'''This is the python code that estimates the interval in which

the nonlinearity of the function given as truth table lies using

a purely quantum method.

1. Please provide the file containing the function values

as data.txt or change accordingly in Line__.'''

import sys

from qiskit import *

from qiskit import IBMQ

from qiskit import BasicAer

from qiskit.aqua.components.oracles import TruthTableOracle

from qiskit.aqua.circuits.gates import mcmt,mct

from math import *

import qconfig

#n = int(sys.argv[1])

threshold = float(sys.argv[1])

delta = float(sys.argv[2])

vflag = int(sys.argv[3])

#print('delta : ', delta);

#print('thresh : ', threshold);

vprint = print if vflag else lambda *a, **k:None

IBMQ.save_account(qconfig.APItoken, overwrite=True)

IBMQ.load_accounts()

backend = IBMQ.get_backend('ibmq_qasm_simulator')

def swap(qc,q1,q2,anc):

qc.cx(q1[i],q2[i])

s=''

dat_file = open('data.txt','r')

n = int(dat_file.readline())

#delta = 100

#threshold = 100

#while delta > 1 or delta <=0:

# delta = float(input('Please enter the maximum error allowed (value between 0 and 1 excluding 0): \n'))

#while threshold >=1 or threshold < (1/2**n):

# threshold = float(input('Please enter the threshold below which the fhat_max lies (value between 1/2^n and 1 excluding 1): '))

#print('delta : ', delta, '\n')

samples = ceil((400/(1-threshold))*log(1/delta))

#print('shots : ', samples)

for i in range(2**n):

temp = dat_file.readline()

s+= list(temp.split("\t"))[1][:1]

dat_file.close()

vprint('Creating and Extracting oracle')

oracle = TruthTableOracle(s)

vr = oracle.variable_register

vr2 = QuantumRegister(len(vr))

anc = QuantumRegister(len(vr))

otr = oracle.output_register

qc1 = QuantumCircuit(vr,vr2,anc,otr)

qc1.h(vr)

qc1.x(otr)

qc1.h(otr)

qc1.barrier()

qc=oracle.circuit

qc2 = QuantumCircuit(vr,vr2,anc,otr)

qc2.h(vr)

swap(qc2,vr,vr2,anc)

qc2.h(vr)

qc3 = QuantumCircuit(vr,vr2,anc,otr)

swap(qc3,vr,vr2,anc)

qc3.h(vr2)

qc3.h(otr)

qc3.x(otr)

for i in range(len(vr)):

qc3.cx(vr[i],vr2[i])

qc3.x(otr)

qc3.x(vr2)

qc3.mct(vr2,otr[0],anc)

qc3.x(vr2)

for i in range(len(vr)):

qc3.cx(vr[i],vr2[i])

qc3.barrier()

vprint('Building circuit')

circ = qc1+qc+qc2+qc+qc3

c = ClassicalRegister(len(otr))

circ.add_register(c)

circ.measure(otr,c)

sims = ceil(samples/8192)

vprint('Simulations : ', sims)

remshots = samples - ((sims-1)*8192)

shots = 8192

counts = [0]*sims

for i in range(sims):

vprint('Running Sim ', i+1)

vprint('Running in backend')

if i+1==sims:

shots = remshots

job = execute(circ,backend,shots=shots)

vprint('Waiting for end of execution and for obtaining results')

result = job.result()

vprint('Aquired Results')

counts[i] = job.result().get_counts()

vprint('counting ends')

favcount = 0

for i in range(sims):

favcount += counts[i]['0']

est = favcount/samples

#upper = (2**(n-1))*(1-sqrt(1-est))

#lower = (2**(n-1))*(1-sqrt(threshold))

upper = (1-sqrt(est))/2

lower = (1-threshold)/2

print('')

if lower<upper:

print('nl(f) belongs to [', round(lower,6), ',', round(upper,6), ']')

vprint('\nTotal number of quantum queries made : ', samples)

else:

print('You have entered a wrong threshold. Please correct it.')