import java.io.*;
import java.util.*;

public class Explain {

  private final Map<String,Handler> exts2handlers = new HashMap<String,Handler>();

  Explain() {
    use(MP3Handler.class); 
    use(ImageHandler.class);
  }

  private void use(Class<? extends Handler> cls) {
    Handler h = null;
    try {
      h = cls.newInstance();
    } catch (InstantiationException e) {
      Util.getInstance().handle("Couldn't create handler for class " + cls,e);
      return;
    } catch (IllegalAccessException e) {
      Util.getInstance().handle("Couldn't create handler for class " + cls,e);
      return;
    }
    for (String ext : h.extensions()) {
      exts2handlers.put(ext.toLowerCase(),h);
    }
  }

  private Handler get(File f) {
    String path = f.getAbsolutePath();
    String ext = Util.getInstance().getExtension(f);
    Handler h = exts2handlers.get(ext);
    return h == null ? TextHandler.getInstance() : h;
  }

  // --------------------------------------------------
  // Main
  // --------------------------------------------------

  public static void main(String[] args) {
    new Explain().realMain(args);
  }

  public void realMain(String[] args) {
    if (args.length == 0) {
      System.out.println("I support the following formats:");
      Set<Class> seen = new HashSet<Class>();
      for (Handler h : exts2handlers.values()) {
        Class cls = h.getClass();
        if (seen.contains(cls)) continue;
        seen.add(cls);
        System.out.println(" - " + h.extensions() + ": " + h.description());
      }
      System.out.println("Everything else is handled as text");
      return;
    }
    for (String infile : args) explain(infile);
  }

  private void explain(String infile) {
    File f = new File(infile);
    Handler h = null;
    try {
      h = get(f);
    } catch (IllegalArgumentException e) {
      Util.getInstance().log("Trouble creating handler for " + f);
      return;
    }
    Map<String,String> hash = h.explain(f);
    System.out.println();
    for (String key : h.keys()) {
      String val = hash.get(key);
      System.out.printf("%-30s: %s\n", key, val);
    }
  }
  
}