/*
 * I expand macros on the form #name[arg1][arg2][arg]
 * where # can be any fixec char and [ ] can be changed
 * to any set of chars.
 * to get the char #, write ##
 * The name is a sequence of java.lang.Character.isLetterOrDogit
 * The left delimiter of the arguments must be a non-letter or digit.
 * It is permittable to have java.lang.Character.isWhitespace between the name
 * and arguments, as well as between args.
 */
package dk.itu.kasper.Macros;

import java.io.Reader;
import java.io.StringReader;
import java.io.PrintStream;
import java.io.IOException;

import java.util.List;
import java.util.ArrayList;

import java.lang.reflect.Method;

public class MacroProcessor {
	public final char macroChar = '#';
	public final char leftChar = '[';
	public final char rightChar = ']';



	private ReadIterator in;
	private PrintStream out;
	private MacroExpander expander;

	public MacroProcessor( Reader r , PrintStream p){
		in = new ReadIterator( r );
		out = p;
	}

	public MacroProcessor( String s, PrintStream p){
		this( new StringReader( s ) , p);
	}

	public MacroProcessor( String s ){
		this( s, System.out );
	}

	public void setExpander(MacroExpander m){
		expander = m;
	}

	public void process() throws IOException{
		while ( in.hasMore() )
			// current has not yet been written
			if ( in.current() != macroChar )
				out.print( in.next() );
			else{
				in.next(); // skip macroChar
				if ( in.hasMore() && (in.current() != macroChar ) )
					processMacro();
				else{
					in.next(); // skip macroChar
					out.print(macroChar);
				}
			}
		out.close();
	}

	private void processMacro(){
		String macroName = getName();
		List<String> args = getArgs();
		out.print(
			expandMacro( macroName, args.subList(0,args.size()-1) ) );
		out.print( args.get( args.size()-1 ) );
	}

	private String getName(){
		StringBuffer sb = new StringBuffer();
		while( in.hasMore() && Character.isLetterOrDigit( in.current() ) )
			sb.append( in.next() );
		return sb.toString();
	}

	private List<String> getArgs(){
		// Last argument is always whitespace following the arguments
		List<String> ls = new ArrayList<String>();
		String whiteSpace = skipWhiteSpace();
		while ( in.hasMore() && in.current() == leftChar ){
			in.next();
			ls.add( getArg() );
			whiteSpace = skipWhiteSpace();
		};
		ls.add( whiteSpace );
		return ls;
	}

	private String getArg(){
		StringBuffer sb = new StringBuffer();
		int level = 1;
		while (in.hasMore() && level > 0 ) {
			if ( in.current() == rightChar )
				level--;
			else if ( in.current() == leftChar )
				level++;
			if (level > 0)
				sb.append( in.current() );
			in.next();
		}
		return sb.toString();
	}

	private String skipWhiteSpace(){
		StringBuffer whiteSpace = new StringBuffer();
		while (in.hasMore() && Character.isWhitespace( in.current() ) )
			whiteSpace.append( in.next() );
		if ( in.hasMore() && in.current() != leftChar )
			return whiteSpace.toString();
		else
			return "";
	}

	public String expandMacro(String name, List<String> args){
		String[] sa = new String[ args.size() ];
		sa = args.toArray( sa );
		return expander.expand(name, sa );
	}

}