implement provider switch

We need a basic api so we can switch between recorded providers when
the user decides that tally should not be the default wallet.

Also implemented basic branding info on the TallyWindowProvider

env.d.ts

@@ -6,6 +6,13 @@
 declare module "styled-jsx/style"
 
 type WalletProvider = {
+  providerInfo?: {
+    label: string
+    injectedNamespace: string
+    iconURL: string
+    identityFlag?: string
+    checkIdentity?: () => boolean
+  }
   on: (
     eventName: string | symbol,
     listener: (...args: unknown[]) => void
@@ -14,6 +21,11 @@ type WalletProvider = {
     eventName: string | symbol,
     listener: (...args: unknown[]) => void
   ) => unknown
+  [optionalProps: string]: unknown
+}
+
+type TallyProvider = WalletProvider & {
+  isTally: true
 }
 
 type WindowEthereum = WalletProvider & {
@@ -25,10 +37,19 @@ interface Window {
   walletRouter?: {
     currentProvider: WalletProvider
     providers: WalletProvider[]
+    switchToPreviousProvider: () => void
+    getProviderInfo: (
+      provider: WalletProvider
+    ) => WalletProvider["providerInfo"]
+    hasProvider: (
+      checkIdentity: (provider: WalletProvider) => boolean
+    ) => boolean
+    setCurrentProvider: (
+      checkIdentity: (provider: WalletProvider) => boolean
+    ) => void
+    addProvider: (newProvider: WalletProvider) => void
   }
-  tally?: WalletProvider & {
-    isTally: boolean
-  }
+  tally?: TallyProvider
   ethereum?: WindowEthereum
   oldEthereum?: WindowEthereum
 }

src/window-provider.ts

@@ -26,6 +26,40 @@ if (!window.walletRouter) {
     value: {
       currentProvider: window.tally,
       providers: [...(window.ethereum ? [window.ethereum] : [])],
+      switchToPreviousProvider() {
+        const previousProvider = this.providers.pop()
+        if (previousProvider) {
+          this.providers.push(this.currentProvider)
+          this.currentProvider = previousProvider
+        }
+      },
+      getProviderInfo(provider: WalletProvider) {
+        return (
+          provider.providerInfo || {
+            label: "Injected Provider",
+            injectedNamespace: "ethereum",
+            iconURL: "TODO",
+          }
+        )
+      },
+      hasProvider(checkIdentity: (provider: WalletProvider) => boolean) {
+        return this.providers.some(checkIdentity)
+      },
+      setCurrentProvider(checkIdentity: (provider: WalletProvider) => boolean) {
+        if (!this.hasProvider(checkIdentity)) {
+          throw new Error(
+            "The given identity did not match to any of the recognized providers!"
+          )
+        }
+        const providerIdex = this.providers.findIndex(checkIdentity)
+        const previousProvider = this.currentProvider
+        this.currentProvider = this.providers[providerIdex]
+        this.providers.splice(providerIdex, 1)
+        this.providers.push(previousProvider)
+      },
+      addProvider(newProvider: WalletProvider) {
+        this.providers.push(newProvider)
+      },
     },
     writable: false,
     configurable: false,
@@ -37,7 +71,7 @@ Object.defineProperty(window, "ethereum", {
     return window.walletRouter?.currentProvider || window.tally
   },
   set(newProvider) {
-    window.walletRouter?.providers.push(newProvider)
+    window.walletRouter?.addProvider(newProvider)
   },
   configurable: false,
 })

window-provider/index.ts

@@ -29,6 +29,15 @@ export default class TallyWindowProvider extends EventEmitter {
 
   bridgeListeners = new Map()
 
+  providerInfo = {
+    label: "Tally Ho!",
+    injectedNamespace: "tally",
+    iconURL: "TODO",
+    identityFlag: "isTally",
+    checkIdentity: (provider: WalletProvider) =>
+      !!provider && !!provider.isTally,
+  } as const
+
   constructor(public transport: ProviderTransport) {
     super()
 
@@ -59,14 +68,24 @@ export default class TallyWindowProvider extends EventEmitter {
       if (isTallyConfigPayload(result)) {
         if (!result.defaultWallet) {
           // if tally is NOT set to be default wallet
-          // AND window.ethereum was taken
-          if (window.oldEthereum) {
+          // AND we have other providers that tried to inject into window.ethereum
+          if (window.walletRouter?.providers.length) {
             // then let's reset window.ethereum to the original value
-            window.ethereum = window.oldEthereum
+            window.walletRouter.switchToPreviousProvider()
           }
 
           // NOTE: we do not remove the TallyWindowProvider from window.ethereum
           // if there is nothing else that want's to use it.
+        } else if (window.walletRouter?.currentProvider !== window.tally) {
+          if (
+            !window.walletRouter?.hasProvider(this.providerInfo.checkIdentity)
+          ) {
+            window.walletRouter?.addProvider(window.tally!)
+          }
+
+          window.walletRouter?.setCurrentProvider(
+            this.providerInfo.checkIdentity
+          )
         }
       } else if (isTallyAccountPayload(result)) {
         this.handleAddressChange.bind(this)(result.address)