package ie.dcu.plugin;

import ie.dcu.util.OsUtils;

import java.io.File;
import java.net.*;

public class PluginClassLoader extends URLClassLoader {

	private final File root;

	public PluginClassLoader(File root, URL[] urls, ClassLoader parent) {
		super(urls, parent);
		this.root = root;
	}

	@Override
	protected String findLibrary(String libname) {
		String path = findLibrary0(libname);
		System.out.println("findLibrary: " + libname + " => " + path);
		return path;
	}
	
	private String[] getPossibleLibraryNames(String libname) {
		if (OsUtils.isLinux64()) {
			return new String[] {
				libname, 
				System.mapLibraryName(libname + "64"),
				System.mapLibraryName(libname)
			};
		} else {
			return new String[] {
				libname, 
				System.mapLibraryName(libname)
			};
		}
	}
	
	private String findLibrary0(String libname) {
		String path;
		
		// Get a list of potential library names
		String[] libnames = getPossibleLibraryNames(libname);
		
		// Try plugin base folder
		if ((path = getPathIfExists(root, libnames)) != null) {
			return path;
		}
		
		// Try plugin lib/ subfolder
		File libFolder = new File(root, "lib");
		if (libFolder.isDirectory()) {
			if ((path = getPathIfExists(libFolder, libnames)) != null) {
				return path;
			}
		}
		
		// Pass off to the superclass
		return super.findLibrary(libname);
	}
	
	private String getPathIfExists(File root, String[] filenames) {
		for (String filename : filenames) {
			File file = new File(root, filename);
			if (file.isFile()) {
				return file.getAbsolutePath();
			}
		}
		return null;
	}
		
}