#!/usr/bin/python3
# TODO: get rid of sqlite cursors; execute on connection
# TODO: add index to table creation
# TODO: why are there TWO sqlite.connect()??
#   try auto-commit (isolation_level = "IMMEDIATE")
#   try dict-parameters in sql statements
# TODO: pick up comment for cwd and display at the top somewhere, or maybe status line
""" a simple gui or command line app
to view and create/edit file comments

comments are stored in an SQLite3 database
  default ~/.dirnotes.db
where possible, comments are duplicated in 
  xattr user.xdg.comment

  some file systems don't allow xattr, and even linux
  doesn't allow xattr on symlinks, so the database is
  considered primary

  these comments stick to the symlink, not the deref

nav tools are enabled, so you can double-click to go into a dir

"""

VERSION = "0.5"

helpMsg = f"""<table width=100%><tr><td><h1>Dirnotes</h1><td>
<td align=right>Version: {VERSION}</td></tr></table>

<h3>Overview</h3>
This app allows you to add comments to files. The comments are stored in 
a <i>database</i>, and where possible, saved in the <i>xattr</i> (hidden attributes) 
field of the file system.

<p> Double click on a comment to create or edit.

<p> You can sort the directory listing by clicking on the column heading.

<p> Double click on directory names to navigate the file system. Hover over
fields for more information.

<h3>xattr extended attributes</h3>
The xattr comment suffers from a few problems:
<ul>
  <li>is not implemented on FAT/VFAT/EXFAT file systems (some USB sticks)
  <li>xattrs are not (by default) copied with the file when it's duplicated 
or backedup (<i>mv, rsync</i> and <i>tar</i> work, <i>ssh</i> and <i>scp</i> don't)
  <li>xattrs are not available for symlinks
  <li>some programs which edit files do not preserve the xattrs during file-save (<i>vim</i>)
</ul>

On the other hand, <i>xattr</i> comments can be bound directly to files on removable
media (as long as the disk format allows it).

<p>When the <i>database</i> version of a comment differs from the <i>xattr</i> version, 
the comment box gets a light yellow background.
"""

import sys,os,argparse,stat,getpass,shutil
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import Qt, pyqtSignal
import sqlite3, json, time

VERSION = "0.4"
xattr_comment = "user.xdg.comment"
xattr_author  = "user.xdg.comment.author"
xattr_date    = "user.xdg.comment.date"
DATE_FORMAT   = "%Y-%m-%d %H:%M:%S"
YEAR          = 3600*25*365

## globals
mode_names = {"db":"<Database mode> ","xattr":"<Xattr mode>"} 
modes = ("db","xattr") 
mode = "db" 

global mainWindow, dbName

DEFAULT_CONFIG_FILE = "~/.dirnotes.conf"

# config
#    we could store the config in the database, in a second table
#    or in a .json file
DEFAULT_CONFIG = {"xattr_tag":"user.xdg.comment",
  "database":"~/.dirnotes.db",
  "start_mode":"xattr",
  "options for database":("~/.dirnotes.db","/etc/dirnotes.db"),
  "options for start_mode":("db","xattr")
}

verbose = None
def print_v(*a):
  if verbose:
    print(*a)

class dnDataBase:
  ''' the database is flat
    fileName: fully qualified name
    st_mtime: a float
    size: a long
    comment: a string
    comment_time: a float, the time of the comment save
    author: the username that created the comment

    the database is associated with a user, in the $HOME dir
  '''
  def __init__(self,dbFile):
    '''try to open the database; if not found, create it'''
    try:
      self.db = sqlite3.connect(dbFile)
    except sqlite3.OperationalError:
      print(f"Database {dbFile} not found")
      raise
    try:
      self.db.execute("select * from dirnotes")
    except sqlite3.OperationalError:
      print_v("Table %s created" % ("dirnotes"))
      self.db.execute("create table dirnotes (name TEXT, date DATETIME, size INTEGER, comment TEXT, comment_date DATETIME, author TEXT)")
      self.db_cursor.execute("create index dirnotes_i on dirnotes(name)") 
  # getData is only used by the restore-from-database.......consider deleting it
  def getData(self, fileName):
    c = self.db.execute("select * from dirnotes where name=? and comment<>'' order by comment_date desc",(os.path.abspath(fileName),))
    return c.fetchone()

  @staticmethod
  def epochToDb(epoch):
    return time.strftime(DATE_FORMAT,time.localtime(epoch))
  @staticmethod
  def DbToEpoch(dbTime):
    return time.mktime(time.strptime(dbTime,DATE_FORMAT))
  @staticmethod
  def getShortDate(longDate):
    now = time.time()
    diff = now - longDate
    if diff > YEAR:
      fmt = "%b %e %Y"
    else:
      fmt = "%b %d %H:%M"
    return time.strftime(fmt, time.localtime(longDate))
    

## one for each file
## and a special one for ".." parent directory
class FileObj():
  FILE_IS_DIR    = -1
  FILE_IS_LINK   = -2
  FILE_IS_SOCKET = -3
  def __init__(self, fileName):
    self.fileName = os.path.abspath(fileName) # full path; dirs end WITHOUT a terminal /
    self.displayName = os.path.split(fileName)[1]   # base name; dirs end with a /
    s = os.lstat(self.fileName)
    self.date = s.st_mtime
    if stat.S_ISDIR(s.st_mode):
      self.size = FileObj.FILE_IS_DIR
      if not self.displayName.endswith('/'):
        self.displayName += '/'
    elif stat.S_ISLNK(s.st_mode):
      self.size = FileObj.FILE_IS_LINK
    elif stat.S_ISSOCK(s.st_mode):
      self.size = FileObj.FILE_IS_SOCKET
    else:
      self.size = s.st_size
    self.xattrComment = ''
    self.xattrAuthor = None
    self.xattrDate = None
    self.dbComment = ''
    self.dbAuthor = None
    self.dbDate = None
    self.commentsDiffer = False
    try:
      self.xattrComment = os.getxattr(fileName, xattr_comment, follow_symlinks=False).decode()
      self.xattrAuthor  = os.getxattr(fileName, xattr_author, follow_symlinks=False).decode()
      self.xattrDate    = os.getxattr(fileName, xattr_date, follow_symlinks=False).decode()
      self.commentsDiffer = True if self.xattrComment == self.dbComment else False
    except:  # no xattr comment
      pass

  def getName(self):
    return self.fileName
  def getDisplayName(self):
    return self.displayName

  # with an already open database cursor
  def loadDbComment(self,db):
    c = db.execute("select comment,author,comment_date from dirnotes where name=? and comment<>'' order by comment_date desc",(self.fileName,))
    a = c.fetchone()
    if a:
      self.dbComment, self.dbAuthor, self.dbDate = a
      self.commentsDiffer = True if self.xattrComment == self.dbComment else False

  def getDbComment(self):
    return self.dbComment
  def getDbAuthor(self):
    return self.dbAuthor
  def getDbDate(self):
    return self.dbDate
  def setDbComment(self,db,newComment):
    s = os.lstat(self.fileName)
    try:
      # TODO: copy from /g/test_file to /home/patb/project/dirnotes/r    fails on database.commit()
      print_v(f"setDbComment db {db}, file: {self.fileName}")
      print_v("insert into dirnotes (name,date,size,comment,comment_date,author) values (?,datetime(?,'unixepoch','localtime'),?,?,datetime(?,'unixepoch','localtime'),?)",
          (self.fileName, s.st_mtime, s.st_size,
          str(newComment), time.time(), getpass.getuser()))
      db.execute("insert into dirnotes (name,date,size,comment,comment_date,author) values (?,datetime(?,'unixepoch','localtime'),?,?,datetime(?,'unixepoch','localtime'),?)",
          (self.fileName, s.st_mtime, s.st_size,
          str(newComment), time.time(), getpass.getuser()))
      print_v(f"setDbComment, execute done, about to commit()")
      db.commit()
      print_v(f"database write for {self.fileName}")
      self.dbComment = newComment
    except sqlite3.OperationalError:
      print_v("database is locked or unwritable")
      errorBox("the database that stores comments is locked or unwritable")
    self.commentsDiffer = True if self.xattrComment == self.dbComment else False

  def getXattrComment(self):
    return self.xattrComment
  def getXattrAuthor(self):
    return self.xattrAuthor
  def getXattrDate(self):
    print_v(f"someone accessed date on {self.fileName} {self.xattrDate}")
    return self.xattrDate
  def setXattrComment(self,newComment):
    print_v(f"set comment {newComment} on file {self.fileName}")
    try:
      os.setxattr(self.fileName,xattr_comment,bytes(newComment,'utf8'),follow_symlinks=False)
      os.setxattr(self.fileName,xattr_author,bytes(getpass.getuser(),'utf8'),follow_symlinks=False)
      os.setxattr(self.fileName,xattr_date,bytes(time.strftime(DATE_FORMAT),'utf8'),follow_symlinks=False)
      self.xattrAuthor = getpass.getuser()
      self.xattrDate = time.strftime(DATE_FORMAT)      # alternatively, re-instantiate this FileObj
      self.xattrComment = newComment
      self.commentsDiffer = True if self.xattrComment == self.dbComment else False
      return True
    # we need to move these cases out to a handler 
    except Exception as e:
      if self.size == FileObj.FILE_IS_LINK:
        errorBox("Linux does not allow xattr comments on symlinks; comment is stored in database")
      elif self.size == FileObj.FILE_IS_SOCKET:
        errorBox("Linux does not allow comments on sockets; comment is stored in database")
      elif os.access(self.fileName, os.W_OK)!=True:
        errorBox("you don't appear to have write permissions on this file")
        # change the listbox background to yellow
        self.displayBox.notifyUnchanged()
      elif "Errno 95" in str(e):
        errorBox("is this a VFAT or EXFAT volume? these don't allow comments")
      self.commentsDiffer = True
      return False
    self.commentsDiffer = True if self.xattrComment == self.dbComment else False

  def getComment(self):
    return self.getDbComment() if mode == "db" else self.getXattrComment()
  def getOtherComment(self):
    return self.getDbComment() if mode == "xattr" else self.getXattrComment()
  def getDate(self):
    return self.date
  def getSize(self):
    return self.size
  def isDir(self):
    return self.size == self.FILE_IS_DIR
  def isLink(self):
    return self.size == self.FILE_IS_LINK

class HelpWidget(QDialog):
  def __init__(self, parent):
    super(QDialog, self).__init__(parent)
    self.layout = QVBoxLayout(self)
    self.tb = QLabel(self)
    self.tb.setWordWrap(True)
    self.tb.setText(helpMsg)
    self.tb.setFixedWidth(500)
    self.pb = QPushButton('OK',self)
    self.pb.setFixedWidth(200)
    self.layout.addWidget(self.tb)
    self.layout.addWidget(self.pb)
    self.pb.clicked.connect(self.close)
    self.show()

class errorBox(QDialog):
  def __init__(self, text):
    print_v(f"errorBox: {text}")
    super(QDialog, self).__init__(mainWindow)
    self.layout = QVBoxLayout(self)
    self.tb = QLabel(self)
    self.tb.setWordWrap(True)
    self.tb.setFixedWidth(500)
    self.tb.setText(text)
    self.pb = QPushButton("OK",self)
    self.layout.addWidget(self.tb)
    self.layout.addWidget(self.pb)
    self.pb.clicked.connect(self.close)
    self.show()

icon = ["32 32 6 1",  # the QPixmap constructor allows for str[]
"   c None",
".  c #666666",
"+  c #FFFFFF",
"@  c #848484",
"#  c #000000",
"$  c #FCE883",
"                                ",
"  ........                      ",
" .++++++++.                     ",
" .+++++++++..................   ",
" .+++++++++++++++++++++++++++.  ",
" .+++++++++++++++++++++++++++.  ",
" .++..+......++@@@@@@@@@@@@@@@@@",
" .++..++++++++#################@",
" .+++++++++++#$$$$$$$$$$$$$$$$$#",
" .++..+.....+#$$$$$$$$$$$$$$$$$#",
" .++..+++++++#$$$$$$$$$$$$$$$$$#",
" .+++++++++++#$$#############$$#",
" .++..+.....+#$$$$$$$$$$$$$$$$$#",
" .++..+++++++#$$########$$$$$$$#",
" .+++++++++++#$$$$$$$$$$$$$$$$$#",
" .++..+.....+#$$$$$$$$$$$$$$$$$#",
" .++..++++++++#######$$$####### ",
" .++++++++++++++++++#$$#++++++  ",
" .++..+............+#$#++++++.  ",
" .++..++++++++++++++##+++++++.  ",
" .++++++++++++++++++#++++++++.  ",
" .++..+............++++++++++.  ",
" .++..+++++++++++++++++++++++.  ",
" .+++++++++++++++++++++++++++.  ",
" .++..+................++++++.  ",
" .++..+++++++++++++++++++++++.  ",
" .+++++++++++++++++++++++++++.  ",
" .++..+................++++++.  ",
" .++..+++++++++++++++++++++++.  ",
" .+++++++++++++++++++++++++++.  ",
"  ...........................   ",
"                                "]


# sortable TableWidgetItem, based on idea by Aledsandar
# http://stackoverflow.com/questions/12673598/python-numerical-sorting-in-qtablewidget
# NOTE: the QTableWidgetItem has setData() and data() which may allow data bonding
# in Qt5, data() binding is more awkward, so do it here
class SortableTableWidgetItem(QTableWidgetItem):
  def __init__(self, text, sortValue, file_object):
    QTableWidgetItem.__init__(self, text, QTableWidgetItem.UserType)
    self.sortValue = sortValue
    self.file_object = file_object
  def __lt__(self, other):
    return self.sortValue < other.sortValue
    
    
class DirNotes(QMainWindow):
  ''' the main window of the app
    '''
  def __init__(self, argFilename, db, start_mode, parent=None):
    super(DirNotes,self).__init__(parent)
    self.db = db
    self.refilling = False
    self.parent = parent

    win = QWidget()
    self.setCentralWidget(win)

    lb = QTableWidget()
    self.lb = lb
    lb.setColumnCount(4)
    lb.horizontalHeader().setSectionResizeMode( 3, QHeaderView.Stretch );
    lb.verticalHeader().setDefaultSectionSize(20);  # thinner rows
    lb.verticalHeader().setVisible(False)

    longPathName = os.path.abspath(argFilename)
    print_v("longpathname is {}".format(longPathName))
    if os.path.isdir(longPathName):
      self.curPath = longPathName
      filename = ''
    else:
      self.curPath, filename = os.path.split(longPathName)
    print_v("working on <"+self.curPath+"> and <"+filename+">")
    
    layout = QVBoxLayout()

    copyIcon = QIcon.fromTheme('drive-harddisk-symbolic')
    changeIcon = QIcon.fromTheme('emblem-synchronizing-symbolic')

    topLayout = QHBoxLayout()
    self.modeShow = QLabel(win)
    topLayout.addWidget(self.modeShow)
    bmode = QPushButton(changeIcon, "change mode",win)
    topLayout.addWidget(bmode)
    cf = QPushButton(copyIcon, "copy file",win)
    topLayout.addWidget(cf)
    layout.addLayout(topLayout)

    layout.addWidget(lb)
    win.setLayout(layout)
    
    lb.itemChanged.connect(self.change)
    lb.cellDoubleClicked.connect(self.double)
    bmode.clicked.connect(self.switchMode)
    cf.clicked.connect(self.copyFile)

    lb.setHorizontalHeaderItem(0,QTableWidgetItem("File"))
    lb.setHorizontalHeaderItem(1,QTableWidgetItem("Date/Time"))
    lb.setHorizontalHeaderItem(2,QTableWidgetItem("Size"))    
    lb.setHorizontalHeaderItem(3,QTableWidgetItem("Comment"))
    lb.setSortingEnabled(True)

    self.refill()
    lb.resizeColumnsToContents()
    
    if len(filename)>0:
      for i in range(lb.rowCount()):
        if filename == lb.item(i,0).data(32).getDisplayName():
          lb.setCurrentCell(i,3)
          break
    
    mb = self.menuBar()
    mf = mb.addMenu('&File')
    mf.addAction("Sort by name", self.sbn, "Ctrl+N")
    mf.addAction("Sort by date", self.sbd, "Ctrl+D")
    mf.addAction("Sort by size", self.sbs, "Ctrl+Z")
    mf.addAction("Sort by comment", self.sbc, "Ctrl+.")
    mf.addAction("Restore comment from database", self.restore_from_database, "Ctrl+R")
    mf.addSeparator()
    mf.addAction("Quit", self.close, QKeySequence.Quit)
    mf.addAction("About", self.about, QKeySequence.HelpContents)

    self.setWindowTitle("DirNotes   Alt-F for menu  Dir: "+self.curPath)
    self.setMinimumSize(600,700)
    self.setWindowIcon(QIcon(QPixmap(icon)))
    lb.setFocus()

  def closeEvent(self,e):
    print("closing")
  def sbd(self):
    print("sort by date")
    self.lb.sortItems(1,Qt.DescendingOrder)
  def sbs(self):
    print("sort by size")
    self.lb.sortItems(2)
  def sbn(self):
    print("sort by name")
    self.lb.sortItems(0)
  def about(self):
    HelpWidget(self)
  def sbc(self):
    print("sort by comment")
    self.lb.sortItems(3,Qt.DescendingOrder)
  def newDir(self):
    print("change dir to "+self.dirLeft.currentPath())
  def double(self,row,col):
    print_v("double click {} {}".format(row, col))
    fo = self.lb.item(row,0).file_object
    if col==0 and fo.isDir():
      print_v("double click on {}".format(fo.getName()))
      self.curPath = fo.getName()
      self.refill()
  def copyFile(self):
    # get current selection
    r, c = self.lb.currentRow(), self.lb.currentColumn()
    fo = self.lb.item(r,c).file_object
    if not fo.isDir() and not fo.isLink():  # TODO: add check for socket 
      print_v(f"copy file {fo.getName()}")
      # open the dir.picker
      r = QFileDialog.getExistingDirectory(self.parent, "Select destination for FileCopy")
      print_v(f"copy to {r}")
      if r:
        dest = os.path.join(r,fo.getDisplayName())
        try:
          shutil.copy2(fo.getName(), dest) # copy2 preserves the xattr
          f = FileObj(dest)       # can't make the FileObj until it exists
          f.setDbComment(self.db,fo.getDbComment())
        except:
          errorBox(f"file copy to <{dest}> failed; check permissions")
    pass
      
  def refill(self):
    self.refilling = True
    self.lb.sortingEnabled = False
    
    (self.modeShow.setText("View and edit file comments stored in extended attributes\n(xattr: user.xdg.comment)") 
      if mode=="xattr" else 
      self.modeShow.setText("View and edit file comments stored in the database \n(~/.dirnotes.db)"))
    self.lb.clearContents()
    small_font = QFont("",8)
    dirIcon = QIcon.fromTheme('folder')
    fileIcon = QIcon.fromTheme('text-x-generic')
    linkIcon = QIcon.fromTheme('emblem-symbolic-link')
    current, dirs, files = next(os.walk(self.curPath,followlinks=True))
    dirs.sort()
    files.sort()
    
    if current != '/':
      dirs.insert(0,"..")
    d = dirs + files
    self.lb.setRowCount(len(d))

    #~ self.files = {}
    self.files = []
    # this is a list of all the file
    #~ print("insert {} items into cleared table {}".format(len(d),current))
    for i,name in enumerate(d):
      this_file = FileObj(os.path.join(current,name))
      this_file.loadDbComment(self.db)
      print_v("FileObj created as {} and the db-comment is <{}>".format(this_file.displayName, this_file.dbComment))
      #~ print("insert order check: {} {} {} {}".format(d[i],i,this_file.getName(),this_file.getDate()))
      #~ self.files.update({this_file.getName(),this_file})
      self.files = self.files + [this_file]
      display_name = this_file.getDisplayName()
      if this_file.getSize() == FileObj.FILE_IS_DIR:
        item = SortableTableWidgetItem(display_name,' '+display_name, this_file)  # directories sort first
      else:
        item = SortableTableWidgetItem(display_name,display_name, this_file)
      item.setData(32,this_file)  # keep a hidden copy of the file object
      item.setToolTip(this_file.getName())
      self.lb.setItem(i,0,item)
      #lb.itemAt(i,0).setFlags(Qt.ItemIsEnabled) #NoItemFlags) 

      # get the comment from database & xattrs, either can fail
      comment = this_file.getComment()
      other_comment = this_file.getOtherComment()
      ci = SortableTableWidgetItem(comment,'',this_file)
      ci.setToolTip(f"comment: {comment}\ncomment date: {this_file.getDbDate()}\nauthor: {this_file.getDbAuthor()}")
      if other_comment != comment:
        ci.setBackground(QBrush(QColor(255,255,160)))
        print_v("got differing comments <{}> and <{}>".format(comment, other_comment))
      self.lb.setItem(i,3,ci)

      dt = this_file.getDate()
      da = SortableTableWidgetItem(dnDataBase.getShortDate(dt),dt,this_file)
      da.setToolTip(time.strftime(DATE_FORMAT,time.localtime(dt)))
      self.lb.setItem(i,1,da)

      si = this_file.getSize()
      if this_file.isDir():
        sa = SortableTableWidgetItem('',0,this_file)
        item.setIcon(dirIcon)
      elif this_file.isLink():
        sa = SortableTableWidgetItem('symlink',-1,this_file)
        item.setIcon(linkIcon)
        dst = os.path.realpath(this_file.getName())
        sa.setToolTip(f"symlink: {dst}")
      else:
        sa = SortableTableWidgetItem(str(si),si,this_file)
        item.setIcon(fileIcon)
      sa.setTextAlignment(Qt.AlignRight)
      self.lb.setItem(i,2,sa)

    self.refilling = False
    self.lb.sortingEnabled = True
    self.lb.resizeColumnToContents(1)
      
  def change(self,x):
    if self.refilling:
      return
    print_v("debugging " + x.text() + " r:" + str(x.row()) + " c:" + str(x.column()))
    print_v("      selected file: "+self.lb.item(x.row(),0).file_object.getName())
    the_file = self.lb.item(x.row(),0).file_object
    print_v("      and the row file is "+the_file.getName())
    the_file.setDbComment(self.db,str(x.text()))
    r = the_file.setXattrComment(str(x.text())) 
    if r:
      the_file.setDbComment(self.db,x.text())

  def switchMode(self):
    global mode
    mode = "xattr" if mode == "db" else "db" 
    self.refill()

  # TODO: this may not be needed
  def restore_from_database(self):
    print("restore from database")
    # retrieve the full path name
    fileName = str(self.lb.item(self.lb.currentRow(),0).file_object.getName())
    print("using filename: "+fileName)
    existing_comment = str(self.lb.item(self.lb.currentRow(),3).text())
    print("restore....existing="+existing_comment+"=")
    if len(existing_comment) > 0:
      m = QMessageBox() 
      m.setText("This file already has a comment. Overwrite?")
      m.setStandardButtons(QMessageBox.Ok | QMessageBox.Cancel);
      if m.exec_() != QMessageBox.Ok:
        return
    fo_row = self.db.getData(fileName)
    if fo_row and len(fo_row)>1:
      comment = fo_row[3]
      print(fileName,fo_row[0],comment) 
      the_file = dn.files[self.lb.currentRow()]
      the_file.setComment(comment)
      self.lb.setItem(self.lb.currentRow(),3,QTableWidgetItem(comment))
    
def parse():
  parser = argparse.ArgumentParser(description='dirnotes application')
  parser.add_argument('dirname',metavar='dirname',type=str,
    help='directory or file [default=current dir]',default=".",nargs='?')
  #parser.add_argument('dirname2',help='comparison directory, shows two-dirs side-by-side',nargs='?')
  parser.add_argument('-V','--version',action='version',version='%(prog)s '+VERSION)
  parser.add_argument('-v','--verbose',action='count',help="verbose, almost debugging")
  group = parser.add_mutually_exclusive_group()
  group.add_argument( '-s','--sort-by-size',action='store_true')
  group.add_argument( '-m','--sort-by-date',action='store_true')
  parser.add_argument('-c','--config', dest='config_file',help="config file (json format; default ~/.dirnotes.json)")
  parser.add_argument('-x','--xattr', action='store_true',help="start up in xattr mode")
  parser.add_argument('-d','--db',    action='store_true',help="start up in database mode (default)")  
  return parser.parse_args()

if __name__=="__main__":
  # TODO: delete this after debugging
  #from PyQt5.QtCore import pyqtRemoveInputHook
  #pyqtRemoveInputHook()

  p = parse()
  if len(p.dirname)>1 and p.dirname[-1]=='/':
    p.dirname = p.dirname[:-1]
  if os.path.isdir(p.dirname):
    p.dirname = p.dirname + '/'
  print_v(f"using {p.dirname}")
  verbose = p.verbose
  
  config_file = p.config_file if p.config_file else DEFAULT_CONFIG_FILE
  config_file = os.path.expanduser(config_file)
  config = DEFAULT_CONFIG
  try:
    with open(config_file,"r") as f:
      config = json.load(f)
  except json.JSONDecodeError:
    print(f"problem reading config file {config_file}; check the .json syntax")
  except FileNotFoundError:
    print(f"config file {config_file} not found, using the default settings and writing a default")
    try:
      with open(config_file,"w") as f:
        json.dump(config,f,indent=4)
    except:
      print(f"problem creating the file {config_file}")
  
  print_v(f"here is the .json {repr(config)}")
  dbName = os.path.expanduser(config["database"])
  db = dnDataBase(dbName).db
  xattr_comment = config["xattr_tag"]
  xattr_author  = xattr_comment + ".author"
  xattr_date    = xattr_comment + ".date"

  mode = "xattr" if p.xattr else "db"

  a = QApplication([])
  mainWindow = DirNotes(p.dirname,db,config["start_mode"])
  mainWindow.show()
  
  if p.sort_by_date:
    mainWindow.sbd()
  if p.sort_by_size:
    mainWindow.sbs()

  a.exec_()
  
  #xattr.setxattr(filename,COMMENT_KEY,commentText)

''' files from directories
use os.isfile()
os.isdir()
current, dirs, files = os.walk("path").next()
possible set folllowLinks=True'''

''' notes from the wdrm project
table showed 
filename, size, date size, date, desc

at start, fills the list of all the files
skip the . entry
'''

''' should we also do user.xdg.tags="TagA,TagB" ?
user.charset
user.creator=application_name or user.xdg.creator
user.xdg.origin.url
user.xdg.language=[RFC3066/ISO639]
user.xdg.publisher
'''

''' TODO: add cut-copy-paste for comments '''

''' TODO: also need a way to display-&-restore comments from the database '''

''' TODO: implement startup -s and -m for size and date '''

''' TODO: add an icon for the app '''

''' TODO: create 'show comment history' popup '''

''' TODO: add dual-pane for file-move, file-copy '''
  
''' commandline xattr
getfattr -h (don't follow symlink) -d (dump all properties)
'''
''' if the args line contains a file, jump to it '''