pypdfocr_watcher.py

"""
Something
"""

import sys, os
import re
import logging
import shutil
import time
import glob

from threading import Lock

from watchdog.observers import Observer
from watchdog.events import LoggingEventHandler
from watchdog.events import FileSystemEventHandler

        
class PyPdfWatcher(FileSystemEventHandler):
    """
        Watch a folder for new pdf files.

        If new file event, then add it to queue with timestamp.
        If file mofified event, then change timestamp in queue.
        Every few seconds pop-off queue and if timestamp older than 3 seconds,
        process the file else, push it back onto queue.
    """
    events = {}
    events_lock = Lock()

    def __init__(self, monitor_dir, config):
        FileSystemEventHandler.__init__(self)

        self.monitor_dir = monitor_dir
        if not config: config = {}

        self.scan_interval = config.get('scan_interval', 3) # If no updates in 3 seconds (or user specified option in config file) process file

    def start(self):
        self.observer = Observer()
        self.observer.schedule(self, self.monitor_dir)
        self.observer.start()
        print("Starting to watch for new pdfs in %s" % (self.monitor_dir))
        while True:
            logging.info("Sleeping for %d seconds" % self.scan_interval)
            time.sleep(self.scan_interval)
            newFile = self.check_queue()
            if newFile:
                yield newFile
        self.observer.join()
            

    def stop(self):
        self.observer.stop()
        
    def rename_file_with_spaces(self, pdf_filename):
        """
            Rename any portion of a filename that has spaces in the basename with underscores.
            Does not affect spaces in the directory path.

            :param pdf_filename: Filename to remove spaces
            :type pdf_filename: string
            :returns: Modified filename
            :rtype: string
        """
        filepath, filename = os.path.split(pdf_filename)
        if ' ' in filename:
            newFilename = os.path.join(filepath, filename.replace(' ','_'))
            logging.debug("Renaming spaces")
            logging.debug("---> %s \n ------> %s" % (pdf_filename, newFilename))
            shutil.move(pdf_filename, newFilename) 
            return newFilename
        else:
            return pdf_filename

    def check_for_new_pdf(self,ev_path):
        """
            Called by the file watching api on any file creations/modifications.
            For any file ending with ".pdf", but not "_ocr.pdf", it adds new files
            to the event queue with the current time stamp, or it updates existing files in
            the queue with the current timestamp.  This queue is used to track files and
            keep track of their last "touched" time, so we can start processing a file if
            :func:`check_queue` finds a file that hasn't been touched in a while.

            If the file does note exist in the events dict:

                - Add it with the current time

            Otherwise:
                
                - If the file time is marked as -1, delete it from the dict
                - Else, update the time in the dict to the current time

        """
        if ev_path.endswith(".pdf"):
            if not ev_path.endswith("_ocr.pdf"):
                PyPdfWatcher.events_lock.acquire()
                if not ev_path in PyPdfWatcher.events:
                    PyPdfWatcher.events[ev_path] = time.time()
                    logging.info ("Adding %s to event queue" % ev_path)
                else:
                    if PyPdfWatcher.events[ev_path] == -1:
                        logging.info ( "%s removing from event queue" % (ev_path))
                        del PyPdfWatcher.events[ev_path]
                    else: 
                        newTime = time.time()
                        logging.debug ( "%s already in event queue, updating timestamp to %d" % (ev_path, newTime))
                        PyPdfWatcher.events[ev_path]  = newTime
                PyPdfWatcher.events_lock.release()

                      
              
    def on_created(self, event):
        logging.debug ("on_created: %s at time %d" % (event.src_path, time.time()))
        self.check_for_new_pdf(event.src_path)

    def on_moved(self, event):
        logging.debug ("on_moved: %s" % event.src_path)
        self.check_for_new_pdf(event.dest_path)

    def on_modified(self, event):
        logging.debug ("on_modified: %s" % event.src_path)
        self.check_for_new_pdf(event.src_path)

    def check_queue(self):
        """
            This function is called at regular intervals by :func:`start`.
            
            Iterate through the events, and if there is any with a timestamp
            greater than the scan_interval, return it and set its timestamp to -1
            for purging later.

            :returns: Filename if available to process, otherwise None.
        """
        now = time.time()
        PyPdfWatcher.events_lock.acquire()
        for monitored_file, timestamp in PyPdfWatcher.events.items():
            if timestamp == -1:
                del PyPdfWatcher.events[monitored_file]
            elif now - timestamp > self.scan_interval:
                logging.info("Processing new file %s" % (monitored_file))
                # Remove this file from the dict
                del PyPdfWatcher.events[monitored_file]
                monitored_file = self.rename_file_with_spaces(monitored_file)
                PyPdfWatcher.events[monitored_file] = -1 # Add back into queue and mark as not needing further action in the event handler
                PyPdfWatcher.events_lock.release()
                return monitored_file
        PyPdfWatcher.events_lock.release()
        return None