Add a model for the statistics block

It's unclear exactly how the data from the CSV files will be used to
display the graphs, so for the moment the unmodified rows are just being
returned.

app/models/block/statistics.rb

@@ -0,0 +1,37 @@
+require "csv"
+
+module Block
+  class Statistics < Block::Base
+    STATISTICS_DATA_PATH = "lib/data/landing_page_content_items/statistics".freeze
+
+    def title
+      data["title"]
+    end
+
+    def x_axis_label
+      data["x_axis_label"]
+    end
+
+    def y_axis_label
+      data["y_axis_label"]
+    end
+
+    def row_header
+      CSV.read(csv_file_path, headers: true).headers
+    end
+
+    def rows
+      CSV.read(csv_file_path, headers: true).map(&:to_h)
+    end
+
+    def data_source_link
+      data["data_source_link"]
+    end
+
+  private
+
+    def csv_file_path
+      @csv_file_path ||= Rails.root.join("#{STATISTICS_DATA_PATH}/#{data['csv_file']}")
+    end
+  end
+end

spec/models/block/statistics_spec.rb

@@ -0,0 +1,60 @@
+RSpec.describe Block::Statistics do
+  let(:blocks_hash) do
+    {
+      "type" => "statistics",
+      "title" => "Chart to visually represent data",
+      "x_axis_label" => "X Axis",
+      "y_axis_label" => "Y Axis",
+      "csv_file" => "data_one.csv",
+      "data_source_link_text" => "Data source",
+      "data_source_link" => "https://www.example.com",
+    }
+  end
+
+  before do
+    stub_const("Block::ChartLayout::STATISTICS_DATA_PATH", "spec/fixtures/landing_page_statistics_data")
+  end
+
+  describe "statistics content" do
+    describe "#title" do
+      it "gets statistics title" do
+        expect(described_class.new(blocks_hash).title).to eq("Chart to visually represent data")
+      end
+    end
+
+    describe "#x_axis_label" do
+      it "gets the label for the x-axix" do
+        expect(described_class.new(blocks_hash).x_axis_label).to eq("X Axis")
+      end
+    end
+
+    describe "#y_axis_label" do
+      it "gets the label for the y-axis" do
+        expect(described_class.new(blocks_hash).y_axis_label).to eq("Y Axis")
+      end
+    end
+  end
+
+  describe "chart data" do
+    describe "#rows" do
+      it "returns the row data for the chart" do
+        expected_rows = [
+          { "Date" => "2024-01-01", "value" => "10", "variable" => "variable_name" },
+          { "Date" => "2024-02-01", "value" => "11", "variable" => "variable_name" },
+          { "Date" => "2024-03-01", "value" => "12", "variable" => "variable_name" },
+          { "Date" => "2024-04-01", "value" => "13", "variable" => "variable_name" },
+          { "Date" => "2024-05-01", "value" => "14", "variable" => "variable_name" },
+          { "Date" => "2024-06-01", "value" => "15", "variable" => "variable_name" },
+        ]
+
+        expect(described_class.new(blocks_hash).rows).to eq(expected_rows)
+      end
+    end
+
+    describe "#data_source_link" do
+      it "returns the link to the external data source" do
+        expect(described_class.new(blocks_hash).data_source_link).to eq("https://www.example.com")
+      end
+    end
+  end
+end