package dk.itu.kasper.Macros;

import java.lang.reflect.*;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.io.Reader;
import java.io.StringReader;
import java.io.IOException;

public class MacroExpander {
	private MacroExpander nextExpander=null;

	public MacroExpander(){
		nextExpander = null;
	}

	public MacroExpander(MacroExpander next){
		nextExpander = next;
	}

	public String undefined(String name, String[] args){
		if ( nextExpander != null )
			return nextExpander.expand( name, args );
		return "*** " + name + " could not be expanded ***";
	}

	public void process(String input, PrintStream out){
		process( new StringReader( input ), out );
	}

	public void process(Reader input, PrintStream out){
		try{
			MacroProcessor mp = new MacroProcessor( input , out );
			mp.setExpander( this );
			mp.process();
		}catch(IOException e){
			out.print( "***MacroProcessing Failed***" );
		}
	}

	protected String process(String s){
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		PrintStream ps = new PrintStream( out );
		this.process( s, ps );
		return out.toString();
	}

	String expand(String name, String[] args){
		final Class[] argTypes = new Class[]{String[].class};
		String expansion;
		try{
			Method m = this.getClass().getMethod( name , argTypes );
			expansion = (String)m.invoke( this , new Object[]{args} );
		}catch(NoSuchMethodException no){
			expansion = undefined( name, args );
		}catch(InvocationTargetException in){
			expansion = "'" + name + " invocation error: " + in.getCause() + "'";
		}catch(Exception e){
			expansion = "Macro "+ name + " failed'"+e+"'";
		}
		return expansion;

	}

}