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/*
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 *
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 *    General Public License Version 2 only ("GPL") or the Common Development
 *    and Distribution License("CDDL") (collectively, the "License").  You
 *    may not use this file except in compliance with the License.  You can
 *    obtain a copy of the License at
 *    https://github.com/payara/Payara/blob/master/LICENSE.txt
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 *
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 *    exception as provided by the Payara Foundation in the GPL Version 2 section of the License
 *    file that accompanied this code.
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package fish.payara.ejb.http.client.adapter;

import javax.naming.Context;
import javax.naming.NamingException;
import java.util.Optional;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;

import static fish.payara.ejb.http.client.adapter.CompositeClientAdapter.Builder.instantiate;

/**
 * Customizer for externalizing JNDI name matching and name transformation.
 * The class creates a decorator that takes care of matching looked up JNDI names and transforming the jndi name before
 * passed to downstream adapter.
 * 
Most common use case is represented by method {@link #matchPrefix(String)}: Given the prefix, the downstream
 * adapter is only called when requested name matches prefix, and it is invoked with the prefix stripped from name.

 * 
Class is intended to use as static import during construction of {@link CompositeClientAdapter}.

 * 
 * {@code
 * import static fish.payara.ejb.http.client.adapter.ClientAdapterCustomizer.*;
 *
 * ...
 * CompositeClientAdapter.builder()
 *     .register(customize(JmsStubAdapter.class).matchPrefix("java:comp/jms"),
 *               customize(new ConnectionFactoryStub()).matchName(Pattern.compile("jms/.+Factory")::matches))
 *     .build()
 * }
 * 

 */
public final class ClientAdapterCustomizer implements ClientAdapter {
    private final Supplier downstreamAdapter;
    private Predicate namePredicate;
    private Function nameTransformation = Function.identity();

    ClientAdapterCustomizer(Supplier downstreamAdapter) {
        this.downstreamAdapter = downstreamAdapter;
    }

    private ClientAdapterCustomizer(ClientAdapterCustomizer previous) {
        this.downstreamAdapter = previous.downstreamAdapter;
        this.namePredicate = previous.namePredicate;
        this.nameTransformation = previous.nameTransformation;
    }

    /**
     * Call downstream adapter when name matches, with jndiName parameter transformed.
     * @param jndiName jndi name requested for lookup
     * @param remoteContext naming context for remote EJB invocation
     * @return looked up adapter if downstream adapter returns one
     * @throws NamingException when downstream adapter throws one
     */
    @Override
    public Optional makeLocalProxy(String jndiName, Context remoteContext) throws NamingException {
        if (namePredicate == null || namePredicate.test(jndiName)) {
            return downstreamAdapter.get().makeLocalProxy(nameTransformation.apply(jndiName), remoteContext);
        } else {
            return Optional.empty();
        }
    }


    /**
     * Return new customizer with specified predicate for matching a name.
     * The predicates is replaced rather than composed, any current predicate is replaced with the new one in returned instance.
     * @param name predicate for matching name
     * @return new customizer instance
     */
    public ClientAdapterCustomizer matchName(Predicate name) {
        ClientAdapterCustomizer conditional = new ClientAdapterCustomizer(this);
        conditional.namePredicate = name;
        return conditional;
    }

    /**
     * Return new customizer with specified name transformation function.
     * The function is replaced rather than composed, any current transformation is replaced with new one in returned instance.
     * Transformation is applied after predicate specified with {@link #matchName(Predicate)} passes
     * @param nameTransformation JNDI name transformation
     * @return new customizer instance
     */
    public ClientAdapterCustomizer transformName(Function nameTransformation) {
        ClientAdapterCustomizer conditional = new ClientAdapterCustomizer(this);
        conditional.nameTransformation = nameTransformation != null ? nameTransformation : Function.identity();
        return conditional;
    }

    /**
     * Return new customizer that matches given prefix, and strips the prefix from the name before invoking downstream
     * adapter.
     * @param prefix JNDI name prefix to match and strip
     * @return new customizer instance
     */
    public ClientAdapterCustomizer matchPrefix(String prefix) {
        return matchName(name -> name.startsWith(prefix)).transformName(name -> name.substring(prefix.length()));
    }

    /**
     * Create customizer of given class. Class is instatiated via default constructor immediately.
     * @param adapterClass
     * @return customizer instance
     */
    public static ClientAdapterCustomizer customize(Class adapterClass) {
        return customize(instantiate(adapterClass));
    }

    /**
     * Create customizer decorating given instance.
     * @param adapterInstance
     * @return customizer instance
     */
    public static ClientAdapterCustomizer customize(ClientAdapter adapterInstance) {
        return customize(() -> adapterInstance);
    }

    /**
     * Create customizer decorating given supplier. Supplier will be invoked at every lookup, but only when JNDI name
     * predicate matches.
     * @param adapterSupplier
     * @return customizer instance
     */
    public static ClientAdapterCustomizer customize(Supplier adapterSupplier) {
        return new ClientAdapterCustomizer(adapterSupplier);
    }
}
 















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