From 2dc1a6873e993e7790f03b07c2a66925434bb83e Mon Sep 17 00:00:00 2001
From: Alexander Lyon <arlyon@me.com>
Date: Fri, 3 Jun 2022 09:36:41 +0100
Subject: [PATCH] feat: add paginator API

---
 src/params.rs | 97 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 69 insertions(+), 28 deletions(-)

diff --git a/src/params.rs b/src/params.rs
index 79b264f3b..594d029ab 100644
--- a/src/params.rs
+++ b/src/params.rs
@@ -185,6 +185,17 @@ where
     }
 }
 
+pub trait Paginable {
+    type O: Object + Send;
+    fn set_last(&mut self, item: Self::O);
+}
+
+#[derive(Debug)]
+pub struct ListPaginator<T, P> {
+    pub page: List<T>,
+    pub params: P,
+}
+
 /// A single page of a cursor-paginated list of an object.
 ///
 /// For more details, see <https://stripe.com/docs/api/pagination>
@@ -213,34 +224,31 @@ impl<T: Clone> Clone for List<T> {
     }
 }
 
-impl<T: DeserializeOwned + Send + 'static> List<T> {
-    /// Prefer `List::next` when possible
-    pub fn get_next(client: &Client, url: &str, last_id: &str) -> Response<List<T>> {
-        if url.starts_with("/v1/") {
-            let path = url.trim_start_matches("/v1/").to_string(); // the url we get back is prefixed
-            client.get_query(
-                &path,
-                [("starting_after", last_id)].iter().cloned().collect::<HashMap<_, _>>(),
-            )
-        } else {
-            err(StripeError::UnsupportedVersion)
-        }
+impl<T> List<T> {
+    pub fn paginate<P>(self, params: P) -> ListPaginator<T, P> {
+        ListPaginator { page: self, params }
     }
 }
 
-impl<T: Paginate + DeserializeOwned + Send + 'static> List<T> {
+impl<
+        T: Paginate + DeserializeOwned + Send + Sync + 'static + Clone + std::fmt::Debug,
+        P: Clone + Serialize + Send + 'static + std::fmt::Debug,
+    > ListPaginator<T, P>
+where
+    P: Paginable<O = T>,
+{
     /// Repeatedly queries Stripe for more data until all elements in list are fetched, using
     /// Stripe's default page size.
     ///
     /// Requires `feature = "blocking"`.
     #[cfg(feature = "blocking")]
     pub fn get_all(self, client: &Client) -> Response<Vec<T>> {
-        let mut data = Vec::new();
-        let mut next = self;
+        let mut data = Vec::with_capacity(self.page.total_count);
+        let mut paginator = self;
         loop {
-            if next.has_more {
-                let resp = next.next(client)?;
-                data.extend(next.data);
+            if paginator.page.has_more {
+                let resp = paginator.next(client)?;
+                data.extend(paginator.page.data);
                 next = resp;
             } else {
                 data.extend(next.data);
@@ -298,18 +306,50 @@ impl<T: Paginate + DeserializeOwned + Send + 'static> List<T> {
     }
 
     /// Fetch an additional page of data from stripe.
-    pub fn next(&self, client: &Client) -> Response<List<T>> {
-        if let Some(last_id) = self.data.last().map(|d| d.cursor()) {
-            List::get_next(client, &self.url, last_id.as_ref())
+    pub fn next(&self, client: &Client) -> Response<Self> {
+        if let Some(last) = self.page.data.last() {
+            if self.page.url.starts_with("/v1/") {
+                let path = self.page.url.trim_start_matches("/v1/").to_string(); // the url we get back is prefixed
+
+                // clone the params and set the cursor
+                let params_next = {
+                    let mut p = self.params.clone();
+                    p.set_last(last.clone());
+                    p
+                };
+
+                println!("next");
+                let page = client.get_query(&path, &params_next);
+
+                ListPaginator::create_paginator(page, params_next)
+            } else {
+                err(StripeError::UnsupportedVersion)
+            }
         } else {
-            ok(List {
-                data: Vec::new(),
-                has_more: false,
-                total_count: self.total_count,
-                url: self.url.clone(),
+            ok(ListPaginator {
+                page: List {
+                    data: Vec::new(),
+                    has_more: false,
+                    total_count: self.page.total_count,
+                    url: self.page.url.clone(),
+                },
+                params: self.params.clone(),
             })
         }
     }
+
+    /// Pin a new future which maps the result inside the page future into
+    /// a ListPaginator
+    #[cfg(feature = "async")]
+    fn create_paginator(page: Response<List<T>>, params: P) -> Response<Self> {
+        use futures_util::FutureExt;
+        Box::pin(page.map(|page| page.map(|page| ListPaginator { page, params })))
+    }
+
+    #[cfg(feature = "blocking")]
+    fn create_paginator(page: Response<List<T>>, params: P) -> Response<Self> {
+        ok(ListPaginator { page, params })
+    }
 }
 
 pub type Metadata = HashMap<String, String>;
@@ -439,7 +479,7 @@ mod tests {
                 "metadata": {},
                 "preferred_locales": [],
                 "tax_exempt": "none"
-              }], "has_more": true, "url": "/v1/customers"}"#,
+              }], "has_more": false, "url": "/v1/customers"}"#,
             );
         });
 
@@ -463,7 +503,8 @@ mod tests {
             );
         });
 
-        let res = Customer::list(&client, ListCustomers::new()).await.unwrap();
+        let params = ListCustomers::new();
+        let res = Customer::list(&client, &params).await.unwrap().paginate(params);
 
         println!("{:?}", res);