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package com.facebook.presto.jdbc.internal.jackson.databind.introspect;

import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.util.Collections;
import java.util.List;

import com.facebook.presto.jdbc.internal.jackson.databind.AnnotationIntrospector;
import com.facebook.presto.jdbc.internal.jackson.databind.JavaType;
import com.facebook.presto.jdbc.internal.jackson.databind.cfg.MapperConfig;
import com.facebook.presto.jdbc.internal.jackson.databind.introspect.ClassIntrospector.MixInResolver;
import com.facebook.presto.jdbc.internal.jackson.databind.type.TypeBindings;
import com.facebook.presto.jdbc.internal.jackson.databind.util.Annotations;
import com.facebook.presto.jdbc.internal.jackson.databind.util.ClassUtil;

/**
 * Helper class that contains logic for resolving annotations to construct
 * {@link AnnotatedClass} instances.
 *
 * @since 2.9
 */
public class AnnotatedClassResolver
{
    private final static Annotations NO_ANNOTATIONS = AnnotationCollector.emptyAnnotations();

    private final MapperConfig _config;
    private final AnnotationIntrospector _intr;
    private final MixInResolver _mixInResolver;
    private final TypeBindings _bindings;

    private final JavaType _type;
    private final Class _class;
    private final Class _primaryMixin;

    AnnotatedClassResolver(MapperConfig config, JavaType type, MixInResolver r) {
        _config = config;
        _type = type;
        _class = type.getRawClass();
        _mixInResolver = r;
        _bindings = type.getBindings();
        _intr = config.isAnnotationProcessingEnabled()
                ? config.getAnnotationIntrospector() : null;
        _primaryMixin = _config.findMixInClassFor(_class);
    }

    AnnotatedClassResolver(MapperConfig config, Class cls, MixInResolver r) {
        _config = config;
        _type = null;
        _class = cls;
        _mixInResolver = r;
        _bindings = TypeBindings.emptyBindings();
        if (config == null) {
            _intr = null;
            _primaryMixin = null;
        } else {
            _intr = config.isAnnotationProcessingEnabled()
                    ? config.getAnnotationIntrospector() : null;
            _primaryMixin = _config.findMixInClassFor(_class);
        }
    }

    public static AnnotatedClass resolve(MapperConfig config, JavaType forType,
            MixInResolver r)
    {
        if (forType.isArrayType() && skippableArray(config, forType.getRawClass())) {
            return createArrayType(config, forType.getRawClass());
        }
        return new AnnotatedClassResolver(config, forType, r).resolveFully();
    }

    public static AnnotatedClass resolveWithoutSuperTypes(MapperConfig config, Class forType) {
        return resolveWithoutSuperTypes(config, forType, config);
    }

    public static AnnotatedClass resolveWithoutSuperTypes(MapperConfig config, JavaType forType,
            MixInResolver r)
    {
        if (forType.isArrayType() && skippableArray(config, forType.getRawClass())) {
            return createArrayType(config, forType.getRawClass());
        }
        return new AnnotatedClassResolver(config, forType, r).resolveWithoutSuperTypes();
    }

    public static AnnotatedClass resolveWithoutSuperTypes(MapperConfig config, Class forType,
            MixInResolver r)
    {
        if (forType.isArray() && skippableArray(config, forType)) {
            return createArrayType(config, forType);
        }
        return new AnnotatedClassResolver(config, forType, r).resolveWithoutSuperTypes();
    }

    private static boolean skippableArray(MapperConfig config, Class type) {
        return (config == null) || (config.findMixInClassFor(type) == null);
                
    }

    /**
     * Internal helper method used for resolving a small set of "primordial" types for which
     * we do not accept any annotation information or overrides. 
     */
    static AnnotatedClass createPrimordial(Class raw) {
        return new AnnotatedClass(raw);
    }

    /**
     * Internal helper method used for resolving array types, unless they happen
     * to have associated mix-in to apply.
     */
    static AnnotatedClass createArrayType(MapperConfig config, Class raw) {
        return new AnnotatedClass(raw);
    }

    AnnotatedClass resolveFully() {
        List superTypes = ClassUtil.findSuperTypes(_type, null, false);
        return new AnnotatedClass(_type, _class, superTypes, _primaryMixin,
                resolveClassAnnotations(superTypes),
                _bindings, _intr, _mixInResolver, _config.getTypeFactory());

    }

    AnnotatedClass resolveWithoutSuperTypes() {
        List superTypes = Collections.emptyList();
        return new AnnotatedClass(null, _class, superTypes, _primaryMixin,
                resolveClassAnnotations(superTypes),
                _bindings, _intr, _config, _config.getTypeFactory());
    }

    /*
    /**********************************************************
    /* Class annotation resolution
    /**********************************************************
     */

    /**
     * Initialization method that will recursively collect Jackson
     * annotations for this class and all super classes and
     * interfaces.
     */
    private Annotations resolveClassAnnotations(List superTypes)
    {
        // Should skip processing if annotation processing disabled
        if (_intr == null) {
            return NO_ANNOTATIONS;
        }
        AnnotationCollector resolvedCA = AnnotationCollector.emptyCollector();
        // add mix-in annotations first (overrides)
        if (_primaryMixin != null) {
            resolvedCA = _addClassMixIns(resolvedCA, _class, _primaryMixin);
        }
        // then annotations from the class itself:
        resolvedCA = _addAnnotationsIfNotPresent(resolvedCA,
                ClassUtil.findClassAnnotations(_class));

        // and then from super types
        for (JavaType type : superTypes) {
            // and mix mix-in annotations in-between
            if (_mixInResolver != null) {
                Class cls = type.getRawClass();
                resolvedCA = _addClassMixIns(resolvedCA, cls,
                        _mixInResolver.findMixInClassFor(cls));
            }
            resolvedCA = _addAnnotationsIfNotPresent(resolvedCA,
                    ClassUtil.findClassAnnotations(type.getRawClass()));
        }
        /* and finally... any annotations there might be for plain
         * old Object.class: separate because for all other purposes
         * it is just ignored (not included in super types)
         */
        // 12-Jul-2009, tatu: Should this be done for interfaces too?
        //  For now, yes, seems useful for some cases, and not harmful for any?
        if (_mixInResolver != null) {
            resolvedCA = _addClassMixIns(resolvedCA, Object.class,
                    _mixInResolver.findMixInClassFor(Object.class));
        }
        return resolvedCA.asAnnotations();
    }

    private AnnotationCollector _addClassMixIns(AnnotationCollector annotations,
            Class target, Class mixin)
    {
        if (mixin != null) {
            // Ok, first: annotations from mix-in class itself:
            annotations = _addAnnotationsIfNotPresent(annotations, ClassUtil.findClassAnnotations(mixin));
    
            // And then from its supertypes, if any. But note that we will only consider
            // super-types up until reaching the masked class (if found); this because
            // often mix-in class is a sub-class (for convenience reasons).
            // And if so, we absolutely must NOT include super types of masked class,
            // as that would inverse precedence of annotations.
            for (Class parent : ClassUtil.findSuperClasses(mixin, target, false)) {
                annotations = _addAnnotationsIfNotPresent(annotations, ClassUtil.findClassAnnotations(parent));
            }
        }
        return annotations;
    }

    private AnnotationCollector _addAnnotationsIfNotPresent(AnnotationCollector c,
            Annotation[] anns)
    {
        if (anns != null) {
            for (Annotation ann : anns) { // first: direct annotations
                // note: we will NOT filter out non-Jackson annotations any more
                if (!c.isPresent(ann)) {
                    c = c.addOrOverride(ann);
                    if (_intr.isAnnotationBundle(ann)) {
                        c = _addFromBundleIfNotPresent(c, ann);
                    }
                }
            }
        }
        return c;
    }

    private AnnotationCollector _addFromBundleIfNotPresent(AnnotationCollector c,
            Annotation bundle)
    {
        for (Annotation ann : ClassUtil.findClassAnnotations(bundle.annotationType())) {
            // minor optimization: by-pass 2 common JDK meta-annotations
            if ((ann instanceof Target) || (ann instanceof Retention)) {
                continue;
            }
            if (!c.isPresent(ann)) {
                c = c.addOrOverride(ann);
                if (_intr.isAnnotationBundle(ann)) {
                    c = _addFromBundleIfNotPresent(c, ann);
                }
            }
        }
        return c;
    }
}