market

api/src/state/market/curve.rs

@@ -0,0 +1,52 @@
+use crate::error::OreError;
+
+use super::Market;
+
+// TODO Add weights.
+
+impl Market {
+    /// Returns the constant product invariant.
+    pub(crate) fn k(&self) -> u128 {
+        let base_reserves = self.base.balance as u128;
+        let quote_reserves = self.quote.balance as u128;
+        (base_reserves * quote_reserves).saturating_sub(1)
+    }
+
+    /// Returns the amount of base tokens that can be bought from a given amount of quote tokens.
+    pub fn get_base_out(&self, quote_in: u128) -> u128 {
+        let base_reserves = self.base.balance as u128;
+        let quote_reserves = self.quote.balance as u128;
+        let base_out = base_reserves - (self.k() / (quote_reserves + quote_in)).saturating_add(1);
+        base_out
+    }
+
+    /// Returns the amount of quote tokens received from selling a given amount of base tokens.
+    pub fn get_quote_out(&self, base_in: u128) -> u128 {
+        let base_reserves = self.base.balance as u128;
+        let quote_reserves = self.quote.balance as u128;
+        let quote_out = quote_reserves - (self.k() / (base_reserves + base_in)).saturating_add(1);
+        quote_out
+    }
+
+    /// Returns the amount of quote tokens needed to buy a given amount of base tokens.
+    pub fn get_quote_in(&self, base_out: u128) -> Result<u128, OreError> {
+        let base_reserves = self.base.balance as u128;
+        let quote_reserves = self.quote.balance as u128;
+        if base_out >= base_reserves {
+            return Err(OreError::InsufficientVaultReserves.into());
+        }
+        let quote_in = (self.k() / (base_reserves - base_out)).saturating_add(1) - quote_reserves;
+        Ok(quote_in)
+    }
+
+    /// Returns the amount of base tokens which must be sold to receive a given amount of quote tokens.
+    pub fn get_base_in(&self, quote_out: u128) -> Result<u128, OreError> {
+        let base_reserves = self.base.balance as u128;
+        let quote_reserves = self.quote.balance as u128;
+        if quote_out >= quote_reserves {
+            return Err(OreError::InsufficientVaultReserves.into());
+        }
+        let base_in = (self.k() / (quote_reserves - quote_out)).saturating_add(1) - base_reserves;
+        Ok(base_in)
+    }
+}