package jalview.io;

import jalview.bin.Cache;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.TreeMap;

/*
 * BackupFiles used for manipulating (naming rolling/deleting) backup/version files when an alignment or project file is saved.
 * User configurable options are:
 * BACKUPFILES_ENABLED - boolean flag as to whether to use this mechanism or act as before, including overwriting files as saved.
 * BACKUPFILES_SUFFIX - a template to insert just before the file extension.  Use '%n' to be replaced by a 0-led SUFFIX_DIGITS long integer.
 * BACKUPFILES_ROLL_MAX - the maximum number of backupfiles to keep for any one alignment or project file.
 * BACKUPFILES_SUFFIX_DIGITS - the number of digits to insert replace %n with (e.g. BACKUPFILES_SUFFIX_DIGITS = 3 would make "001", "002", etc)
 * BACKUPFILES_REVERSE_ORDER - if true then "logfile" style numbering and file rolling will occur. If false then ever-increasing version numbering will occur, but old files will still be deleted if there are more than ROLL_MAX backup files. 
 */

public class BackupFiles
{

  // labels for saved params in Cache and .jalview_properties
  private static String NS = "BACKUPFILES";

  public static String ENABLED = NS + "_ENABLED";

  public static String SUFFIX = NS + "_SUFFIX";

  public static String ROLL_MAX = NS + "_ROLL_MAX";

  public static String SUFFIX_DIGITS = NS + "_SUFFIX_DIGITS";

  protected static String NUM_PLACEHOLDER = "%n";

  public static String REVERSE_ORDER = NS + "_REVERSE_ORDER";

  private static String DEFAULT_TEMP_FILE = "jalview_temp_file_" + NS;

  // file - File object to be backed up and then updated (written over)
  private File file;

  // enabled - default flag as to whether to do the backup file roll (if not
  // defined in preferences)
  private boolean enabled;

  // defaultSuffix - default template to use to append to basename of file
  private String suffix;

  // defaultMax - default max number of backup files
  private int max;

  // defaultDigits - number of zero-led digits to use in the filename
  private int digits;

  // reverseOrder - set to true to make newest (latest) files lowest number
  // (like rolled log files)
  private boolean reverseOrder;

  // temp saved file to become new saved file
  private File tempFile;

  public BackupFiles(String filename)
  {
    this(new File(filename));
  }

  // first time defaults for ENABLED, SUFFIX, ROLL_MAX, SUFFIX_DIGITS and
  // REVERSE_ORDER
  public BackupFiles(File file)
  {
    this(file, true, "-v" + NUM_PLACEHOLDER, 4, 3, false);
  }

  // set, get and rename temp file into place
  public void setTempFile(File temp)
  {
    this.tempFile = temp;
  }

  public File getTempFile()
  {
    return tempFile;
  }

  public boolean renameTempFile()
  {
    return tempFile.renameTo(file);
  }

  public BackupFiles(File file, boolean defaultEnabled,
          String defaultSuffix,
          int defaultMax, int defaultDigits, boolean defaultReverseOrder)
  {
    this.file = file;
    this.enabled = Cache.getDefault(ENABLED, defaultEnabled);
    this.suffix = Cache.getDefault(SUFFIX, defaultSuffix);
    this.max = Cache.getDefault(ROLL_MAX, defaultMax);
    this.digits = Cache.getDefault(SUFFIX_DIGITS, defaultDigits);
    this.reverseOrder = Cache.getDefault(REVERSE_ORDER,
            defaultReverseOrder);
    
    // create a temp file to save new data in
    File temp;
    try
    {
      if (file != null)
      {
        String tempfilename = file.getName();
        File tempdir = file.getParentFile();
        temp = File.createTempFile(tempfilename, ".tmp", tempdir);
      }
      else
      {
        temp = File.createTempFile(DEFAULT_TEMP_FILE, ".tmp");
        setTempFile(temp);
      }
    } catch (IOException e)
    {
      System.out.println(
              "Could not create temp file to save into (IOException)");
    } catch (Exception e)
    {
      System.out.println("Exception ctreating temp file for saving");
    }

  }

  // roll the backupfiles
  public boolean rollBackupFiles()
  {

    // file doesn't yet exist or backups are not enabled
    if ((!file.exists()) || (!enabled) || (max < 1))
    {
      // nothing to do
      return true;
    }

    // split filename up to insert suffix template in the right place. template
    // and backupMax can be set in .jalview_properties
    String dir = "";
    File dirFile;
    try
    {
      dirFile = file.getParentFile();
      dir = dirFile.getCanonicalPath();
    } catch (Exception e)
    {
      System.out.println(
              "Could not get canonical path for file '" + file + "'");
      return false;
    }
    String filename = file.getName();
    String basename = filename;
    String extension = "";
    int dotcharpos = filename.lastIndexOf('.');
    // don't split of filenames with the last '.' at the very beginning or
    // very end of the filename
    if ((dotcharpos > 0) && (dotcharpos < filename.length() - 1))
    {
      basename = filename.substring(0, dotcharpos);
      extension = filename.substring(dotcharpos); // NOTE this includes the '.'
    }

    boolean ret = true;
    // Create/move backups up one
    String numString = null;
    File lastfile = null;

    if (reverseOrder)
    {
      // backup style numbering

      int tempMax = max;
      // max == -1 means no limits
      if (max == -1)
      {
        // do something cleverer here (possibly)!
        tempMax = 10000;
      }

      for (int m = 0; m < tempMax; m++)
      {
        int n = tempMax - m;
        String backupfilename = dir + File.separatorChar
                + BackupFilenameParts.getBackupFilename(n, basename, suffix,
                        digits, extension);
        File backupfile_n = new File(backupfilename);

        if (!backupfile_n.exists())
        {
          lastfile = backupfile_n;
          continue;
        }

        if (m == 0)
        { // Move the max backup to /tmp instead of deleting (Just In
          // Case)
          String tmpfile = "tmp-" + backupfile_n.getName();
          try
          {
            File tmpFile = File.createTempFile(tmpfile, ".tmp");
            ret = ret && backupfile_n.renameTo(tmpFile);
          } catch (IOException e)
          {
            System.out.println(
                    "Could not create temp file '" + tmpfile + ".tmp'");
          }
        }
        else
        {
          // Just In Case
          if (lastfile != null)
          {
            ret = ret && backupfile_n.renameTo(lastfile);
          }
        }

        lastfile = backupfile_n;
      }

      // now actually backup the important file!
      ret = ret && file.renameTo(lastfile);
    }
    else
    {
      // version style numbering (with earliest file deletion if max files
      // reached)

      // find existing backup files
      BackupFilenameFilter bff = new BackupFilenameFilter(basename, suffix,
              digits,
              extension);
      File[] backupFiles = dirFile.listFiles(bff);
      int nextIndexNum;
      
      if (backupFiles.length == 0)
      {
        nextIndexNum = 1;
      } else {

        // and sort them (based on integer found in the suffix) using a
        // precomputed Hashmap for speed
        HashMap bfHashMap = new HashMap<Integer, File>();
        for (int i = 0; i < backupFiles.length; i++)
        {
          File f = backupFiles[i];
          BackupFilenameParts bfp = new BackupFilenameParts(f, basename, suffix, digits, extension);
          bfHashMap.put(bfp.indexNum(), f);
        }
        TreeMap<Integer, File> bfTreeMap = new TreeMap<>();
        bfTreeMap.putAll(bfHashMap);

        bfTreeMap.values().toArray(backupFiles);
        
        // max value of -1 means keep all backup files
        if (bfTreeMap.size() >= max && max != -1)
        {
          // need to delete some files to keep number of backups to designated
          // max
          int numToDelete = bfTreeMap.size() - max;
          File[] filesToDelete = Arrays.copyOfRange(backupFiles, 0,
                  numToDelete - 1);

          /******************************************
           * CONFIRM THESE DELETIONS WITH THE USER! *
           ******************************************/
          for (int i = 0; i < filesToDelete.length; i++)
          {
            File toDelete = filesToDelete[i];
            toDelete.delete();
          }

        }

        nextIndexNum = bfTreeMap.lastKey() + 1;

        // Let's make the new backup file!! yay, got there at last!
        String nextBackupFilename = dir + File.separatorChar
                + BackupFilenameParts.getBackupFilename(nextIndexNum,
                        basename, suffix, digits, extension);
        File nextBackupFile = new File(nextBackupFilename);
        ret = ret && file.renameTo(nextBackupFile);
      }
    }

    return ret;
  }

}