OCRmyPDF/tests/plugins/tesseract_cache.py

# © 2020 James R. Barlow: github.com/jbarlow83
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import argparse
import json
import logging
import platform
import re
import shutil
from functools import partial
from pathlib import Path
from subprocess import PIPE, CalledProcessError, CompletedProcess
from unittest.mock import patch

from ocrmypdf import hookimpl
from ocrmypdf.builtin_plugins.tesseract_ocr import TesseractOcrEngine
from ocrmypdf.exec import run

log = logging.getLogger(__name__)

TESTS_ROOT = Path(__file__).resolve().parent.parent
CACHE_ROOT = TESTS_ROOT / 'cache'


parser = argparse.ArgumentParser(
    prog='tesseract-cache', description='cache output of tesseract'
)
parser.add_argument('-l', '--language', action='append')
parser.add_argument('imagename')
parser.add_argument('outputbase')
parser.add_argument('configfiles', nargs='*')
parser.add_argument('--user-words', type=str)
parser.add_argument('--user-patterns', type=str)
parser.add_argument('-c', action='append')
parser.add_argument('--psm', type=int)
parser.add_argument('--oem', type=int)


def get_cache_folder(source_pdf, run_args, parsed_args):
    def slugs():
        yield ''  # so we don't start with a '-' which makes rm difficult
        for arg in run_args[1:]:
            if arg == parsed_args.imagename:
                yield Path(parsed_args.imagename).name
            elif arg == parsed_args.outputbase:
                yield Path(parsed_args.outputbase).name
            elif arg == '-c' or arg.startswith('textonly'):
                pass
            else:
                yield arg

    argv_slug = '__'.join(slugs())
    argv_slug = argv_slug.replace('/', '___')

    return Path(CACHE_ROOT) / Path(source_pdf).stem / argv_slug


def cached_run(options, run_args, **run_kwargs):
    run_args = [str(arg) for arg in run_args]  # flatten PosixPaths
    args = parser.parse_args(run_args[1:])

    if args.imagename in ('stdin', '-'):
        return run(run_args, **run_kwargs)

    source_file = options.input_file
    cache_folder = get_cache_folder(source_file, run_args, args)
    cache_folder.mkdir(parents=True, exist_ok=True)

    log.debug("Using Tesseract cache {cache_folder}")

    if (cache_folder / 'stderr.bin').exists():
        log.debug("Cache HIT")

        # Replicate stdout/err
        if args.outputbase != 'stdout':
            if not args.configfiles:
                args.configfiles.append('txt')
            for configfile in args.configfiles:
                # cp cache -> output
                tessfile = args.outputbase + '.' + configfile
                shutil.copy(str(cache_folder / configfile) + '.bin', tessfile)
        return CompletedProcess(
            args=run_args,
            returncode=0,
            stdout=(cache_folder / 'stdout.bin').read_bytes(),
            stderr=(cache_folder / 'stderr.bin').read_bytes(),
        )

    log.debug("Cache MISS")

    cache_kwargs = {
        k: v for k, v in run_kwargs.items() if k not in ('stdout', 'stderr')
    }
    assert cache_kwargs['check']
    try:
        p = run(run_args, stdout=PIPE, stderr=PIPE, **cache_kwargs)
    except CalledProcessError as e:
        log.exception(e)
        raise  # Pass exception onward

    # Update cache
    (cache_folder / 'stdout.bin').write_bytes(p.stdout)
    (cache_folder / 'stderr.bin').write_bytes(p.stderr)

    if args.outputbase != 'stdout':
        if not args.configfiles:
            args.configfiles.append('txt')

        for configfile in args.configfiles:
            if configfile not in ('hocr', 'pdf', 'txt'):
                continue
            # cp pwd/{outputbase}.{configfile} -> {cache}/{configfile}
            tessfile = args.outputbase + '.' + configfile
            shutil.copy(tessfile, str(cache_folder / configfile) + '.bin')

    manifest = {}
    manifest['tesseract_version'] = TesseractOcrEngine.version().replace('\n', ' ')
    manifest['platform'] = platform.platform()
    manifest['python'] = platform.python_version()
    manifest['argv_slug'] = cache_folder.name
    manifest['sourcefile'] = str(Path(source_file).relative_to(TESTS_ROOT))

    def clean_sys_argv():
        for arg in run_args[1:]:
            yield re.sub(r'.*/com.github.ocrmypdf[^/]+[/](.*)', r'$TMPDIR/\1', arg)

    manifest['args'] = list(clean_sys_argv())
    with (Path(CACHE_ROOT) / 'manifest.jsonl').open('a') as f:
        json.dump(manifest, f)
        f.write('\n')
        f.flush()


class CacheOcrEngine(TesseractOcrEngine):
    @staticmethod
    def get_orientation(input_file, options):
        with patch('ocrmypdf.exec.tesseract.run', new=partial(cached_run, options)):
            return TesseractOcrEngine.get_orientation(input_file, options)

    @staticmethod
    def generate_hocr(input_file, output_hocr, output_text, options):
        with patch('ocrmypdf.exec.tesseract.run', new=partial(cached_run, options)):
            TesseractOcrEngine.generate_hocr(
                input_file, output_hocr, output_text, options
            )

    @staticmethod
    def generate_pdf(input_file, output_pdf, output_text, options):
        with patch('ocrmypdf.exec.tesseract.run', new=partial(cached_run, options)):
            TesseractOcrEngine.generate_pdf(
                input_file, output_pdf, output_text, options
            )


@hookimpl
def get_ocr_engine():
    return CacheOcrEngine()