source: trunk/src/org/apollo/io/AudioPathManager.java@ 1006

package org.apollo.io;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Random;

import org.apollo.audio.structure.AudioStructureModel;
import org.apollo.util.ApolloSystemLog;
import org.apollo.util.RegExpFileFilter;

/**
 * Generates audio paths.
 * 
 * @author Brook Novak
 *
 */
public class AudioPathManager {

        private AudioPathManager() {
                // util constructor
        }

        /** Suffixed with the native file separator */
        public static String AUDIO_HOME_DIRECTORY = "audio" + File.separatorChar;
        
        /** Stores all virtual names created by this repository. */
        private static final String VIRTUAL_NAME_BASEFILE = ".vnames";

        public static final int PREAMBLE_LENGTH = 6;

        private static long counter = 0;

        private static Random rand = new Random(System.currentTimeMillis());

        /**
         * Class initializer.
         * Ensures that the home directory(ies) exist and preps the counter
         */
        static {

                String expeditee_home = System.getProperty("expeditee.home");

                if (expeditee_home != null) {
                    AUDIO_HOME_DIRECTORY = expeditee_home + File.separator + AUDIO_HOME_DIRECTORY;                  
                }

                // Ensure audio directory exists
                File dir = new File(AUDIO_HOME_DIRECTORY);
                if (!dir.exists()) {
                        if (!dir.mkdir()) {
                                ApolloSystemLog.println("Unable to create missing audio home directory");
                        }
                }

                // Load counter
                loadCounter(dir);
        }

        /**
         * Loads the counter
         * @param dir The dir where the audio files live.
         */
        private static void loadCounter(File dir) {
                String[] files = getAudioFileNames(dir);
                if (files == null) { // Due to IO exception
                        ApolloSystemLog.printError("Failed to read audio directory");
                        return;
                }
                long count = 0;
                if (files != null) {
                        for (String f : files) {
        
                                int start = -1, end = -1;
                                for (int i = 0; i < f.length(); i++) {
                                        if (Character.isDigit(f.charAt(i)) && start == -1) {
                                                start = i;
                                        } else if (!Character.isDigit(f.charAt(i)) && start != -1) {
                                                end = i;
                                                break;
                                        }
                                }
                                
                                if (start >= 0 && end == -1) end = f.length();
        
                                if (start > 0 && end >= start) { // not start >= 0 since missing preable
        
                                        String tmp = f.substring(start, end);
                                        long l = Long.parseLong(tmp);
                                        if (l >= count)
                                                count = l + 1;
                                }
                        }
                }

                counter = count;
        }
        
        /**
         * @param dir
         * @return
         *              Null if an IO exception occurs
         */
        private static String[] getAudioFileNames(File dir) {
                return dir.list(new RegExpFileFilter("^[A-Z]+\\d+.*$"));
        }
        
        /**
         * @return
         *              The list of audio files in the audio home directory.
         *              Can be empty. Null if directory does not exist or failed to
         *              read list of files.
         */
        public static String[] getAudioFileNames() {
                File audioDir = new File(AUDIO_HOME_DIRECTORY);
                if (!audioDir.exists() || !audioDir.isDirectory()) return null;
                return getAudioFileNames(audioDir);
        }
        
        
        /**
         * @return The current counter.
         */
        public static long getCounter() {
                return counter;
        }

        /**
         * Generates a filename that is unique within the AUDIO_HOME_DIRECTORY.
         * 
         * @param extension
         *                      The extension of the filename to generate. Exclude period.
         * 
         * @return 
         *              A free unused filename with the given extension. Excludes directory.
         *              Even if the path return is not used, it will never be re-generated.
         */
        public static String generateLocateFileName(String extension) {

                String filename = generateRandomFilenameBase() + "." + extension;
                
                File f = new File(AUDIO_HOME_DIRECTORY + filename);

                if (AudioStructureModel.getInstance().getTrackGraphInfo(filename, null) != null ||
                                f.exists()) { // recurse: until found a free path:
                        return generateLocateFileName(extension);
                }

                return filename;
        }
        
        private static String generateRandomFilenameBase() {
                
                counter++; 
                if (counter < 0) counter = 0; // wraps positivey

                // Generate random alpha preamble
                byte[] bytes = new byte[PREAMBLE_LENGTH];
                rand.nextBytes(bytes);
                

                for (int i = 0; i < PREAMBLE_LENGTH; i++) {
                        if (bytes[i] < 0) bytes[i] *= -1;
                        int alphacap = (65 + (Math.abs(bytes[i]) % 26)); // A-Z in US ASCII encoding
                        bytes[i] = (byte) alphacap;
                        
                }

                // Decode ASCII Byte array to javas UTF-16 encoding
                String preamble = null;

                try {
                        preamble = new String(bytes, "US-ASCII");
                } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                        preamble = "AUDIO";
                }

                // Build the filename string
                return preamble + counter;
                
        }

        
        
        /**
         * Lots of room for improvement here, ensures that a virtual filename is unique .. stores 
         * allocated virtual filenames on file.
         * 
         * @return
         *                      The new virtual filename.
         */
        public static String generateVirtualFilename() {

                // Ensure that the name base file exists. Assumes the audio home directory exists.
                File vnameBase = new File(AUDIO_HOME_DIRECTORY + VIRTUAL_NAME_BASEFILE);
                if (!vnameBase.exists()) {
                        try {
                                vnameBase.createNewFile();
                        } catch (IOException e) {
                                e.printStackTrace();
                        }
                }
                
                String vname = null;
                
                while (vname == null) {
                        vname = generateRandomFilenameBase() + ".vrt";
                        assert(vname != null);
                        
                        BufferedReader in = null;
                        String line = null;
                        
                        try {
                                
                                // Open the vbase for reading
                                in = new BufferedReader(new FileReader(vnameBase)); 
                                
                                // Read the sbase file and check all names
                                while ((line = in.readLine()) != null) {
                                        line = line.trim();
                                        if (line.equalsIgnoreCase(vname)) break;
                                }
                                
                        } catch (Exception e) {
                                e.printStackTrace();
                                break; // just use the last generated filename...
                        
                        // Clean up
                        } finally {
                                if (in != null) {
                                        try {
                                                in.close();
                                        } catch (IOException e) {
                                                e.printStackTrace();
                                        }
                                }
                        }
                        
                        // Check to see if name is infact unique
                        if (AudioStructureModel.getInstance().getLinkedTrackGraphInfo(vname, null) == null &&
                                        (line == null ||  !line.equalsIgnoreCase(vname))) {
                                // If so, then enter new entry into the db.
                                FileWriter out = null;
                                
                                try {
                                        // Open the vbase for appending
                                        out = new FileWriter(vnameBase, true); 
                                        out.write("\n" + vname);
                                        
                                } catch (IOException e) {
                                        e.printStackTrace();
                                        
                                // Clean up
                                } finally {
                                        if (out != null) {
                                                try {
                                                        out.close();
                                                } catch (IOException e) {
                                                        e.printStackTrace();
                                                }
                                        }
                                }

                        } else vname = null;
                }
                
                // Return the generated vname
                return vname;

        }
}