g1t/services/billing/src/stripe.rs
| 1 | //! The card processor, behind the calls billing needs: start a payment |
| 2 | //! page, ask whether a payment was made, and read or end a monthly plan. Stripe speaks form-encoded |
| 3 | //! requests and JSON answers. |
| 4 | |
| 5 | use serde::Deserialize; |
| 6 | use worker::{Error, Fetch, Headers, Method, Request, RequestInit, Result}; |
| 7 | |
| 8 | const API: &str = "https://api.stripe.com/v1"; |
| 9 | |
| 10 | pub struct Stripe { |
| 11 | key: String, |
| 12 | } |
| 13 | |
| 14 | /// A payment page, and the payment made through it. |
| 15 | #[derive(Deserialize)] |
| 16 | pub struct Session { |
| 17 | pub id: String, |
| 18 | /// Where to send the person. Absent once the page has been used. |
| 19 | pub url: Option<String>, |
| 20 | /// `paid` once the money has been taken. |
| 21 | pub payment_status: String, |
| 22 | /// What was paid, in cents. |
| 23 | pub amount_total: Option<u32>, |
| 24 | pub customer: Option<String>, |
| 25 | /// For a plan's page: the subscription it started. |
| 26 | #[serde(default)] |
| 27 | pub subscription: Option<String>, |
| 28 | } |
| 29 | |
| 30 | /// A monthly plan. |
| 31 | #[derive(Deserialize)] |
| 32 | pub struct StripeSubscription { |
| 33 | pub id: String, |
| 34 | /// `active`, `trialing`, `past_due`, `unpaid`, `canceled`, `incomplete`… |
| 35 | pub status: String, |
| 36 | #[serde(default)] |
| 37 | pub cancel_at_period_end: bool, |
| 38 | /// Unix seconds. Older API versions carry it here… |
| 39 | #[serde(default)] |
| 40 | pub current_period_end: Option<i64>, |
| 41 | /// …newer ones on each item. |
| 42 | #[serde(default)] |
| 43 | pub items: Option<Items>, |
| 44 | } |
| 45 | |
| 46 | #[derive(Deserialize)] |
| 47 | pub struct Items { |
| 48 | pub data: Vec<Item>, |
| 49 | } |
| 50 | |
| 51 | #[derive(Deserialize)] |
| 52 | pub struct Item { |
| 53 | #[serde(default)] |
| 54 | pub current_period_end: Option<i64>, |
| 55 | } |
| 56 | |
| 57 | impl StripeSubscription { |
| 58 | /// When the period paid for ends, in Unix seconds. |
| 59 | pub fn period_end(&self) -> Option<i64> { |
| 60 | self.current_period_end.or_else(|| { |
| 61 | self.items |
| 62 | .as_ref() |
| 63 | .and_then(|items| items.data.iter().filter_map(|item| item.current_period_end).max()) |
| 64 | }) |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /// Percent-encodes a form value. |
| 69 | fn encode(value: &str) -> String { |
| 70 | let mut encoded = String::with_capacity(value.len()); |
| 71 | for byte in value.bytes() { |
| 72 | match byte { |
| 73 | b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => { |
| 74 | encoded.push(byte as char); |
| 75 | } |
| 76 | _ => encoded.push_str(&format!("%{byte:02X}")), |
| 77 | } |
| 78 | } |
| 79 | encoded |
| 80 | } |
| 81 | |
| 82 | /// `name=value` pairs as a form body. |
| 83 | /// A payment made with no one there. |
| 84 | #[derive(Debug, Deserialize)] |
| 85 | pub struct PaymentIntent { |
| 86 | pub id: String, |
| 87 | /// `succeeded`, or anything else when it did not go through. |
| 88 | pub status: String, |
| 89 | #[serde(default)] |
| 90 | pub amount_received: i64, |
| 91 | } |
| 92 | |
| 93 | pub(crate) fn form(fields: &[(&str, String)]) -> String { |
| 94 | fields |
| 95 | .iter() |
| 96 | .map(|(name, value)| format!("{}={}", encode(name), encode(value))) |
| 97 | .collect::<Vec<_>>() |
| 98 | .join("&") |
| 99 | } |
| 100 | |
| 101 | impl Stripe { |
| 102 | pub fn new(key: String) -> Self { |
| 103 | Stripe { key } |
| 104 | } |
| 105 | |
| 106 | /// Whether the key is for real cards, not Stripe's test mode. |
| 107 | pub fn live(&self) -> bool { |
| 108 | is_live(&self.key) |
| 109 | } |
| 110 | |
| 111 | async fn call<T: for<'a> Deserialize<'a>>( |
| 112 | &self, |
| 113 | method: Method, |
| 114 | path: &str, |
| 115 | body: Option<String>, |
| 116 | ) -> Result<T> { |
| 117 | self.send(method, path, body, None).await |
| 118 | } |
| 119 | |
| 120 | async fn send<T: for<'a> Deserialize<'a>>( |
| 121 | &self, |
| 122 | method: Method, |
| 123 | path: &str, |
| 124 | body: Option<String>, |
| 125 | idempotency_key: Option<&str>, |
| 126 | ) -> Result<T> { |
| 127 | let headers = Headers::new(); |
| 128 | headers.set("authorization", &format!("Bearer {}", self.key))?; |
| 129 | if let Some(key) = idempotency_key { |
| 130 | headers.set("idempotency-key", key)?; |
| 131 | } |
| 132 | if body.is_some() { |
| 133 | headers.set("content-type", "application/x-www-form-urlencoded")?; |
| 134 | } |
| 135 | let mut init = RequestInit::new(); |
| 136 | init.with_method(method).with_headers(headers); |
| 137 | if let Some(body) = body { |
| 138 | init.with_body(Some(body.into())); |
| 139 | } |
| 140 | let request = Request::new_with_init(&format!("{API}{path}"), &init)?; |
| 141 | let mut response = Fetch::Request(request).send().await?; |
| 142 | if response.status_code() != 200 { |
| 143 | return Err(Error::RustError(format!( |
| 144 | "the card processor answered {}: {}", |
| 145 | response.status_code(), |
| 146 | response.text().await.unwrap_or_default() |
| 147 | ))); |
| 148 | } |
| 149 | response.json().await |
| 150 | } |
| 151 | |
| 152 | /// Charges the customer's saved card, with no one there: the automatic |
| 153 | /// payment at a workspace's limit. `key` makes a retry the same charge. |
| 154 | pub async fn charge_saved_card( |
| 155 | &self, |
| 156 | customer: &str, |
| 157 | amount_cents: i64, |
| 158 | description: &str, |
| 159 | key: &str, |
| 160 | ) -> Result<PaymentIntent> { |
| 161 | #[derive(Deserialize)] |
| 162 | struct Methods { |
| 163 | data: Vec<Method_>, |
| 164 | } |
| 165 | #[derive(Deserialize)] |
| 166 | struct Method_ { |
| 167 | id: String, |
| 168 | } |
| 169 | let methods: Methods = self |
| 170 | .call(Method::Get, &format!("/payment_methods?customer={}&type=card&limit=1", encode(customer)), None) |
| 171 | .await?; |
| 172 | let Some(card) = methods.data.first() else { |
| 173 | return Err(Error::RustError("no card on file".into())); |
| 174 | }; |
| 175 | let fields = [ |
| 176 | ("amount", amount_cents.to_string()), |
| 177 | ("currency", "usd".to_owned()), |
| 178 | ("customer", customer.to_owned()), |
| 179 | ("payment_method", card.id.clone()), |
| 180 | ("off_session", "true".to_owned()), |
| 181 | ("confirm", "true".to_owned()), |
| 182 | ("description", description.to_owned()), |
| 183 | ]; |
| 184 | self.send(Method::Post, "/payment_intents", Some(form(&fields)), Some(key)).await |
| 185 | } |
| 186 | |
| 187 | /// Starts a page on which `amount_cents` of credit is paid for by card. |
| 188 | /// The card is kept for the workspace, so that topping up again, by |
| 189 | /// hand or automatically, needs no retyping. |
| 190 | pub async fn start_checkout( |
| 191 | &self, |
| 192 | workspace: &str, |
| 193 | amount_cents: u32, |
| 194 | customer: Option<&str>, |
| 195 | return_url: &str, |
| 196 | ) -> Result<Session> { |
| 197 | let separator = if return_url.contains('?') { '&' } else { '?' }; |
| 198 | let mut fields = vec![ |
| 199 | ("mode", "payment".to_owned()), |
| 200 | // Cards only: credit is bought on the spot, and the card is kept |
| 201 | // for topping up again. |
| 202 | ("payment_method_types[0]", "card".to_owned()), |
| 203 | ( |
| 204 | "success_url", |
| 205 | // Stripe fills in the payment's id. |
| 206 | format!("{return_url}{separator}session={{CHECKOUT_SESSION_ID}}"), |
| 207 | ), |
| 208 | ("cancel_url", return_url.to_owned()), |
| 209 | ("client_reference_id", workspace.to_owned()), |
| 210 | ("metadata[workspace]", workspace.to_owned()), |
| 211 | ("line_items[0][quantity]", "1".to_owned()), |
| 212 | ("line_items[0][price_data][currency]", "usd".to_owned()), |
| 213 | ( |
| 214 | "line_items[0][price_data][unit_amount]", |
| 215 | amount_cents.to_string(), |
| 216 | ), |
| 217 | ( |
| 218 | "line_items[0][price_data][product_data][name]", |
| 219 | format!("g1t agent credit for {workspace}"), |
| 220 | ), |
| 221 | ( |
| 222 | "payment_intent_data[setup_future_usage]", |
| 223 | "off_session".to_owned(), |
| 224 | ), |
| 225 | ]; |
| 226 | match customer { |
| 227 | Some(customer) => fields.push(("customer", customer.to_owned())), |
| 228 | None => fields.push(("customer_creation", "always".to_owned())), |
| 229 | } |
| 230 | self.call(Method::Post, "/checkout/sessions", Some(form(&fields))) |
| 231 | .await |
| 232 | } |
| 233 | |
| 234 | /// Starts a page on which a feature's monthly plan is paid for by card. |
| 235 | pub async fn start_subscription( |
| 236 | &self, |
| 237 | workspace: &str, |
| 238 | feature: &str, |
| 239 | title: &str, |
| 240 | monthly_cents: u32, |
| 241 | customer: Option<&str>, |
| 242 | return_url: &str, |
| 243 | ) -> Result<Session> { |
| 244 | let separator = if return_url.contains('?') { '&' } else { '?' }; |
| 245 | let mut fields = vec![ |
| 246 | ("mode", "subscription".to_owned()), |
| 247 | ("payment_method_types[0]", "card".to_owned()), |
| 248 | ( |
| 249 | "success_url", |
| 250 | format!("{return_url}{separator}session={{CHECKOUT_SESSION_ID}}"), |
| 251 | ), |
| 252 | ("cancel_url", return_url.to_owned()), |
| 253 | ("client_reference_id", workspace.to_owned()), |
| 254 | ("metadata[workspace]", workspace.to_owned()), |
| 255 | ("metadata[feature]", feature.to_owned()), |
| 256 | ("subscription_data[metadata][workspace]", workspace.to_owned()), |
| 257 | ("subscription_data[metadata][feature]", feature.to_owned()), |
| 258 | ("line_items[0][quantity]", "1".to_owned()), |
| 259 | ("line_items[0][price_data][currency]", "usd".to_owned()), |
| 260 | ( |
| 261 | "line_items[0][price_data][unit_amount]", |
| 262 | monthly_cents.to_string(), |
| 263 | ), |
| 264 | ( |
| 265 | "line_items[0][price_data][recurring][interval]", |
| 266 | "month".to_owned(), |
| 267 | ), |
| 268 | ( |
| 269 | "line_items[0][price_data][product_data][name]", |
| 270 | format!("g1t {title} for {workspace}"), |
| 271 | ), |
| 272 | ]; |
| 273 | if let Some(customer) = customer { |
| 274 | fields.push(("customer", customer.to_owned())); |
| 275 | } |
| 276 | self.call(Method::Post, "/checkout/sessions", Some(form(&fields))) |
| 277 | .await |
| 278 | } |
| 279 | |
| 280 | pub async fn subscription(&self, id: &str) -> Result<StripeSubscription> { |
| 281 | self.call(Method::Get, &format!("/subscriptions/{}", encode(id)), None) |
| 282 | .await |
| 283 | } |
| 284 | |
| 285 | /// Ends a plan when its period does (`cancel` true), or takes that back. |
| 286 | pub async fn cancel_at_period_end(&self, id: &str, cancel: bool) -> Result<StripeSubscription> { |
| 287 | self.call( |
| 288 | Method::Post, |
| 289 | &format!("/subscriptions/{}", encode(id)), |
| 290 | Some(form(&[("cancel_at_period_end", cancel.to_string())])), |
| 291 | ) |
| 292 | .await |
| 293 | } |
| 294 | |
| 295 | pub async fn session(&self, id: &str) -> Result<Session> { |
| 296 | self.call( |
| 297 | Method::Get, |
| 298 | &format!("/checkout/sessions/{}", encode(id)), |
| 299 | None, |
| 300 | ) |
| 301 | .await |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /// Whether the processor said an id it was given does not exist, as when |
| 306 | /// g1t moves to another Stripe account and ids saved from the old one stay |
| 307 | /// behind. |
| 308 | pub(crate) fn is_missing(error: &Error) -> bool { |
| 309 | error.to_string().contains("resource_missing") |
| 310 | } |
| 311 | |
| 312 | pub(crate) fn is_live(key: &str) -> bool { |
| 313 | key.starts_with("sk_live_") || key.starts_with("rk_live_") |
| 314 | } |
| 315 | |
| 316 | #[cfg(test)] |
| 317 | mod tests { |
| 318 | use super::*; |
| 319 | |
| 320 | #[test] |
| 321 | fn form_values_are_percent_encoded() { |
| 322 | assert_eq!( |
| 323 | form(&[ |
| 324 | ( |
| 325 | "success_url", |
| 326 | "https://g1t.sh/a/-/billing?session={ID}".to_owned() |
| 327 | ), |
| 328 | ("line_items[0][quantity]", "1".to_owned()), |
| 329 | ]), |
| 330 | "success_url=https%3A%2F%2Fg1t.sh%2Fa%2F-%2Fbilling%3Fsession%3D%7BID%7D&line_items%5B0%5D%5Bquantity%5D=1" |
| 331 | ); |
| 332 | } |
| 333 | |
| 334 | #[test] |
| 335 | fn test_keys_are_not_live() { |
| 336 | assert!(is_live("sk_live_abc")); |
| 337 | assert!(!is_live("sk_test_abc")); |
| 338 | assert!(!is_live("")); |
| 339 | } |
| 340 | } |