feat: add subscription and transaction repositories

- Implemented SubscriptionRepository with methods to get, create, and update subscriptions.
- Added BalanceTXRepository for creating and retrieving balance transactions.
- Introduced a test script for simulating Pally webhook for local testing.

bot/handlers/buy.py

@@ -4,31 +4,29 @@ import math
 from aiogram import F, Router
 from aiogram.fsm.context import FSMContext
 from aiogram.types import CallbackQuery
+from sqlalchemy.ext.asyncio import AsyncSession
 
-from bot.keyboards.client import (
-    devices_selector,
-    duration_selector,
-    payment_gateways,
-    return_to_menu,
-)
-from bot.states.buy import BillingStorage, SubscriptionStorage
+from bot.keyboards.client import deposit_kb, devices_selector, duration_selector, return_to_menu
+from bot.states.buy import SubscriptionStorage
 from bot.texts import (
     CALLBACK_FALLBACK,
-    CHECKOUT_PAYMENT_CHOICE,
     CONTEXT_REINITIATED,
+    INSUFFICIENT_FUNDS,
     NOTHING_PLACEHOLDER,
     STANDARD_FALLBACK,
     SUBSCRIPTION_DEVICE_SELECTOR,
     SUBSCRIPTION_DURATION_SELECTOR,
+    SUCCESSFULLY_CREATED_SUBSCRIPTION,
 )
 from config import settings
+from db.models.transactions import BalanceTxType
 from misc.utils import (
     calculate_price,
     convert_duration_to_int,
     convert_int_to_duration,
     get_discount,
 )
-from schemas.billing import BillingContext
+from schemas.di import DependenciesDTO
 from schemas.subscriptions import SubscriptionPlan
 
 router = Router()
@@ -157,7 +155,9 @@ async def select_duration(cb: CallbackQuery, state: FSMContext):
 
 
 @router.callback_query(SubscriptionStorage.duration, F.data == "confirm")
-async def proceed_to_checkout(cb: CallbackQuery, state: FSMContext):
+async def proceed_to_checkout(
+    cb: CallbackQuery, state: FSMContext, session: AsyncSession, deps: DependenciesDTO
+):
     data = await state.get_data()
     await state.clear()
 
@@ -166,11 +166,43 @@ async def proceed_to_checkout(cb: CallbackQuery, state: FSMContext):
         await cb.message.edit_text(STANDARD_FALLBACK, reply_markup=return_to_menu)
         return
 
-    await cb.message.edit_text(
-        CHECKOUT_PAYMENT_CHOICE,
-        reply_markup=payment_gateways,
-    )  # FIXME: temp solution that's incredibly stupid
+    amount = calculate_price(ctx)
+    user = await deps.user_repository.get_user_by_id(session, cb.from_user.id)
 
-    await state.set_state(BillingStorage.pending)
-    billing_context = BillingContext(amount=calculate_price(ctx))
-    await state.set_data({"ctx": billing_context})
+    if user.balance < amount:
+        await cb.message.edit_text(
+            INSUFFICIENT_FUNDS.format(balance=user.balance, amount=amount), reply_markup=deposit_kb
+        )
+        return
+
+    if not user:
+        await cb.message.edit_text(CALLBACK_FALLBACK)
+        return
+
+    try:
+        await deps.user_service.buy_subscription(session, ctx, deps.rw_sdk, cb.from_user)
+    except Exception:
+        logger.exception(
+            "buy_subscription caught an exception on user_id=%s, amount=%s. balance was NOT affected, transaction is rejected.",
+            user.id,
+            amount,
+        )
+        await cb.message.edit_text(CALLBACK_FALLBACK)
+        return
+
+    deducted_user = await deps.user_repository.decrease_user_balance(
+        session,
+        user.id,
+        amount,
+        BalanceTxType.PURCHASE,
+        description=f"subscription purchase: devices={ctx.devices}, duration={ctx.duration}, whitelists={ctx.whitelists}",
+    )
+    if not deducted_user:
+        logger.critical(
+            "RECONCILIATION NEEDED: subscription created for user_id=%s "
+            "but balance deduction FAILED. amount=%s.",
+            cb.from_user.id,
+            amount,
+        )
+
+    await cb.message.edit_text(SUCCESSFULLY_CREATED_SUBSCRIPTION, reply_markup=return_to_menu)