# 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 os
import base64
import logging
import json
from urllib.parse import urljoin
import flask
import requests
import traceback
from ..talerconfig import TalerConfig

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)
APIKEY = TC["frontends"]["backend_apikey"].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 env(name, default=None):
        return os.environ.get(name, default)
    return dict(env=env)


def err_abort(abort_status_code, **params):
    t = flask.render_template("templates/error.html", **params)
    flask.abort(flask.make_response(t, abort_status_code))


def backend_post(endpoint, json):
    headers = {"Authorization": "ApiKey " + APIKEY}
    try:
        resp = requests.post(urljoin(BACKEND_URL, endpoint), json=json, headers=headers)
    except requests.ConnectionError:
        err_abort(500, message="Could not establish connection to backend")
    try:
        response_json = resp.json()
    except ValueError:
        err_abort(500, message="Could not parse response from backend",
                  status_code=resp.status_code)
    if resp.status_code != 200:
        err_abort(500, message="Backend returned error status",
                  json=response_json, status_code=resp.status_code)
    return response_json


def backend_get(endpoint, params):
    headers = {"Authorization": "ApiKey " + APIKEY}
    try:
        resp = requests.get(urljoin(BACKEND_URL, endpoint), params=params, headers=headers)
    except requests.ConnectionError:
        err_abort(500, message="Could not establish connection to backend")
    try:
        response_json = resp.json()
    except ValueError:
        err_abort(500, message="Could not parse response from backend")
    if resp.status_code != 200:
        err_abort(500, message="Backend returned error status",
                  json=response_json, status_code=resp.status_code)
    return response_json


@app.errorhandler(Exception)
def internal_error(e):
    return flask.render_template("templates/error.html",
                                 message="Internal error",
                                 stack=traceback.format_exc())

@app.route("/favicon.ico")
def favicon():
    print("will look into: " + os.path.join(app.root_path, 'static'))
    return flask.send_from_directory(os.path.join(app.root_path, 'static'),
                                     "favicon.ico", mimetype="image/vnd.microsoft.ico")

@app.route("/survey-stats", methods=["GET"])
def survey_stats():
    stats = backend_get("tip-query", dict(instance="default"))
    return flask.render_template("templates/survey_stats.html", stats=stats)


@app.route("/submit-survey", methods=["POST"])
def submit_survey():
    tip_spec = dict(amount=CURRENCY + ":1.0",
                    next_url=os.environ.get("TALER_ENV_URL_INTRO", "https://taler.net/"),
                    instance="default",
                    justification="Payment methods survey")
    resp = backend_post("tip-authorize", tip_spec)

    if resp.get("tip_redirect_url"):
        return flask.redirect(resp["tip_redirect_url"])

    err_abort(500, message="Tipping failed, unexpected backend response",
              json=resp)


@app.route("/", methods=["GET"])
def index():
    return flask.render_template("templates/index.html", merchant_currency=CURRENCY)