VRFS-4113 - lesson analysis error dealt with

ruby/lib/jam_ruby/models/lesson_session_analyser.rb

@@ -285,7 +285,8 @@ module JamRuby
       }
     end
 
-    def self.intersect(a, b)
+    # not OK for time objects.  Here for docs more than anything
+    def self.intersect2(a, b)
       min, max = a.first, a.exclude_end? ? a.max : a.last
       other_min, other_max = b.first, b.exclude_end? ? b.max : b.last
 
@@ -295,6 +296,23 @@ module JamRuby
       new_min && new_max ? Range.new(new_min, new_max) : nil
     end
 
+
+    def self.contained_by(a, test)
+      min, max = a.first, a.exclude_end? ? a.max : a.last
+
+      test >= min && test <= max
+    end
+
+    def self.intersect(a, b)
+      min, max = a.first, a.exclude_end? ? a.max : a.last
+      other_min, other_max = b.first, b.exclude_end? ? b.max : b.last
+
+      new_min = contained_by(a, other_min) ? other_min : contained_by(b, min) ? min : nil
+      new_max = contained_by(a, other_max) ? other_max : contained_by(b, max) ? max : nil
+
+      new_min && new_max ? Range.new(new_min, new_max) : nil
+    end
+
     def self.time_ranges(histories)
       ranges = []
       histories.each do |history|