add upload graph to stats page

assets/css/common/base.scss

@@ -398,6 +398,7 @@ span.stat {
 @import "views/posts";
 @import "views/profiles";
 @import "views/search";
+@import "views/stats";
 @import "views/tags";
 
 .no-overflow {

assets/css/views/stats.scss

@@ -0,0 +1,7 @@
+.upload-stats rect {
+  fill: $sparkline_color;
+}
+
+.upload-stats rect:hover {
+  fill: red;
+}

lib/philomena_web/templates/stat/index.html.slime

@@ -115,4 +115,7 @@ elixir:
     ' On the last 250 reports we've received, it's taken us on average
     span.stat>
       = @response_time
-    ' hour(s) between a report being made and the report being resolved.
+    ' hour(s) between a report being made and the report being resolved.
+
+  h3 Upload History
+  = upload_graph(img_bucket["non_deleted"]["all_time"]["buckets"])

lib/philomena_web/views/stat_view.ex

@@ -1,3 +1,34 @@
 defmodule PhilomenaWeb.StatView do
   use PhilomenaWeb, :view
+
+  def upload_graph(data) do
+    data = Enum.sort_by(data, & &1["key"])
+    n_buckets = length(data)
+
+    {%{"key" => min_time}, %{"key" => max_time}} = Enum.min_max_by(data, & &1["key"], fn -> %{"key" => 0} end)
+    {%{"doc_count" => min_docs}, %{"doc_count" => max_docs}} = Enum.min_max_by(data, & &1["doc_count"], fn -> %{"doc_count" => 0} end)
+
+    graph_width = 950
+    graph_height = 475
+
+    bar_width = safe_div(graph_width, n_buckets)
+    max_bar_height = safe_div(graph_height, max_docs - min_docs)
+
+    content_tag :svg, class: "upload-stats", viewBox: "0 0 #{graph_width} #{graph_height}" do
+      for {datum, i} <- Enum.with_index(data) do
+        bar_height = safe_div(datum["doc_count"], max_docs) * max_bar_height
+
+        x = i * bar_width
+        y = graph_height-bar_height
+        height = bar_height
+
+        content_tag :rect, width: bar_width, height: height, x: x, y: y, fill: "#000" do
+          content_tag :title, "#{datum["key_as_string"]} - #{datum["doc_count"]} uploads"
+        end
+      end
+    end
+  end
+
+  defp safe_div(n, 0), do: 0
+  defp safe_div(n, d), do: n / d
 end