from typing import List, Tuple
from concurrent.futures import ThreadPoolExecutor
from pymongo import UpdateOne
from pymongo.collection import Collection
import math

def get_embedding(text: str, openai_client, model="text-embedding-ada-002") -> list[float]:
    """Get embeddings for given text using OpenAI API"""
    text = text.replace("\n", " ")
    resp = openai_client.embeddings.create(
        input=[text],
        model=model
    )
    return resp.data[0].embedding

def process_batch(docs: List[dict], field_name: str, embedding_field: str, openai_client) -> List[Tuple[str, list]]:
    """Process a batch of documents to generate embeddings"""
    results = []
    for doc in docs:
        # Skip if embedding already exists
        if embedding_field in doc:
            continue
            
        text = doc[field_name]
        if isinstance(text, str):
            embedding = get_embedding(text, openai_client)
            results.append((doc["_id"], embedding))
    return results

def parallel_generate_embeddings(
    collection: Collection,
    cursor,
    field_name: str,
    embedding_field: str,
    openai_client,
    total_docs: int,
    batch_size: int = 20,
    callback=None
) -> int:
    """Generate embeddings in parallel using ThreadPoolExecutor with cursor-based batching
    
    Args:
        collection: MongoDB collection
        cursor: MongoDB cursor for document iteration
        field_name: Field containing text to embed
        embedding_field: Field to store embeddings
        openai_client: OpenAI client instance
        total_docs: Total number of documents to process
        batch_size: Size of batches for parallel processing
        callback: Optional callback function for progress updates
        
    Returns:
        Number of documents processed
    """
    if total_docs == 0:
        return 0
        
    processed = 0
    
    # Initial progress update
    if callback:
        callback(0, 0, total_docs)
        
    # Process documents in batches using cursor
    with ThreadPoolExecutor(max_workers=20) as executor:
        batch = []
        futures = []
        
        # Iterate through cursor and build batches
        for doc in cursor:
            batch.append(doc)
            
            if len(batch) >= batch_size:
                # Submit batch for processing
                future = executor.submit(process_batch, batch.copy(), field_name, embedding_field, openai_client)
                futures.append(future)
                batch = []  # Clear batch for next round
                
                # Process completed futures to free up memory
                completed_futures = [f for f in futures if f.done()]
                for future in completed_futures:
                    results = future.result()
                    if results:
                        # Batch update MongoDB
                        bulk_ops = [
                            UpdateOne({"_id": doc_id}, {"$set": {embedding_field: embedding}})
                            for doc_id, embedding in results
                        ]
                        if bulk_ops:
                            collection.bulk_write(bulk_ops)
                            processed += len(bulk_ops)
                            
                        # Update progress
                        if callback:
                            progress = (processed / total_docs) * 100
                            callback(progress, processed, total_docs)
                            
                futures = [f for f in futures if not f.done()]
        
        # Process any remaining documents in the last batch
        if batch:
            future = executor.submit(process_batch, batch, field_name, embedding_field, openai_client)
            futures.append(future)
        
        # Wait for remaining futures to complete
        for future in futures:
            results = future.result()
            if results:
                bulk_ops = [
                    UpdateOne({"_id": doc_id}, {"$set": {embedding_field: embedding}})
                    for doc_id, embedding in results
                ]
                if bulk_ops:
                    collection.bulk_write(bulk_ops)
                    processed += len(bulk_ops)
                    
                    # Final progress update
                    if callback:
                        progress = (processed / total_docs) * 100
                        callback(progress, processed, total_docs)
                    
    return processed