Add sparkline popchart on server pages

#199

assets/javascripts/sparkline.js

@@ -0,0 +1,67 @@
+var sparkline = function (selector, data_url) {
+  var margin = { top: 5, right: 5, bottom: 5, left: 5 },
+    width = 200 - margin.left - margin.right,
+    height = 25 - margin.top - margin.bottom;
+
+  var parseDate = d3.time.format("%Y%m%d").parse;
+
+  d3.json(data_url, function (error, data) {
+    var data = data["Coldeve"];
+    var data = data.map(function (d) {
+      return {
+        date: parseDate(d.date),
+        count: +d.count,
+      };
+    });
+
+    var x = d3.time
+      .scale()
+      .domain(
+        d3.extent(
+          data.map(function (d) {
+            return d.date;
+          })
+        )
+      )
+      .range([0, width]);
+
+    var y = d3.scale
+      .linear()
+      .domain(
+        d3.extent(
+          data.map(function (d) {
+            return d.count;
+          })
+        )
+      )
+      .range([height, 0]);
+
+    var line = d3.svg
+      .line()
+      .interpolate("linear")
+      .x(function (d) {
+        return x(d.date);
+      })
+      .y(function (d) {
+        return y(d.count);
+      });
+
+    var svg = d3
+      .select(selector)
+      .append("svg")
+      .attr("width", width + margin.left + margin.right)
+      .attr("height", height + margin.top + margin.bottom)
+      .append("g")
+      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
+
+    svg
+      .append("path")
+      .datum(data)
+      .attr("fill", "none")
+      .attr("stroke", "green")
+      .attr("stroke-width", 1.5)
+      .attr("stroke-linejoin", "round")
+      .attr("stroke-linecap", "round")
+      .attr("d", line);
+  });
+};

views/server.haml

@@ -9,6 +9,7 @@
         = @online[:count]
         characters online as of
         = AppHelper.relative_time(@online[:created_at])
+        #sparkline
     %tr
       %td
         Uploaded
@@ -54,3 +55,10 @@
           %td
             %a{:href => "/#{character[:server]}/#{character[:name]}"}= character[:name]
           %td= AppHelper.relative_time(character[:updated_at])
+
+
+%script{:src => javascript_path('d3.min')}
+%script{:src => javascript_path('sparkline')}
+
+:javascript
+  sparkline("#sparkline", "/player_counts.json?range=3mo&servers=#{params[:server]}");