pdf-ocr-hotfolder/pdf_ocr_hotfolder/service.py

"""Hauptservice: Hotfolder via watchdog, ThreadPool für PDF-Verarbeitung."""
from __future__ import annotations

import logging
import shutil
import signal
import threading
import time
from concurrent.futures import Future, ThreadPoolExecutor
from pathlib import Path

from watchdog.events import FileSystemEvent, FileSystemEventHandler
from watchdog.observers import Observer

from .config import Config
from .processor import ProcessResult, process_pdf
from .uploaders import notify_email, upload_folder, upload_nextcloud, upload_sftp

log = logging.getLogger(__name__)


class PreflightError(RuntimeError):
    """Erforderliche externe Binaries fehlen."""


# Pflicht-Binaries für ocrmypdf
_REQUIRED_BINARIES = ("tesseract", "gs")


def check_preflight() -> None:
    """Prüft, ob alle externen Abhängigkeiten (Tesseract, Ghostscript) installiert sind.

    Wirft PreflightError mit Liste der fehlenden Binaries.
    """
    missing = [b for b in _REQUIRED_BINARIES if shutil.which(b) is None]
    if missing:
        raise PreflightError(
            "Fehlende Abhängigkeiten: " + ", ".join(missing)
            + ". Bitte installieren: sudo apt install tesseract-ocr ghostscript"
        )


def _is_pdf(path: Path) -> bool:
    return path.suffix.lower() == ".pdf" and path.is_file()


def _wait_until_stable(path: Path, checks: int = 3, interval: float = 1.0) -> bool:
    """Wartet bis Datei nicht mehr wächst (Scanner schreibt mehrmals)."""
    last = -1
    stable_count = 0
    for _ in range(60):  # max ~60s
        try:
            size = path.stat().st_size
        except FileNotFoundError:
            return False
        if size == last and size > 0:
            stable_count += 1
            if stable_count >= checks:
                return True
        else:
            stable_count = 0
            last = size
        time.sleep(interval)
    return False


class _Handler(FileSystemEventHandler):
    def __init__(self, service: "HotfolderService") -> None:
        self.service = service

    def on_created(self, event: FileSystemEvent) -> None:
        if not event.is_directory:
            self.service.enqueue(Path(event.src_path))

    def on_moved(self, event: FileSystemEvent) -> None:
        if not event.is_directory:
            self.service.enqueue(Path(event.dest_path))

    def on_closed(self, event: FileSystemEvent) -> None:
        if not event.is_directory:
            self.service.enqueue(Path(event.src_path))


class HotfolderService:
    def __init__(self, cfg: Config) -> None:
        self.cfg = cfg
        self._executor = ThreadPoolExecutor(
            max_workers=cfg.ocr.max_workers,
            thread_name_prefix="ocr",
        )
        self._observer: Observer | None = None
        self._stop = threading.Event()
        self._inflight: set[str] = set()
        self._lock = threading.Lock()
        self._success_count = 0
        self._error_count = 0

    @property
    def success_count(self) -> int:
        return self._success_count

    @property
    def error_count(self) -> int:
        return self._error_count

    # ---- Setup ----

    def ensure_dirs(self) -> None:
        for p in (self.cfg.paths.incoming, self.cfg.paths.outgoing,
                  self.cfg.paths.working, self.cfg.paths.error):
            p.mkdir(parents=True, exist_ok=True)

    # ---- Lifecycle ----

    def run(self) -> None:
        check_preflight()
        self.ensure_dirs()
        self._scan_existing()

        self._observer = Observer()
        self._observer.schedule(_Handler(self), str(self.cfg.paths.incoming), recursive=False)
        self._observer.start()
        log.info("Hotfolder läuft. Watching: %s", self.cfg.paths.incoming)

        signal.signal(signal.SIGTERM, lambda *_: self._stop.set())
        signal.signal(signal.SIGINT, lambda *_: self._stop.set())

        try:
            while not self._stop.is_set():
                self._stop.wait(1.0)
        finally:
            self.shutdown()

    def run_once(self) -> int:
        """Verarbeitet alle bereits im incoming-Ordner liegenden PDFs und beendet sich.

        Returns:
            Anzahl fehlgeschlagener PDFs (0 = alles ok).
        """
        check_preflight()
        self.ensure_dirs()
        self._scan_existing()
        self._executor.shutdown(wait=True)
        log.info("One-shot fertig: %d ok, %d Fehler",
                 self._success_count, self._error_count)
        return self._error_count

    def shutdown(self) -> None:
        log.info("Shutdown läuft...")
        if self._observer:
            self._observer.stop()
            self._observer.join(timeout=5)
        self._executor.shutdown(wait=True, cancel_futures=False)
        log.info("Shutdown ok.")

    # ---- Queue ----

    def _scan_existing(self) -> None:
        """Beim Start: bereits liegende PDFs aufgreifen."""
        for p in self.cfg.paths.incoming.iterdir():
            if _is_pdf(p):
                self.enqueue(p)

    def enqueue(self, path: Path) -> None:
        if not _is_pdf(path):
            return
        key = str(path.resolve())
        with self._lock:
            if key in self._inflight:
                return
            self._inflight.add(key)
        fut = self._executor.submit(self._process, path)
        fut.add_done_callback(lambda f, k=key: self._done(k, f))

    def _done(self, key: str, fut: Future) -> None:
        with self._lock:
            self._inflight.discard(key)
        exc = fut.exception()
        if exc:
            log.exception("Worker-Exception", exc_info=exc)

    # ---- Processing ----

    def _process(self, path: Path) -> None:
        if not _wait_until_stable(path):
            log.warning("Datei nicht stabilisiert, überspringe: %s", path)
            return
        if not path.exists():
            return

        result: ProcessResult = process_pdf(
            src=path,
            working_dir=self.cfg.paths.working,
            outgoing_dir=self.cfg.paths.outgoing,
            error_dir=self.cfg.paths.error,
            ocr_cfg=self.cfg.ocr,
            vera_cfg=self.cfg.verapdf,
        )

        with self._lock:
            if result.success:
                self._success_count += 1
            else:
                self._error_count += 1

        if result.success:
            self._dispatch_uploads(result.output)
        self._notify(result)

    def _dispatch_uploads(self, pdf: Path) -> None:
        upload_folder(pdf, self.cfg.folder, self.cfg.paths.outgoing)
        if self.cfg.nextcloud.enabled:
            upload_nextcloud(pdf, self.cfg.nextcloud)
        if self.cfg.sftp.enabled:
            upload_sftp(pdf, self.cfg.sftp)

    def _notify(self, result: ProcessResult) -> None:
        if result.success:
            subject = f"[pdf-ocr] OK: {result.source.name}"
            body = f"Datei verarbeitet: {result.output}\n"
            if result.verapdf_passed is not None:
                body += f"veraPDF: {'PASS' if result.verapdf_passed else 'FAIL'}\n"
        else:
            subject = f"[pdf-ocr] FEHLER: {result.source.name}"
            body = f"Fehler beim Verarbeiten von {result.source}\n\n{result.error}\n"
        notify_email(self.cfg.email, subject, body, result.success)