import java.io.IOException;
import java.io.FileReader;
import java.util.*;

import Dep.Absyn.Module;
import Dep.Absyn.Import;

public class Modules {

        /**
         *  Load the given modules and all their dependencies.
         */
        public static Map<String,Module> loadModules(String[] ms) throws IOException {
                Set<String> toLoad = new HashSet<String>(Arrays.<String>asList(ms));
                Map<String,Module> loaded = new HashMap<String,Module>();

                while (!toLoad.isEmpty()) {
                        String name = removeOne(toLoad);
                        String file = findModule(name);

                        System.err.println("Loading module " + name + " from " + file);

                        Module m = ParseModule.parse(new FileReader(file));
                        loaded.put(name, m);
                        for (Import i : m.listimport_) {
                                if (!loaded.containsKey(i.ident_))
                                        toLoad.add(i.ident_);
                        }
                }
                        
                return loaded;
        }

        private static String findModule(String name) {
                return name + ".dep";
        }

        private static <E> E removeOne(Iterable<E> xs) {
                Iterator<E> it = xs.iterator();
                E x = it.next();
                it.remove();
                return x;
        }

}