[pos] Add epoch argument to vp::pos::rewards

.changelog/unreleased/SDK/4196-rewards-at-past-epoch.md

@@ -0,0 +1,2 @@
+- Allow querying PoS rewards at a specified epoch
+  ([\#4196](https://github.com/anoma/namada/pull/4196))

.vscode/launch.json

@@ -229,6 +229,25 @@
             "args": [],
             "cwd": "${workspaceFolder}"
         },
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug unit tests in library 'namada_sdk'",
+            "cargo": {
+                "args": [
+                    "test",
+                    "--no-run",
+                    "--lib",
+                    "--package=namada_sdk"
+                ],
+                "filter": {
+                    "name": "namada_sdk",
+                    "kind": "lib"
+                }
+            },
+            "args": [],
+            "cwd": "${workspaceFolder}"
+        },
         {
             "type": "lldb",
             "request": "launch",

crates/apps_lib/src/cli.rs

@@ -2049,7 +2049,7 @@ pub mod cmds {
         fn def() -> App {
             App::new(Self::CMD)
                 .about(wrap!(
-                    "Query the latest rewards available to claim for a given \
+                    "Query the rewards available to claim for a given \
                      delegation (or self-bond)."
                 ))
                 .add_args::<args::QueryRewards<args::CliTypes>>()
@@ -7309,6 +7309,7 @@ pub mod args {
                 query: self.query.to_sdk(ctx)?,
                 validator: ctx.borrow_chain_or_exit().get(&self.validator),
                 source: self.source.map(|x| ctx.borrow_chain_or_exit().get(&x)),
+                epoch: self.epoch,
             })
         }
     }
@@ -7318,10 +7319,12 @@ pub mod args {
             let query = Query::parse(matches);
             let source = SOURCE_OPT.parse(matches);
             let validator = VALIDATOR.parse(matches);
+            let epoch = EPOCH.parse(matches);
             Self {
                 query,
                 source,
                 validator,
+                epoch,
             }
         }
 
@@ -7336,6 +7339,14 @@ pub mod args {
                         "Validator address for the rewards query."
                     )),
                 )
+                .arg(EPOCH.def().help(wrap!(
+                    "The epoch at which to query (corresponding to the last \
+                     committed block, if not specified). \
+                     \
+                     Note: when querying by epoch, this returns the accumulated \
+                     rewards that were available to claim at the start of the \
+                     epoch."
+                )))
         }
     }
 

crates/apps_lib/src/client/rpc.rs

@@ -1503,8 +1503,11 @@ pub async fn query_rewards<C: Client + Sync>(
     client: &C,
     source: &Option<Address>,
     validator: &Address,
+    epoch: &Option<Epoch>,
 ) -> token::Amount {
-    unwrap_sdk_result(rpc::query_rewards(client, source, validator).await)
+    unwrap_sdk_result(
+        rpc::query_rewards(client, source, validator, epoch).await,
+    )
 }
 
 /// Query token total supply.
@@ -1920,12 +1923,18 @@ pub async fn query_and_print_rewards<N: Namada>(
     context: &N,
     args: args::QueryRewards,
 ) {
-    let (source, validator) = (args.source, args.validator);
+    let (source, validator, epoch) = (args.source, args.validator, args.epoch);
 
-    let rewards = query_rewards(context.client(), &source, &validator).await;
+    let rewards =
+        query_rewards(context.client(), &source, &validator, &epoch).await;
     display_line!(
         context.io(),
-        "Current rewards available for claim: {} NAM",
+        "{}: {} NAM",
+        epoch
+            .map(|e| format!("Rewards at epoch {}", e))
+            .unwrap_or_else(
+                || "Current rewards available for claim".to_string()
+            ),
         rewards.to_string_native()
     );
 }

crates/sdk/src/args.rs

@@ -2545,6 +2545,8 @@ pub struct QueryRewards<C: NamadaTypes = SdkTypes> {
     pub source: Option<C::Address>,
     /// Address of the validator
     pub validator: C::Address,
+    /// Epoch in which to find rewards
+    pub epoch: Option<Epoch>,
 }
 
 /// Query PoS delegations

crates/sdk/src/queries/shell.rs

@@ -429,7 +429,7 @@ where
 /// borsh-encoded types, it is safe to check `data.is_empty()` to see if the
 /// value was found, except for unit - see `fn query_storage_value` in
 /// `apps/src/lib/client/rpc.rs` for unit type handling via `storage_has_key`.
-fn storage_value<D, H, V, T>(
+pub fn storage_value<D, H, V, T>(
     ctx: RequestCtx<'_, D, H, V, T>,
     request: &RequestQuery,
     storage_key: storage::Key,