package org.geogebra.common.kernel.geos;

import org.geogebra.common.kernel.kernelND.GeoElementND;
import org.geogebra.common.util.CopyPaste;
import org.geogebra.common.util.StringUtil;

/**
 * Library class for labeling geos; label-related static methods should go there
 */
public class LabelManager {

	/**
	 * Checks whether name can be used as label
	 * 
	 * @param geo
	 *            geo to be checked
	 * @param nameToCheck
	 *            potential label
	 * @return true for valid labels
	 */
	public static boolean checkName(GeoElementND geo, String nameToCheck) {
		String name = nameToCheck;
		if (name == null) {
			return true;
		}

		if (name.startsWith(CopyPaste.labelPrefix)) {
			return false;
		}

		name = StringUtil.toLowerCase(name);
		if (geo.isGeoFunction()) {
			if (geo.getKernel().getApplication().getParserFunctions()
					.isReserved(name)) {
				return false;
			}
		}

		return true;
	}

	/**
	 * @param var
	 *            variable name (for CAS cell)
	 * @return whether position(s) od $ are valid in this name
	 */
	public static boolean validVar(String var) {
		// check for invalid assignment variables like $, $$, $1, $2, ...,
		// $1$, $2$, ... which are dynamic references
		if (var.charAt(0) == GeoCasCell.ROW_REFERENCE_DYNAMIC) {
			boolean validVar = false;
			// if var.length() == 1 we have "$" and the for-loop won't be
			// entered
			for (int i = 1; i < var.length(); i++) {
				if (!Character.isDigit(var.charAt(i))) {
					if (i == 1 && var
							.charAt(1) == GeoCasCell.ROW_REFERENCE_DYNAMIC) {
						// "$$" so far, so it can be valid (if var.length >
						// 2) or invalid if "$$" is the whole var
					} else if (i == var.length() - 1 && var.charAt(var.length()
							- 1) == GeoCasCell.ROW_REFERENCE_DYNAMIC) {
						// "$dd...dd$" where all d are digits -> invalid
					} else {
						// "$xx..xx" where not all x are numbers and the
						// first x is not a '$' (there can only be one x)
						validVar = true;
						break;
					}
				}
			}
			return validVar;
		}
		return true;
	}
}