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_any_event(self, event: FileSystemEvent):
  26         if event.is_directory:
  27             return
  28         if not event.src_path.endswith(".pdf"):
  29             return
  30         pdf_file = Path(event.src_path)
  31         if pdf_file.exists():
  32             self.scanner_workflow.process_pdf(pdf_file)
  33
  34
  35 class ScannerWorkflow:
  36     base_dir = None
  37     failure_dir = None
  38     output_dir = None
  39     lock_file = None
  40     input_dir = None
  41     process_dir = None
  42     ocrmypdf_opts = ["-r", "-q", "--deskew", "--clean"]
  43
  44     def __init__(
  45         self,
  46         base_dir: Union[Path, str] = ".",
  47         input_dir: Union[Path, str] = "input",
  48         output_dir: Union[Path, str] = "output",
  49         failure_dir: Union[Path, str] = "failure",
  50         process_dir: Union[Path, str] = "process",
  51         lock_file: Union[Path, str] = ".lock",
  52     ):
  53         def concat_if_not_abs(dir1: Path, dir2: Path):
  54             if dir2.is_absolute():
  55                 return dir2
  56             else:
  57                 return dir1 / dir2
  58
  59         super().__init__()
  60         self.base_dir = Path(base_dir)
  61         self.input_dir = concat_if_not_abs(self.base_dir, Path(input_dir))
  62         self.output_dir = concat_if_not_abs(self.base_dir, Path(output_dir))
  63         self.failure_dir = concat_if_not_abs(self.base_dir, Path(failure_dir))
  64         self.process_dir = concat_if_not_abs(self.base_dir, Path(process_dir))
  65         self.lock_file = concat_if_not_abs(self.base_dir, Path(lock_file))
  66         self.lock = FileLock(self.lock_file)
  67         self.base_dir.mkdir(parents=True, exist_ok=True)
  68         self.input_dir.mkdir(parents=True, exist_ok=True)
  69         self.failure_dir.mkdir(parents=True, exist_ok=True)
  70         self.process_dir.mkdir(parents=True, exist_ok=True)
  71         self.output_dir.mkdir(parents=True, exist_ok=True)
  72
  73     def calculate_name(self, name: str):
  74         res = re.match(
  75             r"(?P<scanner>[^_]+)_(?P<month>\d{2})(?P<day>\d{2})(?P<year>\d{4})_"
  76             r"(?P<time>\d+)_(?P<counter>\d+)\.pdf",
  77             str(name),
  78         )
  79         if res:
  80             name = (
  81                 f"{res.group('scanner')}_"
  82                 f"{res.group('year')}{res.group('month')}{res.group('day')}_"
  83                 f"{res.group('time')}_{res.group('counter')}.pdf"
  84             )
  85         return name
  86
  87     def process_pdf(self, pdf_file: Union[Path, str]):
  88         """Process a single PDF."""
  89         pdf_file = Path(pdf_file)
  90         orig_pdf = pdf_file
  91         # move to the processing directory
  92         pdf_file = pdf_file.rename(
  93             self.process_dir / self.calculate_name(pdf_file.name)
  94         )
  95         output_file = self.output_dir / pdf_file.name
  96         res = subprocess.run(["ocrmypdf", *self.ocrmypdf_opts, pdf_file, output_file])
  97         if res.returncode != 0:
  98             error(f"Unable to properly OCR pdf: {res.stdout} {res.stderr}")
  99             return
 100         pdf_file.unlink()
 101         info("Processed {orig_pdf} into {output_file}")
 102
 103     def event_loop(self):
 104         """Main event loop; called from the command line."""
 105         ev = ScannerWorkflowEvent(scanner_workflow=self)
 106         observer = Observer()
 107         observer.schedule(ev, self.input_dir, recursive=True)
 108         observer.start()
 109         # process any PDFs in input_dir
 110         for file in self.input_dir.iterdir():
 111             self.process_pdf(file)
 112         try:
 113             while observer.is_alive():
 114                 observer.join(1)
 115         finally:
 116             observer.stop()
 117             observer.join()
 118
 119
 120 @click.command()
 121 @click.option(
 122     "-i",
 123     "--input-dir",
 124     default="input",
 125     help="Directory to look for incoming PDFs",
 126 )
 127 @click.option(
 128     "-p",
 129     "--process-dir",
 130     default="process",
 131     help="Directory to store PDFs being processed",
 132 )
 133 @click.option(
 134     "-o",
 135     "--output-dir",
 136     default="output",
 137     help="Directory to output OCRed PDFs",
 138 )
 139 @click.option(
 140     "-f",
 141     "--failure-dir",
 142     default="failure",
 143     help="Directory to store failed PDFs",
 144 )
 145 @click.option(
 146     "-b",
 147     "--base-dir",
 148     default=".",
 149     help="Base directory",
 150 )
 151 @click.option(
 152     "-l",
 153     "--lock-file",
 154     default=".lock",
 155     help="Lock file to ensure only one instance is running",
 156 )
 157 def cli(input_dir, process_dir, output_dir, failure_dir, base_dir, lock_file):
 158     """OCR scanner output and save in directory"""
 159     sw = ScannerWorkflow(
 160         input_dir=input_dir,
 161         process_dir=process_dir,
 162         output_dir=output_dir,
 163         failure_dir=failure_dir,
 164         base_dir=base_dir,
 165         lock_file=lock_file,
 166     )
 167     try:
 168         with sw.lock.acquire(timeout=10):
 169             sw.event_loop()
 170     except Timeout:
 171         print("Another instance holds the lock")
 172         exit(1)
 173
 174
 175 cli()