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With inspiration from other libraries
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/**
 * MVEL (The MVFLEX Expression Language)
 *
 * Copyright (C) 2007 Christopher Brock, MVFLEX/Valhalla Project and the Codehaus
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package org.mvel2.optimizers.impl.refl.nodes;

import org.mvel2.compiler.ExecutableStatement;
import org.mvel2.integration.VariableResolverFactory;

import java.lang.reflect.Method;

import static org.mvel2.util.ParseTools.getBestCandidate;
import static org.mvel2.util.ParseTools.getWidenedTarget;

public class MethodAccessor extends InvokableAccessor {

  private Method method;

  public Object getValue(Object ctx, Object elCtx, VariableResolverFactory vars) {
    if (!coercionNeeded) {
      try {
        if (nextNode != null) {
          return nextNode.getValue(method.invoke(ctx, executeAll(elCtx, vars, method)), elCtx, vars);
        }
        else {
          return method.invoke(ctx, executeAll(elCtx, vars, method));
        }
      }
      catch (IllegalArgumentException e) {
        if (ctx != null && method.getDeclaringClass() != ctx.getClass()) {
          Method o = getBestCandidate(parameterTypes, method.getName(), ctx.getClass(), ctx.getClass().getMethods(), true);
          if (o != null) {
            return executeOverrideTarget(getWidenedTarget(o), ctx, elCtx, vars);
          }
        }

        coercionNeeded = true;
        return getValue(ctx, elCtx, vars);
      }
      catch (Exception e) {
        throw new RuntimeException("cannot invoke method: " + method.getName(), e);
      }

    }
    else {
      try {
        if (nextNode != null) {
          return nextNode.getValue(method.invoke(ctx, executeAndCoerce(parameterTypes, elCtx, vars, method.isVarArgs())), elCtx, vars);
        }
        else {
          return method.invoke(ctx, executeAndCoerce(parameterTypes, elCtx, vars, method.isVarArgs()));
        }
      }
      catch (IllegalArgumentException e) {
        Object[] vs = executeAndCoerce(parameterTypes, elCtx, vars, false);
        Method newMeth;
        if ((newMeth = getWidenedTarget(getBestCandidate(vs, method.getName(), ctx.getClass(),
            ctx.getClass().getMethods(), false))) != null) {
          return executeOverrideTarget(newMeth, ctx, elCtx, vars);
        }
        else {
          throw e;
        }
      }
      catch (Exception e) {
        throw new RuntimeException("cannot invoke method: " + method.getName(), e);
      }
    }
  }

  private Object executeOverrideTarget(Method o, Object ctx, Object elCtx, VariableResolverFactory vars) {
    // this local field is required to make sure exception block works with the same coercionNeeded value
    // and it is not changed by another thread while setter is invoked 
    boolean attemptedCoercion = coercionNeeded;
    if (!coercionNeeded) {
      try {
        try {
          if (nextNode != null) {
            return nextNode.getValue(o.invoke(ctx, executeAll(elCtx, vars, o)), elCtx, vars);
          }
          else {
            return o.invoke(ctx, executeAll(elCtx, vars, o));
          }
        }
        catch (IllegalArgumentException e) {
          if (attemptedCoercion) throw e;

          coercionNeeded = true;
          return executeOverrideTarget(o, ctx, elCtx, vars);
        }
      }
      catch (Exception e2) {
        throw new RuntimeException("unable to invoke method", e2);
      }
    }
    else {
      try {
        if (nextNode != null) {
          return nextNode.getValue(o.invoke(ctx, executeAndCoerce(o.getParameterTypes(), elCtx, vars, o.isVarArgs())), elCtx, vars);
        }
        else {
          return o.invoke(ctx, executeAndCoerce(o.getParameterTypes(), elCtx, vars, o.isVarArgs()));
        }
      }
      catch (IllegalAccessException e) {
        throw new RuntimeException("unable to invoke method (expected target: " + method.getDeclaringClass().getName() + "::" + method.getName() + "; " +
            "actual target: " + ctx.getClass().getName() + "::" + method.getName() + "; coercionNeeded=" + (coercionNeeded ? "yes" : "no") + ")");
      }
      catch (Exception e2) {
        throw new RuntimeException("unable to invoke method (expected target: " + method.getDeclaringClass().getName() + "::" + method.getName() + "; " +
            "actual target: " + ctx.getClass().getName() + "::" + method.getName() + "; coercionNeeded=" + (coercionNeeded ? "yes" : "no") + ")");
      }
    }
  }

  private Object[] executeAll(Object ctx, VariableResolverFactory vars, Method m) {
    if (length == 0) return GetterAccessor.EMPTY;

    Object[] vals = new Object[length];
    for (int i = 0; i < length - (m.isVarArgs() ? 1 : 0); i++) {
      vals[i] = parms[i].getValue(ctx, vars);
    }

    if (m.isVarArgs()) {
     if(parms == null){
        vals[length -1] = new Object[0];
     }
     else if (parms.length == length) {
          Object lastParam = parms[length - 1].getValue(ctx, vars);
          vals[length - 1] = lastParam == null || lastParam.getClass().isArray() ? lastParam : new Object[] {lastParam};
      } else {
        Object[] vararg = new Object[parms.length - length + 1];
        for (int i = 0; i < vararg.length; i++) vararg[i] = parms[length - 1 + i].getValue(ctx, vars);
        vals[length - 1] = vararg;
      }
    }

    return vals;
  }

  public Method getMethod() {
    return method;
  }

  public void setMethod(Method method) {
    this.method = method;
    this.length = (this.parameterTypes = this.method.getParameterTypes()).length;
  }

  public ExecutableStatement[] getParms() {
    return parms;
  }

  public void setParms(ExecutableStatement[] parms) {
    this.parms = parms;
  }

  public MethodAccessor() {
  }

  public MethodAccessor(Method method, ExecutableStatement[] parms) {
    setMethod(method);
    this.parms = parms;
  }

  public Object setValue(Object ctx, Object elCtx, VariableResolverFactory variableFactory, Object value) {
    try {
      return nextNode.setValue(method.invoke(ctx, executeAll(elCtx, variableFactory, method)), elCtx, variableFactory, value);
    }
    catch (IllegalArgumentException e) {
      if (ctx != null && method.getDeclaringClass() != ctx.getClass()) {
        Method o = getBestCandidate(parameterTypes, method.getName(), ctx.getClass(), ctx.getClass().getMethods(), true);
        if (o != null) {
          return nextNode.setValue(executeOverrideTarget(o, ctx, elCtx, variableFactory), elCtx, variableFactory, value);
        }
      }

      coercionNeeded = true;
      return setValue(ctx, elCtx, variableFactory, value);
    }
    catch (Exception e) {
      throw new RuntimeException("cannot invoke method", e);
    }
  }

  public Class getKnownEgressType() {
    return method.getReturnType();
  }
}