converting get-provider-state file to typescript and extracting types…

… to a helper file

app/scripts/lib/rpc-method-middleware/handlers/get-provider-state.ts

@@ -0,0 +1,76 @@
+import type {
+  JsonRpcEngineNextCallback,
+  JsonRpcEngineEndCallback,
+} from '@metamask/json-rpc-engine';
+import type {
+  JsonRpcRequest,
+  JsonRpcResponse,
+  JsonRpcParams,
+  Json,
+} from '@metamask/utils';
+import { MESSAGE_TYPE } from '../../../../../shared/constants/app';
+import {
+  HandlerWrapperType,
+  getProviderStateType,
+  ProviderStateHandlerResult,
+} from './handlers-helper';
+
+type getProviderStateImplementationType<
+  Params extends JsonRpcParams = JsonRpcParams,
+  Result extends Json = Json,
+> = {
+  implementation: (
+    _req: JsonRpcRequest<Params>,
+    res: JsonRpcResponse<Result>,
+    _next: JsonRpcEngineNextCallback,
+    end: JsonRpcEngineEndCallback,
+    { _getProviderState }: Record<string, getProviderStateType>,
+  ) => Promise<void>;
+} & HandlerWrapperType;
+
+/**
+ * This RPC method gets background state relevant to the provider.
+ * The background sends RPC notifications on state changes, but the provider
+ * first requests state on initialization.
+ */
+
+const getProviderState: getProviderStateImplementationType = {
+  methodNames: [MESSAGE_TYPE.GET_PROVIDER_STATE],
+  implementation: getProviderStateHandler,
+  hookNames: {
+    getProviderState: true,
+  },
+};
+export default getProviderState;
+
+/**
+ * @typedef {object} ProviderStateHandlerOptions
+ * @property {() => ProviderStateHandlerResult} getProviderState - A function that
+ * gets the current provider state.
+ */
+
+/**
+ * @param _req - The JSON-RPC request object.
+ * @param res - The JSON-RPC response object.
+ * @param _next - The json-rpc-engine 'next' callback.
+ * @param end - The json-rpc-engine 'end' callback.
+ * @param options
+ * @param options.getProviderState
+ */
+async function getProviderStateHandler<
+  Params extends JsonRpcParams = JsonRpcParams,
+  Result extends Json = Json,
+>(
+  _req: JsonRpcRequest<Params>,
+  res: JsonRpcResponse<Result>,
+  _next: JsonRpcEngineNextCallback,
+  end: JsonRpcEngineEndCallback,
+  {
+    getProviderState: _getProviderState,
+  }: Record<string, (origin: string) => Promise<ProviderStateHandlerResult>>,
+): Promise<void> {
+  res.result = {
+    ...(await _getProviderState((origin = _req.origin))),
+  };
+  return end();
+}

app/scripts/lib/rpc-method-middleware/handlers/handlers-helper.ts

@@ -0,0 +1,22 @@
+export type HandlerWrapperType = {
+  methodNames: [string];
+  hookNames: Record<string, boolean>;
+};
+
+/**
+ * @typedef {object} ProviderStateHandlerResult
+ * @property {string} chainId - The current chain ID.
+ * @property {boolean} isUnlocked - Whether the extension is unlocked or not.
+ * @property {string} networkVersion - The current network ID.
+ * @property {string[]} accounts - List of permitted accounts for the specified origin.
+ */
+export type ProviderStateHandlerResult = {
+  chainId: string;
+  isUnlocked: boolean;
+  networkVersion: string;
+  accounts: string[];
+};
+
+export type getProviderStateType = (
+  origin: string,
+) => Promise<ProviderStateHandlerResult>;