Merge PR #851: Extract core modules and resolve complex routing conflicts

Author: devanshi14malhotra

backend/ai_service.py

@@ -19,7 +19,7 @@
 
 #to generate book spine images dynamically based on title and author
 
-from backend.spine_generator import create_spine
+from spine_generator import create_spine
 
 def process_new_book(book_data):
     # 1. Save book to your database first

backend/app.py

@@ -31,7 +31,7 @@
 
 import logging
 from datetime import datetime, timedelta, timezone
-from sanitizer import sanitize_payload
+from backend.core.security.sanitizer import sanitize_payload
 from reader_identity.routes import reader_identity_bp
 
 # Load environment variables from config directory based on APP_ENV
@@ -51,7 +51,7 @@
 from models import db, User, Book, ShelfItem, BookNote, ReadingGoal, ReadingStats, Collection, CollectionItem, PriceHistory, PriceAlert, Review, register_user, login_user
 from price_tracker import get_price_tracker
 from cache_service import cache_service
-from validators import (
+from backend.core.validators.validators import (
     validate_request,
     validate_schema,
     validate_google_books_id,
@@ -95,7 +95,7 @@
 from collections import defaultdict, deque
 from math import ceil
 from time import time
-from error_responses import (
+from backend.core.responses.error_responses import (
     ErrorCodes, error_response, success_response,
     validation_error, missing_fields_error, invalid_json_error,
     auth_error, forbidden_error, unauthorized_access_error,
@@ -1061,11 +1061,11 @@ def handle_analyze_mood(validated_data):
 @validate_schema(MoodTagsRequest)
 def handle_mood_tags(validated_data):
     """Get mood tags for a book."""
-    from exceptions import (
+    from backend.core.exceptions.exceptions import (
         LLMCircuitBreakerOpenError, AIServiceException, 
         ValidationException, InvalidInputError
     )
-    from error_responses import handle_exception
+    from backend.core.responses.error_responses import handle_exception
 
     try:
 
@@ -1092,11 +1092,11 @@ def handle_mood_tags(validated_data):
 @validate_schema(MoodSearchRequest)
 def handle_mood_search(validated_data):
     """Search for books based on mood/vibe with improved query parsing."""
-    from exceptions import (
+    from backend.core.exceptions.exceptions import (
         LLMCircuitBreakerOpenError, AIServiceException,
         ValidationException, InvalidInputError
     )
-    from error_responses import handle_exception
+    from backend.core.responses.error_responses import handle_exception
 
     try:
 
@@ -1199,12 +1199,12 @@ def handle_purchase_links():
 @validate_schema(GenerateNoteRequest)
 def handle_generate_note(validated_data):
     """Generate AI-powered book recommendation with vibe support."""
-    from exceptions import (
+    from backend.core.exceptions.exceptions import (
         LLMCircuitBreakerOpenError, AIServiceException,
         DatabaseQueryError, DatabaseIntegrityError,
         ValidationException, InvalidInputError
     )
-    from error_responses import handle_exception
+    from backend.core.responses.error_responses import handle_exception
 
     try:
 
@@ -1312,8 +1312,8 @@ def handle_socket_chat(data):
 def add_to_library(validated_data):
     """Add a book to the user's shelf."""
     from sqlalchemy.exc import IntegrityError
-    from exceptions import DatabaseQueryError, DatabaseIntegrityError, ValidationException
-    from error_responses import handle_exception
+    from backend.core.exceptions.exceptions import DatabaseQueryError, DatabaseIntegrityError, ValidationException
+    from backend.core.responses.error_responses import handle_exception
 
     try:
 
@@ -1741,8 +1741,8 @@ def register(validated_data):
 @validate_schema(LoginRequest)
 def login(validated_data):
     """Authenticate user and return JWT token."""
-    from exceptions import DatabaseQueryError, ValidationException
-    from error_responses import handle_exception
+    from backend.core.exceptions.exceptions import DatabaseQueryError, ValidationException
+    from backend.core.responses.error_responses import handle_exception
 
     try:
 

backend/core/__init__.py

@@ -0,0 +1,72 @@
+import os
+from collections import defaultdict, deque
+from math import ceil
+from time import time
+
+# Read defaults from environment, matching original behaviour
+RATE_LIMIT_WINDOW = int(os.getenv('RATE_LIMIT_WINDOW', '60'))
+RATE_LIMIT_MAX_REQUESTS = int(os.getenv('RATE_LIMIT_MAX_REQUESTS', '30'))
+
+# Internal sliding-window state
+_request_log = defaultdict(deque)
+_request_calls = 0
+
+
+def _cleanup_expired_keys(cutoff: float) -> None:
+    """Remove keys whose newest timestamp is already outside the window."""
+    stale_keys = [key for key, dq in _request_log.items() if not dq or dq[-1] <= cutoff]
+    for key in stale_keys:
+        _request_log.pop(key, None)
+
+
+def _rate_limited(endpoint: str) -> tuple[bool, int]:
+    """Sliding window limiter per IP/endpoint."""
+    # Lazy import to avoid circular imports
+    from flask import request
+    from app.config import app_config
+
+    if not app_config.rate_limit.enabled:
+        return False, 0
+    
+    global _request_calls
+    key = f"{request.remote_addr}|{endpoint}"
+    now = time()
+    window_start = now - RATE_LIMIT_WINDOW
+    _request_calls += 1
+
+    dq = _request_log[key]
+    while dq and dq[0] <= window_start:
+        dq.popleft()
+
+    if len(dq) >= RATE_LIMIT_MAX_REQUESTS:
+        oldest = dq[0]
+        retry_after = max(1, ceil(RATE_LIMIT_WINDOW - (now - oldest)))
+        return True, retry_after
+
+    dq.append(now)
+
+    if _request_calls % 100 == 0:
+        _cleanup_expired_keys(window_start)
+
+    return False, 0
+
+
+def rate_limit(endpoint_name: str):
+    """Decorator to apply rate limiting to an endpoint."""
+    def decorator(f):
+        def wrapped(*args, **kwargs):
+            limited, retry_after = _rate_limited(endpoint_name)
+            if limited:
+                from flask import jsonify
+                response = jsonify({
+                    "success": False,
+                    "error": "Rate limit exceeded. Try again shortly.",
+                    "retry_after": retry_after
+                })
+                response.status_code = 429
+                response.headers['Retry-After'] = retry_after
+                return response
+            return f(*args, **kwargs)
+        wrapped.__name__ = f.__name__
+        return wrapped
+    return decorator

backend/core/exceptions/__init__.py

@@ -304,7 +304,7 @@ def handle_exception(exception: Exception, endpoint: str = "unknown") -> tuple:
     Returns:
         Tuple of (error response, status_code)
     """
-    from exceptions import (
+    from core.exceptions.exceptions import (
         LLMRateLimitError, LLMTimeoutError, LLMConnectionError,
         LLMAuthenticationError, LLMCircuitBreakerOpenError,
         DatabaseException, DatabaseConnectionError, DatabaseQueryError,