auction: first pass at schedule DA validation

crates/core/component/auction/src/component/action_handler/dutch/schedule.rs

@@ -1,18 +1,71 @@
-use anyhow::Result;
+use crate::component::auction::StateReadExt;
+use anyhow::{ensure, Result};
 use async_trait::async_trait;
 use cnidarium::StateWrite;
 use cnidarium_component::ActionHandler;
+use penumbra_sct::component::clock::EpochRead; // AuctionRead?
 
 use crate::auction::dutch::actions::ActionDutchAuctionSchedule;
 
 #[async_trait]
 impl ActionHandler for ActionDutchAuctionSchedule {
     type CheckStatelessContext = ();
     async fn check_stateless(&self, _context: ()) -> Result<()> {
+        let schedule = self;
+        let end_height = schedule.description.end_height;
+        let start_height = schedule.description.start_height;
+        let step_count = schedule.description.step_count;
+
+        // Check that the start and end height are valid.
+        ensure!(
+            start_height < end_height,
+            "the start height MUST be strictly less than the end height (got: start={} >= end={})",
+            start_height,
+            end_height
+        );
+
+        // Check that the step count is positive.
+        ensure!(
+            step_count > 0,
+            "step count MUST be greater than zero (got: {step_count})"
+        );
+
+        // Check that the step count is less than 1000.
+        ensure!(
+            step_count <= 1000,
+            "the dutch auction step count MUST be less than 1000 (got: {step_count})",
+        );
+
+        // Check that height delta is a multiple of `step_count`.
+        let block_window = end_height - start_height;
+        ensure!(
+            (block_window % step_count) == 0,
+            "the block window ({block_window}) MUST be a multiple of the step count ({step_count})"
+        );
+
         Ok(())
     }
 
-    async fn check_and_execute<S: StateWrite>(&self, mut _state: S) -> Result<()> {
+    async fn check_and_execute<S: StateWrite>(&self, mut state: S) -> Result<()> {
+        let schedule = self;
+
+        // Check that `start_height` is in the future.
+        let current_height = state.get_block_height().await?;
+        let start_height = schedule.description.start_height;
+        ensure!(
+            start_height > current_height,
+            "dutch auction MUST start in the future (start={}, current={})",
+            start_height,
+            current_height
+        );
+
+        // Check that the `auction_id` is unused.
+        let id = schedule.description.id();
+        ensure!(
+            !state.auction_id_exists(id).await,
+            "the supplied auction id is already known to the chain (id={id})"
+        );
+
         Ok(())
     }
 }