# coding: utf-8

# In[1]:


#!/usr/bin/env python
import pickle
import uuid
import hashlib
from os import path
import rehash


# In[2]:


##This section of the code deals with all the functionalities provided to the admin

def admin_initial():
    username = "admin"
    password = "admin"
    salt = uuid.uuid4().hex
    hashcode = rehash.sha256(salt.encode() + password.encode())
    with open('admin.pickle','wb') as f:
        ret={username : { 'SALT' : salt ,
                    'HASHCODE' : hashcode
                }
            }
        pickle.dump(ret,f,protocol=pickle.HIGHEST_PROTOCOL)
    return 1

def admin():
    admin_user = input("Enter the admin username\n")
    admin_pass = input("Enter the admin password\n")
    with open('admin.pickle', 'rb') as f:
         adminb = pickle.load(f)
    salt = adminb[admin_user]['SALT']
    check = rehash.sha256(salt.encode() + admin_pass.encode())
    return adminb[admin_user]['HASHCODE'].hexdigest() == check.hexdigest()

def admin_pass_change(username):
    with open('admin.pickle','rb') as f:
        pass_chan = pickle.load(f)
    if username in pass_chan:
        new_pass = input("Enter the new password\n")
        new_salt = uuid.uuid4().hex
        new_hashcode = rehash.sha256(new_salt.encode() + new_pass.encode())
        pass_chan[username]['SALT'] = new_salt
        pass_chan[username]['HASHCODE'] = new_hashcode
        with open('admin.pickle','wb') as f:
            pickle.dump(pass_chan,f,protocol=pickle.HIGHEST_PROTOCOL)
        return 1
    else :
        print("Entered username does not match.\n")
        return 0

def admin_dump():
    with open('user.pickle','rb') as f:
            dump = pickle.load(f)
    print(dump)


# In[3]:


##THis function deals with regular user signup
def sign_up():
    username = input("Enter the username:\n")
    password = input("Enter the password:\n")

    salt = uuid.uuid4().hex
    hashcode = rehash.sha256(salt.encode() + password.encode())
    if path.isfile('user.pickle'):
            with open('user.pickle', 'rb') as f:
                up=pickle.load(f)
            if(username in up):
                return 0
            up[username] = {'SALT' : salt ,
                        'HASHCODE' : hashcode
                        }
    else:
            with open('user.pickle','wb') as f:
                up={username : { 'SALT' : salt ,
                                'HASHCODE' : hashcode

                }

                }
                pickle.dump(up,f,protocol=pickle.HIGHEST_PROTOCOL)
                return 1
    with open('user.pickle','wb') as f:
        pickle.dump(up, f, protocol=pickle.HIGHEST_PROTOCOL)
    return 1


# In[4]:


##This function deals with regular user sign in
def sign_in(username):
    with open('user.pickle', 'rb') as f:
         _in = pickle.load(f)
    if username in _in:
        password = input("Enter your password:")
        salt = _in[username]['SALT']
        check = rehash.sha256(salt.encode() + password.encode())
        return _in[username]['HASHCODE'].hexdigest() == check.hexdigest()
    else:
        print("Username does not exist.")
        return -1


# In[5]:


#This function will help the regular user to change the password
def change_password(username):
    new_pass = input("Enter the new password")
    new_salt = uuid.uuid4().hex
    new_hashcode = rehash.sha256(new_salt.encode() + new_pass.encode())
    with open('user.pickle','rb') as f:
        change = pickle.load(f)

    change[username]['SALT'] = new_salt
    change[username]['HASHCODE'] = new_hashcode
    with open('user.pickle','wb') as f:
        pickle.dump(change,f,protocol=pickle.HIGHEST_PROTOCOL)


# In[6]:


#This is the main function logic
admin_initial()
choice = '1'
while(choice < '4'):
    choice = input("1.Admin Login\n2.New User\n3.Existing User\n4.Exit\n")
    if choice == '1':
        ret_admin = admin()
        if ret_admin > 0:
                   print("\nWelcome Administrator\n")
                   val = input("1.Change Password\n2.Dump Passwords\n3.Exit\n")
                   if val == '1':
                        username = input("Re-Enter your admin username\n")
                        admin_val = admin_pass_change(username)
                        if admin_val == 1:
                            print("Password reset successful\n")
                        else :
                            print("Password could not be reset")
                   if val == '2':
                        admin_dump()

        else:
                   print("You cannot bypass this! Hard luck.\n")

    if choice == '2':
        ret = sign_up()
        if ret == 1:
            print("User added successfully\n")
        else:
            print("User could not be added\n")

    if choice == '3' :
        username = input("Hi User! Please enter your username\n")
        ret = sign_in(username)
        if ret > 0 :
            print("Welcome",username)
            choice = input("1 Change Password" + "\n" + "2. Any other key to exit\n")
            if choice == '1':
                change_password(username)
                print("Password reset successful\n")

        else :
            print("Cannot login in\n")


print("Bye!")