# /// script
# requires-python = ">=3.10"
# dependencies = [
#     "datasets>=2.0",
#     "huggingface-hub[hf_transfer]>=0.20",
#     "polars>=1.0",
#     "torch>=2.0",
#     "transformers>=4.40",
#     "tokenizers>=0.19",
#     "toolz",
#     "tqdm",
#     "pyarrow>=15.0",
#     "vllm",
# ]
#
# [[tool.uv.index]]
# url = "https://wheels.vllm.ai/nightly"
# ///
"""
Incremental batch text classification for ArXiv papers.

This script processes new papers from the arxiv-metadata-snapshot dataset
and updates the existing classified dataset. It only processes papers newer
than the last classification run, making it efficient for daily updates.

Example usage:
    # Daily incremental update (only new papers)
    uv run batch_classify_arxiv_incremental.py

    # Monthly full refresh (reprocess everything)
    uv run batch_classify_arxiv_incremental.py --full-refresh
    
    # Test with small sample
    uv run batch_classify_arxiv_incremental.py --limit 100
"""

import argparse
import json
import logging
import os
import shutil
import sys
import tempfile
from datetime import datetime
from pathlib import Path
from typing import Dict, List, Optional, Tuple

import polars as pl
import torch
from datasets import Dataset, load_dataset
from huggingface_hub import HfFolder, login
from toolz import partition_all
from tqdm.auto import tqdm
from transformers import pipeline

# Try to import vLLM - it may not be available in all environments
try:
    import vllm
    from vllm import LLM
    VLLM_AVAILABLE = True
except ImportError:
    VLLM_AVAILABLE = False

logging.basicConfig(
    level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s"
)
logger = logging.getLogger(__name__)

# Constants
DEFAULT_OUTPUT_DATASET = "davanstrien/my-classified-papers"
DEFAULT_INPUT_DATASET = "librarian-bots/arxiv-metadata-snapshot"
DEFAULT_MODEL = "davanstrien/ModernBERT-base-is-new-arxiv-dataset"


def check_backend() -> Tuple[str, int]:
    """
    Check available backend and return (backend_name, recommended_batch_size).
    
    Returns:
        Tuple of (backend_name, batch_size) where backend is 'vllm', 'cuda', 'mps', or 'cpu'
    """
    if torch.cuda.is_available() and VLLM_AVAILABLE:
        gpu_name = torch.cuda.get_device_name(0)
        gpu_memory = torch.cuda.get_device_properties(0).total_memory / 1024**3
        logger.info(f"GPU detected: {gpu_name} with {gpu_memory:.1f} GB memory")
        logger.info(f"vLLM version: {vllm.__version__}")
        return "vllm", 500_000  # Larger batches for A100
    elif torch.cuda.is_available():
        logger.info("CUDA available but vLLM not installed. Using transformers with GPU.")
        return "cuda", 256  # Smaller batch for transformers to avoid OOM
    elif torch.backends.mps.is_available():
        logger.info("Using Apple Silicon MPS device with transformers")
        return "mps", 1_000
    else:
        logger.info("Using CPU device with transformers")
        return "cpu", 100


def get_last_update_date(output_dataset: str, hf_token: Optional[str] = None) -> Optional[str]:
    """
    Get the maximum update_date from the existing classified dataset.
    
    Args:
        output_dataset: HuggingFace dataset ID
        hf_token: Optional HuggingFace token
        
    Returns:
        ISO format date string of the last update, or None if dataset doesn't exist
    """
    try:
        logger.info(f"Checking for existing dataset: {output_dataset}")
        
        # Try to load dataset metadata
        from huggingface_hub import hf_hub_download, list_repo_files
        
        # Check if dataset exists
        try:
            files = list_repo_files(output_dataset, repo_type="dataset", token=hf_token)
            parquet_files = [f for f in files if f.endswith('.parquet')]
            
            if not parquet_files:
                logger.info("No parquet files found in existing dataset")
                return None
                
        except Exception as e:
            logger.info(f"Dataset {output_dataset} not found or inaccessible: {e}")
            return None
        
        # Download and scan parquet files to find max update_date
        temp_dir = Path(tempfile.mkdtemp(prefix="arxiv_incremental_check_"))
        
        try:
            from huggingface_hub import snapshot_download
            local_dir = snapshot_download(
                output_dataset,
                local_dir=str(temp_dir),
                allow_patterns=["*.parquet"],
                repo_type="dataset",
                token=hf_token
            )
            
            # Use Polars to efficiently find max update_date
            lf = pl.scan_parquet(Path(local_dir).rglob("*.parquet"))
            max_date_df = lf.select(pl.col("update_date").max()).collect()
            
            if max_date_df.height > 0 and max_date_df.width > 0:
                max_date = max_date_df[0, 0]
                logger.info(f"Found last update date in existing dataset: {max_date}")
                return max_date
            else:
                logger.info("No update_date found in existing dataset")
                return None
                
        finally:
            # Cleanup temp directory
            if temp_dir.exists():
                shutil.rmtree(temp_dir)
                
    except Exception as e:
        logger.warning(f"Error checking existing dataset: {e}")
        return None


def prepare_incremental_data(
    input_dataset: str,
    temp_dir: Path,
    last_update_date: Optional[str] = None,
    limit: Optional[int] = None,
    full_refresh: bool = False
) -> Optional[Path]:
    """
    Prepare data for incremental classification.
    
    Args:
        input_dataset: Source dataset ID
        temp_dir: Directory for temporary files
        last_update_date: Date of last classification run
        limit: Optional limit for testing
        full_refresh: If True, process all papers regardless of date
        
    Returns:
        Path to filtered parquet file, or None if no new papers
    """
    output_path = temp_dir / "papers_to_classify.parquet"
    
    logger.info(f"Loading source dataset: {input_dataset}")
    
    # Download dataset
    from huggingface_hub import snapshot_download
    local_dir = temp_dir / "raw_data"
    snapshot_download(
        input_dataset,
        local_dir=str(local_dir),
        allow_patterns=["*.parquet"],
        repo_type="dataset",
    )
    parquet_files = list(local_dir.rglob("*.parquet"))
    
    logger.info(f"Found {len(parquet_files)} parquet files")
    
    # Create lazy frame
    lf = pl.scan_parquet(parquet_files)
    
    # Filter to CS papers
    logger.info("Filtering to CS papers...")
    lf_cs = lf.filter(pl.col("categories").str.contains("cs."))
    
    # Apply incremental filter if not full refresh
    if not full_refresh and last_update_date:
        logger.info(f"Filtering for papers newer than {last_update_date}")
        lf_cs = lf_cs.filter(pl.col("update_date") > last_update_date)
    elif full_refresh:
        logger.info("Full refresh mode - processing all CS papers")
    else:
        logger.info("No existing dataset found - processing all CS papers")
    
    # Apply limit if specified (for testing)
    if limit:
        logger.info(f"Limiting to {limit} papers for testing")
        lf_cs = lf_cs.head(limit)
    
    # Add formatted text column
    logger.info("Formatting text for classification...")
    lf_formatted = lf_cs.with_columns(
        pl.concat_str([
            pl.lit("TITLE: "),
            pl.col("title"),
            pl.lit(" \n\nABSTRACT: "),
            pl.col("abstract")
        ]).alias("text_for_classification")
    )
    
    # Collect to check if we have any papers to process
    df_to_classify = lf_formatted.collect(streaming=True)
    
    if df_to_classify.height == 0:
        logger.info("No new papers to classify")
        return None
    
    logger.info(f"Found {df_to_classify.height:,} papers to classify")
    
    # Write to parquet
    df_to_classify.write_parquet(output_path)
    return output_path


def classify_with_vllm(
    dataset: Dataset,
    model_id: str,
    batch_size: int = 100_000
) -> List[Dict]:
    """
    Classify papers using vLLM for efficient GPU inference.
    """
    logger.info(f"Initializing vLLM with model: {model_id}")
    llm = LLM(model=model_id, runner="pooling")
    
    texts = dataset["text_for_classification"]
    total_papers = len(texts)
    
    logger.info(f"Starting vLLM classification of {total_papers:,} papers")
    all_results = []
    
    for batch in tqdm(
        list(partition_all(batch_size, texts)),
        desc="Processing batches",
        unit="batch"
    ):
        batch_results = llm.classify(batch)
        
        for result in batch_results:
            logits = torch.tensor(result.outputs.probs)
            probs = torch.nn.functional.softmax(logits, dim=0)
            top_idx = torch.argmax(probs).item()
            top_prob = probs[top_idx].item()
            
            # Model config: 0 -> new_dataset, 1 -> no_new_dataset
            label = "new_dataset" if top_idx == 0 else "no_new_dataset"
            
            all_results.append({
                "classification_label": label,
                "is_new_dataset": label == "new_dataset",
                "confidence_score": float(top_prob)
            })
    
    return all_results


def classify_with_transformers(
    dataset: Dataset,
    model_id: str,
    batch_size: int = 1_000,
    device: str = "cpu"
) -> List[Dict]:
    """
    Classify papers using transformers pipeline.
    """
    logger.info(f"Initializing transformers pipeline with model: {model_id}")
    
    if device == "cuda":
        device_map = 0
    elif device == "mps":
        device_map = "mps"
    else:
        device_map = None
    
    pipe = pipeline(
        "text-classification",
        model=model_id,
        device=device_map,
        batch_size=batch_size
    )
    
    texts = dataset["text_for_classification"]
    total_papers = len(texts)
    
    logger.info(f"Starting transformers classification of {total_papers:,} papers")
    all_results = []
    
    with tqdm(total=total_papers, desc="Classifying papers", unit="papers") as pbar:
        for batch in partition_all(batch_size, texts):
            batch_list = list(batch)
            predictions = pipe(batch_list)
            
            for pred in predictions:
                label = pred["label"]
                all_results.append({
                    "classification_label": label,
                    "is_new_dataset": label == "new_dataset",
                    "confidence_score": float(pred["score"])
                })
            
            pbar.update(len(batch_list))
    
    return all_results


def merge_with_existing(
    new_dataset: Dataset,
    output_dataset: str,
    temp_dir: Path,
    hf_token: Optional[str] = None
) -> Dataset:
    """
    Merge newly classified papers with existing dataset.
    
    Args:
        new_dataset: Newly classified papers
        output_dataset: Target dataset ID
        temp_dir: Temporary directory
        hf_token: HuggingFace token
        
    Returns:
        Merged dataset
    """
    try:
        logger.info(f"Loading existing dataset from {output_dataset}")
        
        # Download existing dataset
        from huggingface_hub import snapshot_download
        existing_dir = temp_dir / "existing_data"
        snapshot_download(
            output_dataset,
            local_dir=str(existing_dir),
            allow_patterns=["*.parquet"],
            repo_type="dataset",
            token=hf_token
        )
        
        # Load with Polars for efficient merging
        existing_files = list(existing_dir.rglob("*.parquet"))
        
        if existing_files:
            # Convert new dataset to Polars
            new_df = pl.from_arrow(new_dataset.data.table)
            
            # Load existing data
            existing_df = pl.read_parquet(existing_files)
            
            # Combine datasets
            logger.info(f"Merging {new_df.height:,} new papers with {existing_df.height:,} existing papers")
            combined_df = pl.concat([existing_df, new_df], how="vertical")
            
            # Deduplicate by paper ID, keeping the most recent
            logger.info("Deduplicating by paper ID...")
            final_df = combined_df.unique(subset=["id"], keep="last")
            
            logger.info(f"Final dataset has {final_df.height:,} papers after deduplication")
            
            # Convert back to HuggingFace Dataset
            final_dataset = Dataset.from_pandas(final_df.to_pandas())
            
            return final_dataset
        else:
            logger.info("No existing data found, returning new dataset")
            return new_dataset
            
    except Exception as e:
        logger.warning(f"Could not load existing dataset: {e}")
        logger.info("Returning new dataset only")
        return new_dataset


def main(
    input_dataset: str = DEFAULT_INPUT_DATASET,
    output_dataset: str = DEFAULT_OUTPUT_DATASET,
    model_id: str = DEFAULT_MODEL,
    batch_size: Optional[int] = None,
    limit: Optional[int] = None,
    full_refresh: bool = False,
    temp_dir: Optional[str] = None,
    hf_token: Optional[str] = None
):
    """
    Main incremental classification pipeline.
    """
    # Authentication
    HF_TOKEN = hf_token or os.environ.get("HF_TOKEN")
    if HF_TOKEN:
        login(token=HF_TOKEN)
    else:
        logger.warning("No HF_TOKEN found. You may need to login for private datasets.")
    
    # Setup temp directory
    if temp_dir:
        temp_path = Path(temp_dir)
        temp_path.mkdir(parents=True, exist_ok=True)
    else:
        temp_path = Path(tempfile.mkdtemp(prefix="arxiv_incremental_"))
    
    logger.info(f"Using temp directory: {temp_path}")
    
    # Check backend and set batch size
    backend, default_batch_size = check_backend()
    if batch_size is None:
        batch_size = default_batch_size
        logger.info(f"Using batch size: {batch_size:,}")
    
    # Step 1: Check for existing dataset and get last update date
    last_update_date = None
    if not full_refresh:
        last_update_date = get_last_update_date(output_dataset, HF_TOKEN)
        if last_update_date:
            logger.info(f"Will process papers newer than: {last_update_date}")
        else:
            logger.info("No existing dataset found - will process all papers")
    else:
        logger.info("Full refresh mode - will process all papers")
    
    # Step 2: Prepare incremental data
    papers_to_classify = prepare_incremental_data(
        input_dataset,
        temp_path,
        last_update_date,
        limit,
        full_refresh
    )
    
    if papers_to_classify is None:
        logger.info("No new papers to classify. Dataset is up to date!")
        # Cleanup temp directory
        if not temp_dir and temp_path.exists():
            shutil.rmtree(temp_path)
        return
    
    # Step 3: Load as HuggingFace Dataset
    logger.info("Loading papers to classify as HuggingFace Dataset...")
    dataset = load_dataset(
        "parquet",
        data_files=str(papers_to_classify),
        split="train"
    )
    logger.info(f"Dataset loaded with {len(dataset):,} papers to classify")
    
    # Step 4: Classify papers
    if backend == "vllm":
        results = classify_with_vllm(dataset, model_id, batch_size)
    else:
        results = classify_with_transformers(
            dataset, model_id, batch_size, backend
        )
    
    # Step 5: Add results to dataset
    logger.info("Adding classification results to dataset...")
    
    dataset = dataset.add_column("classification_label", [r["classification_label"] for r in results])
    dataset = dataset.add_column("is_new_dataset", [r["is_new_dataset"] for r in results])
    dataset = dataset.add_column("confidence_score", [r["confidence_score"] for r in results])
    
    # Add metadata
    dataset = dataset.add_column("classification_date", [datetime.now().isoformat()] * len(dataset))
    dataset = dataset.add_column("model_version", [model_id] * len(dataset))
    
    # Remove temporary columns and problematic nested columns
    columns_to_remove = ["text_for_classification"]
    if "versions" in dataset.column_names:
        columns_to_remove.append("versions")
    if "authors_parsed" in dataset.column_names:
        columns_to_remove.append("authors_parsed")
    
    dataset = dataset.remove_columns(columns_to_remove)
    
    # Step 6: Merge with existing dataset (if not full refresh)
    if not full_refresh and last_update_date:
        dataset = merge_with_existing(dataset, output_dataset, temp_path, HF_TOKEN)
    
    # Step 7: Push to Hub or save locally
    if HF_TOKEN:
        logger.info(f"Pushing results to: {output_dataset}")
        dataset.push_to_hub(output_dataset, token=HF_TOKEN)
    else:
        local_path = temp_path / "classified_dataset"
        logger.info(f"No HF_TOKEN, saving results locally to: {local_path}")
        dataset.save_to_disk(str(local_path))
    
    # Print statistics
    num_new_datasets = sum(1 for i in range(len(dataset)) if dataset[i]["is_new_dataset"])
    avg_confidence = sum(dataset[i]["confidence_score"] for i in range(len(dataset))) / len(dataset)
    
    logger.info("="*60)
    logger.info("Incremental Classification Complete!")
    logger.info(f"Total papers in dataset: {len(dataset):,}")
    logger.info(f"Papers with new datasets: {num_new_datasets:,} ({num_new_datasets/len(dataset)*100:.1f}%)")
    logger.info(f"Average confidence score: {avg_confidence:.3f}")
    logger.info(f"Results saved to: {output_dataset}")
    if not full_refresh and last_update_date:
        logger.info(f"Processed papers newer than: {last_update_date}")
    logger.info("="*60)
    
    # Cleanup temp directory if not explicitly specified
    if not temp_dir and temp_path.exists():
        logger.info(f"Cleaning up temp directory: {temp_path}")
        shutil.rmtree(temp_path)


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Incremental classification of ArXiv papers for new datasets",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog="""
Examples:
  # Daily incremental update (only new papers)
  uv run batch_classify_arxiv_incremental.py
  
  # Monthly full refresh (reprocess everything)
  uv run batch_classify_arxiv_incremental.py --full-refresh
  
  # Test with small sample
  uv run batch_classify_arxiv_incremental.py --limit 100
  
  # Custom datasets
  uv run batch_classify_arxiv_incremental.py \\
    --input-dataset librarian-bots/arxiv-metadata-snapshot \\
    --output-dataset my-custom-classification
        """
    )
    
    parser.add_argument(
        "--input-dataset",
        type=str,
        default=DEFAULT_INPUT_DATASET,
        help=f"Input dataset on HuggingFace Hub (default: {DEFAULT_INPUT_DATASET})"
    )
    parser.add_argument(
        "--output-dataset",
        type=str,
        default=DEFAULT_OUTPUT_DATASET,
        help=f"Output dataset on HuggingFace Hub (default: {DEFAULT_OUTPUT_DATASET})"
    )
    parser.add_argument(
        "--model",
        type=str,
        default=DEFAULT_MODEL,
        help=f"Model ID for classification (default: {DEFAULT_MODEL})"
    )
    parser.add_argument(
        "--batch-size",
        type=int,
        help="Batch size for inference (auto-detected if not specified)"
    )
    parser.add_argument(
        "--limit",
        type=int,
        help="Limit number of papers for testing"
    )
    parser.add_argument(
        "--full-refresh",
        action="store_true",
        help="Process all papers regardless of update date (monthly refresh)"
    )
    parser.add_argument(
        "--temp-dir",
        type=str,
        help="Directory for temporary files (auto-created if not specified)"
    )
    parser.add_argument(
        "--hf-token",
        type=str,
        help="HuggingFace token (can also use HF_TOKEN env var)"
    )
    
    args = parser.parse_args()
    
    main(
        input_dataset=args.input_dataset,
        output_dataset=args.output_dataset,
        model_id=args.model,
        batch_size=args.batch_size,
        limit=args.limit,
        full_refresh=args.full_refresh,
        temp_dir=args.temp_dir,
        hf_token=args.hf_token
    )