from configparser import ConfigParser
from email.message import EmailMessage
import random
import operator
from os.path import exists
from secrets import token_urlsafe
from smtplib import SMTP
from time import time

import flask
import sqlalchemy
import sqlalchemy.orm

CONFIG_PATH = "/etc/contact-form/config.ini"
OPERATORS = (
    ('+', operator.add),
    ('×', operator.mul),
    ('-', operator.sub),
)

config = ConfigParser()
config.read(CONFIG_PATH)
app = flask.Flask(__name__)
Base = sqlalchemy.orm.declarative_base()



class Captcha(Base):
    __tablename__ = "captcha"

    token = sqlalchemy.Column(sqlalchemy.String(90), primary_key=True) 
    answer = sqlalchemy.Column(sqlalchemy.String(3))
    expiration = sqlalchemy.Column(sqlalchemy.Integer())


def get_session():
    db_path = config.get("app", "db_path", fallback="")
    engine = sqlalchemy.create_engine(f"sqlite:///{db_path}")
    if not exists(db_path):
        Base.metadata.create_all(engine)
    session_factory = sqlalchemy.orm.sessionmaker(engine)
    return session_factory()


def clean_db(session):
    session.query(Captcha).filter(Captcha.expiration < int(time())).delete()


def generate_captacha():
    session = get_session()
    clean_db(session)
    first_number = random.randrange(10)
    second_number = random.randrange(10)
    op_text, op_func = random.choice(OPERATORS)
    if op_text == "-" and first_number < second_number:
        first_number, second_number = second_number, first_number
    result = op_func(first_number, second_number)
    captcha = Captcha(
        token=token_urlsafe(67),
        answer=str(result),
        expiration=int(time()) + config.getint("app", "captcha_timout", fallback=3600),
    )
    session.add(captcha)
    session.commit()
    return {
        "first_number": first_number,
        "second_number": second_number,
        "op_text": op_text,
        "token": captcha.token,
    }


def validate_captcha(token, value):
    result = False
    session = get_session()
    clean_db(session)
    captcha = session.query(Captcha).filter(Captcha.token == token).one_or_none()
    if captcha:
        result = value == captcha.answer
    session.query(Captcha).filter(Captcha.token == token).delete()
    session.commit()
    return result


def send_email(sender, message):
    katzei_email = EmailMessage()
    katzei_email.set_content(message)
    katzei_email["From"] = sender
    katzei_email["To"] = config.get("email", "reciever")
    katzei_email["Subject"] = config.get("email", "subject")

    contact_email = EmailMessage()
    contact_email.set_content(message)
    contact_email["From"] = config.get("email", "sender")
    contact_email["To"] = sender
    contact_email["Subject"] = config.get("email", "subject")

    smtp = SMTP(config.get("email", "server"))
    smtp.send_message(katzei_email)
    smtp.send_message(contact_email)
    smtp.quit()


@app.route(config.get("app", "path"), methods=["GET"])
def get_form(context=None):
    context = (context or {}) | generate_captacha()
    return flask.render_template("form.html", **context)


@app.route(config.get("app", "path"), methods=["POST"])
def validate_form():
    form = flask.request.form
    if not all(form.get(f, False) for f in ("email", "message", "captcha", "token")):
        return "Erreur", 400
    if not validate_captcha(form["token"], form["captcha"]):
        context = dict(**form)
        context["captcha_error"] = True
        context.pop("captcha", None)
        return get_form(context=context)
    send_email(sender=form["email"], message=form["message"])
    return flask.render_template("success.html")

application=app