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Usage of the walletAPIServer in Ledger Live

The react hook useWalletAPIServer is used within Ledger Live to create a walletAPIServer

It is used in ledger-live-common here ledger-live-common/src/wallet-api/react.ts
In this file, a walletAPIServer is created, and exposed through another hook (also called useWalletAPIServer)

This (LLC hook) is in turn used in both LLD and LLM

useWebview()

useWebView() gets called

Both LLD and LLM, when creating live apps, use the hook useWebView, with the main arguments being:

apps/ledger-live-desktop/src/renderer/components/Web3AppWebview/WalletAPIWebview.tsx

const WalletAPIWebview => {
  ({ manifest customHandlers} ) => {
    const { webviewRef } = useWebviewState();
 
    useWebView({ manifest, customHandlers}, webviewRef);
    return <webview />
  }
};

Prepares transport

Will allow communication with the webview.

simplified

const webviewHook =  {
  return {
    postMessage: (message) => {
        webviewRef.current.contentWindow?.postMessage(message);
    },
  };
};

Prepares uiHooks

They will allow walletHandlers to trigger ui actions

LLC useWalletAPIServer() gets called

The goal of LLC’s useWalletAPIServer is simply to call the walletAPIServer hook (also called useWalletAPIServer)

Before doing so it:

Extracts permissions From the manifest
Converts accounts sent from useWebView (coming from redux store) to a format readable by walletAPIServer
Fetches and filters currencies (coming from libs/ledger-live-common/src/currencies/helpers.ts listCurrencies)
Converts filtered currencies to a format readable by wallet-api-server. More on that format here
Creates a transport

function useTransport(postMessage: (message: string) => void | undefined): Transport {
  return useMemo(() => {
    return {
      onMessage: undefined,
      send: postMessage, // will allow WALLETAPISERVER -> LIVEAPP communication (via postMessage)
    };
  }, [postMessage]);
}
 
  const transport = useTransport(webviewHook.postMessage);

walletAPIServer gets instantiated

via the react hook useWalletAPIServer

post-instantiation transport setup

walletAPIServer sends back its onMessage callback, the webview will use it to send message to it.

const { onMessage } = useWalletAPIServer({
  manifest,
  accounts,
  config,
  webviewHook,
  uiHook,
  customHandlers,
});
 
const handleMessage = useCallback(
  (event: Electron.IpcMessageEvent) => {
    if (event.channel === "webviewToParent") {
      onMessage(event.args[0]);
    }
  },
  [onMessage]
);
 
useEffect(() => {
  webviewRef.current.addEventListener("ipc-message", handleMessage);
}, [handleMessage, onLoad]);

post-instantiation setup of wallet handlers

server.setHandler is called to setup Ledger Live Wallet/UI/Store callbacks.

Simplified example of setHandler() call

libs/ledger-live-common/src/wallet-api/react.ts

    server.setHandler("account.request", async ({ accounts$, currencies$ }) => {
      const currencies = await firstValueFrom(currencies$);
      return new Promise((resolve, reject) => {
        let currencyList = currencyList = allCurrenciesAndTokens.filter(({ id }) => currencyIds.includes(id));
        uiAccountRequest({
          accounts$,
          currencies: currencyList,
          onSuccess: (account: AccountLike, parentAccount: Account | undefined) => {
            resolve(accountToWalletAPIAccount(account, parentAccount));
          },
          onCancel: () => {
            reject(new Error("Canceled by user"));
          },
        });
      });
    });
  }, [manifest, server, tracking, uiAccountRequest]);

those handlers are saved in the property WalletAPIServer.walletHandlers

To recap:

WalletAPIServer.walletHandlers -> callbacks defined in LLC, trigger modals / drawers / update redux store, etc.
WalletAPIServer.requestHandlers -> internalHandlers + customHandlers, can call walletHandlers inside of them

With Constructor Account