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backend/services/progress_service.py

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+"""
+Progress Service - Manages document parsing progress for real-time updates
+"""
+import asyncio
+from typing import Dict, Optional, AsyncGenerator
+from datetime import datetime
+from enum import Enum
+
+
+class ProgressStatus(str, Enum):
+    """Progress status types"""
+    PENDING = "pending"
+    PARSING = "parsing"
+    SPLITTING = "splitting"
+    PROCESSING_CHUNK = "processing_chunk"
+    DEDUPLICATING = "deduplicating"
+    SAVING = "saving"
+    COMPLETED = "completed"
+    FAILED = "failed"
+
+
+class ProgressUpdate:
+    """Progress update data structure"""
+    def __init__(
+        self,
+        exam_id: int,
+        status: ProgressStatus,
+        message: str,
+        progress: float = 0.0,
+        total_chunks: int = 0,
+        current_chunk: int = 0,
+        questions_extracted: int = 0,
+        questions_added: int = 0,
+        duplicates_removed: int = 0
+    ):
+        self.exam_id = exam_id
+        self.status = status
+        self.message = message
+        self.progress = progress  # 0-100
+        self.total_chunks = total_chunks
+        self.current_chunk = current_chunk
+        self.questions_extracted = questions_extracted
+        self.questions_added = questions_added
+        self.duplicates_removed = duplicates_removed
+        self.timestamp = datetime.now().isoformat()
+
+    def to_dict(self) -> dict:
+        """Convert to dictionary for JSON serialization"""
+        return {
+            "exam_id": self.exam_id,
+            "status": self.status.value,
+            "message": self.message,
+            "progress": round(self.progress, 1),
+            "total_chunks": self.total_chunks,
+            "current_chunk": self.current_chunk,
+            "questions_extracted": self.questions_extracted,
+            "questions_added": self.questions_added,
+            "duplicates_removed": self.duplicates_removed,
+            "timestamp": self.timestamp
+        }
+
+
+class ProgressService:
+    """Service for managing parsing progress"""
+
+    def __init__(self):
+        # Store progress updates for each exam
+        self._progress: Dict[int, ProgressUpdate] = {}
+        # Store queues for SSE connections
+        self._queues: Dict[int, list] = {}
+
+    async def update_progress(self, update: ProgressUpdate):
+        """
+        Update progress for an exam and notify all listeners
+
+        Args:
+            update: Progress update object
+        """
+        exam_id = update.exam_id
+        self._progress[exam_id] = update
+
+        # Send to all connected SSE clients for this exam
+        if exam_id in self._queues:
+            dead_queues = []
+            for queue in self._queues[exam_id]:
+                try:
+                    await queue.put(update)
+                except Exception as e:
+                    print(f"[Progress] Failed to send update to queue: {e}")
+                    dead_queues.append(queue)
+
+            # Clean up dead queues
+            for dead_queue in dead_queues:
+                self._queues[exam_id].remove(dead_queue)
+
+    def get_progress(self, exam_id: int) -> Optional[ProgressUpdate]:
+        """Get current progress for an exam"""
+        return self._progress.get(exam_id)
+
+    async def subscribe(self, exam_id: int) -> AsyncGenerator[ProgressUpdate, None]:
+        """
+        Subscribe to progress updates for an exam (SSE stream)
+
+        Args:
+            exam_id: Exam ID to subscribe to
+
+        Yields:
+            Progress updates as they occur
+        """
+        # Create a queue for this connection
+        queue = asyncio.Queue()
+
+        # Register the queue
+        if exam_id not in self._queues:
+            self._queues[exam_id] = []
+        self._queues[exam_id].append(queue)
+
+        try:
+            # Send current progress if exists
+            current_progress = self.get_progress(exam_id)
+            if current_progress:
+                yield current_progress
+
+            # Stream updates
+            while True:
+                update = await queue.get()
+                yield update
+
+                # Stop streaming if completed or failed
+                if update.status in [ProgressStatus.COMPLETED, ProgressStatus.FAILED]:
+                    break
+
+        finally:
+            # Cleanup
+            if exam_id in self._queues and queue in self._queues[exam_id]:
+                self._queues[exam_id].remove(queue)
+                if not self._queues[exam_id]:
+                    del self._queues[exam_id]
+
+    def clear_progress(self, exam_id: int):
+        """Clear progress data for an exam"""
+        if exam_id in self._progress:
+            del self._progress[exam_id]
+        if exam_id in self._queues:
+            del self._queues[exam_id]
+
+
+# Singleton instance
+progress_service = ProgressService()