, errors.withSource(rawType));
            }
        }

        errors.throwIfNewErrors(numErrors);

        Factory factoryFactory = new Factory(failIfNotLinked, key);
        InternalFactory scopedFactory
                = Scoping.scope(key, injector, factoryFactory, source, scoping);

        return new ConstructorBindingImpl(
                injector, key, source, scopedFactory, scoping, factoryFactory, constructorInjector);
    }

    /**
     * Returns true if the inject annotation is on the constructor.
     */
    private static boolean hasAtInject(Constructor cxtor) {
        return cxtor.isAnnotationPresent(Inject.class)
                || cxtor.isAnnotationPresent(javax.inject.Inject.class);
    }

    @SuppressWarnings("unchecked") // the result type always agrees with the ConstructorInjector type
    public void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
        factory.constructorInjector =
                (ConstructorInjector) injector.constructors.get(constructorInjectionPoint, errors);
        factory.provisionCallback =
                injector.provisionListenerStore.get(this);
    }

    /**
     * True if this binding has been initialized and is ready for use.
     */
    boolean isInitialized() {
        return factory.constructorInjector != null;
    }

    /**
     * Returns an injection point that can be used to clean up the constructor store.
     */
    InjectionPoint getInternalConstructor() {
        if (factory.constructorInjector != null) {
            return factory.constructorInjector.getConstructionProxy().getInjectionPoint();
        } else {
            return constructorInjectionPoint;
        }
    }

    /**
     * Returns a set of dependencies that can be iterated over to clean up stray JIT bindings.
     */
    Set> getInternalDependencies() {
        ImmutableSet.Builder builder = ImmutableSet.builder();
        if (factory.constructorInjector == null) {
            builder.add(constructorInjectionPoint);
            // If the below throws, it's OK -- we just ignore those dependencies, because no one
            // could have used them anyway.
            try {
                builder.addAll(InjectionPoint.forInstanceMethodsAndFields(constructorInjectionPoint.getDeclaringType()));
            } catch (ConfigurationException ignored) {
            }
        } else {
            builder.add(getConstructor())
                    .addAll(getInjectableMembers());
        }

        return Dependency.forInjectionPoints(builder.build());
    }

    @Override
    public  V acceptTargetVisitor(BindingTargetVisitor visitor) {
        checkState(factory.constructorInjector != null, "not initialized");
        return visitor.visit(this);
    }

    @Override
    public InjectionPoint getConstructor() {
        checkState(factory.constructorInjector != null, "Binding is not ready");
        return factory.constructorInjector.getConstructionProxy().getInjectionPoint();
    }

    @Override
    public Set getInjectableMembers() {
        checkState(factory.constructorInjector != null, "Binding is not ready");
        return factory.constructorInjector.getInjectableMembers();
    }

    @Override
    public Set> getDependencies() {
        return Dependency.forInjectionPoints(new ImmutableSet.Builder()
                .add(getConstructor())
                .addAll(getInjectableMembers())
                .build());
    }

    @Override
    protected BindingImpl withScoping(Scoping scoping) {
        return new ConstructorBindingImpl(
                null, getKey(), getSource(), factory, scoping, factory, constructorInjectionPoint);
    }

    @Override
    protected BindingImpl withKey(Key key) {
        return new ConstructorBindingImpl(
                null, key, getSource(), factory, getScoping(), factory, constructorInjectionPoint);
    }

    @SuppressWarnings("unchecked") // the raw constructor member and declaring type always agree
    public void applyTo(Binder binder) {
        InjectionPoint constructor = getConstructor();
        getScoping().applyTo(binder.withSource(getSource()).bind(getKey()).toConstructor(
                (Constructor) getConstructor().getMember(), (TypeLiteral) constructor.getDeclaringType()));
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(ConstructorBinding.class)
                .add("key", getKey())
                .add("source", getSource())
                .add("scope", getScoping())
                .toString();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof ConstructorBindingImpl) {
            ConstructorBindingImpl o = (ConstructorBindingImpl) obj;
            return getKey().equals(o.getKey())
                    && getScoping().equals(o.getScoping())
                    && Objects.equal(constructorInjectionPoint, o.constructorInjectionPoint);
        } else {
            return false;
        }
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(getKey(), getScoping(), constructorInjectionPoint);
    }

    private static class Factory implements InternalFactory {
        private final boolean failIfNotLinked;
        private final Key key;
        private ConstructorInjector constructorInjector;
        private ProvisionListenerStackCallback provisionCallback;

        Factory(boolean failIfNotLinked, Key key) {
            this.failIfNotLinked = failIfNotLinked;
            this.key = key;
        }

        @SuppressWarnings("unchecked")
        public T get(InternalContext context, Dependency dependency, boolean linked)
                throws InternalProvisionException {
            ConstructorInjector localInjector = constructorInjector;
            if (localInjector == null) {
                throw new IllegalStateException("Constructor not ready");
            }
            if (!linked && failIfNotLinked) {
                throw InternalProvisionException.jitDisabled(key);
            }

            // This may not actually be safe because it could return a super type of T (if that's all the
            // client needs), but it should be OK in practice thanks to the wonders of erasure.
            return (T) localInjector.construct(context, dependency, provisionCallback);
        }
    }
}