package org.simantics.scl.compiler.module;

public class ModuleUtils {
    public static String resolveAbsolutePath(String moduleName, String relativeModuleName) throws InvalidModulePathException {
        if (relativeModuleName.startsWith(".")) {
	    	String originalRelativeModuleName = relativeModuleName;
	        int p = moduleName.lastIndexOf('/');
	        String parentPackage = p < 0 ? "" : moduleName.substring(0, p);
	        while(relativeModuleName.startsWith(".")) {
	            if(relativeModuleName.startsWith("./")) {
	                relativeModuleName = relativeModuleName.substring(2);
	            }
	            else if(relativeModuleName.startsWith("../")) {
	                relativeModuleName = relativeModuleName.substring(3);
	                if(parentPackage.isEmpty()) {
	                    throw new InvalidModulePathException("Couldn't resolve the relative module name " + originalRelativeModuleName + " when the current module name is " + moduleName + ".");
	                }
	                p = parentPackage.lastIndexOf('/');
	                parentPackage = p < 0 ? "" : parentPackage.substring(0, p);
	            }
	            else {
	                throw new InvalidModulePathException("Couldn't resolve the relative module name " + originalRelativeModuleName + ". It has an invalid syntax.");
	            }
	        }
	        return parentPackage + "/" + relativeModuleName;
        } else {
        	return relativeModuleName;
        }
    }
}