import numpy as np

from itertools import permutations

import MDAnalysis as mda
# from MDAnalysis.analysis import dihedrals
from MDAnalysis.analysis import distances


def obtain_self_dist(res):
	try:
		#xx = res.atoms.select_atoms("not name H*")
		xx = res.atoms
		dists = distances.self_distance_array(xx.positions)
		ca = xx.select_atoms("name CA")
		c = xx.select_atoms("name C")
		n = xx.select_atoms("name N")
		o = xx.select_atoms("name O")
		return [dists.max()*0.1, dists.min()*0.1, distances.dist(ca,o)[-1][0]*0.1, distances.dist(o,n)[-1][0]*0.1, distances.dist(n,c)[-1][0]*0.1]
	except:
		return [0, 0, 0, 0, 0]


def obtain_dihediral_angles(res):
	try:
		if res.phi_selection() is not None:
			phi = res.phi_selection().dihedral.value()
		else:
			phi = 0
		if res.psi_selection() is not None:
			psi = res.psi_selection().dihedral.value()
		else:
			psi = 0
		if res.omega_selection() is not None:
			omega = res.omega_selection().dihedral.value()
		else:
			omega = 0
		if res.chi1_selection() is not None:
			chi1 = res.chi1_selection().dihedral.value()
		else:
			chi1 = 0
		return [phi*0.01, psi*0.01, omega*0.01, chi1*0.01]
	except:
		return [0, 0, 0, 0]
##'FE', 'SR', 'GA', 'IN', 'ZN', 'CU', 'MN', 'SR', 'K' ,'NI', 'NA', 'CD' 'MG','CO','HG', 'CS', 'CA',

def obatin_edge(u, cutoff=10.0):
	edgeids = []
	dismin = []
	dismax = []
	for res1, res2 in permutations(u.residues, 2):
		dist = calc_dist(res1, res2)
		if dist.min() <= cutoff:
			edgeids.append([res1.ix, res2.ix])
			dismin.append(dist.min()*0.1)
			dismax.append(dist.max()*0.1)
	return edgeids, np.array([dismin, dismax]).T



def check_connect(u, i, j):
	if abs(i-j) != 1:
		return 0
	else:
		if i > j:
			i = j
		nb1 = len(u.residues[i].get_connections("bonds"))
		nb2 = len(u.residues[i+1].get_connections("bonds"))
		nb3 = len(u.residues[i:i+2].get_connections("bonds"))
		if nb1 + nb2 == nb3 + 1:
			return 1
		else:
			return 0
		
	

def calc_dist(res1, res2):
	#xx1 = res1.atoms.select_atoms('not name H*')
	#xx2 = res2.atoms.select_atoms('not name H*')
	#dist_array = distances.distance_array(xx1.positions,xx2.positions)
	dist_array = distances.distance_array(res1.atoms.positions,res2.atoms.positions)
	return dist_array
	#return dist_array.max()*0.1, dist_array.min()*0.1