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package com.google.inject.internal;

import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Scope;
import com.google.inject.spi.Element;
import com.google.inject.spi.InstanceBinding;

import java.lang.annotation.Annotation;
import java.util.List;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Bind a value or constant.
 *
 */
public abstract class AbstractBindingBuilder {

    public static final String IMPLEMENTATION_ALREADY_SET = "Implementation is set more than once.";
    public static final String SINGLE_INSTANCE_AND_SCOPE =
            "Setting the scope is not permitted when binding to a single instance.";
    public static final String SCOPE_ALREADY_SET = "Scope is set more than once.";
    public static final String BINDING_TO_NULL = "Binding to null instances is not allowed. " +
            "Use toProvider(Providers.of(null)) if this is your intended behaviour.";
    public static final String CONSTANT_VALUE_ALREADY_SET = "Constant value is set more than once.";
    public static final String ANNOTATION_ALREADY_SPECIFIED =
            "More than one annotation is specified for this binding.";

    protected static final Key NULL_KEY = Key.get(Void.class);
    protected final Binder binder;
    protected List elements;
    protected int position;
    private BindingImpl binding;

    public AbstractBindingBuilder(Binder binder, List elements, Object source, Key key) {
        this.binder = binder;
        this.elements = elements;
        this.position = elements.size();
        this.binding = new UntargettedBindingImpl<>(source, key, Scoping.UNSCOPED);
        elements.add(position, this.binding);
    }

    protected BindingImpl getBinding() {
        return binding;
    }

    protected BindingImpl setBinding(BindingImpl binding) {
        this.binding = binding;
        elements.set(position, binding);
        return binding;
    }

    /**
     * Sets the binding to a copy with the specified annotation on the bound key
     */
    protected BindingImpl annotatedWithInternal(Class annotationType) {
        checkNotNull(annotationType, "annotationType");
        checkNotAnnotated();
        return setBinding(binding.withKey(Key.get(this.binding.getKey().getTypeLiteral(), annotationType)));
    }

    /**
     * Sets the binding to a copy with the specified annotation on the bound key
     */
    protected BindingImpl annotatedWithInternal(Annotation annotation) {
        checkNotNull(annotation, "annotation");
        checkNotAnnotated();
        return setBinding(binding.withKey(Key.get(this.binding.getKey().getTypeLiteral(), annotation)));
    }

    public void in(final Class scopeAnnotation) {
        checkNotNull(scopeAnnotation, "scopeAnnotation");
        checkNotScoped();
        setBinding(getBinding().withScoping(Scoping.forAnnotation(scopeAnnotation)));
    }

    public void in(final Scope scope) {
        checkNotNull(scope, "scope");
        checkNotScoped();
        setBinding(getBinding().withScoping(Scoping.forInstance(scope)));
    }

    public void asEagerSingleton() {
        checkNotScoped();
        setBinding(getBinding().withScoping(Scoping.EAGER_SINGLETON));
    }

    protected boolean keyTypeIsSet() {
        return !Void.class.equals(binding.getKey().getTypeLiteral().getType());
    }

    protected void checkNotTargetted() {
        if (!(binding instanceof UntargettedBindingImpl)) {
            binder.addError(IMPLEMENTATION_ALREADY_SET);
        }
    }

    protected void checkNotAnnotated() {
        if (binding.getKey().getAnnotationType() != null) {
            binder.addError(ANNOTATION_ALREADY_SPECIFIED);
        }
    }

    protected void checkNotScoped() {
        // Scoping isn't allowed when we have only one instance.
        if (binding instanceof InstanceBinding) {
            binder.addError(SINGLE_INSTANCE_AND_SCOPE);
            return;
        }

        if (binding.getScoping().isExplicitlyScoped()) {
            binder.addError(SCOPE_ALREADY_SET);
        }
    }
}