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Embedded-Web Distribution of the Payara Project
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package fish.payara.ejb.http.client;

import static javax.naming.Context.SECURITY_CREDENTIALS;
import static javax.naming.Context.SECURITY_PRINCIPAL;
import static jakarta.ws.rs.HttpMethod.POST;
import static jakarta.ws.rs.core.MediaType.APPLICATION_JSON;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.util.Arrays;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.Future;

import jakarta.ws.rs.client.Entity;
import jakarta.ws.rs.client.Invocation;
import jakarta.ws.rs.client.WebTarget;
import jakarta.ws.rs.core.Cookie;
import jakarta.ws.rs.core.GenericType;
import jakarta.ws.rs.core.MultivaluedHashMap;
import jakarta.ws.rs.core.MultivaluedMap;

/**
 * This class handles invocations (method calls) on a proxy generated by {@link EjbRestProxyFactory}.
 * 
 * 
 * This proxy uses REST calls to an endpoint in a given remote Payara server.
 * 
 * @author Arjan Tijms
 * @since Payara 5.191
 *
 */
class EjbHttpProxyHandler implements InvocationHandler {
    
    private final WebTarget target;
    private final MultivaluedMap headers;
    private final List cookies;
    private final String lookup;
    private final Map jndiOptions;
    
    EjbHttpProxyHandler(WebTarget target, MultivaluedMap headers, List cookies, String lookup, Map jndiOptions) {
        this.target = target;
        this.headers = headers;
        this.cookies = cookies;
        this.lookup = lookup;
        this.jndiOptions = jndiOptions;
    }
    
    @Override
    public Object invoke(Object proxy, Method method, Object[] argValues) throws Throwable {
        
        // Check for methods we should not proxy first
        
        if (argValues == null && method.getName().equals("toString")) {
            return toString();
        }

        if (argValues == null && method.getName().equals("hashCode")) {
            // unique instance in the JVM, and no need to override
            return hashCode();
        }

        if (argValues != null && argValues.length == 1 && method.getName().equals("equals")) {
            // unique instance in the JVM, and no need to override
            return equals(argValues[0]);
        }
        
        // Valid method, do invoke it remotely
        return doRemoteInvoke(proxy, method, argValues);
    }
    
    public Object doRemoteInvoke(Object proxy, Method method, Object[] argValues) throws Throwable {
        // HTTP method name; we're always using POST to invoke remote EJBs
        String httpMethod = POST;
        
        // The bare payload being sent 
        Map payload = new HashMap<>();
        payload.put("lookup", lookup);
        payload.put("method", method.getName());
        payload.put("argTypes", Arrays.stream(method.getParameterTypes()).map(Class::getName).toArray());
        payload.put("argValues", argValues == null? new Object[0] : argValues);
        
        if (jndiOptions.containsKey(SECURITY_PRINCIPAL)) {
            payload.put(SECURITY_PRINCIPAL, Lookup.base64Encode(jndiOptions.get(SECURITY_PRINCIPAL)));
        }
        
        if (jndiOptions.containsKey(SECURITY_CREDENTIALS)) {
            payload.put(SECURITY_CREDENTIALS, Lookup.base64Encode(jndiOptions.get(SECURITY_CREDENTIALS)));
        }
        
        // Payload wrapped as entity so it'll be encoded in JSON
        Entity entity = Entity.entity(payload, APPLICATION_JSON);
        
        // Response type
        Class responseType = method.getReturnType();
        GenericType responseGenericType = new GenericType<>(method.getGenericReturnType());

        // Create a new UriBuilder appending the name from the method
        WebTarget newTarget = addPathFromMethod(method, target);
        
        // Start request
        Invocation.Builder builder = newTarget.request();
                
        // Set optional headers and cookies    
        builder.headers(new MultivaluedHashMap(this.headers));
        for (Cookie cookie : new LinkedList<>(this.cookies)) {
            builder = builder.cookie(cookie);
        }
        
        // Call remote server
        
        if (responseType.isAssignableFrom(CompletionStage.class)) {
            
            // Reactive call - the actual response type is T from CompletionStage
            return builder.rx().method(httpMethod, entity, getResponseParameterizedType(method, responseGenericType));
        } else if (responseType.isAssignableFrom(Future.class)) {
            
            // Asynchronous call - the actual response type is T from Future
            return builder.async().method(httpMethod, entity, getResponseParameterizedType(method, responseGenericType));
        }
        
        // Synchronous call           
        return builder.method(httpMethod, entity, responseGenericType);
    }
    
    private GenericType getResponseParameterizedType(Method method, GenericType responseGenericType) {
        if (method.getGenericReturnType() instanceof ParameterizedType) {
            ParameterizedType parameterizedType = (ParameterizedType) method.getGenericReturnType();
            
            return new GenericType<>(parameterizedType.getActualTypeArguments()[0]);
        }
        
        return responseGenericType;
    }
    
    private static WebTarget addPathFromMethod(Method method, WebTarget target) {
        return target.path(method.getName());
    }

    @Override
    public String toString() {
        return target.toString();
    }

}