import hashlib
import logging
import uuid
from collections import defaultdict
from pathlib import Path
from typing import Final

from celery import states
from django.conf import settings
from django.utils import timezone
from tqdm import tqdm

from documents.models import Document
from documents.models import PaperlessTask


class SanityCheckMessages:
    def __init__(self):
        self._messages: dict[int, list[dict]] = defaultdict(list)
        self.has_error = False
        self.has_warning = False

    def error(self, doc_pk, message):
        self._messages[doc_pk].append({"level": logging.ERROR, "message": message})
        self.has_error = True

    def warning(self, doc_pk, message):
        self._messages[doc_pk].append({"level": logging.WARNING, "message": message})
        self.has_warning = True

    def info(self, doc_pk, message):
        self._messages[doc_pk].append({"level": logging.INFO, "message": message})

    def log_messages(self):
        logger = logging.getLogger("paperless.sanity_checker")

        if len(self._messages) == 0:
            logger.info("Sanity checker detected no issues.")
        else:
            # Query once
            all_docs = Document.global_objects.all()

            for doc_pk in self._messages:
                if doc_pk is not None:
                    doc = all_docs.get(pk=doc_pk)
                    logger.info(
                        f"Detected following issue(s) with document #{doc.pk},"
                        f" titled {doc.title}",
                    )
                for msg in self._messages[doc_pk]:
                    logger.log(msg["level"], msg["message"])

    def __len__(self):
        return len(self._messages)

    def __getitem__(self, item):
        return self._messages[item]


class SanityCheckFailedException(Exception):
    pass


def check_sanity(*, progress=False, scheduled=True) -> SanityCheckMessages:
    paperless_task = PaperlessTask.objects.create(
        task_id=uuid.uuid4(),
        type=PaperlessTask.TaskType.SCHEDULED_TASK
        if scheduled
        else PaperlessTask.TaskType.MANUAL_TASK,
        task_name=PaperlessTask.TaskName.CHECK_SANITY,
        status=states.STARTED,
        date_created=timezone.now(),
        date_started=timezone.now(),
    )
    messages = SanityCheckMessages()

    present_files = {
        x.resolve() for x in Path(settings.MEDIA_ROOT).glob("**/*") if not x.is_dir()
    }

    lockfile = Path(settings.MEDIA_LOCK).resolve()
    if lockfile in present_files:
        present_files.remove(lockfile)

    if settings.APP_LOGO:
        logo_file = Path(settings.MEDIA_ROOT / settings.APP_LOGO).resolve()
        if logo_file in present_files:
            present_files.remove(logo_file)

    for doc in tqdm(Document.global_objects.all(), disable=not progress):
        # Check sanity of the thumbnail
        thumbnail_path: Final[Path] = Path(doc.thumbnail_path).resolve()
        if not thumbnail_path.exists() or not thumbnail_path.is_file():
            messages.error(doc.pk, "Thumbnail of document does not exist.")
        else:
            if thumbnail_path in present_files:
                present_files.remove(thumbnail_path)
            try:
                _ = thumbnail_path.read_bytes()
            except OSError as e:
                messages.error(doc.pk, f"Cannot read thumbnail file of document: {e}")

        # Check sanity of the original file
        # TODO: extract method
        source_path: Final[Path] = Path(doc.source_path).resolve()
        if not source_path.exists() or not source_path.is_file():
            messages.error(doc.pk, "Original of document does not exist.")
        else:
            if source_path in present_files:
                present_files.remove(source_path)
            try:
                checksum = hashlib.md5(source_path.read_bytes()).hexdigest()
            except OSError as e:
                messages.error(doc.pk, f"Cannot read original file of document: {e}")
            else:
                if checksum != doc.checksum:
                    messages.error(
                        doc.pk,
                        "Checksum mismatch. "
                        f"Stored: {doc.checksum}, actual: {checksum}.",
                    )

        # Check sanity of the archive file.
        if doc.archive_checksum is not None and doc.archive_filename is None:
            messages.error(
                doc.pk,
                "Document has an archive file checksum, but no archive filename.",
            )
        elif doc.archive_checksum is None and doc.archive_filename is not None:
            messages.error(
                doc.pk,
                "Document has an archive file, but its checksum is missing.",
            )
        elif doc.has_archive_version:
            archive_path: Final[Path] = Path(doc.archive_path).resolve()
            if not archive_path.exists() or not archive_path.is_file():
                messages.error(doc.pk, "Archived version of document does not exist.")
            else:
                if archive_path in present_files:
                    present_files.remove(archive_path)
                try:
                    checksum = hashlib.md5(archive_path.read_bytes()).hexdigest()
                except OSError as e:
                    messages.error(
                        doc.pk,
                        f"Cannot read archive file of document : {e}",
                    )
                else:
                    if checksum != doc.archive_checksum:
                        messages.error(
                            doc.pk,
                            "Checksum mismatch of archived document. "
                            f"Stored: {doc.archive_checksum}, "
                            f"actual: {checksum}.",
                        )

        # other document checks
        if not doc.content:
            messages.info(doc.pk, "Document contains no OCR data")

    for extra_file in present_files:
        messages.warning(None, f"Orphaned file in media dir: {extra_file}")

    paperless_task.status = states.SUCCESS if not messages.has_error else states.FAILURE
    # result is concatenated messages
    paperless_task.result = f"{len(messages)} issues found."
    if messages.has_error:
        paperless_task.result += " Check logs for details."
    paperless_task.date_done = timezone.now()
    paperless_task.save(update_fields=["status", "result", "date_done"])
    return messages