package soot.jimple.infoflow.util;

import soot.ArrayType;
import soot.BooleanType;
import soot.ByteType;
import soot.CharType;
import soot.DoubleType;
import soot.FloatType;
import soot.IntType;
import soot.LongType;
import soot.PrimType;
import soot.RefType;
import soot.Scene;
import soot.ShortType;
import soot.SootClass;
import soot.Type;
import soot.jimple.infoflow.InfoflowManager;
import soot.jimple.infoflow.data.AccessPath;

/**
 * Class containing various utility methods for dealing with type information
 * 
 * @author Steven Arzt
 *
 */
public class TypeUtils {

	private final InfoflowManager manager;

	public TypeUtils(InfoflowManager manager) {
		this.manager = manager;
	}

	/**
	 * Checks whether the given type is a string
	 * 
	 * @param tp
	 *            The type of check
	 * @return True if the given type is a string, otherwise false
	 */
	public static boolean isStringType(Type tp) {
		if (!(tp instanceof RefType))
			return false;
		RefType refType = (RefType) tp;
		return refType.getClassName().equals("java.lang.String");
	}

	/**
	 * Checks whether the given type is java.lang.Object, java.io.Serializable, or
	 * java.lang.Cloneable.
	 * 
	 * @param tp
	 *            The type to check
	 * @return True if the given type is one of the three "object-like" types,
	 *         otherwise false
	 */
	public static boolean isObjectLikeType(Type tp) {
		if (!(tp instanceof RefType))
			return false;

		RefType rt = (RefType) tp;
		return rt.equals(Scene.v().getObjectType()) || rt.getSootClass().getName().equals("java.io.Serializable")
				|| rt.getSootClass().getName().equals("java.lang.Cloneable");
	}

	/**
	 * Checks whether the given source type can be cast to the given destination
	 * type
	 * 
	 * @param destType
	 *            The destination type to which to cast
	 * @param sourceType
	 *            The source type from which to cast
	 * @return True if the given types are cast-compatible, otherwise false
	 */
	public boolean checkCast(Type destType, Type sourceType) {
		if (!manager.getConfig().getEnableTypeChecking())
			return true;

		// If we don't have a source type, we generally allow the cast
		if (sourceType == null)
			return true;

		// If both types are equal, we allow the cast
		if (sourceType == destType)
			return true;

		// If we have a reference type, we use the Soot hierarchy
		if (manager.getHierarchy().canStoreType(destType, sourceType) // cast-up,
																		// i.e.
																		// Object
																		// to
																		// String
				|| manager.getHierarchy().canStoreType(sourceType, destType)) // cast-down,
																				// i.e.
																				// String
																				// to
																				// Object
			return true;

		// If both types are primitive, they can be cast unless a boolean type
		// is involved
		if (destType instanceof PrimType && sourceType instanceof PrimType)
			if (destType != BooleanType.v() && sourceType != BooleanType.v())
				return true;

		return false;
	}

	/**
	 * Checks whether the type of the given taint can be cast to the given target
	 * type
	 * 
	 * @param accessPath
	 *            The access path of the taint to be cast
	 * @param type
	 *            The target type to which to cast the taint
	 * @return True if the cast is possible, otherwise false
	 */
	public boolean checkCast(AccessPath accessPath, Type type) {
		if (!manager.getConfig().getEnableTypeChecking())
			return true;

		int fieldStartIdx = 0;
		if (accessPath.isStaticFieldRef()) {
			if (!checkCast(type, accessPath.getFirstFieldType()))
				return false;

			// If the target type is a primitive array, we cannot have any
			// subsequent field
			if (isPrimitiveArray(type))
				if (accessPath.getFieldCount() > 1)
					return false;
			fieldStartIdx = 1;
		} else {
			if (!checkCast(type, accessPath.getBaseType()))
				return false;
			// If the target type is a primitive array, we cannot have any
			if (isPrimitiveArray(type))
				// subsequent fields
				if (!accessPath.isLocal())
					return false;
		}

		// The next field's base type must also be cast-compatible to the new
		// base type
		if (accessPath.isFieldRef() && accessPath.getFieldCount() > fieldStartIdx)
			if (!checkCast(type, accessPath.getFields()[fieldStartIdx].getDeclaringClass().getType()))
				return false;

		// No type problems found
		return true;
	}

	public static boolean isPrimitiveArray(Type type) {
		if (type instanceof ArrayType) {
			ArrayType at = (ArrayType) type;
			if (at.getArrayElementType() instanceof PrimType)
				return true;
		}
		return false;
	}

	public boolean hasCompatibleTypesForCall(AccessPath apBase, SootClass dest) {
		if (!manager.getConfig().getEnableTypeChecking())
			return true;

		// Cannot invoke a method on a primitive type
		if (apBase.getBaseType() instanceof PrimType)
			return false;
		// Cannot invoke a method on an array
		if (apBase.getBaseType() instanceof ArrayType)
			return dest.getName().equals("java.lang.Object");

		return checkCast(apBase, dest.getType());
	}

	/**
	 * Gets the more precise one of the two given types. If there is no ordering
	 * (i.e., the two types are not cast-compatible) null is returned.
	 * 
	 * @param tp1
	 *            The first type
	 * @param tp2
	 *            The second type
	 * @return The more precise one of the two given types
	 */
	public static Type getMorePreciseType(Type tp1, Type tp2) {
		if (tp1 == null)
			return tp2;
		else if (tp2 == null)
			return tp1;
		else if (tp1 == tp2)
			return tp1;
		else if (TypeUtils.isObjectLikeType(tp1))
			return tp2;
		else if (TypeUtils.isObjectLikeType(tp2))
			return tp1;
		else if (tp1 instanceof PrimType && tp2 instanceof PrimType)
			return tp1; // arbitrary choice
		else if (Scene.v().getFastHierarchy().canStoreType(tp2, tp1))
			return tp2;
		else if (Scene.v().getFastHierarchy().canStoreType(tp1, tp2))
			return tp1;
		else {
			// If one type is an array type and the other one is the base type,
			// we still accept the cast
			if (tp1 instanceof ArrayType && tp2 instanceof ArrayType) {
				ArrayType at1 = (ArrayType) tp1;
				ArrayType at2 = (ArrayType) tp2;
				assert at1.numDimensions == at2.numDimensions;
				Type preciseType = getMorePreciseType(at1.getElementType(), at2.getElementType());
				if (preciseType == null)
					return null;

				return ArrayType.v(preciseType, at1.numDimensions);
			} else if (tp1 instanceof ArrayType) {
				ArrayType at = (ArrayType) tp1;
				return getMorePreciseType(at.getElementType(), tp2);
			} else if (tp2 instanceof ArrayType) {
				ArrayType at = (ArrayType) tp2;
				return getMorePreciseType(tp1, at.getElementType());
			}
		}
		return null;
	}

	/**
	 * Gets the more precise one of the two given types
	 * 
	 * @param tp1
	 *            The first type
	 * @param tp2
	 *            The second type
	 * @return The more precise one of the two given types
	 */
	public static String getMorePreciseType(String tp1, String tp2) {
		Type newType = getMorePreciseType(getTypeFromString(tp1), getTypeFromString(tp2));
		return newType == null ? null : "" + newType;
	}

	/**
	 * Creates a Soot Type from the given string
	 * 
	 * @param type
	 *            A string representing a Soot type
	 * @return The Soot Type corresponding to the given string
	 */
	public static Type getTypeFromString(String type) {
		if (type == null || type.isEmpty())
			return null;

		// Reduce arrays
		int numDimensions = 0;
		while (type.endsWith("[]")) {
			numDimensions++;
			type = type.substring(0, type.length() - 2);
		}

		// Generate the target type
		final Type t;
		if (type.equals("int"))
			t = IntType.v();
		else if (type.equals("long"))
			t = LongType.v();
		else if (type.equals("float"))
			t = FloatType.v();
		else if (type.equals("double"))
			t = DoubleType.v();
		else if (type.equals("boolean"))
			t = BooleanType.v();
		else if (type.equals("char"))
			t = CharType.v();
		else if (type.equals("short"))
			t = ShortType.v();
		else if (type.equals("byte"))
			t = ByteType.v();
		else {
			// Do not create types for stuff that isn't loaded in the current
			// scene, i.e., does not appear in the program under analysis
			if (Scene.v().containsClass(type))
				t = RefType.v(type);
			else
				return null;
		}

		if (numDimensions == 0)
			return t;
		return ArrayType.v(t, numDimensions);
	}

	/**
	 * Builds a new array of the given type if it is a base type or increments the
	 * dimensions of the given array by 1 otherwise.
	 * 
	 * @param type
	 *            The base type or incoming array
	 * @param arrayType
	 *            The declared type of the array
	 * @return The resulting array
	 */
	public static Type buildArrayOrAddDimension(Type type, Type arrayType) {
		// If the given element is a base type and the array has a more general
		// type, we must take the array type instead
		if (!(type instanceof ArrayType)) {
			return arrayType;
		}

		// If code takes a tainted array and recursively creates a higher-
		// dimensional one that receives the old array as an element, we end up
		// with an infinitely growing number of dimensions. We therefore kill
		// the type information if we get more dimensions.
		if (type instanceof ArrayType) {
			ArrayType array = (ArrayType) type;
			if (array.numDimensions >= 3)
				return null;
			return array.makeArrayType();
		} else
			return ArrayType.v(type, 1);
	}

}
