watcher.py

#!/usr/bin/env python

# System imports
import subprocess
import zipfile
import shutil
from pathlib import Path
from os import walk, environ

# Internal imports
from app.helpers import get_iiif_file_destination, check_pronom_id
from viaa.observability import logging
from viaa.configuration import ConfigParser

# External imports
import inotify.adapters


"""
Listen to file write events in a directory.
If a relevant file is written in the directory, execute corresponding scripts.
Remove the original file after the scripts have been executed.
"""

if __name__ == "__main__":
    i = inotify.adapters.InotifyTree("/export/home")
    config = ConfigParser()
    logger = logging.get_logger("watcher", config)

    workfolder_base = "/opt/image-processing-workfolder"

    logger.info("Watching dir : %s", "/export/home")

    for event in i.event_gen(yield_nones=False):
        (_, type_names, path, filename) = event

        # Only listen to write events
        if "IN_CLOSE_WRITE" not in type_names:
            continue

        # Only look at zip files
        if not filename.endswith(".zip"):
            print(f"Ignoring file {filename}")
            continue

        # Unpack zip to working directory
        full_file_path = path + "/" + filename
        workfolder = workfolder_base + "/" + Path(full_file_path).stem

        logger.debug("Received event for %s", full_file_path)

        try:
            with zipfile.ZipFile(full_file_path, "r") as zip_ref:
                zip_ref.extractall(workfolder)
        except zipfile.BadZipFile:
            logger.debug("Invalid zip file %s", full_file_path)
            continue

        essence_files_in_workfolder = [
            file
            for file in next(walk(workfolder), (None, None, []))[2]
            if check_pronom_id(
                workfolder + "/" + file, "fmt/353"
            )  # Tagged Image File Format (tif)
        ]
        file_to_transform = essence_files_in_workfolder[0]

        metadata_files_in_workfolder = [
            file
            for file in next(walk(workfolder), (None, None, []))[2]
            if check_pronom_id(
                workfolder + "/" + file, "fmt/101"
            )  # Extensible Markup Language (xml)
        ]
        file_to_transform_path = workfolder + "/" + file_to_transform
        sidecar_path = workfolder + "/" + metadata_files_in_workfolder[0]

        # Calculate visibilty
        visibility = "public" if "public" in path else "restricted"

        destination = get_iiif_file_destination(
            file_to_transform_path, sidecar_path, visibility
        )

        my_env = environ.copy()
        my_env["PATH"] = f"/opt/iiif-image-processing/env/bin:{my_env['PATH']}"

        logger.debug("Running transform_file for %s", file_to_transform_path)
        logger.debug("Destination %s", destination)

        # Transform image by executing scripts
        subprocess.run(
            "python3 /opt/iiif-image-processing/transform_file.py"
            + f" --file_path {file_to_transform_path}"
            + f" --destination {destination}",
            shell=True,
            check=True,
            env=my_env,
        )

        # Remove temporary files and folders
        logger.debug("Removing zip file %s", full_file_path)
        Path(full_file_path).unlink(missing_ok=True)

        try:
            logger.debug("Removing workfolder %s", workfolder)
            shutil.rmtree(workfolder)
        except OSError:
            logger.debug("Error removing workfolder %s", workfolder)