Initial commit

services/wms/proxy.rb

@@ -0,0 +1,102 @@
+require 'uri'
+require 'nokogiri'
+require_relative '../../lib/carto/http/client'
+
+module CartoDB
+  module WMS
+    class Proxy
+      SERVER_XPATH  = "//OnlineResource[1]"
+      FORMATS_XPATH = "//GetMap/Format"
+      LAYERS_XPATH  = "//Layer/Layer[BoundingBox or LatLonBoundingBox]"
+
+      def initialize(url, preloaded_xml=nil)
+        @url        = url
+        @response   = preloaded_xml
+      end
+
+      def serialize
+        run
+        { server: server, formats: formats, layers: layers }
+      end
+
+      def run
+        request_capabilities unless response
+        self
+      end 
+
+      def request_capabilities
+        http_client = Carto::Http::Client.get('wmsproxy')
+        response = http_client.get(url, followlocation: true)
+        raise URI::InvalidURIError unless [200, 201].include?(response.code)
+        @response = response.response_body
+        nil
+      end 
+
+      def document
+        Nokogiri::XML::Document.parse(response).remove_namespaces!
+      end
+
+      def server
+        (document.at_xpath(SERVER_XPATH) || {})['href']
+      end
+
+      def formats
+        document.xpath(FORMATS_XPATH).map(&:text)
+      end
+
+      def layers
+
+        document.xpath(LAYERS_XPATH).map { |element| 
+          name  = element.xpath("./Name").first
+          title = element.xpath("./Title").first
+          { 
+            name:           (name.text if name),
+            title:          (title.text if title),
+            crs:            crs_for_element(element),
+            srs:            srs_for_element(element),
+            bounding_boxes: bounding_boxes_for(element),
+            attribution:    nil
+          } 
+        }
+      end
+
+      def crs_for_element(element)
+        crs = element.xpath("./CRS").map { |element|
+          element.text
+        }.compact
+      end
+
+      def srs_for_element(element)
+        srs = element.xpath("./SRS").map { |element|
+          element.text
+        }.compact
+      end
+
+      def bounding_boxes_for(element)
+        bounding_boxes = element.xpath("./BoundingBox").map { |element|
+          srs   = element.xpath("./@SRS").first
+          crs   = element.xpath("./@CRS").first
+          minx  = element.xpath("./@minx").first
+          miny  = element.xpath("./@miny").first
+          maxx  = element.xpath("./@maxx").first
+          maxy  = element.xpath("./@maxy").first
+
+          {
+            srs: (srs.value if srs),
+            crs: (crs.value if crs),
+            minx: (minx.value if minx),
+            miny: (miny.value if miny),
+            maxx: (maxx.value if maxx),
+            maxy: (maxy.value if maxy),
+          }
+        }
+      end
+
+      attr_reader :response
+
+      private
+      attr_reader :url
+    end # Proxy
+  end # WMS
+end # CartoDB
+