package java.lang.reflect;

public class Method<T> extends AccessibleObject implements Member {
  private byte vmFlags;
  private byte parameterCount;
  private short parameterFootprint;
  private short flags;
  private short offset;
  private byte[] name;
  private byte[] spec;
  private Class<T> class_;
  private Object code;

  private Method() { }

  public boolean isAccessible() {
    return (vmFlags & Accessible) != 0;
  }

  public void setAccessible(boolean v) {
    if (v) vmFlags |= Accessible; else vmFlags &= ~Accessible;
  }

  public static native Method getCaller();

  public Class<T> getDeclaringClass() {
    return class_;
  }

  public int getModifiers() {
    return flags;
  }

  public String getName() {
    return new String(name, 0, name.length - 1, false);
  }

  private static int next(char c, String s, int start) {
    for (int i = start; i < s.length(); ++i) {
      if (s.charAt(i) == c) return i;
    }
    throw new RuntimeException();
  }

  public Class[] getParameterTypes() {
    int count = parameterCount;
    if ((flags & Modifier.STATIC) == 0) {
      -- count;
    }

    Class[] types = new Class[count];
    int index = 0;

    String spec = new String(this.spec, 1, this.spec.length - 1, false);

    try {
      for (int i = 0; i < spec.length(); ++i) {
        char c = spec.charAt(i);
        if (c == ')') {
          break;
        } else if (c == 'L') {
          int start = i + 1;
          i = next(';', spec, start);
          String name = spec.substring(start, i);
          types[index++] = Class.forName(name);
        } else if (c == '[') {
          int start = i;
          while (spec.charAt(i) == '[') ++i;

          if (spec.charAt(i) == 'L') {
            i = next(';', spec, i + 1);
            String name = spec.substring(start, i);
            types[index++] = Class.forName(name);
          } else {
            String name = spec.substring(start, i + 1);
            types[index++] = Class.forCanonicalName(name);
          }
        } else {
          String name = spec.substring(i, i + 1);
          types[index++] = Class.forCanonicalName(name);
        }
      }
    } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
    }

    return types;
  }

  public Object invoke(Object instance, Object ... arguments)
    throws InvocationTargetException, IllegalAccessException
  {
    if ((flags & Modifier.STATIC) != 0) {
      if (arguments.length == parameterCount) {
        return invoke(this, instance, arguments);
      } else {
        throw new ArrayIndexOutOfBoundsException();
      }
    } else if (class_.isInstance(instance)) {
      if (arguments.length == parameterCount - 1) {
        return invoke(this, instance, arguments);        
      } else {
        throw new ArrayIndexOutOfBoundsException();
      }
    } else {
      throw new IllegalArgumentException();
    }
  }

  public static native Object invoke(Method method, Object instance,
                                     Object ... arguments)
    throws InvocationTargetException, IllegalAccessException;
}