# Generated by Django 3.1.6 on 2021-02-07 22:26
import hashlib
import logging
import os
import shutil

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


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


def archive_name_from_filename_old(filename):
    return os.path.splitext(filename)[0] + ".pdf"


def archive_path_old(doc):
    if doc.filename:
        fname = archive_name_from_filename_old(doc.filename)
    else:
        fname = "{:07}.pdf".format(doc.pk)

    return os.path.join(
        settings.ARCHIVE_DIR,
        fname
    )


def archive_name_from_filename_new(filename):
    name, ext = os.path.splitext(filename)
    if ext == ".pdf":
        return filename
    else:
        return filename + ".pdf"


def archive_path_new(doc):
    if doc.filename:
        fname = archive_name_from_filename_new(doc.filename)
    else:
        fname = "{:07}.pdf".format(doc.pk)

    return os.path.join(
        settings.ARCHIVE_DIR,
        fname
    )


STORAGE_TYPE_GPG = "gpg"


def source_path(doc):
    if doc.filename:
        fname = str(doc.filename)
    else:
        fname = "{:07}{}".format(doc.pk, doc.file_type)
        if doc.storage_type == STORAGE_TYPE_GPG:
            fname += ".gpg"  # pragma: no cover

    return os.path.join(
        settings.ORIGINALS_DIR,
        fname
    )


def move_old_to_new_locations(apps, schema_editor):
    Document = apps.get_model("documents", "Document")

    affected_document_ids = set()

    old_archive_path_to_id = {}

    # check for documents that have incorrect archive versions
    for doc in Document.objects.filter(archive_checksum__isnull=False):
        old_path = archive_path_old(doc)
        new_path = archive_path_new(doc)

        if not os.path.isfile(old_path):
            raise ValueError(
                f"Archived document of {doc.filename} does not exist at: "
                f"{old_path}")

        if old_path != new_path and os.path.isfile(new_path):
            raise ValueError(
                f"Need to move {old_path} to {new_path}, but target file "
                f"already exists")

        if old_path in old_archive_path_to_id:
            affected_document_ids.add(doc.id)
            affected_document_ids.add(old_archive_path_to_id[old_path])
        else:
            old_archive_path_to_id[old_path] = doc.id

    # check that we can regenerate these archive versions
    for doc_id in affected_document_ids:
        from documents.parsers import get_parser_class_for_mime_type

        doc = Document.objects.get(id=doc_id)
        parser_class = get_parser_class_for_mime_type(doc.mime_type)
        if not parser_class:
            raise Exception(
                f"document {doc.filename} has an invalid archived document, "
                f"but no parsers are available. Cannot migrate.")

    # move files
    for doc in Document.objects.filter(archive_checksum__isnull=False):
        old_path = archive_path_old(doc)
        new_path = archive_path_new(doc)

        if doc.id in affected_document_ids:
            # remove affected archive versions
            if os.path.isfile(old_path):
                os.unlink(old_path)
        else:
            # move unaffected archive versions
            if old_path != new_path and os.path.isfile(old_path) and not os.path.isfile(new_path):
                logger.debug(
                    f"Moving {old_path} to {new_path}"
                )
                shutil.move(old_path, new_path)

    # regenerate archive documents
    for doc_id in affected_document_ids:
        from documents.parsers import get_parser_class_for_mime_type, \
            DocumentParser, \
            ParseError

        doc = Document.objects.get(id=doc_id)
        logger.info(
            f"Regenerating archive document for {doc.filename}"
        )
        parser_class = get_parser_class_for_mime_type(doc.mime_type)
        parser: DocumentParser = parser_class(None, None)
        try:
            parser.parse(source_path(doc), doc.mime_type, os.path.basename(doc.filename))
            doc.content = parser.get_text()
            if parser.archive_path and os.path.isfile(parser.archive_path):
                with open(parser.archive_path, "rb") as f:
                    doc.archive_checksum = hashlib.md5(f.read()).hexdigest()
                shutil.copy2(parser.archive_path, archive_path_new(doc))
            else:
                doc.archive_checksum = None
                if os.path.isfile(archive_path_new(doc)):
                    os.unlink(archive_path_new(doc))
            doc.save()
        except ParseError:
            logger.exception(
                f"Unable to regenerate archive document for {doc.filename}"
            )
        finally:
            parser.cleanup()


def move_new_to_old_locations(apps, schema_editor):
    Document = apps.get_model("documents", "Document")

    old_archive_paths = set()

    for doc in Document.objects.filter(archive_checksum__isnull=False):
        new_archive_path = archive_path_new(doc)
        old_archive_path = archive_path_old(doc)
        if old_archive_path in old_archive_paths:
            raise ValueError(
                f"Cannot migrate: Archive file name {old_archive_path} of "
                f"document {doc.filename} would clash with another archive "
                f"filename.")
        old_archive_paths.add(old_archive_path)
        if new_archive_path != old_archive_path and os.path.isfile(old_archive_path):
            raise ValueError(
                f"Cannot migrate: Cannot move {new_archive_path} to "
                f"{old_archive_path}: file already exists."
            )

    for doc in Document.objects.filter(archive_checksum__isnull=False):
        new_archive_path = archive_path_new(doc)
        old_archive_path = archive_path_old(doc)
        if new_archive_path != old_archive_path:
            logger.debug(f"Moving {new_archive_path} to {old_archive_path}")
            shutil.move(new_archive_path, old_archive_path)


class Migration(migrations.Migration):

    dependencies = [
        ('documents', '1011_auto_20210101_2340'),
    ]

    operations = [
        migrations.RunPython(
            move_old_to_new_locations,
            move_new_to_old_locations
        )
    ]