main.py

from flask import Flask, request, session, render_template, jsonify, redirect, url_for
from constants import CONSUMER_ID, CONSUMER_SECRET, APP_SECRET
import requests
"""
This file contains all the functions and routes for our demo app.
"""
app = Flask(__name__)
# comment out when you're done testing
app.debug = True
app.secret_key = APP_SECRET #a secret string that will sign your session cookies

"""
This is the function that will be called when users
visit the home page.

app.route is a function decorator. It takes a URI as an argument, and
whenever a user requests that url, the function it decorates will get called.
In this case, if your app was at www.myapp.com, then someone visiting
www.myapp.com or www.myapp.com/index.html would cause the flask app to call
the index() function. For more information about the app.route decorator
check out http://flask.pocoo.org/docs/quickstart/#routing.
"""
@app.route('/')
@app.route('/index.html')
def index():
    if session.get('venmo_token'):
        data = {'name': session['venmo_username'],
                'consumer_id': CONSUMER_ID,
            'access_token': session['venmo_token'],
            'signed_in': True}
        return render_template('index.html', data=data)
    else:
        data = {'signed_in': False,
        'consumer_id': CONSUMER_ID}
        return render_template('/index.html', data=data)

"""
Example app endpoints to make HTTP requests to a third party API.
In this example, we make POST and GET requests to the Venmo API to
make a sandbox payment and get your 20 most recent payments on Venmo, respectively.
"""
@app.route('/make_payment', methods=["POST"])
def make_payment():
    """
    the 'request' object will contain all information about
    the POST request, including the HTTP status code, the method,
    the url arguments and the POST data.
    take a look at http://flask.pocoo.org/docs/quickstart/#the-request-object
    for more info.

    request.form will have all the information that the incoming post request.
    In this example, our app makes a POST request to /make_payment, and we grab
    those parameters to make a call to the Venmo payments endpoint.
    """
    access_token = request.form['access_token']
    note = request.form['note']
    email = request.form['email']
    amount = request.form['amount']

    """
    the payload contains all the information we are going to send in our
    post request when we make a payment with the Venmo API.
    """
    payload = {
        "access_token":access_token,
        "note":note,
        "amount":amount,
        "email":email
    }

    url = "https://api.venmo.com/payments"
    response = requests.post(url, payload)
    data = response.json()
    return jsonify(data)

@app.route('/get_payments', methods=["GET"])
def get_payments():
    access_token = request.args.get('access_token')
    url = "https://sandbox-api.venmo.com/payments?access_token=" + access_token
    response = requests.get(url)
    data = response.json()
    return jsonify(data)


"""
Example app endpoint that will handle OAuth server-side authentication.
This is the endpoint that Venmo will redirect once a user has successfully logged
in to your Venmo app. For more information on Venmo OAuth and the whole flow, check out
beta-developer.venmo.com/oauth.
"""
@app.route('/oauth-authorized')
def oauth_authorized():
    """
    You can use request.args to get URL arguments from a url. Another name for URL arguments
    is a query string.
    What is a URL argument? It's some data that is appended to the end of a url after a '?'
    that can give extra context or information.

    """
    AUTHORIZATION_CODE = request.args.get('code')
    data = {
        "client_id":CONSUMER_ID,
        "client_secret":CONSUMER_SECRET,
        "code":AUTHORIZATION_CODE
        }
    url = "https://api.venmo.com/oauth/access_token"
    response = requests.post(url, data)
    response_dict = response.json()
    access_token = response_dict.get('access_token')
    user = response_dict.get('user')

    session['venmo_token'] = access_token
    session['venmo_username'] = user['username']

    return redirect(url_for('index'))

"""
Going to this url will delete the current session
and redirect back to the home page.
"""
@app.route('/logout')
def logout():
    session.clear()
    return redirect(url_for('index'))

if __name__ == '__main__':
    app.run()