# -*- coding: utf-8 -*-
"""
Created on Sep 14 17:42:42 2024
@author: tuema
"""

print('HSK qiskit Exercises')

#---------------------------------------------------------------------------
#imports






#qiskit
from qiskit import QuantumCircuit,QuantumRegister,ClassicalRegister,transpile
from qiskit.providers.basic_provider import BasicSimulator
from qiskit.visualization import plot_histogram
from qiskit.circuit.library.standard_gates import XGate, ZGate





#math
import numpy as np

#ploting
import matplotlib.pyplot as plt


#----------------------------------------------------------------------------
#definitions and initialization begin

set_list = []
pi = np.pi

n=5
iterat = int(round((pi/4)*np.sqrt(n-1)))

print('iterat', iterat)

q = QuantumRegister(n)
cr =ClassicalRegister(n)
qc = QuantumCircuit(q,cr)


CtrlXGate = XGate().control(n-1)


#Die Quantenschaltung für das Oracle: 
#Die Markierung erfolgt durch X Gates 
#die für die nicht markierten Bits gesetzt werden
#Dies liegt an der Big Endian-Little Endian Problematik

def add_reflect_oracle(circuit, s_list):
    
    for i in range(0,len(s_list)):
        if s_list[i] == 0:
            circuit.x(i)
        
    circuit.h(n-1)
    circuit.append(CtrlXGate,q)
    circuit.h(n-1)  
    
    for i in range(0,len(s_list)):
        if s_list[i] == 0:
            circuit.x(i)

    qc.barrier()


# Die Quantenschaltung für den Grover-Operator:
# Sie führt die Verstärkung der Amplitudendifferenzen durch

def add_reflect_s(circuit):
    for i in range(n):
        circuit.h(i)
        
    for i in range(n):
        circuit.x(i)
    
    qc.barrier()
    
    circuit.h(n-1)
    circuit.append(CtrlXGate,q)
    circuit.h(n-1) 

    qc.barrier()
      
    for i in range(n):
        circuit.x(i)   
    
    for i in range(n):
        circuit.h(i)  
    
    qc.barrier()
   

#----------------------------------------------------------------------------
#definitions and initialization end


print('\nInitialising Circuit...\n')

### Initialisation ###

#Mark desired state
#example 0110
set_list = [0,1,1,0]


for i in range(n):
    qc.h(i)

qc.barrier()

#
print('\nPreparing Oracle circuit....\n')

### Oracle ###

#amplify

for i in range(iterat):
    add_reflect_oracle(qc, set_list)
    add_reflect_s(qc)       
    


### Measurment ###

for i in range(n-1):
    qc.measure(i,i)




#---------------------------------------------------------------------------
#draw
qc.draw("mpl")
plt.show()


#---------------------------------------------------------------------------
#execute simulation

sim_backend = BasicSimulator()
job = sim_backend.run(transpile(qc, sim_backend), shots=1024)
result = job.result()
counts = result.get_counts(qc)

#---------------------------------------------
#---------------------------------------------



#---------------------------------------------------------------------------
#plot

legend = ['1024 shots']
plot_histogram([counts],
               legend=legend,
               color=['midnightblue'],
               title="Grover"
               )
plt.show()

#---------------------------------------------------------------------------
#end