require 'multi_json'

module Scrivito

class EditingContextMiddleware
  ENVKEY = 'SCRIVITO_EDITING_CONTEXT'

  def self.from_request(request)
    from_env(request.env)
  end

  def self.from_env(env)
    env[ENVKEY] || EditingContext.new
  end

  def initialize(app)
    @app = app
  end

  def call(env)
    request = Rack::Request.new(env)

    url_params    = parse_url_params(request)
    header_params = parse_header_params(env)
    cookie_params = parse_cookie_params(request)

    display_mode = url_params['display_mode'] ||
        header_params['display_mode'] ||
        cookie_params['display_mode']

    workspace_id = url_params['workspace_id'] ||
        header_params['workspace_id'] ||
        cookie_params['workspace_id']

    if cookie_params['workspace_id']
      workspace_changed = workspace_id != cookie_params['workspace_id']
    end

    env[ENVKEY] = EditingContext.new(
      display_mode: display_mode,
      editor: editor_proc(env),
      selected_workspace_id: workspace_id,
      workspace_changed: workspace_changed
    )

    @app.call(env)
  end

  private

  def editor_proc(env)
    if editing_auth_callback = Configuration.editing_auth_callback
      -> { editing_auth_callback.call(env) }
    else
      Scrivito::Warning.warn <<-EOS

        Application is running in "#{Rails.env}" environment, but authentication is not configured.
        For security reasons the in-place editing is disabled.
        Please see https://scrivito.com/permissions for details.

      EOS
      nil
    end
  end

  def parse_url_params(request)
    {
      'display_mode' => request.params['_scrivito_display_mode'],
      'workspace_id' => request.params['_scrivito_workspace_id'],
    }
  end

  def parse_header_params(env)
    parse_json_params(env['HTTP_SCRIVITO_EDITING_CONTEXT'])
  end

  def parse_cookie_params(request)
    parse_json_params(request.cookies['scrivito_editing_context'])
  end

  def parse_json_params(json_params)
    MultiJson.decode(json_params)
  rescue MultiJson::ParseError
    {}
  end
end

end