require 'addressable/uri'

module Scrivito
  class LinkParser
    def initialize(host, port)
      @host = host
      @port = port
    end

    def parse(url)
      uri = Addressable::URI.parse(url)

      if application_uri?(uri) && (params = sdk_route(uri.to_s)) &&
          params[:controller] == 'scrivito/ui'
        uri.path = params[:application_path]
      end

      link_params = {}

      if obj = find_obj(uri)
        link_params[:obj] = obj
      else
        if application_uri?(uri)
          uri.path = '/' unless uri.path.present?
          uri.port = nil
          uri.host = nil
          uri.scheme = nil
        end

        link_params[:url] = uri.to_s
      end

      link_params[:query] = remove_editing_context_params(uri.query_values)
      link_params[:fragment] = uri.fragment

      Link.new(link_params)
    rescue Addressable::URI::InvalidURIError
      Link.new(url: url)
    end

    private

    def application_uri?(uri)
      absolute_uri?(uri) && internal_uri?(uri) || relative_uri?(uri) && uri.path.present?
    end

    def absolute_uri?(uri)
      # Ruby's URI parser assumes URLs without a scheme as relativ, while a browser assumes a
      # schemeless "//scrivito.com" as absolute. Since the URLs are for the browser, we cannot use
      # Ruby's URI here.
      uri.to_s =~ /\A([a-z][a-z\d\-+\.]*:|\/\/).*/i
    end

    def relative_uri?(uri)
      !absolute_uri?(uri)
    end

    def internal_uri?(uri)
      if uri.port.present?
        uri.host == @host && uri.port == Integer(@port)
      else
        uri.host == @host
      end
    end

    def find_obj(uri)
      return nil unless application_uri?(uri)

      route_params = obj_route_params(uri)

      if id = route_params[:id]
        Obj.find(id)
      elsif permalink = route_params[:permalink]
        Obj.find_by_permalink(permalink)
      end
    rescue Scrivito::ResourceNotFound
    end

    def obj_route_params(uri)
      dispatch_route_for(sdk_route(uri)) || dispatch_route_for(route(uri)) || {}
    end

    def dispatch_route_for(route_params)
      if route_params && route_params[:controller] == 'scrivito/cms_dispatch'
        route_params
      end
    end

    def sdk_route(uri)
      Scrivito::SdkEngine.routes.recognize_path(uri.to_s, method: :get)
    rescue ActionController::RoutingError
    end

    def route(uri)
      Rails.application.routes.recognize_path(uri.to_s, method: :get)
    rescue ActionController::RoutingError
    end

    def remove_editing_context_params(query_values)
      if query_values
        query_values.delete('_scrivito_display_mode')
        query_values.delete('_scrivito_workspace_id')
        uri = Addressable::URI.new(query_values: query_values)
        uri.query
      end
    end
  end
end