package org.daisy.pipeline.css;
   
   import java.io.IOException;
   import java.io.Reader;
   import java.net.URI;
   import java.net.URL;
   import java.nio.charset.Charset;
   
   public interface CssPreProcessor {
  
  	public boolean supportsMediaType(String mediaType, URL url);
  
  	public PreProcessingResult compile(PreProcessingSource source) throws IOException;
  
  	public static class PreProcessingSource {
  
  		/**
  		 * The character stream.
  		 */
  		public final Reader stream;
  
  		/**
  		 * The base.
  		 */
  		public final URI base;
  
  		/**
  		 * Read the source again using a different character encoding. Closes {@code stream}.
  		 *
  		 * @throws IOException if the character encoding can not be changed or if the source can not
  		 *                     be read a second time.
  		 */
  		public Reader reread(Charset encoding) throws IOException {
  			throw new IOException();
  		}
  
  		public PreProcessingSource(Reader stream, URI base) {
  			this.stream = stream;
  			this.base = base;
  		}
  	}
  
  	public static final class PreProcessingResult {
  
  		/**
  		 * The CSS stream.
  		 */
  		public final Reader stream;
  
  		/**
  		 * The source map (JSON).
  		 */
  		public final String sourceMap;
  
  		/**
  		 * The base for resolving relative URIs in the CSS stream and source map.
  		 */
  		public final URI base;
  
  		public PreProcessingResult(Reader stream, String sourceMap, URI base) {
  			this.stream = stream;
  			this.sourceMap = sourceMap;
  			this.base = base;
  		}
  	}
  }