sure/app/controllers/api/v1/merchants_controller.rb

# frozen_string_literal: true

module Api
  module V1
    class MerchantsController < BaseController
      before_action -> { authorize_scope!(:read) }, only: [ :index, :show ]
      before_action -> { authorize_scope!(:write) }, only: [ :create ]

      def index
        family = current_resource_owner.family
        user = current_resource_owner

        family_merchant_ids = family.merchants.select(:id)
        accessible_account_ids = family.accounts.accessible_by(user).select(:id)
        provider_merchant_ids = Transaction.joins(:entry)
          .where(entries: { account_id: accessible_account_ids })
          .where.not(merchant_id: nil)
          .select(:merchant_id)

        @merchants = Merchant
          .where(id: family_merchant_ids)
          .or(Merchant.where(id: provider_merchant_ids, type: "ProviderMerchant"))
          .distinct
          .alphabetically

        render json: @merchants.map { |m| merchant_json(m) }
      rescue StandardError => e
        Rails.logger.error("API Merchants Error: #{e.message}")
        render json: { error: "Failed to fetch merchants" }, status: :internal_server_error
      end

      def show
        family = current_resource_owner.family
        user = current_resource_owner

        @merchant = family.merchants.find_by(id: params[:id]) ||
                    Merchant.joins(transactions: :entry)
                            .where(entries: { account_id: family.accounts.accessible_by(user).select(:id) })
                            .distinct
                            .find_by(id: params[:id])

        if @merchant
          render json: merchant_json(@merchant)
        else
          render json: { error: "Merchant not found" }, status: :not_found
        end
      rescue StandardError => e
        Rails.logger.error("API Merchant Show Error: #{e.message}")
        render json: { error: "Failed to fetch merchant" }, status: :internal_server_error
      end

      def create
        family = current_resource_owner.family

        unless params[:file].present?
          return render json: { error: "missing_file", message: "Please provide a CSV file." },
                        status: :unprocessable_entity
        end

        file = params[:file]

        if file.size > Import::MAX_CSV_SIZE
          return render json: {
            error: "file_too_large",
            message: "File is too large. Maximum size is #{Import::MAX_CSV_SIZE / 1.megabyte}MB."
          }, status: :unprocessable_entity
        end

        unless Import::ALLOWED_CSV_MIME_TYPES.include?(file.content_type)
          return render json: {
            error: "invalid_file_type",
            message: "Invalid file type. Please upload a CSV file."
          }, status: :unprocessable_entity
        end

        csv = Import.parse_csv_str(file.read)

        name_header = normalized_header(csv.headers, "name")
        unless name_header
          return render json: {
            error: "missing_column",
            message: "CSV must include a 'name' column."
          }, status: :unprocessable_entity
        end

        color_header = normalized_header(csv.headers, "color")
        website_url_header = normalized_header(csv.headers, "website_url", "website url", "website")

        imported = []
        skipped = []

        csv.each do |row|
          name = row[name_header].to_s.strip
          next if name.blank?

          merchant = family.merchants.find_or_initialize_by(name: name)

          if merchant.persisted?
            skipped << { name: name, reason: "already_exists" }
            next
          end

          merchant.color = row[color_header].to_s.strip.presence if color_header
          merchant.website_url = row[website_url_header].to_s.strip.presence if website_url_header

          if merchant.save
            imported << merchant
          else
            skipped << { name: name, errors: merchant.errors.full_messages }
          end
        end

        render json: {
          imported: imported.count,
          skipped: skipped.count,
          merchants: imported.map { |m| merchant_json(m) }
        }, status: :created
      rescue CSV::MalformedCSVError => e
        render json: { error: "invalid_csv", message: "CSV could not be parsed: #{e.message}" },
               status: :unprocessable_entity
      rescue StandardError => e
        Rails.logger.error("API Merchants Import Error: #{e.message}")
        render json: { error: "internal_server_error", message: "An unexpected error occurred" },
               status: :internal_server_error
      end

      private

        def merchant_json(merchant)
          {
            id: merchant.id,
            name: merchant.name,
            type: merchant.type,
            created_at: merchant.created_at,
            updated_at: merchant.updated_at
          }
        end

        def normalized_header(headers, *candidates)
          normalized_map = headers.to_h { |h| [ normalize(h), h ] }
          candidates.each do |candidate|
            header = normalized_map[normalize(candidate)]
            return header if header.present?
          end
          nil
        end

        def normalize(str)
          str.to_s.strip.downcase.gsub(/\*/, "").gsub(/[\s_-]+/, "_")
        end
    end
  end
end