members/ljp: fix calculation of participants

Implements the correct formula for computing the participant count according to the LJP
regulations. Also adds extensive unit tests for the formula.

jdav_web/members/models.py

@@ -1,5 +1,6 @@
 from datetime import datetime, timedelta
 import uuid
+import math
 import pytz
 import unicodedata
 import re
@@ -1150,13 +1151,47 @@ class Freizeit(CommonModel):
             base_count = 2 + math.ceil((participant_count - 7) / 7)
         return base_count + self.approved_extra_youth_leader_count
 
+    @property
+    def theoretic_ljp_participant_count(self):
+        """
+        Calculate the participant count in the sense of the LJP regulations. This means
+        that all youth leaders are counted and all participants which are at least 6 years old and
+        strictly less than 27 years old. Additionally, up to 20% of the participants may violate the
+        age restrictions.
+
+        This is the theoretic value, ignoring the cutoff at 5 participants.
+        """
+        # participants (possibly including youth leaders)
+        ps = {x.member for x in self.membersonlist.distinct()}
+        # youth leaders
+        jls = set(self.jugendleiter.distinct())
+        # non-youth leader participants
+        ps_only = ps - jls
+        # participants of the correct age
+        ps_correct_age = {m for m in ps_only if m.age() >= 6 and m.age() < 27}
+        # m = the official non-youth-leader participant count
+        # and, assuming there exist enough participants, unrounded m satisfies the equation
+        # len(ps_correct_age) + 1/5 * m = m
+        # if there are not enough participants,
+        # m = len(ps_only)
+        m = min(len(ps_only), math.floor(5/4 * len(ps_correct_age)))
+        return m + len(jls)
+
     @property
     def ljp_participant_count(self):
-        ps = set(map(lambda x: x.member, self.membersonlist.distinct()))
+        """
+        The number of participants in the sense of LJP regulations. If the total
+        number of participants (including youth leaders and too old / young ones) is less
+        than 5, this is zero, otherwise it is `theoretic_ljp_participant_count`.
+        """
+        # participants (possibly including youth leaders)
+        ps = {x.member for x in self.membersonlist.distinct()}
+        # youth leaders
         jls = set(self.jugendleiter.distinct())
-        count = len(ps.union(jls))
+        if len(ps.union(jls)) < 5:
-        return count
+            return 0
-        #return count if count >= 5 else 0
+        else:
+            return self.theoretic_ljp_participant_count
 
     @property
     def maximal_ljp_contributions(self):

jdav_web/members/tests.py

@@ -15,6 +15,8 @@ from django.db import connection
 from django.db.migrations.executor import MigrationExecutor
 import random
 import datetime
+from dateutil.relativedelta import relativedelta
+import math
 
 
 def create_custom_user(username, groups, prename, lastname):
@@ -44,6 +46,14 @@ class BasicMemberTestCase(TestCase):
         self.fritz.group.add(self.jl)
         self.fritz.group.add(self.alp)
         self.fritz.save()
+
+        self.peter = Member.objects.create(prename="Peter", lastname="Wulter",
+                                           birth_date=timezone.now().date(),
+                                           email=settings.TEST_MAIL, gender=MALE)
+        self.peter.group.add(self.jl)
+        self.peter.group.add(self.alp)
+        self.peter.save()
+
         self.lara = Member.objects.create(prename="Lara", lastname="Wallis", birth_date=timezone.now().date(),
                               email=settings.TEST_MAIL, gender=DIVERSE)
         self.lara.group.add(self.alp)
@@ -130,7 +140,9 @@ class PDFTestCase(TestCase):
         self.note = MemberNoteList.objects.create(title='Cool list')
 
         for i in range(7):
-            m = Member.objects.create(prename='Lise {}'.format(i), lastname='Walter', birth_date=timezone.now().date(),
+            m = Member.objects.create(prename='Lise {}'.format(i),
+                                      lastname='Walter',
+                                      birth_date=timezone.now().date(),
                                       email=settings.TEST_MAIL, gender=FEMALE)
             NewMemberOnList.objects.create(member=m, comments='a' * i, memberlist=self.ex)
             NewMemberOnList.objects.create(member=m, comments='a' * i, memberlist=self.note)
@@ -383,6 +395,81 @@ class MemberAdminTestCase(AdminTestCase):
         self.assertEqual(final, final_target, 'Did redirect to wrong url.')
 
 
+class FreizeitTestCase(BasicMemberTestCase):
+    def setUp(self):
+        super().setUp()
+        self.ex = Freizeit.objects.create(name='Wild trip', kilometers_traveled=120,
+                                          tour_type=GEMEINSCHAFTS_TOUR,
+                                          tour_approach=MUSKELKRAFT_ANREISE,
+                                          difficulty=1)
+
+    def _setup_test_ljp_participant_count(self, n_yl, n_correct_age, n_too_old):
+        for i in range(n_yl):
+            # a 50 years old
+            m = Member.objects.create(prename='Peter {}'.format(i),
+                                      lastname='Wulter',
+                                      birth_date=datetime.datetime.today() - relativedelta(years=50),
+                                      email=settings.TEST_MAIL,
+                                      gender=FEMALE)
+            self.ex.jugendleiter.add(m)
+        for i in range(n_correct_age):
+            # a 10 years old
+            m = Member.objects.create(prename='Lise {}'.format(i),
+                                      lastname='Walter',
+                                      birth_date=datetime.datetime.today() - relativedelta(years=10),
+                                      email=settings.TEST_MAIL,
+                                      gender=FEMALE)
+            NewMemberOnList.objects.create(member=m, comments='a', memberlist=self.ex)
+        for i in range(n_too_old):
+            # a 27 years old
+            m = Member.objects.create(prename='Lise {}'.format(i),
+                                      lastname='Walter',
+                                      birth_date=datetime.datetime.today() - relativedelta(years=27),
+                                      email=settings.TEST_MAIL,
+                                      gender=FEMALE)
+            NewMemberOnList.objects.create(member=m, comments='a', memberlist=self.ex)
+
+    def _cleanup_excursion(self):
+        # delete all members on excursion for clean up
+        NewMemberOnList.objects.all().delete()
+        self.ex.jugendleiter.all().delete()
+
+    def _test_theoretic_ljp_participant_count_proportion(self, n_yl, n_correct_age, n_too_old):
+        self._setup_test_ljp_participant_count(n_yl, n_correct_age, n_too_old)
+        self.assertGreaterEqual(self.ex.theoretic_ljp_participant_count, n_yl,
+                                'An excursion with {n_yl} youth leaders and {n_correct_age} participants in the correct age range should have at least {n} participants.'.format(n_yl=n_yl, n_correct_age=n_correct_age, n=n_yl + n_correct_age))
+        self.assertLessEqual(self.ex.theoretic_ljp_participant_count, n_yl + n_correct_age + n_too_old,
+                             'An excursion with a total number of youth leaders and participants of {n} should have not more than {n} participants'.format(n=n_yl + n_correct_age + n_too_old))
+
+        n_parts_only = self.ex.theoretic_ljp_participant_count - n_yl
+        self.assertLessEqual(n_parts_only - n_correct_age, 1/5 * n_parts_only,
+                             'An excursion with {n_parts_only} non-youth-leaders, of which {n_correct_age} have the correct age, the number of participants violating the age range must not exceed 20% of the total participants, i.e. {d}'.format(n_parts_only=n_parts_only, n_correct_age=n_correct_age, d=1/5 * n_parts_only))
+
+        self.assertEqual(n_parts_only - n_correct_age, min(math.floor(1/5 * n_parts_only), n_too_old),
+                         'An excursion with {n_parts_only} non-youth-leaders, of which {n_correct_age} have the correct age, the number of participants violating the age range must be equal to the minimum of {n_too_old} and the smallest integer less than 20% of the total participants, i.e. {d}'.format(n_parts_only=n_parts_only, n_correct_age=n_correct_age, d=math.floor(1/5 * n_parts_only), n_too_old=n_too_old))
+
+        # cleanup
+        self._cleanup_excursion()
+
+    def _test_ljp_participant_count_proportion(self, n_yl, n_correct_age, n_too_old):
+        self._setup_test_ljp_participant_count(n_yl, n_correct_age, n_too_old)
+        if n_yl + n_correct_age + n_too_old < 5:
+            self.assertEqual(self.ex.ljp_participant_count, 0)
+        else:
+            self.assertEqual(self.ex.ljp_participant_count, self.ex.theoretic_ljp_participant_count)
+
+        # cleanup
+        self._cleanup_excursion()
+
+    def test_theoretic_ljp_participant_count(self):
+        self._test_theoretic_ljp_participant_count_proportion(2, 0, 0)
+        for i in range(10):
+            self._test_theoretic_ljp_participant_count_proportion(2, 10 - i, i)
+
+    def test_ljp_participant_count(self):
+        self._test_ljp_participant_count_proportion(2, 1, 1)
+        self._test_ljp_participant_count_proportion(2, 5, 1)
+
 class FreizeitAdminTestCase(AdminTestCase):
     def setUp(self):
         super().setUp(model=Freizeit, admin=FreizeitAdmin)