from mpi4py import MPI
from mpi4py.futures import MPICommExecutor

import warnings
from Bio.PDB import PDBParser, PPBuilder, CaPPBuilder
from Bio.PDB.NeighborSearch import NeighborSearch
from Bio.PDB.Selection import unfold_entities

import numpy as np
import dask.array as da

from rdkit import Chem

from functools import partial

import os
import re
import sys
import io
import random
import gzip
import copy

from atomic_renamer import AtomicNamer

from prody import *

import webdataset as wd

amino_acids = {'L': 'LEU', 'A': 'ALA', 'G': 'GLY', 'V': 'VAL', 'E': 'GLU', 'S': 'SER', 'I': 'ILE', 'K': 'LYS',
               'R': 'ARG', 'D': 'ASP', 'T': 'THR', 'P': 'PRO', 'N': 'ASN', 'Q': 'GLN', 'F': 'PHE', 'Y': 'TYR',
               'M': 'MET', 'H': 'HIS', 'C': 'CYS', 'W': 'TRP'}
nfeat = 15 # number of heavy atom coordinates

# all punctuation
punctuation_regex  = r"""(\(|\)|\.|=|#|-|\+|\\|\/|:|~|@|\?|>>?|\*|\$|\%[0-9]{2}|[0-9])"""

# tokenization regex (Schwaller)
molecule_regex = r"""(\[[^\]]+]|Br?|Cl?|N|O|S|P|F|I|b|c|n|o|s|p|\(|\)|\.|=|#|-|\+|\\|\/|:|~|@|\?|>>?|\*|\$|\%[0-9]{2}|[0-9])"""

def get_protein_sequence_and_coords(structure):
    hv = structure.getHierView()

    seq = ''
    xyz = []
    resindex = []

    for chain in hv:
        cid = chain.getChid()
        calpha = structure.select(f'calpha chain {cid} icode _')
        N = structure.select(f'name N chain {cid} icode _')
        C = structure.select(f'name C chain {cid} icode _')
        xyz += [(ca,n,c) for ca,n,c in zip(calpha.getCoords(), N.getCoords(), C.getCoords())]
        seq += calpha.getSequence()
        resindex += [ca.getResindex() for ca in calpha]
    return seq, xyz, resindex

def get_pdb_components(pdb_id):
    """
    Split a protein-ligand pdb into protein and ligand components
    :param pdb_id:
    :return:
    """
    with open(pdb_id,'r') as f:
        pdb = parsePDBStream(f,model=1)

    protein = pdb.select('protein')
    return protein

def rot_from_two_vecs(e0_unnormalized, e1_unnormalized):
    """Create rotation matrices from unnormalized vectors for the x and y-axes.
    This creates a rotation matrix from two vectors using Gram-Schmidt
    orthogonalization.
    Args:
    e0_unnormalized: vectors lying along x-axis of resulting rotation
    e1_unnormalized: vectors lying in xy-plane of resulting rotation
    Returns:
    Rotations resulting from Gram-Schmidt procedure.
    """
    # Normalize the unit vector for the x-axis, e0.
    e0 = e0_unnormalized / np.linalg.norm(e0_unnormalized)

    # make e1 perpendicular to e0.
    c = np.dot(e1_unnormalized, e0)
    e1 = e1_unnormalized - c * e0
    e1 = e1 / np.linalg.norm(e1)

    # Compute e2 as cross product of e0 and e1.
    e2 = np.cross(e0, e1)

    # local to space frame
    return np.stack([e0,e1,e2]).T

def parse_complex(aa, data_dir, i_pdb_fns):
    shard_idx, pdb_fns = i_pdb_fns

    chunk_name = []
    chunk_smiles = []
    chunk_lig_xyz = []
    chunk_seq = []
    chunk_rec_xyz = []
    chunk_rec_R = []
    chunk_rec_feat = []

    for pdb_fn in pdb_fns:
        try:
            name = os.path.basename(pdb_fn)
            protein = get_pdb_components(pdb_fn+'/'+name+'_protein.pdb')
            seq, xyz, resindex = get_protein_sequence_and_coords(protein)

            if len(seq) < 3:
                raise ValueError

            assert len(xyz) == len(seq), "sequence and coord mismatch"

            R_receptor = []
            for t in xyz:
                CA = np.array(t[0])
                N = np.array(t[1])
                C = np.array(t[2])

                R_receptor.append(rot_from_two_vecs(N-CA,C-CA).flatten().tolist())

            # atom features
            feat = np.zeros((len(resindex),nfeat,3),dtype=np.float32)
            feat[:] = np.nan

            for i,(n, res) in enumerate(zip(resindex, seq)):
                atoms = protein.select(f'resindex {n}')
                ss = io.StringIO()
                prody.writePDBStream(ss, atoms)
                try:
                    mol = Chem.MolFromPDBBlock(ss.getvalue())
                    ref_aa = copy.deepcopy(aa[res])
                    reflabels = [l.split()[0] for l in ref_aa.reflabels]
                    labels = [l.split()[0] for l in ref_aa.name(mol)]
                    pos = mol.GetConformer().GetPositions()
                    xyz_labels = sorted([(xyz, reflabels.index(l)) for xyz,l in zip(pos,labels)
                                         if l in reflabels], key=lambda t: t[1])
                    for r, j in xyz_labels:
                        feat[i,j,:] = r

                except Exception as e:
                    print('Unsuccesful in assigning atoms to amino acid letter {}'.format(res),ss.getvalue(),e)
                    raise

            # parse ligand, convert to SMILES and map atoms
            suppl = Chem.SDMolSupplier(pdb_fn+'/'+name+'_ligand.sdf')
            mol = next(suppl)

            # position of atoms in SMILES (not counting punctuation)
            smi = Chem.MolToSmiles(mol)
            atom_order = [int(s) for s in list(filter(None,re.sub(r'[\[\]]','',mol.GetProp("_smilesAtomOutputOrder")).split(',')))]

            # tokenize the SMILES
            tokens = list(filter(None, re.split(molecule_regex, smi)))

            # remove punctuation
            masked_tokens = [re.sub(punctuation_regex,'',s) for s in tokens]

            k = 0
            token_pos = []

            for i,token in enumerate(masked_tokens):
                if token != '':
                    token_pos.append(tuple(mol.GetConformer().GetAtomPosition(atom_order[k])))
                    k += 1
                else:
                    token_pos.append((np.nan, np.nan, np.nan))

            chunk_name.append(name)
            chunk_seq.append(seq)
            chunk_rec_xyz.append(np.array([np.array(t[0]).tolist() for t in xyz]))
            chunk_rec_R.append(np.array(R_receptor))
            chunk_rec_feat.append(feat)
            chunk_smiles.append(smi)
            chunk_lig_xyz.append(token_pos)

        except Exception as e:
            print(e)
            pass

    try:
        shard_idx = str(shard_idx)
        with wd.TarWriter(f'{data_dir}/part-' + shard_idx + '.tar', compress=True) as sink:
            for index in range(len(chunk_name)):
                sink.write({
                    '__key__': "%s_%06d" % (shard_idx, index),
                    'name.txt': chunk_name[index],
                    'seq.txt': chunk_seq[index],
                    'smiles.txt': chunk_smiles[index],
                    'rec_xyz.pyd': chunk_rec_xyz[index],
                    'rec_R.pyd': chunk_rec_R[index],
                    'rec_feat.pyd': chunk_rec_feat[index],
                    'lig_xyz.pyd': chunk_lig_xyz[index],
                })

        return len(chunk_name)
    except Exception as e:
        print('Exception while writing', repr(e))


if __name__ == '__main__':
    import glob

    filenames = glob.glob('data/pdbbind/v2020-other-PL/*')
    filenames.extend(glob.glob('data/pdbbind/refined-set/*'))
    filenames = sorted(filenames)

    with open('split_direction/timesplit_no_lig_overlap_train','r') as f:
        train_rec = f.read().split()
    with open('split_direction/timesplit_no_lig_overlap_val','r') as f:
        val_rec = f.read().split()
    with open('split_direction/timesplit_test','r') as f:
        test_rec = f.read().split()

    train = [x for x in filenames if x.split('/')[-1] in train_rec]
    val = [x for x in filenames if x.split('/')[-1] in val_rec]
    test = [x for x in filenames if x.split('/')[-1] in test_rec]
    
    print(f'Train has {len(train)} items and first 5 are {train[:5]}')
    print(f'Val has {len(val)} items and first 5 are {val[:5]}')
    print(f'Test has {len(test)} items and first 5 are {test[:5]}')

    def chunks(lst, n):
        """Yield successive n-sized chunks from lst."""
        for i in range(0, len(lst), n):
            yield lst[i:i + n]

    comm = MPI.COMM_WORLD
    with MPICommExecutor(comm, root=0) as executor:
        if executor is not None:
            aa = {k: AtomicNamer(v) for k,v in amino_acids.items()}

            chunk_sizes = executor.map(partial(parse_complex, aa, 'train'), enumerate(chunks(train, 512)))
            total_train_rows = 0
            for s in chunk_sizes:
                total_train_rows += s

            chunk_sizes = executor.map(partial(parse_complex, aa, 'val'), enumerate(chunks(val, 512)))
            total_val_rows = 0
            for s in chunk_sizes:
                total_val_rows += s

            chunk_sizes = executor.map(partial(parse_complex, aa, 'test'), enumerate(chunks(test, 512)))
            total_test_rows = 0
            for s in chunk_sizes:
                total_test_rows += s

            print('Total number of train rows {}'.format(total_train_rows))
            print('Total number of val rows {}'.format(total_val_rows))
            print('Total number of test rows {}'.format(total_test_rows))