package jalview.io;

import jalview.bin.Cache;
import jalview.gui.Desktop;
import jalview.gui.JvOptionPane;
import jalview.util.MessageManager;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
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 after the file extension.  Use '%n' to be replaced by a 0-led SUFFIX_DIGITS long integer.
 * BACKUPFILES_NO_MAX - flag to turn off setting a maximum number of backup files to keep.
 * 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. 
 * BACKUPFILES_CONFIRM_DELETE_OLD - if true then prompt/confirm with the user when deleting older backup/version files.
 */

public class BackupFiles
{

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

  public static final String ENABLED = NS + "_ENABLED";

  public static final String SUFFIX = NS + "_SUFFIX";

  public static final String NO_MAX = NS + "_NO_MAX";

  public static final String ROLL_MAX = NS + "_ROLL_MAX";

  public static final String SUFFIX_DIGITS = NS + "_SUFFIX_DIGITS";

  public static final String NUM_PLACEHOLDER = "%n";

  public static final String REVERSE_ORDER = NS + "_REVERSE_ORDER";

  public static final String CONFIRM_DELETE_OLD = NS
          + "_CONFIRM_DELETE_OLD";

  private static final String DEFAULT_TEMP_FILE = "jalview_temp_file_" + NS;

  private static final String TEMP_FILE_EXT = ".tmp";

  // 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 static boolean enabled;

  // confirmDelete - default flag as to whether to confirm with the user before
  // deleting old backup/version files
  private static boolean confirmDelete;

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

  // noMax - flag to turn off a maximum number of files
  private boolean noMax;

  // 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;

  // flag set to see if file save to temp file was successful
  private boolean tempFileWriteSuccess;

  // array of files to be deleted, with extra information
  private ArrayList<File> deleteFiles = new ArrayList<>();

  // date formatting for modification times
  private static final SimpleDateFormat sdf = new SimpleDateFormat(
          "yyyy-MM-dd HH:mm:ss");

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

  // first time defaults for SUFFIX, NO_MAX, ROLL_MAX, SUFFIX_DIGITS and
  // REVERSE_ORDER
  public BackupFiles(File file)
  {
    this(file, ".bak" + NUM_PLACEHOLDER, false, 3, 3, false);
  }

  public BackupFiles(File file, String defaultSuffix, boolean defaultNoMax,
          int defaultMax, int defaultDigits, boolean defaultReverseOrder)
  {
    classInit();
    this.file = file;
    this.suffix = Cache.getDefault(SUFFIX, defaultSuffix);
    this.noMax = Cache.getDefault(NO_MAX, defaultNoMax);
    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 = null;
    try
    {
      if (file != null)
      {
        String tempfilename = file.getName();
        File tempdir = file.getParentFile();
        temp = File.createTempFile(tempfilename, TEMP_FILE_EXT + "_newfile",
                tempdir);
      }
      else
      {
        temp = File.createTempFile(DEFAULT_TEMP_FILE, TEMP_FILE_EXT);
      }
    } 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");
    }
    this.setTempFile(temp);
  }

  public static void classInit()
  {
    setEnabled(Cache.getDefault(ENABLED, true));
    setConfirmDelete(Cache.getDefault(CONFIRM_DELETE_OLD, true));
  }

  public static void setEnabled(boolean flag)
  {
    enabled = flag;
  }

  public static boolean getEnabled()
  {
    classInit();
    return enabled;
  }

  public static void setConfirmDelete(boolean flag)
  {
    confirmDelete = flag;
  }

  public static boolean getConfirmDelete()
  {
    classInit();
    return confirmDelete;
  }

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

  public File getTempFile()
  {
    return tempFile;
  }

  public String getTempFilePath()
  {
    String path = null;
    try
    {
      path = this.getTempFile().getCanonicalPath();
    } catch (IOException e)
    {
      System.out.println(
              "IOException when getting Canonical Path of temp file '"
                      + this.getTempFile().getName() + "'");
    }
    return path;
  }

  public boolean setWriteSuccess(boolean flag)
  {
    boolean old = this.tempFileWriteSuccess;
    this.tempFileWriteSuccess = flag;
    return old;
  }

  public boolean getWriteSuccess()
  {
    return this.tempFileWriteSuccess;
  }

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

  // roll the backupfiles
  public boolean rollBackupFiles()
  {
    return this.rollBackupFiles(true);
  }

  public boolean rollBackupFiles(boolean tidyUp)
  {
    // file doesn't yet exist or backups are not enabled or template is null or
    // empty
    if ((!file.exists()) || (!enabled) || max < 0 || suffix == null
            || suffix.length() == 0)
    {
      // nothing to do
      return true;
    }

    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;

    boolean ret = true;
    // Create/move backups up one

    deleteFiles.clear();

    // find existing backup files
    BackupFilenameFilter bff = new BackupFilenameFilter(basename, suffix,
            digits);
    File[] backupFiles = dirFile.listFiles(bff);
    int nextIndexNum = 0;

    if (backupFiles.length == 0)
    {
      // No other backup files. Just need to move existing file to backupfile_1
      nextIndexNum = 1;
    }
    else
    {
      TreeMap<Integer, File> bfTreeMap = sortBackupFilesAsTreeMap(
              backupFiles, basename);
      // bfTreeMap now a sorted list of <Integer index>,<File backupfile>
      // mappings

      if (reverseOrder)
      {
        // backup style numbering


        int tempMax = noMax ? -1 : max;
        // noMax == true means no limits
        // look for first "gap" in backupFiles
        // if tempMax is -1 at this stage just keep going until there's a gap,
        // then hopefully tempMax gets set to the right index (a positive
        // integer so the loop breaks)...
        // why do I feel a little uneasy about this loop?..
        for (int i = 1; tempMax < 0 || i <= max; i++)
        {
          if (!bfTreeMap.containsKey(i)) // first index without existent
                                         // backupfile
          {
            tempMax = i;
          }
        }
        
        File previousFile = null;
        File fileToBeDeleted = null;
        for (int n = tempMax; n > 0; n--)
        {
          String backupfilename = dir + File.separatorChar
                  + BackupFilenameParts.getBackupFilename(n, basename,
                          suffix, digits);
          File backupfile_n = new File(backupfilename);

          if (!backupfile_n.exists())
          {
            // no "oldest" file to delete
            previousFile = backupfile_n;
            fileToBeDeleted = null;
            continue;
          }

          // check the modification time of this (backupfile_n) and the previous
          // file (fileToBeDeleted) if the previous file is going to be deleted
          if (fileToBeDeleted != null)
          {
            File replacementFile = backupfile_n;
            long fileToBeDeletedLMT = fileToBeDeleted.lastModified();
            long replacementFileLMT = replacementFile.lastModified();

            try
            {
              File oldestTempFile = nextTempFile(fileToBeDeleted.getName(),
                      dirFile);
              
              if (fileToBeDeletedLMT > replacementFileLMT)
              {
                String fileToBeDeletedLMTString = sdf
                        .format(fileToBeDeletedLMT);
                String replacementFileLMTString = sdf
                        .format(replacementFileLMT);
                System.out.println("WARNING! I am set to delete backupfile "
                        + fileToBeDeleted.getName()
                        + " has modification time "
                        + fileToBeDeletedLMTString
                        + " which is newer than its replacement "
                        + replacementFile.getName()
                        + " with modification time "
                        + replacementFileLMTString);

                boolean delete = confirmNewerDeleteFile(fileToBeDeleted,
                        replacementFile, true);

                if (delete)
                {
                  // User has confirmed delete -- no need to add it to the list
                  fileToBeDeleted.delete();
                }
                else
                {
                  fileToBeDeleted.renameTo(oldestTempFile);
                }
              }
              else
              {
                fileToBeDeleted.renameTo(oldestTempFile);
                addDeleteFile(oldestTempFile);
              }

            } catch (Exception e)
            {
              System.out.println(
                      "Error occurred, probably making new temp file for '"
                              + fileToBeDeleted.getName() + "'");
              e.printStackTrace();
            }

            // reset
            fileToBeDeleted = null;
          }

          if (!noMax && n == tempMax && backupfile_n.exists())
          {
            fileToBeDeleted = backupfile_n;
          }
          else
          {
            if (previousFile != null)
            {
              ret = ret && backupfile_n.renameTo(previousFile);
            }
          }

          previousFile = backupfile_n;
        }

        // index to use for the latest backup
        nextIndexNum = 1;
      }
      else
      {
        // version style numbering (with earliest file deletion if max files
        // reached)

        bfTreeMap.values().toArray(backupFiles);

        // noMax == true means keep all backup files
        if ((!noMax) && bfTreeMap.size() >= max)
        {
          // need to delete some files to keep number of backups to designated
          // max
          int numToDelete = bfTreeMap.size() - max + 1;
          // the "replacement" file is the latest backup file being kept (it's
          // not replacing though)
          File replacementFile = numToDelete < backupFiles.length
                  ? backupFiles[numToDelete]
                  : null;
          for (int i = 0; i < numToDelete; i++)
          {
            // check the deletion files for modification time of the last
            // backupfile being saved
            File fileToBeDeleted = backupFiles[i];
            boolean delete = true;

            boolean newer = false;
            if (replacementFile != null)
            {
              long fileToBeDeletedLMT = fileToBeDeleted.lastModified();
              long replacementFileLMT = replacementFile != null
                      ? replacementFile.lastModified()
                      : Long.MAX_VALUE;
              if (fileToBeDeletedLMT > replacementFileLMT)
              {
                String fileToBeDeletedLMTString = sdf
                        .format(fileToBeDeletedLMT);
                String replacementFileLMTString = sdf
                        .format(replacementFileLMT);

                System.out
                        .println("WARNING! I am set to delete backupfile '"
                                + fileToBeDeleted.getName()
                                + "' has modification time "
                        + fileToBeDeletedLMTString
                                + " which is newer than the oldest backupfile being kept '"
                        + replacementFile.getName()
                                + "' with modification time "
                        + replacementFileLMTString);

                delete = confirmNewerDeleteFile(fileToBeDeleted,
                        replacementFile, false);
                if (delete)
                {
                  // User has confirmed delete -- no need to add it to the list
                  fileToBeDeleted.delete();
                  delete = false;
                }
                else
                {
                  // keeping file, nothing to do!
                }
              }
            }
            if (delete)
            {
              addDeleteFile(fileToBeDeleted);
            }

          }

        }

        nextIndexNum = bfTreeMap.lastKey() + 1;
      }
    }

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

    if (tidyUp)
    {
      tidyUpFiles();
    }

    return ret;
  }

  private static File nextTempFile(String filename, File dirFile)
          throws IOException
  {
    File temp = null;
    COUNT: for (int i = 1; i < 1000; i++)
    {
      File trythis = new File(dirFile,
              filename + '~' + Integer.toString(i));
      if (!trythis.exists())
      {
        temp = trythis;
        break COUNT;
      }

    }
    if (temp == null)
    {
      temp = File.createTempFile(filename, TEMP_FILE_EXT, dirFile);
    }
    return temp;
  }

  private void tidyUpFiles()
  {
    deleteOldFiles();
  }

  private static boolean confirmNewerDeleteFile(File fileToBeDeleted,
          File replacementFile, boolean replace)
  {
    StringBuilder messageSB = new StringBuilder();

    File ftbd = fileToBeDeleted;
    String ftbdLMT = sdf.format(ftbd.lastModified());
    String ftbdSize = Long.toString(ftbd.length());

    File rf = replacementFile;
    String rfLMT = sdf.format(rf.lastModified());
    String rfSize = Long.toString(rf.length());

    int confirmButton = JvOptionPane.NO_OPTION;
    if (replace)
    {
      File saveFile = null;
      try
      {
        saveFile = nextTempFile(ftbd.getName(), ftbd.getParentFile());
      } catch (Exception e)
      {
        System.out.println(
                "Error when confirming to keep backup file newer than other backup files.");
        e.printStackTrace();
      }
      messageSB.append(MessageManager.formatMessage(
              "label.newerdelete_replacement_line", new String[]
              { ftbd.getName(), rf.getName(), ftbdLMT, rfLMT, ftbdSize,
                  rfSize }));
      messageSB.append("\n\n");
      messageSB.append(MessageManager.formatMessage(
              "label.confirm_deletion_or_rename", new String[]
              { ftbd.getName(), saveFile.getName() }));
      String[] options = new String[] {
          MessageManager.getString("label.delete"),
          MessageManager.getString("label.rename") };

      confirmButton = JvOptionPane.showOptionDialog(Desktop.desktop,
              messageSB.toString(),
              MessageManager.getString("label.backupfiles_confirm_delete"),
              JvOptionPane.YES_NO_OPTION, JvOptionPane.WARNING_MESSAGE,
              null, options, options[0]);
    }
    else
    {
      messageSB.append(MessageManager
              .formatMessage("label.newerdelete_line", new String[]
              { ftbd.getName(), rf.getName(), ftbdLMT, rfLMT, ftbdSize,
                  rfSize }));
      messageSB.append("\n\n");
      messageSB.append(MessageManager
              .formatMessage("label.confirm_deletion", new String[]
              { ftbd.getName() }));
      String[] options = new String[] {
          MessageManager.getString("label.delete"),
          MessageManager.getString("label.keep") };

      confirmButton = JvOptionPane.showOptionDialog(Desktop.desktop,
              messageSB.toString(),
              MessageManager.getString("label.backupfiles_confirm_delete"),
              JvOptionPane.YES_NO_OPTION, JvOptionPane.WARNING_MESSAGE,
              null, options, options[0]);
    }


    // return should be TRUE if file is to be deleted
    return (confirmButton == JvOptionPane.YES_OPTION);
  }

  private void deleteOldFiles()
  {
    if (deleteFiles != null && !deleteFiles.isEmpty())
    {
      boolean doDelete = false;
      StringBuilder messageSB = null;
      if (confirmDelete && deleteFiles.size() > 0)
      {
        messageSB = new StringBuilder();
        messageSB.append(MessageManager
                .getString("label.backupfiles_confirm_delete_old_files"));
        for (int i = 0; i < deleteFiles.size(); i++)
        {
          File df = deleteFiles.get(i);
          messageSB.append("\n");
          messageSB.append(df.getName());
          messageSB.append(" ");
          messageSB.append(MessageManager.formatMessage("label.file_info",
                  new String[]
                  { sdf.format(df.lastModified()),
                      Long.toString(df.length()) }));
        }

        int confirmButton = JvOptionPane.showConfirmDialog(Desktop.desktop,
                messageSB.toString(),
                MessageManager
                        .getString("label.backupfiles_confirm_delete"),
                JvOptionPane.YES_NO_OPTION, JvOptionPane.WARNING_MESSAGE);

        doDelete = (confirmButton == JvOptionPane.YES_OPTION);
      }
      else
      {
        doDelete = true;
      }

      if (doDelete)
      {
        for (int i = 0; i < deleteFiles.size(); i++)
        {
          File fileToDelete = deleteFiles.get(i);
          fileToDelete.delete();
          System.out.println("DELETING '" + fileToDelete.getName() + "'");
        }
      }

    }

    deleteFiles.clear();
  }

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

  public boolean rollBackupsAndRenameTempFile()
  {
    boolean write = this.getWriteSuccess();

    boolean roll = false;
    boolean rename = false;
    if (write)
    {
      roll = this.rollBackupFiles(false);
      rename = this.renameTempFile();
    }

    /*
     * Not sure that this confirmation is desirable.  By this stage the new file is
     * already written successfully, but something (e.g. disk full) has happened while 
     * trying to roll the backup files, and most likely the filename needed will already
     * be vacant so renaming the temp file is nearly always correct!
     */
    boolean okay = roll && rename;
    if (!okay)
    {
      StringBuilder messageSB = new StringBuilder();
      messageSB.append(MessageManager.getString( "label.backupfiles_confirm_save_file_backupfiles_roll_wrong"));
      if (rename)
      {
        if (messageSB.length() > 0)
        {
          messageSB.append("\n");
        }
        messageSB.append(MessageManager.getString(
                "label.backupfiles_confirm_save_new_saved_file_ok"));
      }
      else
      {
        if (messageSB.length() > 0)
        {
          messageSB.append("\n");
        }
        messageSB.append(MessageManager.getString(
                "label.backupfiles_confirm_save_new_saved_file_not_ok"));
      }

      int confirmButton = JvOptionPane.showConfirmDialog(Desktop.desktop,
              messageSB.toString(),
              MessageManager
                      .getString("label.backupfiles_confirm_save_file"),
              JvOptionPane.OK_OPTION, JvOptionPane.WARNING_MESSAGE);
      okay = confirmButton == JvOptionPane.OK_OPTION;
    }
    if (okay)
    {
      tidyUpFiles();
    }

    return rename;
  }

  public static TreeMap<Integer, File> getBackupFilesAsTreeMap(
          String fileName, String suffix, int digits)
  {
    File[] backupFiles = null;

    File file = new File(fileName);

    File dirFile;
    try
    {
      dirFile = file.getParentFile();
    } catch (Exception e)
    {
      System.out.println(
              "Could not get canonical path for file '" + file + "'");
      return new TreeMap<>();
    }

    String filename = file.getName();
    String basename = filename;

    // find existing backup files
    BackupFilenameFilter bff = new BackupFilenameFilter(basename, suffix,
            digits);
    backupFiles = dirFile.listFiles(bff); // is clone needed?

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

    return bfTreeMap;
  }

  /*
  private boolean addDeleteFile(File fileToBeDeleted, File originalFile,
          boolean delete, boolean newer)
  {
    return addDeleteFile(fileToBeDeleted, originalFile, null, delete, newer);
  }
  */
  private boolean addDeleteFile(File fileToBeDeleted)
  {
    boolean ret = false;
    int pos = deleteFiles.indexOf(fileToBeDeleted);
    if (pos > -1)
    {
      return true;
    }
    else
    {
      deleteFiles.add(fileToBeDeleted);
    }
    return ret;
  }

}