akkounts/app/controllers/well_known_controller.rb

class WellKnownController < ApplicationController
  before_action :require_nostr_enabled, only: [ :nostr ]
  before_action :allow_cross_origin_requests, only: [ :nostr ]

  layout false

  def nostr
    http_status :unprocessable_entity and return if params[:name].blank?
    domain = request.headers["X-Forwarded-Host"].presence || Setting.primary_domain
    relay_url = Setting.nostr_relay_url.presence

    if params[:name] == "_"
      if domain == Setting.primary_domain
        # pubkey for the primary domain without a username (e.g. kosmos.org)
        res = { names: { "_": Setting.nostr_public_key_primary_domain.presence || Setting.nostr_public_key } }
      else
        # pubkey for the akkounts domain without a username (e.g. accounts.kosmos.org)
        res = { names: { "_": Setting.nostr_public_key } }
      end

      res[:relays] = { "_" => [ relay_url ] } if relay_url
    else
      @user = User.where(cn: params[:name], ou: domain).first
      http_status :not_found and return if @user.nil? || @user.nostr_pubkey.blank?

      res = { names: { @user.cn => @user.nostr_pubkey } }
      res[:relays] = { @user.nostr_pubkey => [ relay_url ] } if relay_url
    end

    respond_to do |format|
      format.json do
        render json: res.to_json
      end
    end
  end

  private

    def require_nostr_enabled
      http_status :not_found unless Setting.nostr_enabled?
    end

    def allow_cross_origin_requests
      headers['Access-Control-Allow-Origin'] = "*"
      headers['Access-Control-Allow-Methods'] = "GET"
    end
end