Refactor TimeSeries artifacts

app/models/time_series.rb

@@ -1,20 +1,21 @@
 class TimeSeries
-  attr_reader :type
+  DIRECTIONS = %w[ up down ].freeze
 
-  def self.from_collection(collection, value_method, options = {})
-    data = collection.map do |obj|
-      { date: obj.date, value: obj.public_send(value_method), original: obj }
-    end
-    new(data, options)
+  attr_reader :values, :favorable_direction
+
+  def self.from_collection(collection, value_method)
+    collection.map do |obj|
+      {
+        date: obj.date,
+        value: obj.public_send(value_method),
+        original: obj
+      }
+    end.then { |data| new(data) }
   end
 
-  def initialize(data, options = {})
-    @type = options[:type] || :normal
-    initialize_series_data(data)
-  end
-
-  def values
-    @values ||= add_trends_to_series
+  def initialize(data, favorable_direction: "up")
+    @favorable_direction = (favorable_direction.presence_in(DIRECTIONS) || "up").inquiry
+    @values = initialize_values data
   end
 
   def first
@@ -30,53 +31,27 @@ class TimeSeries
   end
 
   def trend
-    TimeSeries::Trend.new(
+    TimeSeries::Trend.new \
       current: last&.value,
       previous: first&.value,
-      type: @type
-    )
+      series: self
   end
 
-  # Data shape that frontend expects for D3 charts
-  def to_json(*_args)
+  # `to_json` returns the data shape used by D3 charts
+  def to_json
     {
-      values: values.map do |v|
-        {
-          date: v.date,
-          value: JSON.parse(v.value.to_json),
-          trend: {
-            type: v.trend.type,
-            direction: v.trend.direction,
-            value: JSON.parse(v.trend.value.to_json),
-            percent: v.trend.percent
-          }
-        }
-      end,
-      trend: {
-        type: @type,
-        direction: trend.direction,
-        value: JSON.parse(trend.value.to_json),
-        percent: trend.percent
-      },
-      type: @type
+      values: values.map(&:as_json),
+      trend: trend.as_json,
+      favorable_direction: favorable_direction
     }.to_json
   end
 
   private
-    def initialize_series_data(data)
-      @series_data = data.nil? || data.empty? ? [] : data.map { |d| TimeSeries::Value.new(d) }.sort_by(&:date)
-    end
-
-    def add_trends_to_series
-      [ nil, *@series_data ].each_cons(2).map do |previous, current|
-        unless current.trend
-          current.trend = TimeSeries::Trend.new(
-            current: current.value,
-            previous: previous&.value,
-            type: @type
-          )
-        end
-        current
+    def initialize_values(data)
+      [ nil, *data ].each_cons(2).map do |previous, current|
+        TimeSeries::Value.new current,
+          previous: (TimeSeries::Value.new(previous) if previous),
+          series: self
       end
     end
 end