From adcc342c9c1674ce88ebaf7f9359bde9665ca3f8 Mon Sep 17 00:00:00 2001
From: David Blajda <blajda@hotmail.com>
Date: Wed, 26 Dec 2018 06:17:23 +0000
Subject: :WIP: Allow iteration over endpoints that provide pagination

---
 src/helix/mod.rs | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 99 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/helix/mod.rs b/src/helix/mod.rs
index 5c51c22..5daa498 100644
--- a/src/helix/mod.rs
+++ b/src/helix/mod.rs
@@ -356,7 +356,8 @@ struct RequestRef {
 }
 
 enum RequestState<T> {
-    Uninitalized,
+    SetupRequest,
+    SetupBarriers,
     WaitAuth(WaiterState<AuthWaiter>),
     SetupRatelimit,
     WaitLimit(WaiterState<RatelimitWaiter>),
@@ -369,6 +370,19 @@ pub struct ApiRequest<T> {
     state: RequestState<T>,
     attempt: u32,
     max_attempts: u32,
+    pagination: Option<String>,
+}
+
+enum IterableApiRequestState<T> {
+    Start,
+    PollInner(ApiRequest<T>),
+    Finished,
+}
+
+pub struct IterableApiRequest<T> {
+    inner: Arc<RequestRef>,
+    pagination: Option<String>,
+    state: IterableApiRequestState<T>, 
 }
 
 use self::models::PaginationTrait;
@@ -394,9 +408,10 @@ impl<T: DeserializeOwned + PaginationTrait + 'static + Send> ApiRequest<T> {
                 method: method,
                 ratelimit: ratelimit,
             }),
-            state: RequestState::Uninitalized,
+            state: RequestState::SetupRequest,
             attempt: 0,
             max_attempts: 1,
+            pagination: None,
         }
     }
 }
@@ -492,7 +507,7 @@ use crate::sync::waiter::Waiter;
 
 struct WaiterState<W: Waiter> {
     polling: bool,
-    shared_future: Option<(Shared<Box< Future<Item=(), Error=ConditionError> + Send>>)>,
+    shared_future: Option<(Shared<Box<Future<Item=(), Error=ConditionError> + Send>>)>,
     waiter: W,
     barrier: Barrier,
 }
@@ -552,7 +567,7 @@ impl Waiter for AuthWaiter {
 
     fn condition(&self) ->
         Shared<Box<Future<Item=(), Error=ConditionError> + Send>> {
-        /* If a secret is not provided than just immediately return */
+        /* If a secret is not provided then just immediately return */
         let secret = self.waiter.secret().unwrap();
         let bottom_client = self.waiter.get_bottom_client();
         let client = self.waiter.clone();
@@ -613,7 +628,7 @@ macro_rules! retry_ready {
         Err(e) => {
             if $s.attempt < $s.max_attempts {
                 $s.attempt += 1;
-                $s.state = RequestState::Uninitalized;
+                $s.state = RequestState::SetupBarriers;
                 continue;
             } else {
                 return Err(e.into());
@@ -622,6 +637,79 @@ macro_rules! retry_ready {
     })
 }
 
+use futures::Stream;
+
+/*
+impl<T: DeserializeOwned + 'static + Send> Future for ApiRequest<T> {
+    type Item = <Self as Stream>::Item;
+    type Error = <Self as Stream>::Error;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        let stream = self as &mut Stream<Item=Self::Item, Error=Self::Error>;
+        let state = stream.poll();
+        
+        match state {
+            Err(err) => Err(err),
+            Ok(maybe_ready) => {
+                match maybe_ready {
+                    Async::NotReady => Ok(Async::NotReady),
+                    Async::Ready(item) => {
+                        match item {
+                            Some(result) => Ok(Async::Ready(result)),
+                            None => panic!("Request future returned None for first result!")
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+*/
+impl<T: DeserializeOwned + 'static + Send> Stream for IterableApiRequest<T> {
+    type Item = T;
+    type Error = Error;
+
+    fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
+        loop {
+            match &mut self.state {
+                IterableApiRequestState::Start => {
+                    self.state = 
+                        IterableApiRequestState::PollInner(
+                            ApiRequest {
+                                inner: self.inner.clone(),
+                                state: RequestState::SetupRequest,
+                                attempt: 0,
+                                max_attempts: 1,
+                                pagination: None
+                            });
+                },
+                IterableApiRequestState::PollInner(request) => {
+                    let f = request as &mut Future<Item=Self::Item, Error=Self::Error>;
+                    match f.poll() {
+                        Err(err) => {
+                            self.state = IterableApiRequestState::Finished;
+                            return Err(err);
+                        },
+                        Ok(state) => {
+                            match state {
+                                Async::NotReady => return Ok(Async::NotReady),
+                                Async::Ready(res) => {
+                                    //TODO check pagination
+                                    self.state = IterableApiRequestState::Finished;
+                                    return Ok(Async::Ready(Some(res)));
+                                }
+                            }
+                        }
+                    }
+                },
+                IterableApiRequestState::Finished => {
+                    return Ok(Async::Ready(None));
+                }
+            }
+        }
+    }
+}
+
 impl<T: DeserializeOwned + 'static + Send> Future for ApiRequest<T> {
     type Item = T;
     type Error = Error;
@@ -629,7 +717,11 @@ impl<T: DeserializeOwned + 'static + Send> Future for ApiRequest<T> {
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
         loop {
             match &mut self.state {
-                RequestState::Uninitalized => {
+                RequestState::SetupRequest => {
+                    self.attempt = 0;
+                    self.state = RequestState::SetupBarriers;
+                }
+                RequestState::SetupBarriers => {
                     match self.inner.client.inner.as_ref() {
                         ClientType::Auth(inner) => {
                             let waiter = AuthWaiter {
@@ -729,7 +821,7 @@ impl<T: DeserializeOwned + 'static + Send> Future for ApiRequest<T> {
                 RequestState::PollParse(future) => {
                     let res = retry_ready!(self, future.poll());
                     return Ok(Async::Ready(res));
-                }
+                },
             }
         }
     }
-- 
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