Merge pull request #27 from sergerad/serge/peter-pool-calcs

Handle error, underflow and denominator

crates/uniswapv3pool/src/pool_calcs.rs

@@ -1,3 +1,4 @@
+use eyre::{eyre, Result};
 use uniswap_v3_sdk::prelude::FeeAmount;
 
 pub fn fee_to_float(fee: FeeAmount) -> f32 {
@@ -6,12 +7,24 @@ pub fn fee_to_float(fee: FeeAmount) -> f32 {
     fee_num / 10000.0
 }
 
-pub fn tick_to_exchange_rate(tick: i32, token_one_decimals: u64, token_two_decimals: u64) -> f64 {
+pub fn tick_to_exchange_rate(
+    tick: i32,
+    token_one_decimals: u64,
+    token_two_decimals: u64,
+) -> Result<f64> {
     let tick = tick as f64;
-    let val: f64 = 1.0001;
+    let base: f64 = 1.0001;
 
-    if token_one_decimals != token_two_decimals {
-        println!("Exchange when token decimals not the same not yet supported");
+    let token_decimals_diff = token_one_decimals.checked_sub(token_two_decimals);
+    match token_decimals_diff {
+        None => Err(eyre!(
+            "Token decimals subtraction overflow: ({} - {})",
+            token_one_decimals,
+            token_two_decimals
+        )),
+        Some(diff) => {
+            let denominator = 10u64.pow(diff.try_into()?);
+            Ok(base.powf(tick) / denominator as f64)
+        }
     }
-    val.powf(tick)
 }

crates/uniswapv3pool/src/univ3sdk.rs

@@ -137,7 +137,7 @@ impl UniswapV3PoolSdk {
 
     pub fn one_line_info(&self) -> Result<()> {
         let fee_num = crate::pool_calcs::fee_to_float(self.pool.fee);
-        let rate = crate::pool_calcs::tick_to_exchange_rate(self.pool.tick_current, 18, 18);
+        let rate = crate::pool_calcs::tick_to_exchange_rate(self.pool.tick_current, 18, 18)?;
         println!(
             "{:<4}%  {}  {:<25}  {:<12}  {}",
             fee_num,