/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.core.api.model.resolvers;

import org.mule.runtime.core.api.Event;
import org.mule.runtime.core.api.MuleEventContext;
import org.mule.runtime.core.api.model.InvocationResult;
import org.mule.runtime.core.routing.filters.WildcardFilter;
import org.mule.runtime.core.util.ClassUtils;
import org.mule.runtime.core.util.StringMessageUtils;
import org.mule.runtime.core.util.StringUtils;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * <code>ReflectEntryPointResolver</code> is used to determine the entry point on a service after an event has been received for
 * it. The entrypoint is discovered using the event payload type(s) as the argument using reflection. An entry point will try and
 * match for different argument types, so it's possible to have multiple entry points on a single service.
 * <p/>
 * For multiple parameters the payload of context.getResult().getPayload().getValue() should be an Array of objects. If the
 * message payload is of type {@link org.mule.runtime.api.message.NullPayload} the resolver will look for a no-argument method to
 * call that doesn't match the set of ignoredMethods on the resolver.
 * <p/>
 * Also a set of 'ignored' methods are available (and the use can add others) to tell the resolver to not resolve to these
 * methods. The default ones are:
 * <ul>
 * <li>{@link #toString()}
 * <li>{@link #getClass()}
 * <li>{@link #notify}
 * <li>{@link #notifyAll}
 * <li>{@link #hashCode}
 * <li>{@link #wait}
 * <li>{@link java.lang.reflect.Proxy#getInvocationHandler}
 * <li>'is*'
 * <li>'get*'.
 * <li>'set*'.
 * </ul>
 * <p/>
 * Note that wildcard expressions can be used.
 */
public class ReflectionEntryPointResolver extends AbstractEntryPointResolver {

  // we don't want to match these methods when looking for a service method
  private Set<String> ignoredMethods =
      new HashSet<String>(Arrays.asList("equals", "getInvocationHandler", "set*", "toString", "getClass", "notify", "notifyAll",
                                        "wait", "hashCode", "clone", "is*", "get*", "apply"));

  protected WildcardFilter filter;

  public ReflectionEntryPointResolver() {
    updateFilter();
  }

  private void updateFilter() {
    filter = new WildcardFilter(StringUtils.join(ignoredMethods, ','));
  }

  /**
   * Returns an unmodifiable Set of ignoredMethods on this resolver To add method to the resolver use
   * {@link #addIgnoredMethod(String)}
   *
   * @return unmodifiable set of method names set on this resolver
   */
  public Set<String> getIgnoredMethods() {
    return Collections.unmodifiableSet(ignoredMethods);
  }

  public void setIgnoredMethods(Set<String> methods) {
    this.ignoredMethods = new HashSet<String>(methods);
    updateFilter();
  }

  public void addIgnoredMethod(String name) {
    this.ignoredMethods.add(name);
    updateFilter();
  }

  public boolean removeIgnoredMethod(String name) {
    boolean result = this.ignoredMethods.remove(name);
    updateFilter();
    return result;
  }

  /**
   * Will discover the entrypoint on the service using the payload type to figure out the method to call. For multiple parameters
   * the payload of context.getResult().geTPayload() should be an Array of objects. If the message payload is of type
   * {@link org.mule.runtime.api.message.NullPayload} the resolver will look for a no-argument method to call that doesn't match
   * the set of ignoredMethods on the resover.
   *
   * @throws Exception
   */
  public InvocationResult invoke(Object component, MuleEventContext context, Event.Builder eventBuilder) throws Exception {
    Object[] payload = getPayloadFromMessage(context);

    Method method;
    InvocationResult result;

    method = this.getMethodByArguments(component, payload);

    if (method != null) {
      return invokeMethod(component, method, payload);
    }

    Class<?>[] types = ClassUtils.getClassTypes(payload);

    // do any methods on the service accept a context?
    List<Method> methods =
        ClassUtils.getSatisfiableMethods(component.getClass(), types, isAcceptVoidMethods(), false, ignoredMethods, filter);

    int numMethods = methods.size();
    if (numMethods > 1) {
      result = new InvocationResult(this, InvocationResult.State.FAILED);
      // too many methods match the context argument
      result.setErrorTooManyMatchingMethods(component, types, StringMessageUtils.toString(methods));
      return result;

    } else if (numMethods == 1) {
      // found exact match for method with context argument
      method = this.addMethodByArguments(component, methods.get(0), payload);
    } else {
      methods =
          ClassUtils.getSatisfiableMethods(component.getClass(), ClassUtils.getClassTypes(payload), true, true, ignoredMethods);

      numMethods = methods.size();

      if (numMethods > 1) {
        result = new InvocationResult(this, InvocationResult.State.FAILED);
        // too many methods match the context argument
        result.setErrorTooManyMatchingMethods(component, types, StringMessageUtils.toString(methods));
        return result;
      } else if (numMethods == 1) {
        // found exact match for payload argument
        method = this.addMethodByArguments(component, methods.get(0), payload);
      } else {
        result = new InvocationResult(this, InvocationResult.State.FAILED);
        // no method for payload argument either - bail out
        result.setErrorNoMatchingMethods(component, ClassUtils.getClassTypes(payload));
        return result;
      }
    }

    return invokeMethod(component, method, payload);
  }


  @Override
  public String toString() {
    final StringBuilder sb = new StringBuilder();
    sb.append("ReflectionEntryPointResolver");
    sb.append("{ignoredMethods=").append(StringMessageUtils.toString(ignoredMethods));
    sb.append(", acceptVoidMethods=").append(isAcceptVoidMethods());
    sb.append('}');
    return sb.toString();
  }
}