make pdf links clickable

lib/templates/build_annotations.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module Templates
+  module BuildAnnotations
+    module_function
+
+    def call(data)
+      pdf = PDF::Reader.new(StringIO.new(data))
+
+      pdf.pages.flat_map.with_index do |page, index|
+        annotations = page.objects.deref!(page.attributes[:Annots]) || []
+        annotations.filter_map do |annot|
+          next if annot[:A].blank? || annot[:A][:URI].blank?
+          next unless annot[:Subtype] == :Link
+          next if !annot[:A][:URI].starts_with?('https://') && !annot[:A][:URI].starts_with?('http://')
+
+          build_external_link_hash(page, annot).merge('page' => index)
+        end
+      end
+    end
+
+    def build_external_link_hash(page, annot)
+      left, bottom, right, top = annot[:Rect]
+
+      {
+        'type' => 'external_link',
+        'value' => annot[:A][:URI],
+        'x' => left / page.width,
+        'y' => (page.height - top) / page.height,
+        'w' => (right - left) / page.width,
+        'h' => (top - bottom) / page.height
+      }
+    end
+  end
+end