New preselection

app/services/semester.rb

@@ -16,6 +16,21 @@ class Semester
     11 => 2
   }.freeze
 
+  SEMESTER_PRESELECTION_MAP = {
+    1 => 2,
+    2 => 2,
+    3 => 2,
+    4 => 1,
+    5 => 1,
+    6 => 1,
+    7 => 1,
+    8 => 1,
+    9 => 1,
+    10 => 2,
+    11 => 2,
+    12 => 2,
+  }.freeze
+
   class << self
     def parse(string)
       return unless string
@@ -116,10 +131,12 @@ class Semester
     )
   end
 
-  def preselect_semester(offset = -4.months)
-    Semester.semester_range_from_start(
-      Semester.semester_start_time(@context + offset)
-    )
+  def preselect_semester
+    if SEMESTER_PRESELECTION_MAP[@context.month] == Semester.number(current)
+      current
+    else
+      previous
+    end
   end
 
   # params: