Getting rid of the sign in front of amount's "value" field,

and implementing a flag-based way of accounting debts.

Any bank account has now a 'debit' field, and whenever it
turns True then the user is in debt and the balance indicates
how much debt the user has.

5 files changed, 95 insertions, 7 deletions

diff --git a/talerbank/app/amounts.py b/talerbank/app/amounts.py
index d76eaff..8f713c4 100644
--- a/talerbank/app/amounts.py
+++ b/talerbank/app/amounts.py
@@ -19,11 +19,15 @@
 import re
 import math
 import logging
+from django.conf import settings
 
 logger = logging.getLogger(__name__)
 
 FRACTION = 100000000
 
+def get_zero():
+    return dict(value=0, fraction=0, currency=settings.TALER_CURRENCY)
+
 def amount_add(a1, a2):
     assert(a1["currency"] == a2["currency"])
     a1_float = floatify(a1)
@@ -36,9 +40,21 @@ def amount_sub(a1, a2):
     a2_float = floatify(a2)
     sub = a1_float - a2_float
     fmt = "%s %s" % (str(sub), a2["currency"])
-    logger.info(fmt)
     return parse_amount(fmt)
 
+# Return -1 if a1 < a2, 0 if a1 == a2, 1 if a1 > a2
+def amount_cmp(a1, a2):
+    assert(a1["currency"] == a2["currency"])
+    a1_float = floatify(a1)
+    a2_float = floatify(a2)
+
+    if a1_float < a2_float:
+        return -1
+    elif a1_float == a2_float:
+        return 0
+
+    return 1
+
 
 def floatify(amount_dict):
     return amount_dict['value'] + (float(amount_dict['fraction']) / float(FRACTION))
@@ -52,7 +68,7 @@ def parse_amount(amount_str):
     Parse amount of return None if not a
     valid amount string
     """
-    parsed = re.search("^\s*((-)?[0-9]+)(\.[0-9]+)? ([-_*A-Za-z0-9]+)\s*$", amount_str)
+    parsed = re.search("^\s*([0-9]+)(\.[0-9]+)? ([-_*A-Za-z0-9]+)\s*$", amount_str)
     if not parsed:
         return None
     value = int(parsed.group(1))
diff --git a/talerbank/app/migrations/0001_initial.py b/talerbank/app/migrations/0001_initial.py
index 983ed1e..ff05150 100644
--- a/talerbank/app/migrations/0001_initial.py
+++ b/talerbank/app/migrations/0001_initial.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Generated by Django 1.10.2 on 2017-03-20 16:24
+# Generated by Django 1.10.3 on 2017-03-22 20:22
 from __future__ import unicode_literals
 
 from django.conf import settings
@@ -20,6 +20,7 @@ class Migration(migrations.Migration):
             name='BankAccount',
             fields=[
                 ('is_public', models.BooleanField(default=False)),
+                ('debit', models.BooleanField(default=False)),
                 ('balance_value', models.IntegerField(default=0)),
                 ('balance_fraction', models.IntegerField(default=0)),
                 ('balance', models.FloatField(default=0)),
diff --git a/talerbank/app/models.py b/talerbank/app/models.py
index f87caa2..f1c3485 100644
--- a/talerbank/app/models.py
+++ b/talerbank/app/models.py
@@ -22,6 +22,7 @@ from django.db import models
 
 class BankAccount(models.Model):
     is_public = models.BooleanField(default=False)
+    debit = models.BooleanField(default=False)
     balance_value = models.IntegerField(default=0)
     balance_fraction = models.IntegerField(default=0)
     balance = models.FloatField(default=0)
diff --git a/talerbank/app/tests.py b/talerbank/app/tests.py
index 7b437f1..a0236b5 100644
--- a/talerbank/app/tests.py
+++ b/talerbank/app/tests.py
@@ -20,6 +20,8 @@ from django.conf import settings
 from django.contrib.auth.models import User
 from .models import BankAccount
 from . import urlsadmin, urls
+from . import amounts
+from .views import wire_transfer
 
 import logging
 
@@ -63,11 +65,9 @@ class LoginTestCase(TestCase):
                                    currency=settings.TALER_CURRENCY)
         user_account.save()
 
-
     def tearDown(self):
         clearDb()
     
-
     def test_login(self):
         c = Client()
         response = c.post(reverse("login", urlconf=urls),
@@ -75,3 +75,63 @@ class LoginTestCase(TestCase):
                            "password": "test_password"},
                            follow=True)
         self.assertIn(("/profile", 302), response.redirect_chain)
+
+
+class AmountTestCase(TestCase):
+    
+    def test_cmp(self):
+        a1 = dict(value=1, fraction=0, currency="X")
+        _a1 = dict(value=1, fraction=0, currency="X")
+        a2 = dict(value=2, fraction=0, currency="X")
+        self.assertEqual(-1, amounts.amount_cmp(a1, a2))
+        self.assertEqual(1, amounts.amount_cmp(a2, a1))
+        self.assertEqual(0, amounts.amount_cmp(a1, _a1))
+
+
+# This tests whether a bank account goes red and then
+# goes green again
+class DebitTestCase(TestCase):
+
+    def setUp(self):
+        u = User.objects.create_user(username='U')
+        u0 = User.objects.create_user(username='U0')
+        ua = BankAccount(user=u, currency=settings.TALER_CURRENCY)
+        u0a = BankAccount(user=u0, currency=settings.TALER_CURRENCY)
+
+        ua.save()
+        u0a.save()
+
+    def test_green(self):
+        u = User.objects.get(username='U')
+        ub = BankAccount.objects.get(user=u)
+        self.assertEqual(False, ub.debit)
+
+    def test_red(self):
+        u = User.objects.get(username='U')
+        u0 = User.objects.get(username='U0')
+
+        ub = BankAccount.objects.get(user=u)
+        ub0 = BankAccount.objects.get(user=u0)
+
+        wire_transfer(dict(value=10, fraction=0, currency=settings.TALER_CURRENCY),
+                      ub0,
+                      ub,
+                      "Go green")
+        tmp = amounts.get_zero()
+        tmp["value"] = 10
+
+        self.assertEqual(0, amounts.amount_cmp(ub.balance_obj, tmp))
+        self.assertEqual(False, ub.debit)
+        self.assertEqual(True, ub0.debit)
+
+        wire_transfer(dict(value=11, fraction=0, currency=settings.TALER_CURRENCY),
+                      ub,
+                      ub0,
+                      "Go red")
+
+        self.assertEqual(True, ub.debit)
+        self.assertEqual(False, ub0.debit)
+
+        tmp["value"] = 1
+
+        self.assertEqual(0, amounts.amount_cmp(ub0.balance_obj, tmp))
diff --git a/talerbank/app/views.py b/talerbank/app/views.py
index 57dc42a..f93df1c 100644
--- a/talerbank/app/views.py
+++ b/talerbank/app/views.py
@@ -391,8 +391,18 @@ def wire_transfer(amount,
                                        credit_account=credit_account,
                                        debit_account=debit_account,
                                        subject=subject)
-    debit_account.balance_obj = amounts.amount_sub(debit_account.balance_obj, amount)
-    credit_account.balance_obj = amounts.amount_add(credit_account.balance_obj, amount)
+
+    if -1 == amounts.amount_cmp(debit_account.balance_obj, amount):
+        debit_account.debit = True
+        debit_account.balance_obj = amounts.amount_sub(amount, debit_account.balance_obj)
+    else:
+        debit_account.balance_obj = amounts.amount_sub(debit_account.balance_obj, amount)
+
+    if 1 == amounts.amount_cmp(amount, credit_account.balance_obj):
+        credit_account.debit = False
+        credit_account.balance_obj = amounts.amount_sub(amount, credit_account.balance_obj)
+    else:
+        credit_account.balance_obj = amounts.amount_add(credit_account.balance_obj, amount)
 
     with transaction.atomic():
         debit_account.save()