From 5bb2614f9d4bac48b927183036604217149afe0c Mon Sep 17 00:00:00 2001
From: Matt-Yorkley <9029026+Matt-Yorkley@users.noreply.github.com>
Date: Tue, 7 Apr 2020 17:58:37 +0200
Subject: [PATCH] Refactor PagedFetcher so it makes one request at a time

---
 .../services/paged_fetcher.js.coffee          | 29 +++++++++++--------
 .../variant_overrides_controller.js.coffee    |  9 +++---
 ...ariant_overrides_controller_spec.js.coffee |  4 +--
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/app/assets/javascripts/admin/index_utils/services/paged_fetcher.js.coffee b/app/assets/javascripts/admin/index_utils/services/paged_fetcher.js.coffee
index 82487996ae..96836ef9cc 100644
--- a/app/assets/javascripts/admin/index_utils/services/paged_fetcher.js.coffee
+++ b/app/assets/javascripts/admin/index_utils/services/paged_fetcher.js.coffee
@@ -2,19 +2,24 @@ angular.module("admin.indexUtils").factory "PagedFetcher", (dataFetcher) ->
   new class PagedFetcher
     # Given a URL like http://example.com/foo?page=::page::&per_page=20
     # And the response includes an attribute pages with the number of pages to fetch
-    # Fetch each page async, and call the processData callback with the resulting data
-    fetch: (url, processData, onLastPageComplete) ->
-      dataFetcher(@urlForPage(url, 1)).then (data) =>
-        processData data
+    # Fetch each page async, and call the pageCallback callback with the resulting data
+    # Developer note: this class should not be re-used!
+    page: 1
+    last_page: 1
 
-        if data.pages > 1
-          for page in [2..data.pages]
-            lastPromise = dataFetcher(@urlForPage(url, page)).then (data) ->
-              processData data
-          onLastPageComplete && lastPromise.then onLastPageComplete
-          return
-        else
-          onLastPageComplete && onLastPageComplete()
+    fetch: (url, pageCallback) ->
+      @fetchPages(url, @page, pageCallback)
 
     urlForPage: (url, page) ->
       url.replace("::page::", page)
+
+    fetchPages: (url, page, pageCallback) ->
+      dataFetcher(@urlForPage(url, page)).then (data) =>
+        @page++
+        @last_page = data.pages
+
+        pageCallback(data) if pageCallback
+
+        if @page <= @last_page
+          @fetchPages(url, @page, pageCallback)
+
diff --git a/app/assets/javascripts/admin/variant_overrides/controllers/variant_overrides_controller.js.coffee b/app/assets/javascripts/admin/variant_overrides/controllers/variant_overrides_controller.js.coffee
index c37ba72071..b890d2ffd5 100644
--- a/app/assets/javascripts/admin/variant_overrides/controllers/variant_overrides_controller.js.coffee
+++ b/app/assets/javascripts/admin/variant_overrides/controllers/variant_overrides_controller.js.coffee
@@ -43,12 +43,11 @@ angular.module("admin.variantOverrides").controller "AdminVariantOverridesCtrl",
 
   $scope.fetchProducts = ->
     url = "/api/products/overridable?page=::page::;per_page=100"
-    PagedFetcher.fetch url, (data) => $scope.addProducts data.products
+    PagedFetcher.fetch url, $scope.addProducts
 
-
-  $scope.addProducts = (products) ->
-    $scope.products = $scope.products.concat products
-    VariantOverrides.ensureDataFor hubs, products
+  $scope.addProducts = (data) ->
+    $scope.products = $scope.products.concat data.products
+    VariantOverrides.ensureDataFor hubs, data.products
 
   $scope.displayDirty = ->
     if DirtyVariantOverrides.count() > 0
diff --git a/spec/javascripts/unit/admin/controllers/variant_overrides_controller_spec.js.coffee b/spec/javascripts/unit/admin/controllers/variant_overrides_controller_spec.js.coffee
index 5724fe1353..1c860e8e91 100644
--- a/spec/javascripts/unit/admin/controllers/variant_overrides_controller_spec.js.coffee
+++ b/spec/javascripts/unit/admin/controllers/variant_overrides_controller_spec.js.coffee
@@ -51,9 +51,9 @@ describe "VariantOverridesCtrl", ->
   it "adds products", ->
     spyOn(VariantOverrides, "ensureDataFor")
     expect(scope.products).toEqual []
-    scope.addProducts ['a', 'b']
+    scope.addProducts { products: ['a', 'b'] }
     expect(scope.products).toEqual ['a', 'b']
-    scope.addProducts ['c', 'd']
+    scope.addProducts { products: ['c', 'd'] }
     expect(scope.products).toEqual ['a', 'b', 'c', 'd']
     expect(VariantOverrides.ensureDataFor).toHaveBeenCalled()