package org.carrot2.labs.smartsprites;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.InputStream;
import java.io.Reader;

import org.apache.commons.io.FilenameUtils;
import org.carrot2.labs.smartsprites.message.Message;
import org.carrot2.labs.smartsprites.message.MessageLog;
import org.carrot2.labs.smartsprites.message.Message.MessageType;
import org.carrot2.util.FileUtils;

/**
 * This class defines the resource handler which manage resources from the file system.
 * 
 * @author Ibrahim Chaehoi
 *
 */
public class FileSystemResourceHandler implements ResourceHandler {

	/** The message log */
	private MessageLog messageLog;
	
	/** The root directory */
	private File rootDir;
	
	/**
	 * Constructor.
	 * 
	 * @param rootDir the root directory
	 * @param messageLog the message log
	 */
	public FileSystemResourceHandler(File rootDir, MessageLog messageLog) {
		this.rootDir = rootDir;
		this.messageLog = messageLog;
	}
	
	/* (non-Javadoc)
	 * @see org.carrot2.labs.smartsprites.ResourceHandler#getResourceAsStream(java.lang.String)
	 */
	public InputStream getResourceAsStream(String cssFile, String imagePath) {
		
		File file = getResourceFile(cssFile, imagePath);
        InputStream is = null;
		try {
			is = new FileInputStream(file);
		} catch (FileNotFoundException e) {
			messageLog.info(Message.MessageType.GENERIC, e.getMessage());
		}
		
		return is;
	}

	/**
	 * Retrieves the resource file from a base file. 
	 * @param baseFile the base file.
	 * @param filePath the file path, which can be relative to the base file or relative to the root directory if it starts with a "/"  
	 * @return the resource file.
	 */
	private File getResourceFile(String baseFile, String filePath) {
		File file = null;
		if (filePath.startsWith("/"))
        {
            if (rootDir != null)
            {
            	file = new File(FileUtils.getCanonicalOrAbsoluteFile(rootDir), filePath.substring(1));
            }
            else
            {
                messageLog.warning(MessageType.ABSOLUTE_PATH_AND_NO_DOCUMENT_ROOT,
                    filePath);
            }
        }else{
        	
        	String parentPath = "";
            int idx = FilenameUtils.indexOfLastSeparator(baseFile);
            if(idx != -1){
            	parentPath = baseFile.substring(0, idx);
            }
            file = new File(FilenameUtils.concat(parentPath, filePath));
        }
		return file;
	}

	/* (non-Javadoc)
	 * @see org.carrot2.labs.smartsprites.ResourceHandler#getReader(java.lang.String)
	 */
	public Reader getReader(String path) {
	
		Reader rd = null;
		try {
			rd = new FileReader(new File(path));
		} catch (FileNotFoundException e) {
			messageLog.info(Message.MessageType.GENERIC, e.getMessage());
		}
		
		return rd;
	}

	/* (non-Javadoc)
	 * @see org.carrot2.labs.smartsprites.ResourceHandler#getResourcePath(java.lang.String, java.lang.String)
	 */
	public String getResourcePath(String cssFile, String imagePath) {
		
		return FileUtils.getCanonicalOrAbsolutePath(getResourceFile(cssFile, imagePath));
	}

}