from base64 import b64decode
import functools
import re

from nanoid import generate

from flask import Blueprint
from flask import flash
from flask import current_app
from flask import g
from flask import redirect
from flask import url_for
from flask import request
from flask import session
from flask import render_template
from flask_mail import Message
from werkzeug.exceptions import abort

from capsulflask.db import get_model

bp = Blueprint("auth", __name__, url_prefix="/auth")

def account_required(view):
    """View decorator that redirects non-logged-in users to the login page."""

    @functools.wraps(view)
    def wrapped_view(**kwargs):
        api_token = request.headers.get('authorization', None)
        if api_token is not None:
            email = get_model().authenticate_token(b64decode(api_token).decode('utf-8'))

            if email is not None:
                session.clear()
                session["account"] = email
                session["csrf-token"] = generate()

        if session.get("account") is None or session.get("csrf-token") is None :
            return redirect(url_for("auth.login"))

        return view(**kwargs)

    return wrapped_view


def admin_account_required(view):
    """View decorator that redirects non-admin users to the login page."""

    @functools.wraps(view)
    def wrapped_view(**kwargs):
        if session.get("account") is None or session.get("csrf-token") is None:
            return abort(404)

        if session.get("account") not in current_app.config["ADMIN_PANEL_ALLOW_EMAIL_ADDRESSES"].split(","):
            return abort(404)

        return view(**kwargs)

    return wrapped_view

@bp.route("/login", methods=("GET", "POST"))
def login():
    if request.method == "POST":
        email = request.form["email"]
        errors = list()

        if not email:
            errors.append("email is required")
        elif len(email.strip()) < 6 or email.count('@') != 1 or email.count('.') == 0: 
            errors.append("enter a valid email address")

        if len(errors) == 0:
            result = get_model().login(email)
            token = result[0]
            ignoreCaseMatches = result[1]
            if token is None:
                errors.append("too many logins. please use one of the existing login links that have been emailed to you")
            else:
                link = f"{current_app.config['BASE_URL']}/auth/magic/{token}"

                message = (f"Navigate to {link} to log into Capsul.\n"
                            "\nIf you didn't request this, ignore this message.")

                if len(ignoreCaseMatches) > 0:
                  joinedMatches = " or ".join(map(lambda x: f"'{x}'", ignoreCaseMatches))
                  message = (f"You tried to log in as '{email}', but that account doesn't exist yet. \n"
                              f"If you would like to create a new account for '{email}', click here {link} \n\n"
                              f"If you meant to log in as {joinedMatches}, please return to https://capsul.org \n"
                              "and log in again with the correct (case-sensitive) email address.")

                current_app.config["FLASK_MAIL_INSTANCE"].send(
                    Message(
                        "Click This Link to Login to Capsul",
                        sender=current_app.config["MAIL_DEFAULT_SENDER"],
                        body=message,
                        recipients=[email]
                    )
                )

                return render_template("login-landing.html", email=email, has_smtp=(current_app.config["MAIL_SERVER"] != ""))

        for error in errors:
            flash(error)

    return render_template("login.html")

@bp.route("/magic/<string:token>", methods=("GET", ))
def magiclink(token):
    email = get_model().consume_token(token)
    if email is not None:
        session.clear()
        session["account"] = email
        session["csrf-token"] = generate()
        
        return redirect(url_for("console.index"))
    else:
        # this is here to prevent xss
        if token and not re.match(r"^[a-zA-Z0-9_-]+$", token):
          token = '___________'

        abort(404, f"Token {token} doesn't exist or has already been used.")

@bp.route("/logout")
def logout():
    session.clear()
    return redirect(url_for("index"))