/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.ode.bpel.runtime;

import java.net.URI;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ode.bpel.common.FaultException;
import org.apache.ode.bpel.evt.ScopeEvent;
import org.apache.ode.bpel.evt.VariableReadEvent;
import org.apache.ode.bpel.explang.EvaluationContext;
import org.apache.ode.bpel.o.OConstantVarType;
import org.apache.ode.bpel.o.OExpression;
import org.apache.ode.bpel.o.OLink;
import org.apache.ode.bpel.o.OMessageVarType;
import org.apache.ode.bpel.o.OProcess;
import org.apache.ode.bpel.o.OScope;
import org.apache.ode.bpel.o.OMessageVarType.Part;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * The context in which BPEL expressions are evaluated. This class is handed of
 * the {@link org.apache.ode.bpel.o.OExpression} instances to provide access to
 * variables, link statuses, and the like.
 */
public class ExprEvaluationContextImpl implements EvaluationContext {
	private static final Log __log = LogFactory
			.getLog(ExprEvaluationContextImpl.class);

	private BpelRuntimeContext _native;

	private ScopeFrame _scopeInstance;

	private Map<OLink, Boolean> _linkVals;

	private Node _root;

	public ExprEvaluationContextImpl(ScopeFrame scopeInstace,
			BpelRuntimeContext ntv) {
		_native = ntv;
		_scopeInstance = scopeInstace;
	}

	public ExprEvaluationContextImpl(ScopeFrame scopeInstace,
			BpelRuntimeContext ntv, Node root) {
		this(scopeInstace, ntv);
		_root = root;
	}

	public ExprEvaluationContextImpl(ScopeFrame scopeInstnce,
			BpelRuntimeContext ntv, Map<OLink, Boolean> linkVals) {
		this(scopeInstnce, ntv);
		_linkVals = linkVals;
	}

	public Node readVariable(OScope.Variable variable, OMessageVarType.Part part)
			throws FaultException {
		if (__log.isTraceEnabled())
			__log.trace("readVariable(" + variable + "," + part + ")");

		// TODO: check for null _scopeInstance

		Node ret;
		if (variable.type instanceof OConstantVarType) {
			ret = ((OConstantVarType) variable.type).getValue();
		} else {
			VariableInstance varInstance = _scopeInstance.resolve(variable);
			if (varInstance == null)
				return null;
			VariableReadEvent vre = new VariableReadEvent();
			vre.setVarName(varInstance.declaration.name);
			sendEvent(vre);
			ret = _scopeInstance.fetchVariableData(_native,varInstance, part, false);
		}
		return ret;
	}

	public Node evaluateQuery(Node root, OExpression expr)
			throws FaultException {
		try {
			return _native.getExpLangRuntime()
					.evaluateNode(
							expr,
							new ExprEvaluationContextImpl(_scopeInstance,
									_native, root));
		} catch (org.apache.ode.bpel.explang.EvaluationException e) {
			throw new InvalidProcessException("Expression Failed: " + expr, e);
		}
	}

	public String readMessageProperty(OScope.Variable variable,
			OProcess.OProperty property) throws FaultException {
		VariableInstance varInstance = _scopeInstance.resolve(variable);
		return _native.readProperty(varInstance, property);
	}

	public boolean isLinkActive(OLink olink) throws FaultException {
		return _linkVals.get(olink);
	}

	public String toString() {
		return "{ExprEvaluationContextImpl scopeInstance=" + _scopeInstance
				+ ", activeLinks=" + _linkVals + "}";
	}

	public Node getRootNode() {
		return _root;
	}

	public Node getPartData(Element message, Part part) throws FaultException {
		return _scopeInstance.getPartData(message, part);
	}

	public Long getProcessId() {
		return _native.getPid();
	}

	public boolean narrowTypes() {
		return true;
	}

	private void sendEvent(ScopeEvent se) {
		_scopeInstance.fillEventInfo(se);
		_native.sendEvent(se);
	}

	public URI getBaseResourceURI() {
		return _native.getBaseResourceURI();
	}

}