Match behavior query params (#785)

* Match the behavior of v1 interface for old query parameters in swap/send

* Handle matching input/output currencies better

* Another test

src/state/swap/reducer.test.ts

+import { ChainId, WETH } from '@uniswap/sdk'
+import { createStore } from 'redux'
+import { Field, setDefaultsFromURL } from './actions'
+import reducer from './reducer'
+
+describe('swap reducer', () => {
+  let store
+
+  beforeEach(() => {
+    store = createStore(reducer, {
+      [Field.OUTPUT]: { address: '' },
+      [Field.INPUT]: { address: '' },
+      typedValue: '',
+      independentField: Field.INPUT
+    })
+  })
+
+  describe('setDefaultsFromURL', () => {
+    test('ETH to DAI', () => {
+      store.dispatch(
+        setDefaultsFromURL({
+          chainId: ChainId.MAINNET,
+          queryString:
+            '?inputCurrency=ETH&outputCurrency=0x6b175474e89094c44da98b954eedeac495271d0f&exactAmount=20.5&exactField=outPUT'
+        })
+      )
+
+      expect(store.getState()).toEqual({
+        [Field.OUTPUT]: { address: '0x6B175474E89094C44Da98b954EedeAC495271d0F' },
+        [Field.INPUT]: { address: WETH[ChainId.MAINNET].address },
+        typedValue: '20.5',
+        independentField: Field.OUTPUT
+      })
+    })
+
+    test('output ETH only', () => {
+      store.dispatch(
+        setDefaultsFromURL({
+          chainId: ChainId.MAINNET,
+          queryString: '?outputCurrency=eth&exactAmount=20.5'
+        })
+      )
+
+      expect(store.getState()).toEqual({
+        [Field.OUTPUT]: { address: WETH[ChainId.MAINNET].address },
+        [Field.INPUT]: { address: '' },
+        typedValue: '20.5',
+        independentField: Field.INPUT
+      })
+    })
+  })
+})

src/state/swap/reducer.ts

@@ -26,30 +26,50 @@ const initialState: SwapState = {
   }
 }
 
-function parseTokenURL(input: any, chainId: number): string {
-  if (typeof input !== 'string') return ''
-  const valid = isAddress(input)
-  if (valid) return valid
-  if (input.toLowerCase() === 'eth') return WETH[chainId]?.address ?? ''
-  return ''
+function parseCurrencyFromURLParameter(urlParam: any, chainId: number): string {
+  if (typeof urlParam === 'string') {
+    const valid = isAddress(urlParam)
+    if (valid) return valid
+    if (urlParam.toLowerCase() === 'eth') return WETH[chainId]?.address ?? ''
+    if (valid === false) return WETH[chainId]?.address ?? ''
+  }
+
+  return WETH[chainId]?.address
+}
+
+function parseTokenAmountURLParameter(urlParam: any): string {
+  return typeof urlParam === 'string' && !isNaN(parseFloat(urlParam)) ? urlParam : ''
+}
+
+function parseIndependentFieldURLParameter(urlParam: any): Field {
+  return typeof urlParam === 'string' && urlParam.toLowerCase() === 'output' ? Field.OUTPUT : Field.INPUT
 }
 
 export default createReducer<SwapState>(initialState, builder =>
   builder
     .addCase(setDefaultsFromURL, (state, { payload: { queryString, chainId } }) => {
       if (queryString && queryString.length > 1) {
-        const result = parse(queryString.substr(1), { parseArrays: false })
-        const inToken = parseTokenURL(result.inputToken, chainId)
-        const outToken = parseTokenURL(result.outputToken, chainId)
+        const parsedQs = parse(queryString.substr(1), { parseArrays: false })
+
+        let inputCurrency = parseCurrencyFromURLParameter(parsedQs.inputCurrency, chainId)
+        let outputCurrency = parseCurrencyFromURLParameter(parsedQs.outputCurrency, chainId)
+        if (inputCurrency === outputCurrency) {
+          if (typeof parsedQs.inputCurrency === 'string') {
+            outputCurrency = ''
+          } else if (typeof parsedQs.outputCurrency === 'string') {
+            inputCurrency = ''
+          }
+        }
+
         return {
           [Field.INPUT]: {
-            address: inToken
+            address: inputCurrency
           },
           [Field.OUTPUT]: {
-            address: inToken === outToken ? '' : outToken
+            address: outputCurrency
           },
-          typedValue: typeof result.amount === 'string' ? result.amount : '',
-          independentField: result.exact === 'out' ? Field.OUTPUT : Field.INPUT
+          typedValue: parseTokenAmountURLParameter(parsedQs.exactAmount),
+          independentField: parseIndependentFieldURLParameter(parsedQs.exactField)
         }
       }