/*
    * Copyright 2002-2014 the original author or authors.
    *
    * 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.springframework.expression.spel.ast;
  
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  import org.springframework.expression.EvaluationException;
  import org.springframework.expression.TypedValue;
  import org.springframework.expression.spel.ExpressionState;
  import org.springframework.expression.spel.SpelNode;
  
  /**
   * Represent a map in an expression, e.g. '{name:'foo',age:12}'
   *
   * @author Andy Clement
   * @since 4.1
   */
  public class InlineMap extends SpelNodeImpl {
  
  	// If the map is purely literals, it is a constant value and can be computed and cached
  	private TypedValue constant = null;
  
  
  	public InlineMap(int pos, SpelNodeImpl... args) {
  		super(pos, args);
  		checkIfConstant();
  	}
  
  
  	/**
  	 * If all the components of the list are constants, or lists/maps that themselves
  	 * contain constants, then a constant list can be built to represent this node.
  	 * This will speed up later getValue calls and reduce the amount of garbage created.
  	 */
  	private void checkIfConstant() {
  		boolean isConstant = true;
  		for (int c = 0, max = getChildCount(); c < max; c++) {
  			SpelNode child = getChild(c);
  			if (!(child instanceof Literal)) {
  				if (child instanceof InlineList) {
  					InlineList inlineList = (InlineList) child;
  					if (!inlineList.isConstant()) {
  						isConstant = false;
  						break;
  					}
  				}
  				else if (child instanceof InlineMap) {
  					InlineMap inlineMap = (InlineMap) child;
  					if (!inlineMap.isConstant()) {
  						isConstant = false;
  						break;
  					}
  				}
  				else if (!((c%2)==0 && (child instanceof PropertyOrFieldReference))) {					
  					isConstant = false;
  					break;
  				}
  			}
  		}
  		if (isConstant) {
  			Map<Object,Object> constantMap = new LinkedHashMap<Object,Object>();			
  			int childCount = getChildCount();
  			for (int c = 0; c < childCount; c++) {
  				SpelNode keyChild = getChild(c++);
  				SpelNode valueChild = getChild(c);
  				Object key = null;
  				Object value = null;
  				if (keyChild instanceof Literal) {
  					key = ((Literal) keyChild).getLiteralValue().getValue();
  				}
  				else if (keyChild instanceof PropertyOrFieldReference) {
  					key = ((PropertyOrFieldReference) keyChild).getName();
  				}
  				else {
  					return;
  				}
  				if (valueChild instanceof Literal) {
  					value = ((Literal) valueChild).getLiteralValue().getValue();
  				}
  				else if (valueChild instanceof InlineList) {
  					value = ((InlineList) valueChild).getConstantValue();
  				}
  				else if (valueChild instanceof InlineMap) {
 					value = ((InlineMap) valueChild).getConstantValue();
 				}
 				constantMap.put(key, value);
 			}
 			this.constant = new TypedValue(Collections.unmodifiableMap(constantMap));
 		}
 	}
 
 	@Override
 	public TypedValue getValueInternal(ExpressionState expressionState) throws EvaluationException {
 		if (this.constant != null) {
 			return this.constant;
 		}
 		else {
 			Map<Object, Object> returnValue = new LinkedHashMap<Object, Object>();
 			int childcount = getChildCount();
 			for (int c = 0; c < childcount; c++) {
 				// TODO allow for key being PropertyOrFieldReference like Indexer on maps
 				SpelNode keyChild = getChild(c++);
 				Object key = null;
 				if (keyChild instanceof PropertyOrFieldReference) {
 					PropertyOrFieldReference reference = (PropertyOrFieldReference) keyChild;
 					key = reference.getName();
 				}
 				else {
 					key = keyChild.getValue(expressionState);
 				}
 				Object value = getChild(c).getValue(expressionState);
 				returnValue.put(key,  value);
 			}
 			return new TypedValue(returnValue);
 		}
 	}
 
 	@Override
 	public String toStringAST() {
 		StringBuilder sb = new StringBuilder("{");
 		int count = getChildCount();
 		for (int c = 0; c < count; c++) {
 			if (c > 0) {
 				sb.append(",");
 			}
 			sb.append(getChild(c++).toStringAST());
 			sb.append(":");
 			sb.append(getChild(c).toStringAST());
 		}
 		sb.append("}");
 		return sb.toString();
 	}
 
 	/**
 	 * @return whether this list is a constant value
 	 */
 	public boolean isConstant() {
 		return this.constant != null;
 	}
 
 	@SuppressWarnings("unchecked")
 	public Map<Object,Object> getConstantValue() {
 		return (Map<Object,Object>) this.constant.getValue();
 	}
 
 }