feat(gui, swap): allow change-address to be omitted and default to internal wallet (#68)

This PR:
- allows --change-address to be omitted and default to internal wallet address (https://github.com/comit-network/xmr-btc-swap/pull/1709). This is a change that is merged from upstream into our fork
- adds the necessary components for the tauri integration and the ui components to allow toggling between internal vs external refund address

Co-authored-by: binarybaron <86064887+binarybaron@users.noreply.github.com>
Co-authored-by: Einliterflasche <81313171+Einliterflasche@users.noreply.github.com>
Co-authored-by: Byron Hambly <byron@hambly.dev>

src-gui/src/renderer/components/modal/swap/pages/init/InitPage.tsx

@@ -1,4 +1,11 @@
-import { Box, DialogContentText, makeStyles } from "@material-ui/core";
+import {
+  Box,
+  makeStyles,
+  Paper,
+  Tab,
+  Tabs,
+  Typography,
+} from "@material-ui/core";
 import PlayArrowIcon from "@material-ui/icons/PlayArrow";
 import { useState } from "react";
 import BitcoinAddressTextField from "renderer/components/inputs/BitcoinAddressTextField";
@@ -21,61 +28,90 @@ const useStyles = makeStyles((theme) => ({
 
 export default function InitPage() {
   const classes = useStyles();
+
   const [redeemAddress, setRedeemAddress] = useState("");
   const [refundAddress, setRefundAddress] = useState("");
+  const [useExternalRefundAddress, setUseExternalRefundAddress] =
+    useState(false);
+
   const [redeemAddressValid, setRedeemAddressValid] = useState(false);
   const [refundAddressValid, setRefundAddressValid] = useState(false);
+
   const selectedProvider = useAppSelector(
     (state) => state.providers.selectedProvider,
   );
 
   async function init() {
-    await buyXmr(selectedProvider, refundAddress, redeemAddress);
+    await buyXmr(
+      selectedProvider,
+      useExternalRefundAddress ? refundAddress : null,
+      redeemAddress,
+    );
   }
 
   return (
     <Box>
       <RemainingFundsWillBeUsedAlert />
-      <DialogContentText>
-        Please specify the address to which the Monero should be sent upon
-        completion of the swap and the address for receiving a Bitcoin refund if
-        the swap fails.
-      </DialogContentText>
-
       <Box className={classes.fieldsOuter}>
         <MoneroAddressTextField
           label="Monero redeem address"
           address={redeemAddress}
           onAddressChange={setRedeemAddress}
           onAddressValidityChange={setRedeemAddressValid}
-          helperText="The monero will be sent to this address"
+          helperText="The monero will be sent to this address if the swap is successful."
           fullWidth
         />
 
-        <BitcoinAddressTextField
-          label="Bitcoin refund address"
-          address={refundAddress}
-          onAddressChange={setRefundAddress}
-          onAddressValidityChange={setRefundAddressValid}
-          helperText="In case something goes terribly wrong, all Bitcoin will be refunded to this address"
-          fullWidth
-        />
+        <Paper variant="outlined" style={{}}>
+          <Tabs
+            value={useExternalRefundAddress ? 1 : 0}
+            indicatorColor="primary"
+            variant="fullWidth"
+            onChange={(_, newValue) =>
+              setUseExternalRefundAddress(newValue === 1)
+            }
+          >
+            <Tab label="Refund to internal Bitcoin wallet" value={0} />
+            <Tab label="Refund to external Bitcoin address" value={1} />
+          </Tabs>
+          <Box style={{ padding: "16px" }}>
+            {useExternalRefundAddress ? (
+              <BitcoinAddressTextField
+                label="External Bitcoin refund address"
+                address={refundAddress}
+                onAddressChange={setRefundAddress}
+                onAddressValidityChange={setRefundAddressValid}
+                helperText="In case something goes wrong, the Bitcoin will be refunded to this address."
+                fullWidth
+              />
+            ) : (
+              <Typography variant="caption">
+                In case something goes wrong, the Bitcoin will be refunded to
+                the internal Bitcoin wallet of the GUI. You can then withdraw
+                them from there or use them for another swap directly.
+              </Typography>
+            )}
+          </Box>
+        </Paper>
+      </Box>
+      <Box style={{ display: "flex", justifyContent: "center" }}>
+        <PromiseInvokeButton
+          disabled={
+            (!refundAddressValid && useExternalRefundAddress) ||
+            !redeemAddressValid ||
+            !selectedProvider
+          }
+          variant="contained"
+          color="primary"
+          size="large"
+          className={classes.initButton}
+          endIcon={<PlayArrowIcon />}
+          onInvoke={init}
+          displayErrorSnackbar
+        >
+          Request quote and start swap
+        </PromiseInvokeButton>
       </Box>
-
-      <PromiseInvokeButton
-        disabled={
-          !refundAddressValid || !redeemAddressValid || !selectedProvider
-        }
-        variant="contained"
-        color="primary"
-        size="large"
-        className={classes.initButton}
-        endIcon={<PlayArrowIcon />}
-        onInvoke={init}
-        displayErrorSnackbar
-      >
-        Start swap
-      </PromiseInvokeButton>
     </Box>
   );
 }

src-gui/src/renderer/rpc.ts

@@ -89,14 +89,22 @@ export async function withdrawBtc(address: string): Promise<string> {
 
 export async function buyXmr(
   seller: Provider,
-  bitcoin_change_address: string,
+  bitcoin_change_address: string | null,
   monero_receive_address: string,
 ) {
-  await invoke<BuyXmrArgs, BuyXmrResponse>("buy_xmr", {
-    seller: providerToConcatenatedMultiAddr(seller),
-    bitcoin_change_address,
-    monero_receive_address,
-  });
+  await invoke<BuyXmrArgs, BuyXmrResponse>(
+    "buy_xmr",
+    bitcoin_change_address == null
+      ? {
+          seller: providerToConcatenatedMultiAddr(seller),
+          monero_receive_address,
+        }
+      : {
+          seller: providerToConcatenatedMultiAddr(seller),
+          monero_receive_address,
+          bitcoin_change_address,
+        },
+  );
 }
 
 export async function resumeSwap(swapId: string) {