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/*
 * TokenResolver.java
 *
 * Created on April 20, 2007, 11:59 AM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package com.sun.enterprise.admin.servermgmt.launch;

import java.util.*;
import com.sun.enterprise.util.StringUtils;
import com.sun.enterprise.util.SystemPropertyConstants;
/**
 * Here is the contract:
 * You give me a Properties object.
 * Then you can call  resolve(List<String>) and/or resolve(String)
 * I will find and replace the tokens, e.g.,  ${foo} with the value of "foo" in the properties.
 * If the token has no such property -- then I leave the token as is.
 * It purposely does not handle nested tokens.  E.g. if the "foo" property has another
 * token embedded in the value -- it will not be further resolved.
 * This is the KISS principle in action...
 * @author bnevins
 */
class TokenResolver
{
    TokenResolver(Properties p)
    {
        props = p;
    }
    
    ///////////////////////////////////////////////////////////////////////////
    
    void resolve(List<String> list)
    {
        for(int i = 0; i < list.size(); i++)
        {
            String s = list.get(i);
            
            if(hasToken(s))
                list.set(i, resolve(s));
        }
    }
    
    ///////////////////////////////////////////////////////////////////////////

    String resolve(String s)
    {
        List<Token> tokens = getTokens(s);
        String resolved = s;
        
        for(Token token : tokens)
            resolved = StringUtils.replace(resolved, token.token, token.value);
        
        return resolved;
    }
    
    ///////////////////////////////////////////////////////////////////////////

    private List<Token> getTokens(String s)
    {
        int index = 0;        
        List<Token> tokens = new ArrayList<Token>();
     
        while(true)
        {
            Token token = getToken(s, index);
            
            if(token == null)
                break;
            
            tokens.add(token);
            index = token.start + Token.TOKEN_START.length();
        }

        return tokens;
    }
    
    ///////////////////////////////////////////////////////////////////////////

    private Token getToken(String s, int index)
    {
        if(s == null || index >= s.length())
            return null;
        
        Token token = new Token();
        token.start = s.indexOf(token.TOKEN_START, index);
        token.end   = s.indexOf(token.TOKEN_END, token.start + 2);
        
        if(token.end <= 0 || token.start < 0)
            return null;
        
        token.token = s.substring(token.start, token.end + 1);
        token.name = s.substring(token.start + Token.TOKEN_START.length(), token.end);
        
        // if the token exists, but it's value is null -- then set the value 
        // back to the token.

        token.value = props.getProperty(token.name, token.token);
        return token;
    }
    
    ///////////////////////////////////////////////////////////////////////////
    
    private static boolean hasToken(String s)
    {
        return s != null && s.indexOf(Token.TOKEN_START) >= 0;
    }
    
    ///////////////////////////////////////////////////////////////////////////
    
    private final Properties props;

    private static class Token
    {
        int                 start;
        int                 end;
        String              token;
        String              name;
        String              value;
        final static String TOKEN_START = SystemPropertyConstants.OPEN;
        final static String TOKEN_END = SystemPropertyConstants.CLOSE;
        public String toString()
        {
            return "name: " + name + ", token: " + token + ", value: " + value;
        }
    }
}