reports: add non-timeseries charts.

Add bar charts for non-timeseries data. For example, a bar chart of the
top 10 uploaders overall in the last month, rather than a timeseries
chart of the number of uploads per day for the last month.

app/components/time_series_component.rb

@@ -3,11 +3,123 @@
 class TimeSeriesComponent < ApplicationComponent
   delegate :current_page_path, :search_params, to: :helpers
 
-  attr_reader :dataframe, :group, :mode
+  attr_reader :dataframe, :x_axis, :y_axis, :mode
 
-  def initialize(dataframe, group: nil, mode: :table)
+  def initialize(dataframe, x_axis:, mode: :table)
     @dataframe = dataframe
-    @group = group
+    @x_axis = x_axis
+    @y_axis = columns.without(x_axis)
     @mode = mode.to_sym
   end
+
+  def columns
+    dataframe.types.keys
+  end
+
+  def chart_height
+    if x_axis != "date"
+      dataframe[x_axis].size * 30
+    end
+  end
+
+  def chart_options
+    if x_axis == "date"
+      stacked_area_chart
+    else
+      horizontal_bar_chart
+    end
+  end
+
+  def base_options
+    {
+      dataset: {
+        dimensions: columns,
+        source: dataframe.each_row.map(&:values),
+      },
+      tooltip: {
+        trigger: "axis",
+        axisPointer: {
+          type: "cross",
+          label: {
+            backgroundColor: "#6a7985"
+          }
+        }
+      },
+      toolbox: {
+        feature: {
+          dataView: {},
+          restore: {},
+          saveAsImage: {}
+        }
+      },
+      grid: {
+        left: "1%",
+        right: "1%",
+        containLabel: true
+      },
+      legend: {
+        data: y_axis.map(&:capitalize),
+        type: "scroll",
+        left: 0,
+        padding: [8, 200, 0, 15],
+        orient: "horizontal",
+      },
+    }
+  end
+
+  def stacked_area_chart
+    base_options.deep_merge(
+      toolbox: {
+        feature: {
+          dataZoom: {
+            yAxisIndex: "none"
+          },
+          magicType: {
+            type: ["line", "bar"],
+          },
+        }
+      },
+      dataZoom: [
+        { type: "inside" },
+        { type: "slider" }
+      ],
+      xAxis: { type: "time" },
+      yAxis: [type: "value"] * y_axis.size,
+      series: y_axis.map do |name|
+        {
+          name: name.capitalize,
+          type: "line",
+          areaStyle: {},
+          stack: "all",
+          emphasis: {
+            focus: "series"
+          },
+          encode: {
+            x: x_axis,
+            y: name
+          }
+        }
+      end
+    )
+  end
+
+  def horizontal_bar_chart
+    base_options.deep_merge(
+      xAxis: { type: "value" },
+      yAxis: [type: "category", inverse: true] * y_axis.size,
+      series: y_axis.map do |name|
+        {
+          name: name.capitalize,
+          type: "bar",
+          emphasis: {
+            focus: "series"
+          },
+          encode: {
+            x: name,
+            y: x_axis,
+          }
+        }
+      end
+    )
+  end
 end