/**
 *
 * Copyright (c) 2009-2012,
 *
 *  Galois, Inc. (Aaron Tomb <atomb@galois.com>, 
 *                Rogan Creswick <creswick@galois.com>, 
 *                Adam Foltzer <acfoltzer@galois.com>)
 *  Steve Suh    <suhsteve@gmail.com>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. The names of the contributors may not be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *
 */

package org.scandroid.flow.functions;

import java.util.List;
import java.util.Map;
import java.util.Set;

import org.scandroid.domain.CodeElement;
import org.scandroid.domain.DomainElement;
import org.scandroid.domain.IFDSTaintDomain;
import org.scandroid.domain.LocalElement;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.ibm.wala.dataflow.IFDS.IUnaryFlowFunction;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.util.intset.IntSet;
import com.ibm.wala.util.intset.MutableSparseIntSet;

/**
 * @author creswick
 * @author acfoltzer
 * 
 */
public class CallFlowFunction<E extends ISSABasicBlock> implements
		IUnaryFlowFunction {
	private static final Logger logger = LoggerFactory
			.getLogger(CallFlowFunction.class);

	/**
	 * A map from the code elements of actual parameters, to the set of code
	 * elements for formal parameters
	 */
	private final Map<CodeElement, Set<CodeElement>> paramArgsMap;

	private final IFDSTaintDomain<E> domain;

	public CallFlowFunction(IFDSTaintDomain<E> domain,
			List<CodeElement> actualParams) {
		this.domain = domain;

		final int numParams = actualParams.size();
		this.paramArgsMap = Maps.newHashMapWithExpectedSize(numParams);
		for (int i = 0; i < numParams; i++) {
			// add a mapping for each parameter
			final CodeElement actual = actualParams.get(i);
			if (!(actual instanceof LocalElement)) {
				logger.warn("non-local code element in actual params list");
			}
			final CodeElement formal = new LocalElement(i + 1); // +1 for SSA
			Set<CodeElement> existingFormals = paramArgsMap.get(actual);
			if (null == existingFormals) {
				existingFormals = Sets.newHashSetWithExpectedSize(numParams);
			}
			existingFormals.add(formal);
			paramArgsMap.put(actual, existingFormals);
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.ibm.wala.dataflow.IFDS.IUnaryFlowFunction#getTargets(int)
	 */
	@Override
	public IntSet getTargets(int d1) {
		if (0 == d1) {
			return TaintTransferFunctions.ZERO_SET;
		}
		DomainElement de = domain.getMappedObject(d1);
		MutableSparseIntSet set = MutableSparseIntSet.makeEmpty();

		/*
		 * We're in the situation of calling a function:
		 * 
		 * f(x, y, z)
		 * 
		 * And determining how taints flow from that call site to the entry of
		 * the function
		 * 
		 * ... f(X x, Y y, Z z) { ... }
		 * 
		 * Our goals are twofold: 1. Propagate taints from the actual parameter
		 * x to the formal parameter x 2. Exclude any other non-local
		 * information from propagating to callee
		 * 
		 * Since we're unioning the result of this with the
		 * GlobalIdentityFunction, we don't have to worry about 2 for this
		 * IntSet.
		 */

		final Set<CodeElement> formals = paramArgsMap.get(de.codeElement);
		if (null != formals) {
			for (CodeElement formal : formals) {
				set.add(domain.getMappedIndex(new DomainElement(formal,
						de.taintSource)));
			}
		}		
		return set;
	}
}
