feat: show statistics in the dashboard front

app/components/dashboard/dashboard_statistic_component.html.erb

@@ -0,0 +1,5 @@
+<div class="col text-center">
+  <p class="mb-0"><strong><%= label %></strong></p>
+  <p class="mb-0 lead"><%= value %></h5>
+  <p><small class="badge rounded-pill <%= pill_class %>">(<%= increment %>% to previous)</small></p>
+</div>

app/components/dashboard/dashboard_statistic_component.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Dashboard
+  class DashboardStatisticComponent < ViewComponent::Base
+    def initialize(label:, value:, increment:)
+      @label = label
+      @value = value
+      @increment = increment
+    end
+
+    private
+
+    attr_reader :label, :value, :increment
+
+    def pill_class
+      if increment > 0
+        'text-bg-success'
+      elsif increment < 0
+        'text-bg-warning'
+      else
+        'text-bg-secondary'
+      end
+    end
+  end
+end

app/controllers/dashboard/dashboard_controller.rb

@@ -12,6 +12,15 @@ def index
       @topics = Topic.count
       @users = User.count
       @opinions = Opinion.count
+      @statistics = fetch_statistics
+    end
+
+    private
+
+    def fetch_statistics
+      Plausible::Integration.last_30_days(true)
+    rescue Net::HTTPError
+      nil
     end
   end
 end

app/services/plausible/client.rb

@@ -43,7 +43,7 @@ def client
 
     def timeseries_params
       yesterday = DateTime.current.yesterday
-      sixty_days_ago = yesterday - 60.days
+      sixty_days_ago = yesterday - 59.days # one less because otherwise it is one more
 
       date = "#{sixty_days_ago.strftime('%F')},#{yesterday.strftime('%F')}"
       { site_id:, period: 'custom', date:, metrics: 'visits,pageviews,visit_duration' }

app/services/plausible/integration.rb

@@ -6,6 +6,17 @@ def self.client
       Plausible::Integration.new.client
     end
 
+    def self.last_30_days(compare = false)
+      data = Rails.cache.fetch('plausible:last_30_days', expires_in: 2.hours) do
+        client.time_series
+      end
+      if compare
+        Plausible::MonthAnalyzer.new(data).month_compare
+      else
+        Plausible::MonthAnalyzer.new(data).month_forecast
+      end
+    end
+
     def client
       Plausible::Client.new(site_id, api_key)
     end

app/services/plausible/month_analyzer.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Plausible
+  class MonthAnalyzer
+    def initialize(value)
+      @value = value
+      @this_month = @value[30..]
+      @previous_month = @value[0..29]
+    end
+
+    def month_compare
+      this_sum = month_forecast
+      prev_sum = reduce_month(previous_month)
+      %i[visits pageviews visit_duration].index_with { |k| fold_comparison(this_sum, prev_sum, k) }
+    end
+
+    def month_forecast
+      reduce_month(this_month)
+    end
+
+    private
+
+    attr_reader :value, :this_month, :previous_month
+
+    def fold_comparison(this, previous, key)
+      delta = (((this[key].to_f / previous[key]) - 1) * 100).round
+      { value: this[key], previous: previous[key], delta: delta }
+    end
+
+    def reduce_month(month)
+      accum = month.reduce(Hash::new(0)) do |total, day|
+        duration = day["visit_duration"] * day["visits"]
+        { pageviews: total[:pageviews] + day["pageviews"],
+          visit_duration: total[:visit_duration] + duration,
+          visits: total[:visits] + day["visits"] }
+      end
+      accum[:visit_duration] = (accum[:visit_duration].to_f / accum[:visits]).round
+      accum
+    end
+  end
+end

app/views/dashboard/dashboard/index.html.erb

@@ -35,6 +35,22 @@
     </div>
   </div>
   <div class="col-sm-9 col-md-9 col-lg-10">
+
+    <div class="card mb-5">
+      <div class="card-header">
+        Últimos 30 días
+      </div>
+      <div class="card-body row">
+        <% if @statistics.present? %>
+          <%= render Dashboard::DashboardStatisticComponent.new(label: 'Sesiones', value: @statistics[:visits][:value], increment: @statistics[:visits][:delta]) %>
+          <%= render Dashboard::DashboardStatisticComponent.new(label: 'Páginas', value: @statistics[:pageviews][:value], increment: @statistics[:pageviews][:delta]) %>
+          <%= render Dashboard::DashboardStatisticComponent.new(label: 'Tiempo', value: running_time(@statistics[:visit_duration][:value]), increment: @statistics[:visit_duration][:delta]) %>
+        <% else %>
+          <p class="card-text">No se ha podido consultar el servicio de estadísticas externas.</p>
+        <% end %>
+      </div>
+    </div>
+
     <div class="card mb-5">
       <div class="card-header">
         Acciones rápidas