scanner_workflow.py

   1 #!/usr/bin/env python3
   2
   3 import click
   4 from watchdog.observers import Observer
   5 from watchdog.events import FileSystemEventHandler, FileSystemEvent
   6 from pathlib import Path
   7 from typing import Union
   8 from filelock import Timeout, FileLock
   9 import subprocess
  10 from logging import error, info, debug, warning
  11 import re
  12
  13
  14 class ScannerWorkflowEvent(FileSystemEventHandler):
  15     """Subclass of FileSystemEventHandler to handle OCRing PDFs"""
  16
  17     scanner_workflow = None
  18
  19     def __init__(self, scanner_workflow=None):
  20         super().__init__()
  21         self.scanner_workflow = scanner_workflow
  22         if not self.scanner_workflow:
  23             raise Error("No scanner_workflow passed to ScannerWorkflowEvent")
  24
  25     def on_closed(self, event: FileSystemEvent):
  26         if event.is_directory:
  27             return
  28         if not event.src_path.endswith(".pdf"):
  29             return
  30         self.scanner_workflow.process_pdf(event.src_path)
  31
  32
  33 class ScannerWorkflow:
  34     base_dir = None
  35     failure_dir = None
  36     output_dir = None
  37     lock_file = None
  38     input_dir = None
  39     process_dir = None
  40     ocrmypdf_opts = ["-r", "-q", "--deskew", "--clean"]
  41
  42     def __init__(
  43         self,
  44         base_dir: Union[Path, str] = ".",
  45         input_dir: Union[Path, str] = "input",
  46         output_dir: Union[Path, str] = "output",
  47         failure_dir: Union[Path, str] = "failure",
  48         process_dir: Union[Path, str] = "process",
  49         lock_file: Union[Path, str] = ".lock",
  50     ):
  51         def concat_if_not_abs(dir1: Path, dir2: Path):
  52             if dir2.is_absolute():
  53                 return dir2
  54             else:
  55                 return dir1 / dir2
  56
  57         super().__init__()
  58         self.base_dir = Path(base_dir)
  59         self.input_dir = concat_if_not_abs(self.base_dir, Path(input_dir))
  60         self.output_dir = concat_if_not_abs(self.base_dir, Path(output_dir))
  61         self.failure_dir = concat_if_not_abs(self.base_dir, Path(failure_dir))
  62         self.process_dir = concat_if_not_abs(self.base_dir, Path(process_dir))
  63         self.lock_file = concat_if_not_abs(self.base_dir, Path(lock_file))
  64         self.lock = FileLock(self.lock_file)
  65         self.base_dir.mkdir(parents=True, exist_ok=True)
  66         self.input_dir.mkdir(parents=True, exist_ok=True)
  67         self.failure_dir.mkdir(parents=True, exist_ok=True)
  68         self.process_dir.mkdir(parents=True, exist_ok=True)
  69         self.output_dir.mkdir(parents=True, exist_ok=True)
  70
  71     def calculate_name(self, name: str):
  72         res = re.match(
  73             r"(?P<scanner>[^_]+)_(?P<month>\d{2})(?P<day>\d{2})(?P<year>\d{4})_"
  74             r"(?P<time>\d+)_(?P<counter>\d+)\.pdf",
  75             str(name),
  76         )
  77         if res:
  78             name = (
  79                 f"{res.group('scanner')}_"
  80                 f"{res.group('year')}{res.group('month')}{res.group('day')}_"
  81                 f"{res.group('time')}_{res.group('counter')}.pdf"
  82             )
  83         return name
  84
  85     def process_pdf(self, pdf_file: Union[Path, str]):
  86         """Process a single PDF."""
  87         pdf_file = Path(pdf_file)
  88         # move to the processing directory
  89         pdf_file = pdf_file.rename(
  90             self.process_dir / self.calculate_name(pdf_file.name)
  91         )
  92         res = subprocess.run(
  93             ["ocrmypdf", *self.ocrmypdf_opts, pdf_file, self.output_dir / pdf_file.name]
  94         )
  95         if res.returncode != 0:
  96             error(f"Unable to properly OCR pdf: {res.stdout} {res.stderr}")
  97             return
  98         pdf_file.unlink()
  99
 100     def event_loop(self):
 101         """Main event loop; called from the command line."""
 102         ev = ScannerWorkflowEvent(scanner_workflow=self)
 103         observer = Observer()
 104         observer.schedule(ev, self.input_dir, recursive=True)
 105         observer.start()
 106         # process any PDFs in input_dir
 107         for file in self.input_dir.iterdir():
 108             self.process_pdf(file)
 109         try:
 110             while observer.is_alive():
 111                 observer.join(1)
 112         finally:
 113             observer.stop()
 114             observer.join()
 115
 116
 117 @click.command()
 118 @click.option(
 119     "-i",
 120     "--input-dir",
 121     default="input",
 122     help="Directory to look for incoming PDFs",
 123 )
 124 @click.option(
 125     "-p",
 126     "--process-dir",
 127     default="process",
 128     help="Directory to store PDFs being processed",
 129 )
 130 @click.option(
 131     "-o",
 132     "--output-dir",
 133     default="output",
 134     help="Directory to output OCRed PDFs",
 135 )
 136 @click.option(
 137     "-f",
 138     "--failure-dir",
 139     default="failure",
 140     help="Directory to store failed PDFs",
 141 )
 142 @click.option(
 143     "-b",
 144     "--base-dir",
 145     default=".",
 146     help="Base directory",
 147 )
 148 @click.option(
 149     "-l",
 150     "--lock-file",
 151     default=".lock",
 152     help="Lock file to ensure only one instance is running",
 153 )
 154 def cli(input_dir, process_dir, output_dir, failure_dir, base_dir, lock_file):
 155     """OCR scanner output and save in directory"""
 156     sw = ScannerWorkflow(
 157         input_dir=input_dir,
 158         process_dir=process_dir,
 159         output_dir=output_dir,
 160         failure_dir=failure_dir,
 161         base_dir=base_dir,
 162         lock_file=lock_file,
 163     )
 164     try:
 165         with sw.lock.acquire(timeout=10):
 166             sw.event_loop()
 167     except Timeout:
 168         print("Another instance holds the lock")
 169         exit(1)
 170
 171
 172 cli()