package org.simantics.scl.compiler.source.repository;

import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.junit.Test;
import org.simantics.scl.runtime.SCLContext;

public class ModuleBrowsingUtil {
    
    public static final String SCL_EXTENSION = ".scl";
    public static final int SCL_EXTENSION_LENGTH = SCL_EXTENSION.length();
    
    public static void collectModuleSourcesAt(Collection<String> result, URL url) throws IOException {
        String protocol = url.getProtocol();
        if("jar".equals(protocol)) {
            URLConnection connection = url.openConnection(); 
            if(!(connection instanceof JarURLConnection))
                throw new UnsupportedOperationException("Expected JarURLConnection when opening connection to " + url + ".");
            JarURLConnection jarConnection = (JarURLConnection)connection;
            collectModuleSourcesAt(result, jarConnection.getEntryName(), jarConnection.getJarFile());
        }
        else if("file".equals(protocol)) {
            File file = new File(url.getPath());
            if(!file.exists())
                throw new UnsupportedOperationException("File " + url + " not found.");
            collectModuleSourcesAt(result, file);
        }
        else if("bundleresource".equals(protocol)) {
            URLConnection connection = url.openConnection();
            Class<?> connectionClass = connection.getClass();
            // We don't want an explicit dependency to osgi, therefore using reflection
            if(!connectionClass.getSimpleName().equals("BundleURLConnection")) {
                throw new UnsupportedOperationException("Expected BundleURLConnection when opening connection to " + url + ".");
            }
            URL localURL;
            try {
                localURL = (URL) connectionClass.getMethod("getLocalURL").invoke(connection);
            } catch (Exception e) {
                throw new UnsupportedOperationException("Couldn't browse " + url + ".", e);
            }
            collectModuleSourcesAt(result, localURL);
        }
        else
            throw new UnsupportedOperationException("Protocol of " + url + " does not support directory browsing.");
    }       
    
    public static void collectModuleSourcesAt(Collection<String> result, File file) {
        for(File child : file.listFiles()) {
            String name = child.getName();
            if(child.isDirectory())
                collectModuleSourcesAt(result, name + "/", child);
            else
                if(name.endsWith(SCL_EXTENSION))
                    result.add(name.substring(0, name.length()-SCL_EXTENSION_LENGTH));
        }
    }
    
    private static void collectModuleSourcesAt(Collection<String> result, String prefix, File file) {
        for(File child : file.listFiles()) {
            String name = child.getName();
            if(child.isDirectory())
                collectModuleSourcesAt(result, prefix + name + "/", child);
            else
                if(name.endsWith(SCL_EXTENSION))
                    result.add(prefix + name.substring(0, name.length()-SCL_EXTENSION_LENGTH));
        }
    }
    
    private static void collectModuleSourcesAt(Collection<String> result, String entryName, JarFile jarFile) throws IOException {
        int entryNameLength = entryName.length();
        JarEntry entry;
        for(Enumeration<JarEntry> e = jarFile.entries();e.hasMoreElements()
                && (entry = e.nextElement()) != null;) {
            String name = entry.getName();
            if(name.startsWith(entryName) && name.endsWith(SCL_EXTENSION))
                result.add(name.substring(entryNameLength+1, name.length()-SCL_EXTENSION_LENGTH));
        }
    }
    
    @Test
    public void osgiTest() throws IOException {
        ArrayList<String> l = new ArrayList<String>();
        collectModuleSourcesAt(l, SCLContext.class.getResource("prelude"));
        System.out.println(l);
    }

    public static File toFile(URL url) {
        String protocol = url.getProtocol();
        if("file".equals(protocol)) {
            File file = new File(url.getPath());
            if(file.exists())
                return file;
        }
        return null;
    }
    
}