# This file is part of GNU TALER.
# Copyright (C) 2017 Taler Systems SA
#
# TALER is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free Software
# Foundation; either version 2.1, or (at your option) any later version.
#
# TALER is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License along with
# GNU TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
#
# @author Marcello Stanisci

import flask
import os
import base64
import requests
import logging
from .amount import Amount
from talersurvey.talerconfig import TalerConfig
from urllib.parse import urljoin


base_dir = os.path.dirname(os.path.abspath(__file__))
app = flask.Flask(__name__, template_folder=base_dir)
app.debug = True
app.secret_key = base64.b64encode(os.urandom(64)).decode('utf-8')
tc = TalerConfig.from_env()
BACKEND_URL = tc["frontends"]["backend"].value_string(required=True)
CURRENCY = tc["taler"]["currency"].value_string(required=True)
app.config.from_object(__name__)
logger = logging.getLogger(__name__)


def backend_error(requests_response):
    logger.error("Backend error: status code: "
                 + str(requests_response.status_code))
    try:
        return flask.jsonify(requests_response.json()), requests_response.status_code
    except json.decoder.JSONDecodeError:
        logger.error("Backend error (NO JSON returned): status code: "
                     + str(requests_response.status_code))
        return flask.jsonify(dict(error="Backend died, no JSON got from it")), 502

@app.context_processor
def utility_processor():
    def join_urlparts(*parts):
        s = ""
        i = 0
        while i < len(parts):
            n = parts[i]
            i += 1
            if s.endswith("/"):
                n = n.lstrip("/")
            elif s and  not n.startswith("/"):
                n = "/" + n
            s += n
        return s

    def url(my_url):
        return join_urlparts(flask.request.script_root, my_url)
    def env(name, default=None):
        return os.environ.get(name, default)
    return dict(url=url, env=env)

@app.route("/pick", methods=["POST"])
def pick():
    body = flask.request.get_json()
    # Let the backend complain!
    r = requests.post(urljoin(BACKEND_URL, 'tip-pickup'),
                      json=body)
    if 200 != r.status_code:
        return backend_error(r)
    else:
        return flask.jsonify(r.json())

@app.route("/", methods=["GET", "POST"])
def survey():
    if flask.request.method == "GET":
        return flask.render_template("templates/index.html", merchant_currency=CURRENCY)
    success = False
    amount = Amount(CURRENCY, 1)
    if flask.request.method == "POST":
        r = requests.post(urljoin(BACKEND_URL, 'tip-authorize'),
                          json=dict(amount=amount.dump(),
                                    instance="default",
                                    justification="Payment methods survey"))
        if 200 != r.status_code:
            return backend_error(r)
        else:
            success = True

    response = flask.make_response(flask.render_template("templates/index.html", success=success), 402)
    response.headers["X-Taler-Tipping-Url"] = urljoin(
        flask.request.base_url,
        flask.url_for("pick", tip_id=r.json().get("tip_id")))
    response.headers["X-Taler-Tipping-Exchange"] = r.json().get("exchange_uri")
    response.headers["X-Taler-Tipping-Amount"] = amount.stringify(2)
    response.headers["X-Taler-Tipping-Deadline"] = r.json().get("expiration")

    return response