test.cr

require "kemal"

class RequestPathMiddleware < Kemal::Handler
  def initialize(@number : String, @use_header : Bool = false)
  end

  def call(env)
    if @use_header
      process_request(env)
    end
    call_next(env)
  end

  private def process_request(env)
    if env.request.headers["Accept"] &&
        env.request.headers["Accept"].match(/application\/vnd\.api\.(v\d+)\+json/) &&
        $1 == "v#{@number}"
      puts "Matched on number: #{@number}"
      env.request.path = "/route"
    end
  end
end

add_handler RequestPathMiddleware.new("1")
add_handler RequestPathMiddleware.new("2")
add_handler RequestPathMiddleware.new("3", true)

get "/" do |env|
  "Home"
end

get "/route" do |env|
  "Route matched"
end

Kemal.run