earthsnake/earthsnake/path.py

"""Path handling"""

from .exc import ValidationError
from .identity import Identity
from .types import ALPHA_LOWER, ALPHA_UPPER, DIGIT

PATH_PUNCTUATION = "/'()-._~!$&+,:=@%"
PATH_CHARACTER = ALPHA_LOWER + ALPHA_UPPER + DIGIT + PATH_PUNCTUATION


class Path:
    """A document path"""

    _SEGMENT_PATTERN = f'/[{PATH_CHARACTER}]+'.replace('$', '\\$')
    PATTERN = f'^({_SEGMENT_PATTERN})+$'

    def __init__(self, path: str) -> None:
        self.validate(path, allow_ephemeral=True)
        self.path = path

    @staticmethod
    def validate(path: str, allow_ephemeral: bool = False) -> None:
        """Validate a path"""

        if not 2 <= len(path) <= 512:
            raise ValidationError('Path length must be between 2 and 512')

        if not path.startswith('/'):
            raise ValidationError('Paths must start with a /')

        if path.endswith('/'):
            raise ValidationError('Paths must not end with a /')

        if path.startswith('/@'):
            raise ValidationError('Paths must not start with /@')

        if '//' in path:
            raise ValidationError('Paths must not contain //')

        if path.count('!') > 1:
            raise ValidationError('Only one ! is allowed in paths')

        if '!' in path and not allow_ephemeral:
            raise ValidationError('Only ephemeral paths may contain !')

    @property
    def is_shared(self) -> bool:
        """Check if the path is shared"""

        return '~' not in self.path

    @property
    def is_ephemeral(self) -> bool:
        """Check if the path is ephemeral"""

        return '!' in self.path

    def can_write(self, author: Identity) -> bool:
        """Check if a specific author has write access over a document"""

        if self.is_shared:
            return True

        segments = self.path.split('/')

        for segment in segments:
            for allowed_author in segment.split('~'):
                if Identity.valid_address(allowed_author) and str(author) == allowed_author:
                    return True

        return False

    def __str__(self) -> str:
        return self.path

    def __repr__(self) -> str:
        return f'<Path {self.path}>'