feat(promotion code): Promotion code system done

I added the features for users to use promotion code
and for promoters to create on their events.
May be rewrite to discount code?

app/controllers/promoter/promotion_codes_controller.rb

@@ -0,0 +1,82 @@
+class Promoter::PromotionCodesController < ApplicationController
+  before_action :authenticate_user!
+  before_action :set_event
+  before_action :set_promotion_code, only: [ :edit, :update, :destroy ]
+
+  # GET /promoter/events/:event_id/promotion_codes
+  # Display all promotion codes for a specific event
+  def index
+    @promotion_codes = @event.promotion_codes.includes(:user)
+  end
+
+  
+  # GET /promoter/events/:event_id/promotion_codes/new
+  # Show form to create a new promotion code
+  def new
+    @promotion_code = @event.promotion_codes.new
+  end
+
+  # GET /promoter/events/:event_id/promotion_codes/:id/edit
+  # Show form to edit an existing promotion code
+  def edit
+  end
+
+  # POST /promoter/events/:event_id/promotion_codes
+  # Create a new promotion code for the event
+  def create
+    @promotion_code = @event.promotion_codes.new(promotion_code_params_with_conversion)
+    @promotion_code.user = current_user
+
+    if @promotion_code.save
+      redirect_to promoter_event_promotion_codes_path(@event), notice: "Promotion code was successfully created."
+    else
+      render :new, status: :unprocessable_entity
+    end
+  end
+
+  # PATCH/PUT /promoter/events/:event_id/promotion_codes/:id
+  # Update an existing promotion code
+  def update
+    if @promotion_code.update(promotion_code_params_with_conversion)
+      redirect_to promoter_event_promotion_codes_path(@event), notice: "Promotion code was successfully updated."
+    else
+      render :edit, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE /promoter/events/:event_id/promotion_codes/:id
+  # Delete a promotion code
+  def destroy
+    @promotion_code.destroy
+    redirect_to promoter_event_promotion_codes_path(@event), notice: "Promotion code was successfully destroyed."
+  end
+
+  private
+
+  # Find the event based on the URL parameter
+  def set_event
+    @event = Event.find(params[:event_id])
+  end
+
+  # Find the promotion code based on the URL parameter
+  def set_promotion_code
+    @promotion_code = @event.promotion_codes.find(params[:id])
+  end
+
+  # Strong parameters for promotion code form (accepts euros for display)
+  def promotion_code_params
+    params.require(:promotion_code).permit(:code, :discount_amount_euros, :expires_at, :active, :usage_limit)
+  end
+
+  # Convert euros to cents for database storage
+  # The form displays euros for user convenience, but the database stores cents
+  def promotion_code_params_with_conversion
+    params = promotion_code_params
+    if params[:discount_amount_euros].present?
+      # Convert euros to cents (e.g., 20.50 -> 2050)
+      params[:discount_amount_cents] = (params[:discount_amount_euros].to_f * 100).to_i
+      params.delete(:discount_amount_euros) # Remove the temporary euro parameter
+    end
+    params
+  end
+end