Re-add donations via Stripe

Multiple people have been asking me how they can make a one-time
donation without going through GitHub or Patreon, so I'll re-add this
for now but will need to keep an eye out for fraud and potentially
disable it again soon.

tildes/production.ini.example

@@ -23,6 +23,8 @@ redis.sessions.timeout = 3600
 
 sqlalchemy.url = postgresql+psycopg2://tildes:@:6432/tildes
 
+stripe.recurring_donation_product_id = prod_ProductID
+
 tildes.default_user_comment_label_weight = 1.0
 
 # Path to the file to use to check for passwords that have been in data breaches, which
@@ -42,4 +44,6 @@ webassets.manifest = json
 
 # API keys for external APIs
 api_keys.embedly = embedlykeygoeshere
+api_keys.stripe.publishable = pk_live_ActualKeyShouldGoHere
+api_keys.stripe.secret = sk_live_ActualKeyShouldGoHere
 api_keys.youtube = youtubekeygoeshere

tildes/requirements.in

@@ -34,6 +34,7 @@ requests
 sentry-sdk
 SQLAlchemy<1.4
 SQLAlchemy-Utils
+stripe
 titlecase
 webargs
 wrapt

tildes/static/js/behaviors/stripe-checkout.js

@@ -0,0 +1,10 @@
+// Copyright (c) 2019 Tildes contributors <code@tildes.net>
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+$.onmount("[data-js-stripe-checkout]", function() {
+    /* eslint-disable-next-line no-undef */
+    var stripe = Stripe($(this).attr("data-js-stripe-checkout"));
+    stripe.redirectToCheckout({
+        sessionId: $(this).attr("data-js-stripe-checkout-session")
+    });
+});

tildes/static/js/behaviors/stripe-donate-form.js

@@ -0,0 +1,28 @@
+// Copyright (c) 2019 Tildes contributors <code@tildes.net>
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+$.onmount("[data-js-stripe-donate-form]", function() {
+    $(this).on("submit", function(event) {
+        var $amountInput = $(this).find("#amount");
+        var amount = $amountInput.val();
+
+        var $errorDiv = $(this).find(".text-status-message");
+
+        // remove dollar sign and/or comma, then parse into float
+        amount = amount.replace(/[$,]/g, "");
+        amount = parseFloat(amount);
+
+        if (isNaN(amount)) {
+            $errorDiv.text("Please enter a valid dollar amount.");
+            event.preventDefault();
+            return;
+        } else if (amount < 1.0) {
+            $errorDiv.text("Donation amount must be at least $1.");
+            event.preventDefault();
+            return;
+        }
+
+        // set the value in case any of the replacements happened
+        $amountInput.val(amount);
+    });
+});

tildes/tildes/lib/ratelimit.py

@@ -308,6 +308,10 @@ _RATE_LIMITED_ACTIONS = (
     RateLimitedAction("register", timedelta(hours=1), 50),
     RateLimitedAction("topic_post", timedelta(hours=4), 10, max_burst=4),
     RateLimitedAction("comment_post", timedelta(hours=1), 10, max_burst=5),
+    RateLimitedAction("donate_stripe", timedelta(hours=1), 5, by_user=False),
+    RateLimitedAction(
+        "global_donate_stripe", timedelta(hours=1), 50, by_user=False, by_ip=False
+    ),
 )
 
 # (public) dict to be able to look up the actions by name

tildes/tildes/routes.py

@@ -115,6 +115,10 @@ def includeme(config: Configurator) -> None:
     # Route to expose metrics to Prometheus
     config.add_route("metrics", "/metrics")
 
+    # Routes for Stripe donations (linked from Docs site)
+    config.add_route("donate_stripe", "/donate_stripe")
+    config.add_route("donate_success", "/donate_success")
+
     # Add all intercooler routes under the /api/web path
     with config.route_prefix_context("/api/web"):
         add_intercooler_routes(config)

tildes/tildes/templates/donate_stripe.jinja2

@@ -0,0 +1,54 @@
+{# Copyright (c) 2019 Tildes contributors <code@tildes.net> #}
+{# SPDX-License-Identifier: AGPL-3.0-or-later #}
+
+{% extends 'base_no_sidebar.jinja2' %}
+
+{% block title %}Donate to Tildes{% endblock %}
+
+{% block main_heading %}Credit card donation (via Stripe){% endblock %}
+
+{% block content %}
+<p>After submitting this form, you will be redirected to the Stripe site to enter your payment info.</p>
+
+<p>Note that the donation is in Canadian Dollars (CAD) by default, but you can switch to USD if you prefer. At the moment, $10 CAD is about $7.50 USD.</p>
+
+<div class="divider"></div>
+
+<form class="form-narrow" method="post" data-js-stripe-donate-form>
+  <input type="hidden" name="csrf_token" value="{{ get_csrf_token() }}">
+
+  <div class="form-group">
+    <label class="form-label">Donation type</label>
+    <label class="form-radio">
+      <input type="radio" name="interval" value="onetime" checked>
+      <i class="form-icon"></i> One time
+    </label>
+    <label class="form-radio">
+      <input type="radio" name="interval" value="month">
+      <i class="form-icon"></i> Monthly
+    </label>
+    <label class="form-radio">
+      <input type="radio" name="interval" value="year">
+      <i class="form-icon"></i> Yearly
+    </label>
+  </div>
+
+  <div class="form-group">
+    <label class="form-label" for="amount">Donation amount (must be at least $1)</label>
+
+    <div class="input-group">
+      <span class="input-group-addon">$</span>
+      <input class="form-input" id="amount" name="amount" type="text" data-js-auto-focus>
+      <select class="form-select" id="currency" name="currency">
+        <option value="CAD" selected>CAD</option>
+        <option value="USD">USD</option>
+      </select>
+    </div>
+  </div>
+
+  <div class="form-buttons">
+    <button class="btn btn-primary" type="submit">Donate</button>
+    <div class="text-status-message text-error"></div>
+  </div>
+</form>
+{% endblock %}

tildes/tildes/templates/donate_stripe_redirect.jinja2

@@ -0,0 +1,18 @@
+{# Copyright (c) 2018 Tildes contributors <code@tildes.net> #}
+{# SPDX-License-Identifier: AGPL-3.0-or-later #}
+
+{% extends 'base_no_sidebar.jinja2' %}
+
+{% block title %}Stripe donation{% endblock %}
+
+{% block content %}
+  <script src="https://js.stripe.com/v3/"></script>
+
+  <p>Redirecting to Stripe...</p>
+
+  {# This div will cause the page to redirect to the Stripe Checkout page #}
+  <div
+    data-js-stripe-checkout="{{ publishable_key }}"
+    data-js-stripe-checkout-session="{{ session_id }}"
+  ></div>
+{% endblock %}

tildes/tildes/templates/donate_success.jinja2

@@ -0,0 +1,15 @@
+{# Copyright (c) 2019 Tildes contributors <code@tildes.net> #}
+{# SPDX-License-Identifier: AGPL-3.0-or-later #}
+
+{% extends 'base_no_sidebar.jinja2' %}
+
+{% block title %}Thanks for donating!{% endblock %}
+
+{% block content %}
+<div class="empty">
+  <h2 class="empty-title">Thanks for donating to Tildes!</h2>
+  <p class="empty-subtitle">You should receive an email receipt. If you have any questions, please feel free to contact <a href="mailto:donate@tildes.net">donate@tildes.net</a></p>
+
+  <div class="empty-action"><a href="/" class="btn btn-primary">Back to the home page</a></div>
+</div>
+{% endblock %}

tildes/tildes/views/donate.py

@@ -0,0 +1,115 @@
+# Copyright (c) 2018 Tildes contributors <code@tildes.net>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+"""The view for donating via Stripe."""
+
+import stripe
+from marshmallow.fields import Float, String
+from marshmallow.validate import OneOf, Range
+from pyramid.httpexceptions import HTTPInternalServerError
+from pyramid.request import Request
+from pyramid.security import NO_PERMISSION_REQUIRED
+from pyramid.view import view_config
+
+from tildes.metrics import incr_counter
+from tildes.views.decorators import rate_limit_view, use_kwargs
+
+
+@view_config(
+    route_name="donate_stripe",
+    request_method="GET",
+    renderer="donate_stripe.jinja2",
+    permission=NO_PERMISSION_REQUIRED,
+)
+def get_donate_stripe(request: Request) -> dict:
+    """Display the form for donating with Stripe."""
+    # pylint: disable=unused-argument
+    return {}
+
+
+@view_config(
+    route_name="donate_stripe",
+    request_method="POST",
+    renderer="donate_stripe_redirect.jinja2",
+    permission=NO_PERMISSION_REQUIRED,
+)
+@use_kwargs(
+    {
+        "amount": Float(required=True, validate=Range(min=1.0)),
+        "currency": String(required=True, validate=OneOf(("CAD", "USD"))),
+        "interval": String(required=True, validate=OneOf(("onetime", "month", "year"))),
+    },
+    location="form",
+)
+@rate_limit_view("global_donate_stripe")
+@rate_limit_view("donate_stripe")
+def post_donate_stripe(
+    request: Request, amount: int, currency: str, interval: str
+) -> dict:
+    """Process a Stripe donation."""
+    try:
+        stripe.api_key = request.registry.settings["api_keys.stripe.secret"]
+        publishable_key = request.registry.settings["api_keys.stripe.publishable"]
+        product_id = request.registry.settings["stripe.recurring_donation_product_id"]
+    except KeyError as exc:
+        raise HTTPInternalServerError from exc
+
+    incr_counter("donation_initiations", type="stripe")
+
+    if interval == "onetime":
+        session = stripe.checkout.Session.create(
+            payment_method_types=["card"],
+            line_items=[
+                {
+                    "name": "One-time donation - tildes.net",
+                    "amount": int(amount * 100),
+                    "currency": currency,
+                    "quantity": 1,
+                }
+            ],
+            submit_type="donate",
+            success_url="https://tildes.net/donate_success",
+            cancel_url="https://docs.tildes.net/donate",
+        )
+    else:
+        product = stripe.Product.retrieve(product_id)
+        existing_plans = stripe.Plan.list(product=product, active=True, limit=100)
+
+        # look through existing plans to see if there's already a matching one, or
+        # create a new plan if not
+        for existing_plan in existing_plans:
+            if (
+                existing_plan.amount == int(amount * 100)
+                and existing_plan.currency == currency.lower()
+                and existing_plan.interval == interval
+            ):
+                plan = existing_plan
+                break
+        else:
+            plan = stripe.Plan.create(
+                amount=int(amount * 100),
+                currency=currency,
+                interval=interval,
+                product=product,
+            )
+
+        session = stripe.checkout.Session.create(
+            payment_method_types=["card"],
+            subscription_data={"items": [{"plan": plan.id}]},
+            success_url="https://tildes.net/donate_success",
+            cancel_url="https://docs.tildes.net/donate",
+        )
+
+    return {"publishable_key": publishable_key, "session_id": session.id}
+
+
+@view_config(route_name="donate_success", renderer="donate_success.jinja2")
+def get_donate_success(request: Request) -> dict:
+    """Display a message after a successful donation."""
+    # pylint: disable=unused-argument
+
+    # incrementing this metric on page-load and hard-coding Stripe isn't ideal, but it
+    # should do the job for now
+    incr_counter("donations", type="stripe")
+
+    return {}