Set up sms reminders in Bangladesh for Feb to Apr (#5382)

**Story card:**
[sc-11826](https://app.shortcut.com/simpledotorg/story/11826/set-up-sms-reminders-in-bangladesh)

This PR sets up sms reminders in Bangladesh for February to April 2024.

---------

Co-authored-by: Priyanga P Kini <priyangapkini99@gmail.com>

db/data/20240125122939_set_up_sms_reminders_bd_feb_apr_2024.rb

@@ -0,0 +1,57 @@
+class SetUpSmsRemindersBdFebApr2024 < ActiveRecord::Migration[6.1]
+  EXPERIMENTS_DATA = (2..4).map do |month_number|
+    month = Date::ABBR_MONTHNAMES[month_number]
+    {
+      current_experiment_name: "Current patients #{month} 2024",
+      stale_experiment_name: "Stale patients #{month} 2024",
+      start_time: DateTime.new(2024, month_number).beginning_of_month,
+      end_time: DateTime.new(2024, month_number).end_of_month
+    }
+  end
+  MAX_PATIENTS_PER_DAY = 5000
+  REGION_FILTERS = {
+    "districts" => {"include" => ["Sylhet", "Moulvibazar", "Habiganj", "Sunamganj", "Barishal", "Jhalokathi", " Feni",
+      "Chattogram", "Bandarban", "Pabna", "Rajshahi", "Sirajganj", "Sherpur", "Jamalpur"]}
+  }.freeze
+
+  def up
+    return unless CountryConfig.current_country?("Bangladesh") && SimpleServer.env.production?
+
+    EXPERIMENTS_DATA.each do |experiment_data|
+      ActiveRecord::Base.transaction do
+        Experimentation::Experiment.current_patients.create!(
+          name: experiment_data[:current_experiment_name],
+          start_time: experiment_data[:start_time],
+          end_time: experiment_data[:end_time],
+          max_patients_per_day: MAX_PATIENTS_PER_DAY,
+          filters: REGION_FILTERS
+        ).tap do |experiment|
+          treatment_group = experiment.treatment_groups.create!(description: "cascade_free")
+          treatment_group.reminder_templates.create!(message: "notifications.set03.free", remind_on_in_days: 1)
+          treatment_group.reminder_templates.create!(message: "notifications.set03.free", remind_on_in_days: 3)
+        end
+      end
+
+      ActiveRecord::Base.transaction do
+        Experimentation::Experiment.stale_patients.create!(
+          name: experiment_data[:stale_experiment_name],
+          start_time: experiment_data[:start_time],
+          end_time: experiment_data[:end_time],
+          max_patients_per_day: MAX_PATIENTS_PER_DAY,
+          filters: REGION_FILTERS
+        ).tap do |experiment|
+          treatment_group = experiment.treatment_groups.create!(description: "cascade_free")
+          treatment_group.reminder_templates.create!(message: "notifications.set02.free", remind_on_in_days: 0)
+          treatment_group.reminder_templates.create!(message: "notifications.set03.free", remind_on_in_days: 3)
+        end
+      end
+    end
+  end
+
+  def down
+    EXPERIMENTS_DATA.each do |experiment_data|
+      Experimentation::Experiment.current_patients.find_by_name(experiment_data[:current_experiment_name])&.cancel
+      Experimentation::Experiment.stale_patients.find_by_name(experiment_data[:stale_experiment_name])&.cancel
+    end
+  end
+end