fix: allow defaultTokens to reset state in Widget (#6131)

fix: tdp widget bug

src/components/Widget/inputs.tsx

@@ -18,6 +18,25 @@ function missingDefaultToken(tokens: SwapTokens) {
   return !tokens[Field.INPUT]?.equals(tokens.default) && !tokens[Field.OUTPUT]?.equals(tokens.default)
 }
 
+function currenciesEqual(a: Currency | undefined, b: Currency | undefined) {
+  if (a && b) {
+    return a.equals(b)
+  } else {
+    return !a && !b
+  }
+}
+
+function tokensEqual(a: SwapTokens | undefined, b: SwapTokens | undefined) {
+  if (!a || !b) {
+    return !a && !b
+  }
+  return (
+    currenciesEqual(a[Field.INPUT], b[Field.INPUT]) &&
+    currenciesEqual(a[Field.OUTPUT], b[Field.OUTPUT]) &&
+    currenciesEqual(a.default, b.default)
+  )
+}
+
 /**
  * Integrates the Widget's inputs.
  * Treats the Widget as a controlled component, using the app's own token selector for selection.
@@ -37,18 +56,21 @@ export function useSyncWidgetInputs({
 
   const [type, setType] = useState<SwapValue['type']>(TradeType.EXACT_INPUT)
   const [amount, setAmount] = useState<SwapValue['amount']>(EMPTY_AMOUNT)
-  const [tokens, setTokens] = useState<SwapTokens>(defaultTokens)
+  const [tokens, setTokens] = useState<SwapTokens>({
+    ...defaultTokens,
+    [Field.OUTPUT]: defaultTokens[Field.OUTPUT] ?? defaultTokens.default,
+  })
 
+  // The most recent set of defaults, which can be used to check when the defaults are actually changing.
+  const baseTokens = usePrevious(defaultTokens)
   useEffect(() => {
-    if (!tokens[Field.INPUT] && !tokens[Field.OUTPUT]) {
+    if (!tokensEqual(baseTokens, defaultTokens)) {
       setTokens({
-        ...tokens,
-        [Field.INPUT]: defaultTokens[Field.INPUT] ?? tokens[Field.INPUT],
-        [Field.OUTPUT]: defaultTokens[Field.OUTPUT] ?? tokens[Field.OUTPUT] ?? defaultTokens.default,
-        default: defaultTokens.default,
+        ...defaultTokens,
+        [Field.OUTPUT]: defaultTokens[Field.OUTPUT] ?? defaultTokens.default,
       })
     }
-  }, [defaultTokens, tokens])
+  }, [baseTokens, defaultTokens])
 
   useEffect(() => {
     if (chainId !== previousChainId && !!previousChainId && isSupportedChain(chainId)) {
@@ -117,6 +139,7 @@ export function useSyncWidgetInputs({
 
       if (missingDefaultToken(update)) {
         onDefaultTokenChange?.(update[Field.OUTPUT] ?? selectingToken)
+        return
       }
       setTokens(update)
     },