feat: Implement complete ticket purchasing flow with new TicketsController

- Create new TicketsController with actions for name collection, creation, and checkout
- Add dedicated ticket views (new.html.erb, checkout.html.erb, show.html.erb)
- Update ticket_selection_controller.js to handle form submission via AJAX
- Add store_cart endpoint in EventsController for session-based cart management
- Update routes to support new ticket flow: /tickets/new, /create, /checkout
- Fix attribute name consistency across views (title→name, starts_at→start_time)
- Add Stripe checkout integration with proper error handling
- Remove deprecated collect_names flow in favor of streamlined approach

The flow is now: Event selection → AJAX cart storage → Name collection → Checkout → Payment

app/controllers/tickets_controller.rb

@@ -0,0 +1,171 @@
+# Manage tickets creation
+#
+# This controller permit users to create a new ticket for an event,
+# complete their details and proceed to payment
+class TicketsController < ApplicationController
+  before_action :authenticate_user!, only: [ :new ]
+  before_action :set_event, only: [ :new ]
+
+  # Handle new ticket creation
+  #
+  # Once user selected ticket types he wans for an event
+  # he cames here where he can complete his details (first_name, last_name)
+  # for each ticket ordered
+  def new
+    @cart_data = session[:pending_cart] || {}
+
+    if @cart_data.empty?
+      redirect_to event_path(@event.slug, @event), alert: "Veuillez sélectionner au moins un billet"
+      return
+    end
+
+    # Build list of tickets requiring names
+    @tickets_needing_names = []
+    @cart_data.each do |ticket_type_id, item|
+      ticket_type = @event.ticket_types.find_by(id: ticket_type_id)
+      next unless ticket_type
+
+      quantity = item["quantity"].to_i
+      next if quantity <= 0
+
+      quantity.times do |i|
+        @tickets_needing_names << {
+          ticket_type_id: ticket_type.id,
+          ticket_type_name: ticket_type.name,
+          index: i
+        }
+      end
+    end
+  end
+
+  # Create a new ticket
+  #
+  # Here new tickets are created but still in draft state.
+  # When user is ready he can proceed to payment
+  def create
+    @cart_data = session[:pending_cart] || {}
+
+    if @cart_data.empty?
+      redirect_to event_path(params[:slug], params[:id]), alert: "Aucun billet sélectionné"
+      return
+    end
+
+    @event = Event.includes(:ticket_types).find(params[:id])
+    @tickets = []
+
+    ActiveRecord::Base.transaction do
+      ticket_params[:tickets_attributes]&.each do |index, ticket_attrs|
+        next if ticket_attrs[:first_name].blank? || ticket_attrs[:last_name].blank?
+
+        ticket_type = @event.ticket_types.find(ticket_attrs[:ticket_type_id])
+
+        ticket = current_user.tickets.build(
+          ticket_type: ticket_type,
+          first_name: ticket_attrs[:first_name],
+          last_name: ticket_attrs[:last_name],
+          status: "draft"
+        )
+
+        if ticket.save
+          @tickets << ticket
+        else
+          flash[:alert] = "Erreur lors de la création des billets: #{ticket.errors.full_messages.join(', ')}"
+          raise ActiveRecord::Rollback
+        end
+      end
+
+      if @tickets.present?
+        session[:draft_ticket_ids] = @tickets.map(&:id)
+        session.delete(:pending_cart)
+        redirect_to ticket_checkout_path(@event.slug, @event.id)
+      else
+        flash[:alert] = "Aucun billet valide créé"
+        redirect_to ticket_new_path(@event.slug, @event.id)
+      end
+    end
+  rescue => e
+    flash[:alert] = "Une erreur est survenue: #{e.message}"
+    redirect_to ticket_new_path(params[:slug], params[:id])
+  end
+
+  # Display payment page
+  #
+  # Display a sumup of all tickets ordered by user and permit it
+  # to go to payment page.
+  # Here the user can pay for a ticket a bundle of tickets
+  def checkout
+    @event = Event.includes(:ticket_types).find(params[:id])
+    draft_ticket_ids = session[:draft_ticket_ids] || []
+
+    if draft_ticket_ids.empty?
+      redirect_to event_path(@event.slug, @event), alert: "Aucun billet en attente de paiement"
+      return
+    end
+
+    @tickets = current_user.tickets.includes(:ticket_type)
+                           .where(id: draft_ticket_ids, status: "draft")
+
+    if @tickets.empty?
+      redirect_to event_path(@event.slug, @event), alert: "Billets non trouvés ou déjà traités"
+      return
+    end
+
+    @total_amount = @tickets.sum(&:price_cents)
+
+    # Create Stripe checkout session if Stripe is configured
+    if Rails.application.config.stripe[:secret_key].present?
+      begin
+        @checkout_session = create_stripe_session
+      rescue => e
+        Rails.logger.error "Stripe checkout session creation failed: #{e.message}"
+        flash[:alert] = "Erreur lors de la création de la session de paiement"
+      end
+    end
+  end
+
+  def show
+    @ticket = current_user.tickets.includes(:ticket_type, :event).find(params[:ticket_id])
+    @event = @ticket.event
+  rescue ActiveRecord::RecordNotFound
+    redirect_to dashboard_path, alert: "Billet non trouvé"
+  end
+
+  private
+
+  def set_event
+    @event = Event.includes(:ticket_types).find(params[:id])
+  end
+
+  def ticket_params
+    params.permit(tickets_attributes: [ :ticket_type_id, :first_name, :last_name ])
+  end
+
+  def create_stripe_session
+    line_items = @tickets.map do |ticket|
+      {
+        price_data: {
+          currency: "eur",
+          product_data: {
+            name: "#{@event.name} - #{ticket.ticket_type.name}",
+            description: ticket.ticket_type.description
+          },
+          unit_amount: ticket.price_cents
+        },
+        quantity: 1
+      }
+    end
+
+    Stripe::Checkout::Session.create(
+      payment_method_types: [ "card" ],
+      line_items: line_items,
+      mode: "payment",
+      success_url: payment_success_url + "?session_id={CHECKOUT_SESSION_ID}",
+      cancel_url: ticket_checkout_url(@event.slug, @event.id),
+      metadata: {
+        event_id: @event.id,
+        user_id: current_user.id,
+        ticket_ids: @tickets.pluck(:id).join(",")
+      }
+    )
+  end
+end