from datetime import datetime
from flask import Flask
from flask import render_template, make_response
from flask import request, redirect, g
from flask import url_for
from flask import Response
import hashlib
import os.path
import time

from functools import wraps

import db

app = Flask(__name__)
DATABASE = '/data/rollerverbrauch.db'
DEBUG = True
SECRET_KEY = 'development key'
app.config.from_object(__name__)


def check_auth(username, password):
    salt = g.db2.get_salt_for_user(username)
    if salt is None:
        return False
    m = hashlib.sha256(password.encode('utf-8'))
    m = hashlib.sha256((m.hexdigest()+salt).encode('utf-8'))
    digest = m.hexdigest()
    ok = g.db2.check_password_for_user(username, digest)
    if not ok:
        app.logger.error("digest: " + digest)
    return ok


def authenticate():
    resp = make_response(render_template('login_required.html'), 401)
    resp.headers['WWW-Authenticate'] = 'Basic realm="Login Required"'
    return resp


def requires_auth(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        auth = request.authorization
        if not auth or not check_auth(auth.username, auth.password):
            return authenticate()
        return f(*args, **kwargs)
    return decorated


@app.before_request
def before_request():
    g.db2 = db.Db(app.config['DATABASE'])
    g.data = {}


@app.teardown_request
def teardown_request(exception):
    pass


@app.route('/')
@requires_auth
def index():
    return redirect(url_for('get_pit_stops'))


@app.route('/pitstops', methods=['POST'])
@requires_auth
def create_pit_stop():
    last_pitstop = g.db2.get_last_pit_stop()
    error_msg = {}
    
    date = request.form['date']
    try:
        date = datetime.strptime(date, '%Y-%m-%d').strftime('%Y-%m-%d')
    except ValueError:
        error_msg['date'] = 'invalid date, only YYYY-MM-DD is allowed'
        date = request.form['date']
    
    odometer = request.form['odometer']
    try:
        odometer = int(odometer)
    except ValueError:
        error_msg['odometer'] = 'Illegal Value, only Integers allowed'
        odometer = None
    if odometer is not None and odometer <= last_pitstop['odometer']:
        error_msg['odometer'] = 'Illegal Value, new Value must be bigger as given value'
        odometer = request.form['odometer']
    if odometer is None:
        odometer = request.form['odometer']
    
    litres = request.form['litres']
    try:
        litres = float(litres)
    except ValueError:
        error_msg['litres'] = 'Illegal Value, only floating point allowed'
        litres = None
    if litres is not None and litres <= 0:
        error_msg['litres'] = 'Litres must not be 0'
        litres = request.form['litres']
    if litres is None:
        litres = request.form['litres']
        
    # error checking here
    if len(error_msg) > 0:
        data = {'last': {'date': date, 'odometer': odometer, 'litres': litres}, 'error': error_msg}
        return render_template('newPitStopForm.html', data=data)

    g.db2.add_pit_stop(date, odometer, litres)

    return redirect(url_for('get_pit_stops'))


@app.route('/pitstops/createForm', methods=['GET'])
@requires_auth
def create_pit_stop_form():
    values = g.db2.get_last_pit_stop()
    values['date'] = time.strftime("%Y-%m-%d")
    g.data['last'] = values
    g.data['error'] = None
    return render_template('newPitStopForm.html', data=g.data)


@app.route('/pitstops', methods=['GET'])
@requires_auth
def get_pit_stops():
    data = prepare_pit_stops(g.db2.get_all_pit_stops())
    g.data['pitstops'] = data
    return render_template('pitstops.html', data=g.data)


@app.route('/manual', methods=['GET'])
@requires_auth
def get_manual():
    return render_template('manual.html', data=g.data)


@app.route('/statistics', methods=['GET'])
@requires_auth
def get_statistics():
    pitstops = g.db2.get_all_pit_stops()
    count = len(pitstops)
    distance = 0
    sum_litres = 0
    average_distance = 0
    average_litres_fuelled = 0
    average_litres_used = 0
    
    if count > 0:
        sum_litres = 0
        for pitstop in pitstops:
            sum_litres += pitstop['litres']
        average_litres_fuelled = sum_litres/count
    if count > 1:
        distance = pitstops[-1]['odometer'] - pitstops[0]['odometer']
        average_distance = distance/(count - 1)
        average_litres_used = 100 * (sum_litres-pitstops[0]['litres'])/distance
    g.data['distance'] = distance
    g.data['count'] = count
    g.data['litres'] = sum_litres
    g.data['averageDistance'] = average_distance
    g.data['averageListresFuelled'] = average_litres_fuelled
    g.data['averageListresUsed'] = average_litres_used
    return render_template('statistics.html', data=g.data)


def prepare_pit_stops(pitstops):
    for index in range(1, len(pitstops)):
        last = pitstops[index - 1]
        curr = pitstops[index]
        curr['distance'] = curr['odometer'] - last['odometer']
        curr['average'] = 100 * curr['litres']/curr['distance']
        last_date = datetime.strptime(last['date'], '%Y-%m-%d')
        curr_date = datetime.strptime(curr['date'], '%Y-%m-%d')
        curr['days'] = (curr_date - last_date).days
    pitstops.reverse()
    return pitstops

if __name__ == '__main__':
    if not os.path.isfile(DATABASE) or os.stat(DATABASE).st_size == 0:
        db = db.Db(app.config['DATABASE'])
        db.init_db(app.open_resource('schema.sql', mode='r'))
    app.run(debug=True, host='0.0.0.0')