fix: de-duplicate intermediate pairs (#2396)

* make useAllCurrencyCombinations return uniques

* consolidate useBestV3Trade* functions

* consolidate useBestV2Trade

* typo

* reverted changes to trade hooks

* reverted changes to trade hooks
Co-authored-by: Noah Zinsmeister <noahwz@gmail.com>

src/hooks/useAllCurrencyCombinations.ts

@@ -19,7 +19,11 @@ export function useAllCurrencyCombinations(currencyA?: Currency, currencyB?: Cur
   }, [chainId, tokenA, tokenB])
 
   const basePairs: [Token, Token][] = useMemo(
-    () => bases.flatMap((base): [Token, Token][] => bases.map((otherBase) => [base, otherBase])),
+    () =>
+      bases
+        .flatMap((base): [Token, Token][] => bases.map((otherBase) => [base, otherBase]))
+        // though redundant with the first filter below, that expression runs more often, so this is probably worthwhile
+        .filter(([t0, t1]) => !t0.equals(t1)),
     [bases]
   )
 
@@ -28,7 +32,7 @@ export function useAllCurrencyCombinations(currencyA?: Currency, currencyB?: Cur
       tokenA && tokenB
         ? [
             // the direct pair
-            [tokenA, tokenB],
+            [tokenA, tokenB] as [Token, Token],
             // token A against all bases
             ...bases.map((base): [Token, Token] => [tokenA, base]),
             // token B against all bases
@@ -36,8 +40,18 @@ export function useAllCurrencyCombinations(currencyA?: Currency, currencyB?: Cur
             // each base against all bases
             ...basePairs,
           ]
-            .filter((tokens): tokens is [Token, Token] => Boolean(tokens[0] && tokens[1]))
-            .filter(([t0, t1]) => t0.address !== t1.address)
+            // filter out invalid pairs comprised of the same asset (e.g. WETH<>WETH)
+            .filter(([t0, t1]) => !t0.equals(t1))
+            // filter out duplicate pairs
+            .filter(([t0, t1], i, otherPairs) => {
+              // find the first index in the array at which there are the same 2 tokens as the current
+              const firstIndexInOtherPairs = otherPairs.findIndex(([t0Other, t1Other]) => {
+                return (t0.equals(t0Other) && t1.equals(t1Other)) || (t0.equals(t1Other) && t1.equals(t0Other))
+              })
+              // only accept the first occurence of the same 2 tokens
+              return firstIndexInOtherPairs === i
+            })
+            // optionally filter out some pairs for tokens with custom bases defined
             .filter(([tokenA, tokenB]) => {
               if (!chainId) return true
               const customBases = CUSTOM_BASES[chainId]