"""meta_entity - Validate entity metadata"""
# Copyright © 2020  Brett Smith
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# Type stubs aren't available for regex.
# Fortunately, we're using it in a way that's API-compatible with the re
# module. We mitigate the lack of type stubs by providing type declarations
# for returned objects. This way, the only thing that isn't type checked are
# the calls to regex functions.
import regex  # type:ignore[import]

from . import core
from .. import data
from .. import errors as errormod
from ..beancount_types import (
    MetaKey,
    MetaValue,
    Transaction,
)

from typing import (
    MutableMapping,
    Optional,
    Pattern,
    Tuple,
)

class MetaEntity(core.TransactionHook):
    METADATA_KEY = 'entity'
    HOOK_GROUPS = frozenset(['posting', 'metadata', METADATA_KEY])

    # chars is the set of characters we always accept in entity metadata:
    # letters, digits, and ASCII punctuation, except `-` and the Latin 1 supplement
    # (i.e., Roman letters with diacritics: áÁàÀâÂåÅäÄãà çÇ ðÐ ñÑ øØ ß etc.)
    # See the tests for specific cases.
    chars = r'\u0021-\u002c\u002e-\u007e\p{Letter}\p{Digit}--\p{Block=Latin_1_Supplement}'
    ENTITY_RE: Pattern[str] = regex.compile(f'^[{chars}][-{chars}]*$', regex.VERSION1)
    ANONYMOUS_RE: Pattern[str] = regex.compile(r'^[-_.?!\s]*$', regex.VERSION1)
    del chars

    def _check_entity(self,
                      meta: MutableMapping[MetaKey, MetaValue],
                      default: Optional[str]=None,
    ) -> Tuple[Optional[str], Optional[bool]]:
        entity = meta.get(self.METADATA_KEY, default)
        if entity is None:
            return None, None
        elif not isinstance(entity, str):
            return None, False
        elif self.ANONYMOUS_RE.match(entity):
            entity = 'Anonymous'
            meta[self.METADATA_KEY] = entity
            return entity, True
        else:
            return entity, self.ENTITY_RE.match(entity) is not None

    def run(self, txn: Transaction) -> errormod.Iter:
        if not self._run_on_txn(txn):
            return
        txn_entity, txn_entity_ok = self._check_entity(txn.meta, txn.payee)
        if txn_entity_ok is False:
            yield errormod.InvalidMetadataError(txn, self.METADATA_KEY, txn_entity)
        if txn_entity is txn.payee:
            txn.meta[self.METADATA_KEY] = txn.payee
        for post in data.Posting.from_txn(txn):
            if not post.account.is_under(
                    'Assets:Receivable',
                    'Expenses',
                    'Income',
                    'Liabilities:Payable',
            ):
                continue
            entity, entity_ok = self._check_entity(post.meta, txn_entity)
            if entity is txn_entity and entity is not None:
                pass
            elif not entity_ok:
                yield errormod.InvalidMetadataError(txn, self.METADATA_KEY, entity, post)