1 files changed, 81 insertions, 0 deletions
diff --git a/devtools/client/netmonitor/src/selectors/ui.js b/devtools/client/netmonitor/src/selectors/ui.js
new file mode 100644
index 0000000000..d9d8995a71
--- /dev/null
+++ b/devtools/client/netmonitor/src/selectors/ui.js
@@ -0,0 +1,81 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createSelector,
+} = require("resource://devtools/client/shared/vendor/reselect.js");
+const {
+  REQUESTS_WATERFALL,
+} = require("resource://devtools/client/netmonitor/src/constants.js");
+
+const EPSILON = 0.001;
+
+const getWaterfallScale = createSelector(
+  state => state.requests.firstStartedMs,
+  state => state.requests.lastEndedMs,
+  state => state.timingMarkers.firstDocumentDOMContentLoadedTimestamp,
+  state => state.timingMarkers.firstDocumentLoadTimestamp,
+  state => state.ui.waterfallWidth,
+  (
+    firstStartedMs,
+    lastEndedMs,
+    firstDocumentDOMContentLoadedTimestamp,
+    firstDocumentLoadTimestamp,
+    waterfallWidth
+  ) => {
+    if (firstStartedMs === +Infinity || waterfallWidth === null) {
+      return null;
+    }
+
+    const lastEventMs = Math.max(
+      lastEndedMs,
+      firstDocumentDOMContentLoadedTimestamp,
+      firstDocumentLoadTimestamp
+    );
+    const longestWidth = lastEventMs - firstStartedMs;
+
+    // Reduce 20px for the last request's requests-list-timings-total
+    return Math.min(
+      Math.max(
+        (waterfallWidth - REQUESTS_WATERFALL.LABEL_WIDTH - 20) / longestWidth,
+        EPSILON
+      ),
+      1
+    );
+  }
+);
+
+function getVisibleColumns(columns) {
+  return Object.entries(columns).filter(([_, shown]) => shown);
+}
+
+const getColumns = createSelector(
+  state => state.ui,
+  state => state.search,
+  (ui, search) => {
+    if (
+      ((ui.networkDetailsOpen || search.panelOpen) &&
+        getVisibleColumns(ui.columns).length === 1 &&
+        ui.columns.waterfall) ||
+      (!ui.networkDetailsOpen && !search.panelOpen)
+    ) {
+      return ui.columns;
+    }
+
+    // Remove the Waterfall/Timeline column from the list of available
+    // columns if the details side-bar is opened and more than one column is
+    // visible.
+    const columns = { ...ui.columns };
+    delete columns.waterfall;
+    return columns;
+  }
+);
+
+module.exports = {
+  getColumns,
+  getVisibleColumns,
+  getWaterfallScale,
+};