Implement Stripe payment integration (Task 6)

.env.sample

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+DJANGO_SECRET_KEY=your_django_secret_key_here
+DJANGO_DEBUG=True
+TELEGRAM_BOT_TOKEN=your_telegram_bot_token_here
+TELEGRAM_CHAT_ID=your_telegram_chat_id_here
+STRIPE_PUBLIC_KEY=your_stripe_public_key_here
+STRIPE_SECRET_KEY=your_stripe_secret_key_here
+STRIPE_SUCCESS_URL=http://127.0.0.1:8000/api/payments/success/
+STRIPE_CANCEL_URL=http://127.0.0.1:8000/api/payments/cancel/

.gitignore

@@ -2,4 +2,5 @@ venv/
 *.pyc
 __pycache__/
 db.sqlite3
-.env
+.env
+celerybeat-schedule*

Dockerfile

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+FROM python:3.11-slim
+LABEL maintainer="velviktor831@gmail.com"
+
+ENV PYTHONUNBUFFERED=1
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt /app/
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . /app/

README.md

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+# 📚 Library Service API
+
+This is a REST API for a Library Management System built with Django and Django REST Framework. It allows managing books, users, and borrowings, and features automated Telegram notifications with Stripe payment integration.
+
+## 🛠 Features Implemented So Far
+
+- **Books Service**: Manage book inventory, titles, authors, cover types, and daily fees.
+- **Users Service**: User registration, authentication (JWT tokens), and profile management.
+- **Borrowings Service**: Create and manage book borrowings with validation (prevents borrowing if out of stock).
+- **Telegram Notifications**: 
+  - Instant alerts when a new borrowing is created.
+  - Instant notifications when a book is successfully returned.
+  - **Daily Overdue Task**: Automated check for late returns via Celery and Celery Beat.
+- **Payments Service (Stripe Integration)**: 
+  - Automated Stripe Checkout Session creation for every new borrowing.
+  - Handling successful payments and canceling sessions.
+  - Automatic status updates (`PENDING` -> `PAID`) in the database upon successful transaction.
+
+---
+
+## 🚀 Installation & Setup
+
+1. Clone the repository:
+```bash
+git clone https://github.com/Viktor395/library-service-api.git
+cd library-service-api
+
+2. Set up virtual environment
+
+python -m venv .venv
+source .venv/bin/activate  # On Windows use: .venv\Scripts\activate
+pip install -r requirements.txt
+
+3. Environment Variables
+Create a `.env` file in the root directory and add the following keys (you can use `.env.sample` as a template):
+
+DJANGO_SECRET_KEY=your_django_secret_key_here
+DJANGO_DEBUG=True
+TELEGRAM_BOT_TOKEN=your_telegram_bot_token_here
+TELEGRAM_CHAT_ID=your_telegram_chat_id_here
+STRIPE_PUBLIC_KEY=your_stripe_public_key_here
+STRIPE_SECRET_KEY=your_stripe_secret_key_here
+STRIPE_SUCCESS_URL=http://127.0.0.1:8000/api/payments/success/
+STRIPE_CANCEL_URL=http://127.0.0.1:8000/api/payments/cancel/
+
+4. Apply Migrations & Run Server
+
+python manage.py migrate
+python manage.py runserver
+
+🐳 Running with Docker
+If you prefer to run the entire infrastructure (Django with SQLite, Redis, and Celery) inside Docker containers, follow these steps:
+
+1. Ensure you have Docker and Docker Compose installed.
+
+2. Create and fill your .env file based on .env.sample.
+
+3. Build and launch the containers using the following command in the root directory:
+
+docker-compose up --build
+
+This command automatically applies database migrations, starts the DRF web server on http://127.0.0.1:8000/, runs the Redis instance, and boots up both the Celery worker and Celery Beat scheduler in separate containers.
+
+
+
+⏰ Background Tasks (Celery & Redis)
+To run the automated background tasks (like daily overdue notifications), make sure Redis server is running, then start Celery components in separate terminal windows:
+
+Run Celery Worker:
+# For Windows:
+celery -A library_config worker --loglevel=info -P threads
+# For Linux/macOS:
+celery -A library_config worker --loglevel=info
+
+Run Celery Beat (Scheduler):
+
+celery -A library_config beat --loglevel=info
+
+## 🗺 API Endpoints for Payments
+
+| Method | Endpoint | Description | Access |
+| :--- | :--- | :--- | :--- |
+| `GET` | `/api/payments/` | List user's payments (or all for admin) | Authenticated |
+| `GET` | `/api/payments/success/` | Stripe success callback (updates status to PAID) | Public |
+| `GET` | `/api/payments/cancel/` | Stripe cancel callback | Public |

book/admin.py

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+from django.contrib import admin
+from .models import Book
+
+
+@admin.register(Book)
+class BookAdmin(admin.ModelAdmin):
+    list_display = ("title", "author", "cover", "inventory", "daily_fee")
+    list_filter = ("cover",)
+    search_fields = ("title", "author")

book/apps.py

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+from django.apps import AppConfig
+
+
+class BookConfig(AppConfig):
+    default_auto_field = "django.db.models.BigAutoField"
+    name = "book"

book/migrations/0001_initial.py

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+# Generated by Django 5.0.14 on 2026-05-17 11:05
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = []
+
+    operations = [
+        migrations.CreateModel(
+            name="Book",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("title", models.CharField(max_length=255)),
+                ("author", models.CharField(max_length=255)),
+                (
+                    "cover",
+                    models.CharField(
+                        choices=[("HARD", "Hardcover"), ("SOFT", "Softcover")],
+                        default="SOFT",
+                        max_length=4,
+                    ),
+                ),
+                ("inventory", models.PositiveIntegerField()),
+                ("daily_fee", models.DecimalField(decimal_places=2, max_digits=6)),
+            ],
+        ),
+    ]

book/models.py

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+from django.db import models
+
+
+class Book(models.Model):
+    class CoverChoices(models.TextChoices):
+        HARD = "HARD", "Hardcover"
+        SOFT = "SOFT", "Softcover"
+
+    title = models.CharField(max_length=255)
+    author = models.CharField(max_length=255)
+    cover = models.CharField(
+        max_length=4,
+        choices=CoverChoices.choices,
+        default=CoverChoices.SOFT
+    )
+    inventory = models.PositiveIntegerField()
+    daily_fee = models.DecimalField(max_digits=6, decimal_places=2)
+
+    def __str__(self):
+        return f"{self.title} by {self.author} ({self.cover})"

book/serializers.py

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+from rest_framework import serializers
+from .models import Book
+
+
+class BookSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Book
+        fields = ("id", "title", "author", "cover", "inventory", "daily_fee")

book/tests.py

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+from django.test import TestCase
+
+# Create your tests here.

book/urls.py

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+from django.urls import path, include
+from rest_framework.routers import DefaultRouter
+from .views import BookViewSet
+
+router = DefaultRouter()
+router.register("", BookViewSet)
+
+urlpatterns = [
+    path("", include(router.urls)),
+]
+
+app_name = "book"

book/views.py

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+from rest_framework import viewsets
+from rest_framework.permissions import IsAdminUser, AllowAny
+from .models import Book
+from .serializers import BookSerializer
+
+
+class BookViewSet(viewsets.ModelViewSet):
+    queryset = Book.objects.all()
+    serializer_class = BookSerializer
+
+    def get_permissions(self):
+        if self.action in ["list", "retrieve"]:
+            return [AllowAny()]
+        return [IsAdminUser()]

borrowing/admin.py

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+from django.contrib import admin
+from .models import Borrowing
+
+admin.site.register(Borrowing)

borrowing/apps.py

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+from django.apps import AppConfig
+
+
+class BorrowingConfig(AppConfig):
+    default_auto_field = "django.db.models.BigAutoField"
+    name = "borrowing"

borrowing/migrations/0001_initial.py

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+# Generated by Django 4.2.30 on 2026-05-19 14:30
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ("book", "0001_initial"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Borrowing",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("borrow_date", models.DateField(auto_now_add=True)),
+                ("expected_return_date", models.DateField()),
+                ("actual_return_date", models.DateField(blank=True, null=True)),
+                (
+                    "book",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="borrowings",
+                        to="book.book",
+                    ),
+                ),
+                (
+                    "user",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="borrowings",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+        ),
+    ]

borrowing/models.py

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+from django.conf import settings
+from django.db import models
+from book.models import Book
+
+
+class Borrowing(models.Model):
+    borrow_date = models.DateField(auto_now_add=True)
+    expected_return_date = models.DateField()
+    actual_return_date = models.DateField(null=True, blank=True)
+    book = models.ForeignKey(Book, on_delete=models.CASCADE, related_name="borrowings")
+    user = models.ForeignKey(
+        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="borrowings"
+    )
+
+    def __str__(self):
+        return f"{self.user.email} borrowed {self.book.title} on {self.borrow_date}"
+
+    def save(self, *args, **kwargs):
+        is_new = self.pk is None
+
+        is_returning = False
+        if not is_new:
+            old_instance = Borrowing.objects.get(pk=self.pk)
+            if old_instance.actual_return_date is None and self.actual_return_date is not None:
+                is_returning = True
+
+        super().save(*args, **kwargs)
+
+        from borrowing.notification_helper import send_telegram_message
+
+        if is_new:
+            message = (
+                f"🎉 <b>New Borrowing Created!</b>\n\n"
+                f"👤 <b>User:</b> {self.user.email}\n"
+                f"📚 <b>Book:</b> {self.book.title}\n"
+                f"📅 <b>Borrow Date:</b> {self.borrow_date}\n"
+                f"⏳ <b>Expected Return:</b> {self.expected_return_date}"
+            )
+            send_telegram_message(message)
+
+        elif is_returning:
+            message = (
+                f"✅ <b>Book Returned Successfully!</b>\n\n"
+                f"👤 <b>User:</b> {self.user.email}\n"
+                f"📚 <b>Book:</b> {self.book.title}\n"
+                f"📅 <b>Returned On:</b> {self.actual_return_date}\n"
+                f"stocked back to inventory ✨"
+            )
+            send_telegram_message(message)

borrowing/notification_helper.py

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+import os
+import requests
+from django.conf import settings
+
+def send_telegram_message(message: str) -> None:
+    bot_token = settings.TELEGRAM_BOT_TOKEN
+    chat_id = settings.TELEGRAM_CHAT_ID
+
+    if not bot_token or not chat_id:
+        print("Telegram bot credentials are not set in .env")
+        return
+
+    url = f"https://api.telegram.org/bot{bot_token}/sendMessage"
+
+    payload = {
+        "chat_id": chat_id,
+        "text": message,
+        "parse_mode": "HTML"
+    }
+
+    try:
+        response = requests.post(url, json=payload)
+        if response.status_code != 200:
+            print(f"Failed to send telegram message: {response.text}")
+    except requests.RequestException as e:
+        print(f"Error connecting to Telegram API: {e}")