wip: feat: respect Scryfall's rate limits by default

Author: voidcontext

Cargo.toml

@@ -14,14 +14,15 @@ categories = ["api-bindings", "games"]
 features = ["unknown_variants"]
 
 [features]
-default = ["bulk_caching", "default-tls"]
+default = ["bulk_caching", "default-tls", "auto_rate_limit"]
 # default = []
 bulk_caching = ["dep:heck"]
 default-tls = ["reqwest/default-tls"]
 native-tls = ["reqwest/native-tls"]
 rustls-tls = ["reqwest/rustls-tls"]
 unknown_variants = []
 unknown_variants_slim = []
+auto_rate_limit = []
 bin = ["tokio/macros", "tokio/rt-multi-thread"]
 
 [dependencies]

src/uri.rs

@@ -6,6 +6,7 @@
 use std::convert::TryFrom;
 use std::marker::PhantomData;
 
+use cfg_if::cfg_if;
 use httpstatus::StatusCode;
 use reqwest::header::{self, HeaderValue};
 use serde::de::DeserializeOwned;
@@ -139,6 +140,19 @@ impl<T: DeserializeOwned> Uri<T> {
     }
 
     pub(crate) async fn fetch_raw(&self) -> crate::Result<reqwest::Response> {
+        // Respect Scryfall's rate limits
+        cfg_if! {
+            if #[cfg(feature = "auto_rate_limit")] {
+                let limit = match self.url.path() {
+                    "/cards/search" | "/cards/named" | "cards/random" | "/cards/collection" => 500,
+                    "/cards/search/" | "/cards/named/" | "cards/random/" | "/cards/collection/" => 500,
+                    "/cards/manifest" => 6000,
+                    _ => 110,
+                };
+                tokio::time::sleep(tokio::time::Duration::from_millis(limit)).await;
+            }
+        }
+
         match client().get(self.url.clone()).send().await {
             Ok(response) => match response.status().as_u16() {
                 400..=599 => Err(Error::ScryfallError(response.json().await.map_err(