import java.util.Collections;
import java.util.Vector;
import java.util.stream.Collectors;

/**
 * The class represent the type of each parameters and function return value.
 */
public class VariableType {
	/**
	 * The base type of this variable removing all ending stars (remove all pointer
	 * levels) Each item in this a part of namespace and the last one must be the
	 * type itself (without any namespace restriction). If no namespace restriction
	 * for this type, this Vector will only have one item.
	 * <p>
	 * For end user, it is enough that knowing the last item is type itself.
	 */
	private Vector<String> mBaseType;
	/**
	 * The pointer level of this type. It is equal to the count of trailing star of
	 * this field in C style representation.
	 */
	private int mPointerLevel;

	/**
	 * Construct an empty varible type. This is commonly used constructor.
	 */
	public VariableType() {
		mBaseType = new Vector<String>();
		mPointerLevel = 0;
	}

	/**
	 * The constructor used for cloning self. This constructor is only can be used
	 * by self.
	 * 
	 * @param base_type     The hierarchy of the variable type.
	 * @param pointer_level The pointer level of new created variable type.
	 */
	private VariableType(Vector<String> base_type, int pointer_level) {
		mBaseType = (Vector<String>) base_type.clone();
		mPointerLevel = pointer_level;
	}

	/**
	 * Set this variable type with a type string in C/C++ style. For example
	 * "NSTest::NSTest2::MyType**".
	 * 
	 * @param ctype The type string in C/C++ style.
	 */
	public void fromCType(String ctype) {
		if (ctype.isEmpty())
			throw new IllegalArgumentException("empty string can not be parsed.");

		// get pointer part and name part
		int len = ctype.length();
		int star_pos = ctype.indexOf('*');
		String namepart;
		if (star_pos == -1) {
			// no star
			namepart = ctype;
			mPointerLevel = 0;
		} else {
			// has star
			if (star_pos == 0)
				throw new IllegalArgumentException("base type not found.");
			namepart = ctype.substring(0, star_pos);
			mPointerLevel = len - star_pos;
		}

		// resolve name part
		mBaseType.clear();
		for (String item : namepart.split("::")) {
			mBaseType.add(item);
		}
	}

	/**
	 * Build a type string represented by this variable type in C/C++ style.
	 * 
	 * @return The type string in C/C++ style.
	 */
	public String toCType() {
		return mBaseType.stream().collect(Collectors.joining("::"))
				+ String.join("", Collections.nCopies(mPointerLevel, "*"));
	}

	/**
	 * Get the base type of this variable type without any namespace. It just simply
	 * get the last entry in type hierarchy.
	 * 
	 * @return The base type string without namespace prefix.
	 */
	public String getBaseType() {
		return mBaseType.lastElement();
	}

	/**
	 * Check whether this variable type is a pointer. This function just check
	 * whether the pointer level of this variavle type is zero.
	 * 
	 * @return True if it is pointer, otherwise false.
	 */
	public boolean isPointer() {
		return mPointerLevel != 0;
	}

	/**
	 * Return the pointer level of this variable type. You can simply assume the
	 * pointer level is equal to the count of trailing star.
	 * 
	 * @return The pointer level integer. Zero means that this type is not a
	 *         pointer.
	 */
	public int getPointerLevel() {
		return mPointerLevel;
	}

	/**
	 * Return the clone of the type hierarchy of this variable type.
	 * <p>
	 * It is rarely used. This only should be used when you need the namespace
	 * hierarchy of this variable type.
	 * 
	 * @return The clone of current variable type hierarchy.
	 */
	public Vector<String> getBaseTypeHierarchy() {
		return (Vector<String>) mBaseType.clone();
	}

	/**
	 * Check whether this type is a valid one. It actually check whether type
	 * hierarchy include at least one entry.
	 * 
	 * @return True if no problem of this type, otherwise false.
	 */
	public boolean isValid() {
		return mBaseType.size() != 0;
	}

	/**
	 * Return a new created variable type which is the pointer of this variable
	 * type.
	 * <p>
	 * In internal implementation, it just create a clone of current variable type
	 * with the increase of pointer level by 1.
	 * 
	 * @return The new created pointer type of this variable type.
	 */
	public VariableType getPointerOfThis() {
		return new VariableType(mBaseType, mPointerLevel + 1);
	}

}