# Generated by Django 4.1.9 on 2023-06-29 19:29
import logging
import multiprocessing.pool
import shutil
import tempfile
import time
from pathlib import Path

import gnupg
from django.conf import settings
from django.db import migrations

from documents.parsers import run_convert

logger = logging.getLogger("paperless.migrations")


def _do_convert(work_package):
    (
        existing_encrypted_thumbnail,
        converted_encrypted_thumbnail,
        passphrase,
    ) = work_package

    try:
        gpg = gnupg.GPG(gnupghome=settings.GNUPG_HOME)

        logger.info(f"Decrypting thumbnail: {existing_encrypted_thumbnail}")

        # Decrypt png
        decrypted_thumbnail = existing_encrypted_thumbnail.with_suffix("").resolve()

        with open(existing_encrypted_thumbnail, "rb") as existing_encrypted_file:
            raw_thumb = gpg.decrypt_file(
                existing_encrypted_file,
                passphrase=passphrase,
                always_trust=True,
            ).data
            with open(decrypted_thumbnail, "wb") as decrypted_file:
                decrypted_file.write(raw_thumb)

        converted_decrypted_thumbnail = Path(
            str(converted_encrypted_thumbnail).replace("webp.gpg", "webp"),
        ).resolve()

        logger.info(f"Converting decrypted thumbnail: {decrypted_thumbnail}")

        # Convert to webp
        run_convert(
            density=300,
            scale="500x5000>",
            alpha="remove",
            strip=True,
            trim=False,
            auto_orient=True,
            input_file=f"{decrypted_thumbnail}[0]",
            output_file=str(converted_decrypted_thumbnail),
        )

        logger.info(
            f"Encrypting converted thumbnail: {converted_decrypted_thumbnail}",
        )

        # Encrypt webp
        with open(converted_decrypted_thumbnail, "rb") as converted_decrypted_file:
            encrypted = gpg.encrypt_file(
                fileobj_or_path=converted_decrypted_file,
                recipients=None,
                passphrase=passphrase,
                symmetric=True,
                always_trust=True,
            ).data

            with open(converted_encrypted_thumbnail, "wb") as converted_encrypted_file:
                converted_encrypted_file.write(encrypted)

        # Copy newly created thumbnail to thumbnail directory
        shutil.copy(converted_encrypted_thumbnail, existing_encrypted_thumbnail.parent)

        # Remove the existing encrypted PNG version
        existing_encrypted_thumbnail.unlink()

        # Remove the decrypted PNG version
        decrypted_thumbnail.unlink()

        # Remove the decrypted WebP version
        converted_decrypted_thumbnail.unlink()

        logger.info(
            "Conversion to WebP completed, "
            f"replaced {existing_encrypted_thumbnail.name} with {converted_encrypted_thumbnail.name}",
        )

    except Exception as e:
        logger.error(f"Error converting thumbnail (existing file unchanged): {e}")


def _convert_encrypted_thumbnails_to_webp(apps, schema_editor):
    start = time.time()

    with tempfile.TemporaryDirectory() as tempdir:
        work_packages = []

        if len(list(Path(settings.THUMBNAIL_DIR).glob("*.png.gpg"))) > 0:
            passphrase = settings.PASSPHRASE

            if not passphrase:
                raise Exception(
                    "Passphrase not defined, encrypted thumbnails cannot be migrated"
                    "without this",
                )

            for file in Path(settings.THUMBNAIL_DIR).glob("*.png.gpg"):
                existing_thumbnail = file.resolve()

                # Change the existing filename suffix from png to webp
                converted_thumbnail_name = Path(
                    str(existing_thumbnail).replace(".png.gpg", ".webp.gpg"),
                ).name

                # Create the expected output filename in the tempdir
                converted_thumbnail = (
                    Path(tempdir) / Path(converted_thumbnail_name)
                ).resolve()

                # Package up the necessary info
                work_packages.append(
                    (existing_thumbnail, converted_thumbnail, passphrase),
                )

            if len(work_packages):
                logger.info(
                    "\n\n"
                    "  This is a one-time only migration to convert thumbnails for all of your\n"
                    "  *encrypted* documents into WebP format. If you have a lot of encrypted documents, \n"
                    "  this may take a while, so a coffee break may be in order."
                    "\n",
                )

                with multiprocessing.pool.Pool(
                    processes=min(multiprocessing.cpu_count(), 4),
                    maxtasksperchild=4,
                ) as pool:
                    pool.map(_do_convert, work_packages)

                    end = time.time()
                    duration = end - start

                logger.info(f"Conversion completed in {duration:.3f}s")


class Migration(migrations.Migration):
    dependencies = [
        ("documents", "1036_alter_savedviewfilterrule_rule_type"),
    ]

    operations = [
        migrations.RunPython(
            code=_convert_encrypted_thumbnails_to_webp,
            reverse_code=migrations.RunPython.noop,
        ),
    ]