from __future__ import annotations

import os
import typing as T
import warnings

from datetime import datetime
from pathlib import Path

from pycs import db
from pycs.database.Collection import Collection
from pycs.database.Result import Result
from pycs.database.Label import Label
from pycs.database.base import NamedBaseModel
from pycs.database.util import commit_on_return


class File(NamedBaseModel):
    """ DB Model for files """

    # table columns
    uuid = db.Column(db.String, nullable=False)

    extension = db.Column(db.String, nullable=False)

    type = db.Column(db.String, nullable=False)

    size = db.Column(db.Integer, nullable=False)

    created = db.Column(db.DateTime, default=datetime.utcnow,
        index=True, nullable=False)

    path = db.Column(db.String, nullable=False)

    frames = db.Column(db.Integer)

    fps = db.Column(db.Float)

    project_id = db.Column(
        db.Integer,
        db.ForeignKey("project.id", ondelete="CASCADE"),
        nullable=False)

    collection_id = db.Column(
        db.Integer,
        db.ForeignKey("collection.id", ondelete="SET NULL"))

    # contraints
    __table_args__ = (
        db.UniqueConstraint('project_id', 'path'),
    )


    results = db.relationship("Result",
        backref="file",
        lazy="dynamic",
        passive_deletes=True,
    )


    serialize_only = NamedBaseModel.serialize_only + (
        "uuid",
        "extension",
        "type",
        "size",
        "created",
        "path",
        "frames",
        "fps",
        "project_id",
        "collection_id",
    )

    @property
    def filename(self):
        """ filename consisting of a name and an extension """
        return f"{self.name}{self.extension}"

    @property
    def absolute_path(self) -> str:
        """ returns an absolute of the file """
        path = Path(self.path)

        if path.is_absolute():
            return str(path)

        return str(Path.cwd() / path)

    # pylint: disable=arguments-differ
    def delete(self, commit: bool = True):
        """
            after the object is deleted, the according physical file
            is also delete if commit was True
        """

        # pylint: disable=unexpected-keyword-arg
        dump = super().delete(commit=commit)

        if commit:
            os.remove(self.path)

        # TODO: remove temp files
        warnings.warn("Temporary files may still exist!")
        return dump

    @commit_on_return
    def set_collection(self, collection_id: T.Optional[int]):
        """
        set this file's collection

        :param collection_id: new collection id
        :return:
        """

        self.collection_id = collection_id

    @commit_on_return
    def set_collection_by_reference(self, collection_reference: T.Optional[str]):
        """
        set this file's collection

        :param collection_reference: collection reference
        :return:
        """
        if self.collection_reference is None:
            self.set_collection(None)

        collection = Collection.query.filter_by(reference=collection_reference).one()
        self.collection_id = collection.id

    def _get_another_file(self, *query) -> T.Optional[File]:
        """
        get the first file matching the query ordered by descending id

        :return: another file or None
        """
        return File.query.filter(File.project_id == self.project_id, *query)

    def next(self) -> T.Optional[File]:
        """
        get the successor of this file

        :return: another file or None
        """

        return self._get_another_file(File.id > self.id)\
            .order_by(File.id).first()


    def previous(self) -> T.Optional[File]:
        """
        get the predecessor of this file

        :return: another file or None
        """

        # pylint: disable=no-member
        return self._get_another_file(File.id < self.id)\
            .order_by(File.id.desc()).first()


    def next_in_collection(self) -> T.Optional[File]:
        """
        get the predecessor of this file

        :return: another file or None
        """
        return self._get_another_file(
            File.id > self.id, File.collection_id == self.collection_id)\
            .order_by(File.id).first()


    def previous_in_collection(self) -> T.Optional[File]:
        """
        get the predecessor of this file

        :return: another file or None
        """

        # pylint: disable=no-member
        return self._get_another_file(
            File.id < self.id, File.collection_id == self.collection_id)\
            .order_by(File.id.desc()).first()


    def result(self, identifier: int) -> T.Optional[Result]:
        """
        get one of the file's results

        :return: result object or None
        """
        return self.results.get(identifier)


    @commit_on_return
    def create_result(self,
                      origin: str,
                      result_type: str,
                      label: T.Optional[T.Union[Label, int]] = None,
                      data: T.Optional[dict] = None) -> Result:
        """
        Creates a result and returns the created object

        :return: result object
        """

        result = Result.new(commit=False,
                            file_id=self.id,
                            origin=origin,
                            type=result_type)

        result.data = data

        if label is not None:
            assert isinstance(label, (int, Label)), f"Wrong label type: {type(label)}"

            if isinstance(label, Label):
                label = label.id

            result.label_id = label

        return result


    def remove_results(self, origin='pipeline') -> T.List[Result]:
        """
        Remove assigned results, but return them.

        :return: list of result objects
        """

        results = Result.query.filter(
            Result.file_id == self.id,
            Result.origin == origin)

        _results = [r.serialize() for r in results.all()]
        results.delete()

        return _results