require 'rack/utils'

module Acfs

  # Global handler for stubbing resources.
  #
  class Stub
    ACTIONS = [ :read, :create, :update, :delete, :list ]

    class << self

      # Stub a resource with given handler block. An already created handler
      # for same resource class will be overridden.
      #
      def resource(klass, action, opts = {}, &block)
        action = action.to_sym
        raise ArgumentError, "Unknown action `#{action}`." unless ACTIONS.include? action

        stubs[klass] ||= {}
        stubs[klass][action] ||= []
        stubs[klass][action] << opts
      end

      def allow_requests=(allow)
        @allow_requests = allow ? true : false
      end

      def allow_requests?
        @allow_requests ||= false
      end

      def enabled?
        @enabled ||= false
      end

      def enable; @enabled = true end
      def disable; @enabled = false end

      # Clear all stubs.
      #
      def clear(klass = nil)
        klass.nil? ? stubs.clear : stubs[klass].try(:clear)
      end

      def stubs
        @stubs ||= {}
      end

      def stub_for(op)
        return false unless (classes = stubs[op.resource])
        return false unless (actions = classes[op.action])

        params = op.params
        params.merge! id: op.id unless op.id.nil?
        actions.select! { |stub| stub[:with] == params || stub[:with] == op.data }
        actions.first
      end

      def stubbed(op)
        stub = stub_for op
        unless stub
          return false if allow_requests?
          raise RealRequestNotAllowedError, "No stub found for `#{op.resource.name}` with params `#{op.params}`"
        end

        if (data = stub[:return])
          op.callback.call data
        elsif (err = stub[:raise])
          raise_error op, err, stub[:return]
        else
          raise ArgumentError, 'Unsupported stub.'
        end

        true
      end

      private
      def raise_error(op, name, data)
        raise name if name.is_a? Class

        op.handle_failure ::Acfs::Response.new nil, status: Rack::Utils.status_code(name), data: data
      end
    end
  end
end