IcecastMetadata.java

/*
   Copyright 2014 John Selbie

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/


package com.selbie.wrek.metaproxy;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.HashMap;
import android.util.Log;

public class IcecastMetadata
{
    static final String TAG = IcecastMetadata.class.getSimpleName();
    
    private HashMap<String, String> _map;

    private static String urlDecodeWrapper(String s)
    {
        String result = s;
        
        try
        {
            result = URLDecoder.decode(s, "UTF-8");
        }
        catch (UnsupportedEncodingException e)
        {
            Log.d(TAG, "urlDecodeWrapper failed", e);
        }
        catch(RuntimeException rtex)
        {
            // UrlDecoder.decode will throw IllegalArgumentException if it encounters a badly formatted % sequence
            //
            // For the sake of robustness, since we are parsing network data, let's go ahead and catch all
            // RT exceptions.
            Log.d(TAG, "urlDecodeWrapper failed on runtime exception", rtex);
        }
        
        return result;
    }
    
    public IcecastMetadata(String metadata)
    {
        // tick marks within a key or value will be URL escaped (in theory), so let's parse off of that
        // example: StreamTitle='Ozzy Osbourne - Crazy Train';Foobar='';StreamUrl='http://myserver.org/music';
        
        int length = (metadata == null) ? 0 : metadata.length();
        int start=0;
        int end;
        String key, val;
        _map = new HashMap<String, String>();
        
        while (start < length)
        {
            end = metadata.indexOf("='", start);
            
            if ((end == -1) || (end <= start)) // you can't have an empty key
            {
                break;
            }
            
            key = metadata.substring(start, end);
            
            start = end+2;
            if (start >= length)
            {
                break;
            }
            
            end = metadata.indexOf("';", start);
            
            if ((end == -1) || (end < start)) // but you can have an empty value where (end == start) (e.g. foobar='';)
            {
                break;
            }
            
            val = metadata.substring(start, end);
            
            key = urlDecodeWrapper(key);
            val = urlDecodeWrapper(val);
            
            _map.put(key, val);
            
            start = end+2;
        }
        
    }
    
    public String getValue(String key)
    {
        return _map.get(key);
    }
    
    public String getStreamTitle()
    {
        String result = getValue("StreamTitle");
        return (result == null) ? "" : result;
    }
}