add price_oracle_aggregator

ken-underscore · Dec 31, 2024 · b494ebf · b494ebf
1 parent 701f626
commit b494ebf
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Showing 4 changed files with 46 additions and 22 deletions.
diff --git a/lib/datums.ak b/lib/datums.ak
@@ -9,7 +9,7 @@ pub type PoolDatum {
 }
 
 pub type HusdParamsDatum {
-  price_oracle_hash: ScriptHash,
+  price_oracle_aggregator_hash: ScriptHash,
   min_reserve_ratio: Fraction,
   pool_script: ScriptHash,
   price_oracles: List<ScriptHash>,

diff --git a/lib/utils.ak b/lib/utils.ak
@@ -43,3 +43,11 @@ pub fn get_husd_params(
   expect params: HusdParamsDatum = husd_datum
   params
 }
+
+pub fn sum(xs: List<Int>) -> Int {
+  list.reduce(xs, 0, fn(total, x) { total + x })
+}
+
+pub fn average(xs: List<Int>) -> Int {
+  sum(xs) / list.length(xs)
+}
diff --git a/validators/pool.ak b/validators/pool.ak
@@ -99,14 +99,17 @@ validator pool(husd_policy: ScriptHash) {
             withdrawals,
           )
         //price oracle validator withdrawal present
-        let HusdParamsDatum { price_oracle_hash, min_reserve_ratio, .. } =
-          get_husd_params(reference_inputs, husd_policy)
+        let HusdParamsDatum {
+          price_oracle_aggregator_hash,
+          min_reserve_ratio,
+          ..
+        } = get_husd_params(reference_inputs, husd_policy)
         expect Some(Pair(price_oracle_cred, _)) =
           list.find(
             withdrawals,
             fn(Pair(cred, _)) {
               when cred is {
-                Script(hash) -> hash == price_oracle_hash
+                Script(hash) -> hash == price_oracle_aggregator_hash
                 _other -> False
               }
             },
@@ -175,14 +178,17 @@ validator pool(husd_policy: ScriptHash) {
         expect own_dat == expected_dat
         //price oracle validator withdrawal present
         //price oracle validator withdrawal present
-        let HusdParamsDatum { price_oracle_hash, min_reserve_ratio, .. } =
-          get_husd_params(reference_inputs, husd_policy)
+        let HusdParamsDatum {
+          price_oracle_aggregator_hash,
+          min_reserve_ratio,
+          ..
+        } = get_husd_params(reference_inputs, husd_policy)
         expect Some(Pair(price_oracle_cred, _)) =
           list.find(
             withdrawals,
             fn(Pair(cred, _)) {
               when cred is {
-                Script(hash) -> hash == price_oracle_hash
+                Script(hash) -> hash == price_oracle_aggregator_hash
                 _other -> False
               }
             },

diff --git a/validators/price_oracle.ak b/validators/price_oracle.ak
@@ -9,28 +9,38 @@ use cardano/transaction.{
 }
 use datums.{HusdParamsDatum, PoolDatum}
 use redeemers.{PriceOracleRedeemer, ResolvedOraclePrice}
-use utils.{get_husd_params, staking_cred_approves}
+use utils.{average, get_husd_params}
 
-validator price_oracle(husd_policy: ScriptHash) {
+//all price oracles specified in husd_params must be present, aggregation of those prices must match ResolvedOraclePrice
+validator price_oracle_aggregator(husd_policy: ScriptHash) {
   withdraw(
     redeemer: ResolvedOraclePrice,
-    credential: Credential,
+    _credential: Credential,
     transaction: Transaction,
   ) {
-    let Transaction {
-      inputs,
-      reference_inputs,
-      outputs,
-      mint,
-      withdrawals,
-      extra_signatories,
-      redeemers,
-      id,
-      ..
-    } = transaction
+    let Transaction { reference_inputs, redeemers, .. } = transaction
     let HusdParamsDatum { price_oracles, .. } =
       get_husd_params(reference_inputs, husd_policy)
-
+    let prices: List<Int> =
+      list.filter_map(
+        redeemers,
+        fn(Pair(purpose, rdmr)) {
+          when purpose is {
+            Withdraw(Script(hash)) ->
+              if list.has(price_oracles, hash) {
+                expect PriceOracleRedeemer { price } = rdmr
+                Some(price)
+              } else {
+                None
+              }
+            _other -> None
+          }
+        },
+      )
+    //all price oracles must be present in redeemers
+    expect list.length(price_oracles) == list.length(prices)
+    //aggregated price must match ResolvedOraclePrice, todo: more advanced handling than average
+    expect average(prices) == redeemer.price
     True
   }