from flask import *
import secrets, hashlib
from model.models import *
import json

app = Blueprint('nounce', __name__)

SID = 'SID'
nonces = {}
authSessions = {}
users = {}

def loadUsers(path):
    global users
    with open(path) as json_file:
        users = json.load(json_file)

@app.route('/nonce', methods=['GET'])
def nounce():
    n = tryGetSessionNonce()
    if n == None or n.expired():
        n = generateSessionNonce()
    n.bump()
    return jsonify(n.__dict__),201

@app.route('/login', methods=['POST'])
def login():    
    if isLoggedIn():
        return 'already logged in', 400

    n = tryGetSessionNonce()
    if n == None:
        return 'no nonce was generated', 400
    if n.expired():
        clearSessionNonce()
        return 'nonce expired', 408
    
    user = request.form['user']
    cnonce = request.form['cnonce']
    pwdhash = request.form['pwdhash']

    pwdHashed_sha256 = ''
    if user in users:
        pwdHashed_sha256 = users[user]
    else:
        abort(403)

    hash = generateHash(pwdHashed_sha256, cnonce, n.token)
    if hash == pwdhash:
        s = generateAuthSession(user)
        return jsonify(s.__dict__),201
    else:
        abort(403)

@app.route('/check-login', methods=['GET'])
def checkLogin():
    if isLoggedIn():
        asession = authSessions[session[SID]]
        asession.bumpExpiration()
        return jsonify(asession.__dict__)
    else:
        return abort(403)

@app.route('/login-page', methods=['GET'])
def loginPage():
    return render_template('login-page.html')

def isLoggedIn():
    if SID in session and session[SID] in authSessions:
        return not(authSessions[session[SID]].expired())
    return False
    
def generateAuthSession(username):
    asession = AuthSession(username)
    authSessions[session[SID]] = asession
    return asession

def getAuthSession():
    if not SID in session:
        return None
    if not session[SID]:
        return None
    return authSessions[session[SID]]

def clearSessionNonce():
    if not SID in session:
        return
    if not session[SID] in nonces:
        return
    del nonces[session[SID]]

def tryGetSessionNonce():
    if not SID in session:
        return None
    if not session[SID] in nonces:
        return None
    return nonces[session[SID]]

def generateSessionNonce():
    n = Nounce()
    session[SID] = secrets.token_urlsafe()
    nonces[session[SID]] = n
    return n

def generateHash(pwdsha256,cnonce,nonce):
    all = pwdsha256+cnonce+nonce
    sha256 = hashlib.sha256( )
    sha256.update( all.encode('utf8') )
    return sha256.hexdigest()