"""

Part of the bsie module.
A copy of the license is provided with the project.
Author: Matthias Baumgartner, 2022
"""
# standard imports
import os
import typing

# bsie imports
from bsie.extractor import base
from bsie.utils import bsfs, node, ns

# exports
__all__: typing.Sequence[str] = (
    'Path',
    )


## code ##

class Path(base.Extractor):
    """Extract information from file's path."""

    CONTENT_READER = 'bsie.reader.path.Path'

    # mapping from predicate to handler function.
    _callmap: typing.Dict[bsfs.schema.Predicate, typing.Callable[[str], typing.Any]]

    def __init__(self):
        super().__init__(bsfs.schema.from_string(base.SCHEMA_PREAMBLE + '''
            bse:filename rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:File ;
                rdfs:range xsd:string ;
                rdfs:label "File name"^^xsd:string ;
                schema:description "Filename of entity in some filesystem."^^xsd:string ;
                bsfs:unique "false"^^xsd:boolean .
            '''))
        self._callmap = {
            self.schema.predicate(ns.bse.filename): self.__filename,
            }

    def extract(
            self,
            subject: node.Node,
            content: str,
            principals: typing.Iterable[bsfs.schema.Predicate],
            ) -> typing.Iterator[typing.Tuple[node.Node, bsfs.schema.Predicate, typing.Any]]:
        for pred in principals:
            # find callback
            clbk = self._callmap.get(pred)
            if clbk is None:
                continue
            # get value
            value = clbk(content)
            if value is None:
                continue
            # produce triple
            yield subject, pred, value

    def __filename(self, path: str) -> typing.Optional[str]:
        try:
            return os.path.basename(path)
        except Exception: # pylint: disable=broad-except # we explicitly want to catch everything
            # some error, skip
            # FIXME: some kind of error reporting (e.g. logging)?
            # Options: (a) Fail silently (current); (b) Skip and report to log;
            # (c) Raise ExtractorError (aborts extraction); (d) separate content type
            # checks from basename errors (report content type errors, skip basename
            # errors)
            return None

## EOF ##