Create an app only when needed

src/modules/oauth.js

@@ -1,5 +1,27 @@
+import { createApp, getClientToken, verifyAppToken } from 'src/services/new_api/oauth.js'
+
+// status codes about verifyAppToken (GET /api/v1/apps/verify_credentials)
+const isAppTokenRejected = error => (
+  // Pleroma API docs say it returns 422 when unauthorized
+  error.statusCode === 422 ||
+  // but it actually returns 400 (as of 2.9.0)
+  // NOTE: don't try to match against the error message, it is translatable
+  error.statusCode === 400 ||
+  // and Mastodon docs say it returns 401
+  error.statusCode === 401
+)
+
+// status codes about getAppToken (GET /oauth/token)
+const isClientDataRejected = error => (
+  // Mastodon docs say it returns 401
+  error.statusCode === 401 ||
+  // but Pleroma actually returns 400 (as of 2.9.0)
+  // NOTE: don't try to match against the error message, it is translatable
+  error.statusCode === 400
+)
+
 const oauth = {
-  state: {
+  state: () => ({
     clientId: false,
     clientSecret: false,
     /* App token is authentication for app without any user, used mostly for
@@ -11,7 +33,7 @@ const oauth = {
      * that need authorized user to be successful (i.e. posting, liking etc)
      */
     userToken: false
-  },
+  }),
   mutations: {
     setClientData (state, { clientId, clientSecret }) {
       state.clientId = clientId
@@ -41,6 +63,88 @@ const oauth = {
       // added here for smoother transition, otherwise user will be logged out
       return state.userToken || state.token
     }
+  },
+  actions: {
+    async createApp ({ rootState, commit }) {
+      const instance = rootState.instance.server
+      const app = await createApp(instance)
+      commit('setClientData', app)
+      return app
+    },
+    /// Use this if you want to get the client id and secret but are not interested
+    /// in whether they are valid.
+    /// @return {{ clientId: string, clientSecret: string }} An object representing the app
+    ensureApp ({ state, dispatch }) {
+      if (state.clientId && state.clientSecret) {
+        return {
+          clientId: state.clientId,
+          clientSecret: state.clientSecret
+        }
+      } else {
+        return dispatch('createApp')
+      }
+    },
+    async getAppToken ({ state, rootState, commit }) {
+      const res = await getClientToken({
+        clientId: state.clientId,
+        clientSecret: state.clientSecret,
+        instance: rootState.instance.server
+      })
+      commit('setAppToken', res.access_token)
+      return res.access_token
+    },
+    /// Use this if you want to ensure the app is still valid to use.
+    /// @return {string} The access token to the app (not attached to any user)
+    async ensureAppToken ({ state, rootState, dispatch, commit }) {
+      if (state.appToken) {
+        try {
+          await verifyAppToken({
+            instance: rootState.instance.server,
+            appToken: state.appToken
+          })
+          return state.appToken
+        } catch (e) {
+          if (!isAppTokenRejected(e)) {
+            // The server did not reject our token, but we encountered other problems. Maybe the server is down.
+            throw e
+          } else {
+            // The app token is rejected, so it is no longer useful.
+            commit('setAppToken', false)
+          }
+        }
+      }
+
+      // appToken is not available, or is rejected: try to get a new one.
+      // First, make sure the client id and client secret are filled.
+      try {
+        await dispatch('ensureApp')
+      } catch (e) {
+        console.error('Cannot create app', e)
+        throw e
+      }
+
+      // Note that at this step, the client id and secret may be invalid
+      // (because the backend may have already deleted the app due to no user login)
+      try {
+        return await dispatch('getAppToken')
+      } catch (e) {
+        if (!isClientDataRejected(e)) {
+          // Non-credentials problem, fail fast
+          console.error('Cannot get app token', e)
+          throw e
+        } else {
+          // the client id and secret are invalid, so we should clear them
+          // and re-create our app
+          commit('setClientData', {
+            clientId: false,
+            clientSecret: false
+          })
+          await dispatch('createApp')
+          // try once again to get the token
+          return await dispatch('getAppToken')
+        }
+      }
+    }
   }
 }