import pathlib

from .model import model
from .proxy import proxy
from .field_generator import field_generator
from .constants import constants
from .validators import validators
from .attachment_file import attachment_file
from .exceptions import resources_not_exists

class attachment(model):
    """
    That model store attachment to the item. Attachment is file, which could
    be downloaded by the user, like instruction in PDF, or used in frontend 
    like images.

    Fields
    ------
    name : str
        Name of the attachment visible for user.

    description : str
        Description of the attachment visible for user.
    """

    name = field_generator.name()
    description = field_generator.description()
    resources = field_generator.path()
    

    def _validators(self) -> dict:
        """
        That function return dict of validators which would be used to 
        validate text fields of the model.

        Returns
        -------
        dict
            Validators which would be used to validate text fields.
        """

        return {
            "name": validators.name,
            "description": validators.description,
            "resources": validators.path
        }

class attachment_proxy(proxy):   
    """
    That class is proxy for the attachment. It could be used to working
    witch attachments in cleaner and better way.

    Methods
    -------
    @classmethod create : proxy
        That create new attachment from that name.

    set_name : None
        That change visible name of the attachment.

    set_description : None
        That change description of the attachment.
    """

    @classmethod
    def create(cls, name: str, resources: attachment_file) -> proxy:
        """
        That create new proxy with new object, which does not exists in 
        database inside.

        Parameters
        ----------
        name : str
            Name of the new attachment.
        resources : str
            Path in the resources directory to the attachment file.

        Raises
        ------
        resources_not_exists
            When attachment file does not exists on disk.

        Returns
        -------
        proxy
            New proxy with new attachment inside it.
        """

        if not resources.exists():
            raise resources_not_exists(resources.path)

        return cls(attachment(
            name = name,
            description = constants.empty_text(),
            resources = resources.name
        ))

    def set_resources(self, target: attachment_file) -> None:
        """
        That change path to the attachment file in the resources directory.

        Parameters
        ----------
        target : pathlib.Path
            Path to new attachment file in the resources directory.

        Raises
        ------
        resources_not_exists
            When attachment file does not exists on disk.
        """
        
        if not target.exists():
            raise resources_not_exists(target.path)

        self._target.resources = target.name

    def set_name(self, target: str) -> None:
        """
        That change name of the attachment

        Parameters
        ----------
        target : str
            New name of the attachment to set.
        """

        self._target.name = target

    def set_description(self, target: str) -> None:
        """
        That chanhe description of the attachment.

        Parameters
        ----------
        target : str
            New description of the attachment to set.
        """

        self._target.description = target