# -*- coding: utf-8 -*-
"""
molvs.validations
~~~~~~~~~~~~~~~~~

This module contains all the built-in :class:`Validations <molvs.validations.Validation>`.

:copyright: Copyright 2016 by Matt Swain.
:license: MIT, see LICENSE file for more details.
"""

from __future__ import print_function
from __future__ import unicode_literals
from __future__ import division
import logging

from rdkit import Chem

from .errors import StopValidateError
from .fragment import REMOVE_FRAGMENTS


class Validation(object):
    """The base class that all :class:`~molvs.validations.Validation` subclasses must inherit from."""

    def __init__(self, log):
        self.log = logging.LoggerAdapter(log, {'validation': type(self).__name__})

    def __call__(self, mol):
        try:
            self.log.debug('Running %s', type(self).__name__)
            self.run(mol)
        except Exception as e:
            if isinstance(e, StopValidateError):
                raise e
            else:
                self.log.debug('Validation failed: %s', e)

    def run(self, mol):
        """"""
        raise NotImplementedError("Validation subclasses must implement the run method")


class SmartsValidation(Validation):
    """Abstract superclass for :class:`Validations <molvs.validations.Validation>` that log a message if a SMARTS
    pattern matches the molecule.

    Subclasses can override the following attributes:
    """

    #: The logging level of the message.
    level = logging.INFO

    #: The message to log if the SMARTS pattern matches the molecule.
    message = 'Molecule matched %(smarts)s'

    #: Whether the SMARTS pattern should match an entire covalent unit.
    entire_fragment = False

    def __init__(self, log):
        super(SmartsValidation, self).__init__(log)
        self._smarts = Chem.MolFromSmarts(self.smarts)

    @property
    def smarts(self):
        """The SMARTS pattern as a string. Subclasses must implement this."""
        raise NotImplementedError('SmartsValidation subclasses must have a smarts attribute')

    def _check_matches(self, mol):
        if mol.HasSubstructMatch(self._smarts):
            self.log.log(self.level, self.message, {'smarts': self.smarts})

    def _check_matches_fragment(self, mol):
        matches = frozenset(frozenset(match) for match in mol.GetSubstructMatches(self._smarts))
        fragments = frozenset(frozenset(frag) for frag in Chem.GetMolFrags(mol))
        if matches & fragments:
            self.log.log(self.level, self.message, {'smarts': self.smarts})

    def run(self, mol):
        if self.entire_fragment:
            self._check_matches_fragment(mol)
        else:
            self._check_matches(mol)


class IsNoneValidation(Validation):
    """Logs an error if ``None`` is passed to the Validator.

    This can happen if RDKit failed to parse an input format. If the molecule is ``None``, no subsequent validations
    will run.
    """

    def run(self, mol):
        if mol is None:
            self.log.error('Molecule is None')
            raise StopValidateError()


class NoAtomValidation(Validation):
    """Logs an error if the molecule has zero atoms.

    If the molecule has no atoms, no subsequent validations will run.
    """

    def run(self, mol):
        if mol.GetNumAtoms() == 0:
            self.log.error('No atoms are present')
            raise StopValidateError()


class DichloroethaneValidation(SmartsValidation):
    """Logs if 1,2-dichloroethane is present.

    This is provided as an example of how to subclass :class:`~molvs.validations.SmartsValidation` to check for the
    presence of a substructure.
    """
    level = logging.INFO
    smarts = '[Cl]-[#6]-[#6]-[Cl]'
    entire_fragment = True
    message = '1,2-Dichloroethane is present'


class FragmentValidation(Validation):
    """Logs if certain fragments are present.

    Subclass and override the ``fragments`` class attribute to customize the list of
    :class:`FragmentPatterns <molvs.fragment.FragmentPattern>`.
    """

    #: A list of :class:`FragmentPatterns <molvs.fragment.FragmentPattern>` to check for.
    fragments = REMOVE_FRAGMENTS

    def run(self, mol):
        for fp in self.fragments:
            matches = frozenset(frozenset(match) for match in mol.GetSubstructMatches(fp.smarts))
            fragments = frozenset(frozenset(frag) for frag in Chem.GetMolFrags(mol))
            if matches & fragments:
                self.log.info('%s is present', fp.name)


class NeutralValidation(Validation):
    """Logs if not an overall neutral system."""

    def run(self, mol):
        charge = Chem.GetFormalCharge(mol)
        if not charge == 0:
            chargestring = '+%s' % charge if charge > 0 else '%s' % charge
            self.log.info('Not an overall neutral system (%s)', chargestring)


class IsotopeValidation(Validation):
    """Logs if molecule contains isotopes."""

    def run(self, mol):
        isotopes = set()
        for atom in mol.GetAtoms():
            isotope = atom.GetIsotope()
            if not isotope == 0:
                isotopes.add('%s%s' % (isotope, atom.GetSymbol()))
        for isotope in isotopes:
            self.log.info('Molecule contains isotope %s', isotope)


#: The default list of :class:`Validations <molvs.validations.Validation>` used by :class:`~molvs.validate.Validator`.
VALIDATIONS = (
    IsNoneValidation,
    NoAtomValidation,
    #DichloroethaneValidation,
    FragmentValidation,
    NeutralValidation,
    IsotopeValidation,
)



# - WARN/ERROR: Are all atoms defined/real - no query atoms or invalid elements, r-group things
# - INFO: Contains unknown stereo (Perform stereochemistry perception first?)
# - INFO: Nonstandard tautomer (log SMILES of tautomer parent, or the name of the tautomer transform?)
# - WARN: InChI generation failed
# - WARN: Contains covalent bond to metal (that would be broken by MetalDisconnector)
# - WARN: Contains solvent molecules (in addition other fragment)
# - WARN: More than 99 rings causes problems with SMILES
# - INFO: Cis azo dye is unusual
# - WARN: Adjacent atoms with like charges (i.e. both positive or both negative)
# - INFO: Has more than one radical centre
# - INFO: ethane, methane molecules present
# - INFO: Boron, Sulfur atoms with no explicit bonds
# - INFO: Solvent molecules present (only if also other fragments)
# - INFO: One unknown stereocentre and no defined stereocentres (probably racemate, so info not warn)
# - WARN: More than one undefined stereocentre and no defined stereocentres
# - INFO: One undefined stereocentre and at least one defined stereocentre (epimer or mixture of anomers, so info not warn)
# - WARN: More than one undefined stereocentre and at least one defined stereocentre
# - INFO: Unknown double bond stereochemistry
# - WARN: Ring containing stereobonds?
# - INFO: Not canonical tautomer


# Coordinates?
# Info - Lack of coordinates? Uneven bond lengths?

# Web services (needs to be optional)
# Info - Could not match to ChemSpider ID, PubChem CID
# UniChem from EBI could be useful here, otherwise use each API directly




# Allow definition of MolSchema to set custom validations on e.g.

# People can define a filterer
# This has a series of validations, and the required output - e.g. no error or no warns?

