UX: Make sentiment trends more readable (#1018)

Instead of a stacked chart showing a separate series for positive and negative, this PR introduces a simplification to the overall sentiment dashboard. It comprises the sentiment into a single series of the difference between `positive - negative` instead. This should allow for the data to be more easy to scan and look for trends

config/locales/server.en.yml

@@ -400,9 +400,7 @@ en:
 
     sentiment:
       reports:
-        overall_sentiment:
-          positive: "Positive"
-          negative: "Negative"
+        overall_sentiment: "Overall sentiment (Positive - Negative)"
         post_emotion:
           sadness: "Sadness 😢"
           surprise: "Surprise 😱"

lib/sentiment/sentiment_dashboard_report.rb

@@ -11,16 +11,15 @@ def self.register!(plugin)
           sentiment_count_sql = Proc.new { |sentiment| <<~SQL }
             COUNT(
               CASE WHEN (cr.classification::jsonb->'#{sentiment}')::float > :threshold THEN 1 ELSE NULL END
-            ) AS #{sentiment}_count
+            )
           SQL
 
           grouped_sentiments =
             DB.query(
               <<~SQL,
             SELECT
               DATE_TRUNC('day', p.created_at)::DATE AS posted_at,
-              #{sentiment_count_sql.call("positive")},
-              -#{sentiment_count_sql.call("negative")}
+              #{sentiment_count_sql.call("positive")} - #{sentiment_count_sql.call("negative")} AS sentiment_count
             FROM
               classification_results AS cr
             INNER JOIN posts p ON p.id = cr.target_id AND cr.target_type = 'Post'
@@ -32,28 +31,24 @@ def self.register!(plugin)
               cr.model_used = 'cardiffnlp/twitter-roberta-base-sentiment-latest' AND
               (p.created_at > :report_start AND p.created_at < :report_end)
             GROUP BY DATE_TRUNC('day', p.created_at)
+            ORDER BY 1 ASC
           SQL
               report_start: report.start_date,
               report_end: report.end_date,
               threshold: threshold,
             )
 
-          data_points = %w[positive negative]
-
           return report if grouped_sentiments.empty?
 
-          report.data =
-            data_points.map do |point|
-              {
-                req: "sentiment_#{point}",
-                color: point == "positive" ? report.colors[:lime] : report.colors[:purple],
-                label: I18n.t("discourse_ai.sentiment.reports.overall_sentiment.#{point}"),
-                data:
-                  grouped_sentiments.map do |gs|
-                    { x: gs.posted_at, y: gs.public_send("#{point}_count") }
-                  end,
-              }
-            end
+          report.data = {
+            req: "overall_sentiment",
+            color: report.colors[:lime],
+            label: I18n.t("discourse_ai.sentiment.reports.overall_sentiment"),
+            data:
+              grouped_sentiments.map do |gs|
+                { x: gs.posted_at, y: gs.public_send("sentiment_count") }
+              end,
+          }
         end
       end
     end

spec/lib/modules/sentiment/entry_point_spec.rb

@@ -77,11 +77,8 @@ def sentiment_classification(post, classification)
         sentiment_classification(pm, positive_classification)
 
         report = Report.find("overall_sentiment")
-        positive_data_point = report.data[0][:data].first[:y].to_i
-        negative_data_point = report.data[1][:data].first[:y].to_i
-
-        expect(positive_data_point).to eq(1)
-        expect(negative_data_point).to eq(-1)
+        overall_sentiment = report.data[:data][0][:y].to_i
+        expect(overall_sentiment).to eq(0)
       end
     end