Bug 1520691 - Add Discovery components, search polish and bug fixes to Activity Stream r=k88hudson

Differential Revision: https://phabricator.services.mozilla.com/D16784

browser/components/newtab/content-src/lib/selectLayoutRender.js

@@ -0,0 +1,51 @@
+import {createSelector} from "reselect";
+
+function calculateSpocs(component, spocs) {
+  let spocIndex = 0;
+  return component.spocs.positions.map(position => {
+    const rickRoll = Math.random();
+    if (spocs.data.spocs[spocIndex] && rickRoll <= component.spocs.probability) {
+      return {
+        ...position,
+        result: spocs.data.spocs[spocIndex++],
+      };
+    }
+    return position;
+  });
+}
+
+export const selectLayoutRender = createSelector(
+  // Selects layout, feeds, spocs so that we only recompute if
+  // any of these values change.
+  [
+    state => state.DiscoveryStream.layout,
+    state => state.DiscoveryStream.feeds,
+    state => state.DiscoveryStream.spocs,
+  ],
+
+  // Adds data to each component from feeds. This function only re-runs if one of the inputs change.
+  // TODO: calculate spocs
+  function layoutRender(layout, feeds, spocs) {
+    return layout.map(row => ({
+      ...row,
+
+      // Loops through all the components and adds a .data property
+      // containing data from feeds
+      components: row.components.map(component => {
+        if (!component.feed || !feeds[component.feed.url]) {
+          return component;
+        }
+
+        // Calculate if we should display a spoc or not.
+        if (component.spocs && spocs.data.spocs && spocs.data.spocs.length) {
+          component.spocs = {
+            ...component.spocs,
+            positions: calculateSpocs(component, spocs),
+          };
+        }
+
+        return {...component, data: feeds[component.feed.url].data};
+      }),
+    }));
+  }
+);