refactor(ink-backend): perform sanity checks at root of middleware

instead of doing sanity checks in each function, we can assume they will not be used independently
and check for missing config only once

re #351

packages/components/packages/Ink-server/InkBackend.js

@@ -22,11 +22,13 @@ function checkInkConfig(inkConfig) {
   /**
    * Sanity checks on inkConfig
    *
-   * config must have pubsweet-component-ink-backend with
-   * { inkEndpoint, email, password, recipes, pusher }
+   * @param {object} inkConfig - pubsweet-component-ink-backend config
    *
-   * config.get will throw if there is no pubsweet-component-ink-backend
-   * so no need to worry about that
+   * @typedef {object} inkConfigReturn
+   * @property {boolean} correct - ink config is correct or not
+   * @property {string} errorMessage - error message to be printed
+   *
+   * @returns {inkConfigReturn}
    *
    * More at
    * https://gitlab.coko.foundation/pubsweet/pubsweet/tree/master/packages/components/packages/Ink-server
@@ -50,13 +52,20 @@ function checkInkConfig(inkConfig) {
     maxRetries: Joi.number(),
   }
   const { error } = Joi.validate(inkConfig, inkSchema)
-  if (error === null) return
+  if (error === null) return { correct: true, errorMessage: '' }
 
   // error here
   logger.warn(baseInkConfigErrorMessage + error)
+  return {
+    correct: false,
+    errorMessage: baseInkConfigErrorMessage + error,
+  }
 }
 
-checkInkConfig(inkConfig)
+const {
+  correct: correctInkConfig,
+  errorMessage: inkConfigErrorMessage,
+} = checkInkConfig(inkConfig)
 
 // Generate the absolute URL
 const inkUrl = path => `${inkConfig.inkEndpoint}api/${path}`
@@ -64,23 +73,13 @@ const inkUrl = path => `${inkConfig.inkEndpoint}api/${path}`
 // Connect to the INK Pusher/Slanger endpoint
 const connectToPusher = ({ appKey, ...options }) => new Pusher(appKey, options)
 let pusher
-if (typeof inkConfig.pusher !== 'undefined') {
+if (correctInkConfig) {
   pusher = connectToPusher(inkConfig.pusher)
 }
 
 // Sign in
-const authorize = async () => {
-  if (typeof inkConfig.email === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the email field`,
-    )
-  }
-  if (typeof inkConfig.password === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the password field`,
-    )
-  }
-  return rp({
+const authorize = async () =>
+  rp({
     method: 'POST',
     uri: inkUrl('auth/sign_in'),
     formData: {
@@ -95,16 +94,10 @@ const authorize = async () => {
     client: res.headers.client,
     'access-token': res.headers['access-token'],
   }))
-}
 
 // Upload file to INK and execute the recipe
-const upload = async (recipeId, inputFile, auth) => {
-  if (typeof inkConfig.email === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the email field`,
-    )
-  }
-  return rp({
+const upload = async (recipeId, inputFile, auth) =>
+  rp({
     method: 'POST',
     uri: inkUrl(`recipes/${recipeId}/execute`),
     headers: {
@@ -117,16 +110,10 @@ const upload = async (recipeId, inputFile, auth) => {
     json: true,
     timeout: 60 * 60 * 1000, // 3600 seconds
   })
-}
 
 // Download the output file
-const download = async (chainId, auth, outputFileName) => {
-  if (typeof inkConfig.email === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the email field`,
-    )
-  }
-  return rp({
+const download = async (chainId, auth, outputFileName) =>
+  rp({
     uri: inkUrl(`process_chains/${chainId}/download_output_file`),
     qs: {
       relative_path: outputFileName,
@@ -136,16 +123,10 @@ const download = async (chainId, auth, outputFileName) => {
       ...auth,
     },
   })
-}
 
 // Find the ID of a recipe by name
-const findRecipeId = async (name = 'Editoria Typescript', auth) => {
-  if (typeof inkConfig.email === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the email field`,
-    )
-  }
-  return rp({
+const findRecipeId = async (name = 'Editoria Typescript', auth) =>
+  rp({
     method: 'GET',
     uri: inkUrl('recipes'),
     headers: {
@@ -158,7 +139,6 @@ const findRecipeId = async (name = 'Editoria Typescript', auth) => {
 
     return recipe ? recipe.id : null
   })
-}
 
 const process = async (inputFile, options) => {
   const auth = await authorize().catch(err => {
@@ -167,11 +147,6 @@ const process = async (inputFile, options) => {
   })
 
   // either use the recipe id from the configuration or search for it by name
-  if (typeof inkConfig.recipes === 'undefined') {
-    throw new Error(
-      `${baseInkConfigErrorMessage}ink config is missing the recipes field`,
-    )
-  }
   const recipeId =
     inkConfig.recipes[options.recipe] ||
     (await findRecipeId(options.recipe, auth))
@@ -186,11 +161,6 @@ const process = async (inputFile, options) => {
 
   return new Promise((resolve, reject) => {
     // subscribe to the "process chain execution" channel
-    if (typeof pusher === 'undefined') {
-      throw new Error(
-        `${baseInkConfigErrorMessage}ink config is missing the pusher field`,
-      )
-    }
     const channel = pusher.subscribe('process_chain_execution')
 
     // wait for a "subscription succeeded" event
@@ -255,6 +225,10 @@ const process = async (inputFile, options) => {
 const InkBackend = app => {
   // TODO: authentication on this route
   app.use('/api/ink', (req, res, next) => {
+    if (!correctInkConfig) {
+      next(new Error(inkConfigErrorMessage))
+      return
+    }
     const fileStream = new Busboy({ headers: req.headers })
 
     fileStream.on(