/*
 * 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.el.mvel.datatype;

import org.mule.mvel2.ast.ASTNode;
import org.mule.mvel2.ast.AssignmentNode;
import org.mule.mvel2.ast.DeepAssignmentNode;
import org.mule.mvel2.compiler.AccessorNode;
import org.mule.mvel2.compiler.CompiledAccExpression;
import org.mule.mvel2.compiler.ExecutableLiteral;
import org.mule.mvel2.optimizers.impl.refl.nodes.MapAccessor;
import org.mule.mvel2.optimizers.impl.refl.nodes.MapAccessorNest;
import org.mule.mvel2.optimizers.impl.refl.nodes.VariableAccessor;
import org.mule.runtime.api.metadata.TypedValue;
import org.mule.runtime.core.api.Event;

import java.lang.reflect.Field;

/**
 * Base class {@link EnricherDataTypePropagator} that propagate data type to message properties.
 */
public abstract class AbstractVariableEnricherDataTypePropagator extends AbstractEnricherDataTypePropagator {

  private final String propertyName;
  private final Field accExprFieldForMapSyntax;
  private final Field accExprFieldForDotSyntax;

  public AbstractVariableEnricherDataTypePropagator(String propertyName) {
    this.propertyName = propertyName;
    try {
      // Needs to use reflection to access parsing information not available on the available interfaces
      accExprFieldForMapSyntax = AssignmentNode.class.getDeclaredField("accExpr");
      accExprFieldForMapSyntax.setAccessible(true);

      accExprFieldForDotSyntax = DeepAssignmentNode.class.getDeclaredField("acc");
      accExprFieldForDotSyntax.setAccessible(true);
    } catch (NoSuchFieldException e) {
      throw new IllegalStateException(e);
    }
  }

  @Override
  protected boolean doPropagate(Event event, Event.Builder builder, TypedValue typedValue, ASTNode node) {
    if (isAssignmentNode(node)) {
      CompiledAccExpression compiledAccExpression = getCompiledAccExpression(node);

      if (compiledAccExpression.getAccessor() instanceof VariableAccessor) {
        VariableAccessor variableAccessor = (VariableAccessor) compiledAccExpression.getAccessor();
        if (variableAccessor.getProperty().equals(propertyName)) {
          final AccessorNode nextNode = variableAccessor.getNextNode();

          if (nextNode.getNextNode() == null) {
            String propertyName = null;
            if (nextNode instanceof MapAccessorNest) {
              final MapAccessorNest mapAccesorNest = (MapAccessorNest) nextNode;
              if (mapAccesorNest.getProperty().isLiteralOnly()) {
                propertyName = (String) ((ExecutableLiteral) mapAccesorNest.getProperty()).getLiteral();
              }
            } else if (nextNode instanceof MapAccessor) {
              propertyName = (String) ((MapAccessor) nextNode).getProperty();
            }

            if (propertyName != null && containsVariable(event, propertyName)) {
              propertyName = getUnescapedPropertyName(propertyName);
              addVariable(event, builder, typedValue, propertyName);
              return true;
            }
          }
        }
      }
    }

    return false;
  }

  protected abstract void addVariable(Event event, Event.Builder builder, TypedValue typedValue, String propertyName);

  protected abstract boolean containsVariable(Event event, String propertyName);

  private String getUnescapedPropertyName(String propertyName) {
    if (propertyName.startsWith("'") && propertyName.endsWith("'")) {
      propertyName = propertyName.substring(1, propertyName.length() - 1);
    }

    return propertyName;
  }

  private boolean isAssignmentNode(ASTNode node) {
    return node instanceof AssignmentNode && ((AssignmentNode) node).getAssignmentVar().startsWith(propertyName)
        || node instanceof DeepAssignmentNode && ((DeepAssignmentNode) node).getAssignmentVar().startsWith(propertyName);
  }

  private CompiledAccExpression getCompiledAccExpression(ASTNode node) {
    try {
      if (node instanceof AssignmentNode) {
        return (CompiledAccExpression) accExprFieldForMapSyntax.get(node);
      } else {
        return (CompiledAccExpression) accExprFieldForDotSyntax.get(node);
      }
    } catch (IllegalAccessException e) {
      throw new IllegalStateException(e);
    }
  }

}