Do not use cookies for pagination, fix/simplify logic

1 files changed, 32 insertions, 47 deletions

diff --git a/talerbank/app/views.py b/talerbank/app/views.py
index 55686ce..8c05868 100644
--- a/talerbank/app/views.py
+++ b/talerbank/app/views.py
@@ -48,6 +48,10 @@ class LoginFailed(Exception):
     hint = "Wrong username/password"
     http_status_code = 401
 
+class PrivateAccountException(Exception):
+    hint = "The selected account is private"
+    http_status_code = 402
+
 class DebitLimitException(Exception):
     hint = "Debit too high, operation forbidden."
     http_status_code = 403
@@ -346,7 +350,6 @@ def extract_history(account, delta=None, start=-1, sign="+"):
 
 
 def serve_public_accounts(request, name=None, page=None):
-    
     try:
         page = int(page)
     except Exception:
@@ -355,54 +358,28 @@ def serve_public_accounts(request, name=None, page=None):
     if not name:
         name = settings.TALER_PREDEFINED_ACCOUNTS[0]
     user = User.objects.get(username=name)
+    if not user.bankaccount.is_public:
+        raise PrivateAccountException("Can't display public history for private account")
 
-    if "public_history_count" not in request.session:
-        qs = extract_history(user.bankaccount, sign="-")
-        youngest = -1
-        if qs:
-            youngest = qs[0]["row_id"]
-        request.session["public_history_account"] = \
-            len(qs), youngest
+    num_records = query_history_raw(user.bankaccount, "both", start=-1, sign="-").count()
 
     DELTA = 30
-    youngest = request.session["public_history_account"][1]
-    # normalize page
-    if not page or page in [0, 1]:
-        page = 1
-    # page 0 and 1 give both the youngest 100 records.
-    if page > 1:
-        youngest = youngest - (DELTA * (page - 1)) # goes backwards.
-    if not user.bankaccount.is_public:
-        request.session["public_accounts_hint"] = \
-            True, False, "Could not query private accounts!"
-    fail_message, success_message, hint = \
-        get_session_hint(request, "public_accounts_hint")
-    public_accounts = BankAccount.objects.filter(is_public=True)
+    youngest = 1 + DELTA * (page - 1)
 
-    # Retrieve DELTA records older than 'start'.
-    history = extract_history(
-        user.bankaccount, DELTA,
-        -1 if youngest < 2 else youngest, "-")
+    public_accounts = BankAccount.objects.filter(is_public=True)
 
-    num_pages = max(
-        request.session["public_history_account"][0] / DELTA,
-        1) # makes sure pages[0] exists, below.
+    # Retrieve DELTA records, starting from 'youngest'
+    history = extract_history(user.bankaccount, DELTA, youngest - 1, "+")
 
-    pages = list(
-        range(max(1, page - 3),
-              # need +1 because the range is not inclusive for
-              # the upper limit.
-              min(page + 4, (math.ceil(num_pages) + 1))))
+    num_pages = max(num_records // DELTA, 1)
+    pages = list(range(1, num_pages + 1))
 
     context = dict(
         current_page=page,
-        back = page - 1 if pages[0] > 1 else None,
-        forth = page + 1 if pages[-1] < num_pages else None,
+        back = page - 1 if page > 1 else None,
+        forth = page + 1 if page < num_pages else None,
         public_accounts=public_accounts,
         selected_account=dict(
-            fail_message=fail_message,
-            success_message=success_message,
-            hint=hint,
             name=name,
             number=user.bankaccount.account_no,
             history=history,
@@ -411,6 +388,7 @@ def serve_public_accounts(request, name=None, page=None):
     )
     return render(request, "public_accounts.html", context)
 
+
 def login_via_headers(view_func):
     def _decorator(request, *args, **kwargs):
         user_account = auth_and_login(request)
@@ -436,15 +414,23 @@ def login_via_headers(view_func):
 #   than 'start'.
 
 def query_history(bank_account, direction, delta, start, sign):
+    qs = query_history_raw(bank_account, direction, start, sign)
+    # '-id' does descending ordering.
+    ordering = "-id" if sign in ["-", "*"] else "id"
+    return qs.order_by(ordering)[:delta]
+
+
+def query_history_raw(bank_account, direction, start, sign):
     direction_switch = {
-        "both": Q(debit_account=bank_account) \
-                | Q(credit_account=bank_account),
+        "both": (Q(debit_account=bank_account) |
+                 Q(credit_account=bank_account))
         "credit": Q(credit_account=bank_account),
         "debit": Q(debit_account=bank_account),
-        "cancel+": Q(credit_account=bank_account) \
-                      & Q(cancelled=True),
-        "cancel-": Q(debit_account=bank_account) \
-                      & Q(cancelled=True)}
+        "cancel+": (Q(credit_account=bank_account) &
+                    Q(cancelled=True)),
+        "cancel-": (Q(debit_account=bank_account) &
+                    Q(cancelled=True))
+    }
 
     sign_filter = {
         "+": Q(id__gt=start),
@@ -457,9 +443,8 @@ def query_history(bank_account, direction, delta, start, sign):
 
     return BankTransaction.objects.filter(
         direction_switch.get(direction),
-        sign_filter.get(sign)).order_by(
-            # '-id' does descending ordering.
-            "-id" if sign in ["-", "*"] else "id")[:delta]
+        sign_filter.get(sign));
+
 
 @require_GET
 @login_via_headers