#
# calculation of synthetic accessibility score as described in:
#
# Estimation of Synthetic Accessibility Score of Drug-like Molecules based on Molecular Complexity and Fragment Contributions
# Peter Ertl and Ansgar Schuffenhauer
# Journal of Cheminformatics 1:8 (2009)
# http://www.jcheminf.com/content/1/1/8
#
# several small modifications to the original paper are included
# particularly slightly different formula for marocyclic penalty
# and taking into account also molecule symmetry (fingerprint density)
#
# for a set of 10k diverse molecules the agreement between the original method
# as implemented in PipelinePilot and this implementation is r2 = 0.97
#
# peter ertl & greg landrum, september 2013
#
from __future__ import print_function

from rdkit import Chem
from rdkit.Chem import rdMolDescriptors
from rdkit.six.moves import cPickle
from rdkit.six import iteritems

import math
from collections import defaultdict

import os.path as op

_fscores = None
def readFragmentScores(name='fpscores'):
    import gzip
    global _fscores
    # generate the full path filename:
    if name == "fpscores":
        name = op.join(op.dirname(__file__), name)
    _fscores = cPickle.load(gzip.open('%s.pkl.gz'%name))
    outDict = {}
    for i in _fscores:
        for j in range(1,len(i)):
            outDict[i[j]] = float(i[0])
    _fscores = outDict

def numBridgeheadsAndSpiro(mol,ri=None):
  nSpiro = rdMolDescriptors.CalcNumSpiroAtoms(mol)
  nBridgehead = rdMolDescriptors.CalcNumBridgeheadAtoms(mol)
  return nBridgehead,nSpiro

def calculateScore(m):
  if _fscores is None: readFragmentScores()

  # fragment score
  fp = rdMolDescriptors.GetMorganFingerprint(m,2)  #<- 2 is the *radius* of the circular fingerprint
  fps = fp.GetNonzeroElements()
  score1 = 0.
  nf = 0
  for bitId,v in iteritems(fps):
    nf += v
    sfp = bitId
    score1 += _fscores.get(sfp,-4)*v
  score1 /= nf

  # features score
  nAtoms = m.GetNumAtoms()
  nChiralCenters = len(Chem.FindMolChiralCenters(m,includeUnassigned=True))
  ri = m.GetRingInfo()
  nBridgeheads,nSpiro=numBridgeheadsAndSpiro(m,ri)
  nMacrocycles=0
  for x in ri.AtomRings():
    if len(x)>8: nMacrocycles+=1

  sizePenalty = nAtoms**1.005 - nAtoms
  stereoPenalty = math.log10(nChiralCenters+1)
  spiroPenalty = math.log10(nSpiro+1)
  bridgePenalty = math.log10(nBridgeheads+1)
  macrocyclePenalty = 0.
  # ---------------------------------------
  # This differs from the paper, which defines:
  #  macrocyclePenalty = math.log10(nMacrocycles+1)
  # This form generates better results when 2 or more macrocycles are present
  if nMacrocycles > 0: macrocyclePenalty = math.log10(2)

  score2 = 0. -sizePenalty -stereoPenalty -spiroPenalty -bridgePenalty -macrocyclePenalty

  # correction for the fingerprint density
  # not in the original publication, added in version 1.1
  # to make highly symmetrical molecules easier to synthetise
  score3 = 0.
  if nAtoms > len(fps):
    score3 = math.log(float(nAtoms) / len(fps)) * .5

  sascore = score1 + score2 + score3

  # need to transform "raw" value into scale between 1 and 10
  min = -4.0
  max = 2.5
  sascore = 11. - (sascore - min + 1) / (max - min) * 9.
  # smooth the 10-end
  if sascore > 8.: sascore = 8. + math.log(sascore+1.-9.)
  if sascore > 10.: sascore = 10.0
  elif sascore < 1.: sascore = 1.0 

  return sascore
    

def processMols(mols):
  print('smiles\tName\tsa_score')
  for i,m in enumerate(mols):
    if m is None:
      continue
 
    s = calculateScore(m)

    smiles = Chem.MolToSmiles(m)
    print(smiles+"\t"+m.GetProp('_Name') + "\t%3f"%s)


if __name__=='__main__':
  import sys,time

  t1=time.time()
  readFragmentScores("fpscores")
  t2=time.time()

  suppl = Chem.SmilesMolSupplier(sys.argv[1])
  t3=time.time()
  processMols(suppl)
  t4=time.time()

  print('Reading took %.2f seconds. Calculating took %.2f seconds'%((t2-t1),(t4-t3)), file=sys.stderr)

  
#
#  Copyright (c) 2013, Novartis Institutes for BioMedical Research Inc.
#  All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met: 
#
#     * Redistributions of source code must retain the above copyright 
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
#       copyright notice, this list of conditions and the following 
#       disclaimer in the documentation and/or other materials provided 
#       with the distribution.
#     * Neither the name of Novartis Institutes for BioMedical Research Inc. 
#       nor the names of its contributors may be used to endorse or promote 
#       products derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
