import hashlib
import os
import signal
import sys

from pandas.io import sql as psql
from sqlalchemy import create_engine, text
from utils.os_specific_functions import FOLDER_SEPARATOR

LOWER_CASE = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
UPPER_CASE = [letter.upper() for letter in LOWER_CASE]
NUMBERS = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
SPECIAL_CHARACTERS = ['!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '<', '>', '?', '/', '\\', '[', ']', '{', '}', '|', '~', '`', ';', ':']

IGNORED_FILE = 'Instructions.md'
SQLITE_DB_FILE = 'common_passwords.sqlite'

base_directory = os.getcwd() + FOLDER_SEPARATOR + 'auth_tools'

def create_sqlite_engine():
    db_uri = 'sqlite:///' + base_directory + FOLDER_SEPARATOR + SQLITE_DB_FILE
    # Configure pool_size, max_overflow, and pool_timeout to handle connection loads gracefully
    sqlite_engine = create_engine(
        url=db_uri,
        pool_size=20,
        max_overflow=0,
        pool_timeout=30,
        pool_recycle=1800
    )
    return sqlite_engine

def query_db(query):
    response = psql.read_sql_query(query, con=sqlite_engine)
    return response


def execute_db(query):
    with sqlite_engine.connect() as conn, conn.begin():
        conn.execute(text(query))

def create_md5_hash(word):
    hashed = hashlib.md5(word.encode())
    hash_text = hashed.hexdigest()
    return hash_text

def add_password_heuristics():
    common_passwords = []
    heuristics_folder = base_directory + FOLDER_SEPARATOR + 'add_password_heuristics'
    heuristic_files = os.listdir(heuristics_folder)
    if IGNORED_FILE in heuristic_files:
        heuristic_files.remove(IGNORED_FILE)
    if len(heuristic_files) == 0:
        return
    i = 0
    for heuristic_file in heuristic_files:
        if heuristic_file == IGNORED_FILE:
            continue
        print(f'Adding new definitions from {heuristic_file}')
        file_loc = heuristics_folder + FOLDER_SEPARATOR + heuristic_file
        with open(file_loc, 'r', encoding='utf-8') as file:
            for line in file:
                clean_line = line.strip()
                i += 1
                if i % 1000 == 0 and i != 1:
                    print(f'{int(i / 1000)}k passwords collected')
                if clean_line not in common_passwords and simple_check(clean_line):
                    common_passwords.append(clean_line)
    i = 0
    print(f'Adding {len(common_passwords)} Passwords to DB.')
    for password in common_passwords:
        hashed_pass = create_md5_hash(password)
        query = query_db(f"SELECT id FROM common_passwords WHERE password_hash = '{hashed_pass}'")
        if len(query) == 0:
            i += 1
            execute_db(f"INSERT INTO common_passwords(password_hash) VALUES('{hashed_pass}')")
            if i % 1000 == 0:
                print(f'{int(i / 1000)}k passwords added to db')
    for heuristic_file in heuristic_files:
        os.remove(heuristics_folder + FOLDER_SEPARATOR + heuristic_file)

def simple_check(password):
    if len(password) < 8:
        return False
    contains_lower, contains_upper, contains_special = False, False, False
    for letter in password:
        if letter in LOWER_CASE:
            contains_lower = True
        elif letter in UPPER_CASE:
            contains_upper = True
        elif letter in SPECIAL_CHARACTERS:
            contains_special = True
    if contains_lower and contains_upper and contains_special:
        return True
    return False



def confirm_strong_password(password):
    if not simple_check(password):
        return False
    hashed_pass = create_md5_hash(password)
    query = query_db(f"SELECT id FROM common_passwords WHERE password_hash = '{hashed_pass}'")
    if len(query) != 0:
        return False
    return True

def graceful_exit(signum, frame):
    sqlite_engine.dispose()
    print(f'Disposing SQL Engine')
    sys.exit(0)

signal.signal(signal.SIGINT, graceful_exit)
signal.signal(signal.SIGTERM, graceful_exit)

sqlite_engine = create_sqlite_engine()

add_password_heuristics()