"""Chart-to-CSV extraction using Granite Vision.

Converts chart images to tabular CSV data using ibm-granite/granite-vision-4.1-4b.
"""

import threading
from collections.abc import Generator
from PIL import Image
from typing import Any

import torch
from PIL import Image
from transformers import TextIteratorStreamer
from model_loader import load_model, use_api_mode, use_mlx_mode


def extract_csv(image: Image.Image) -> str:
    """Extract CSV data from a chart image using Granite Vision.

    Args:
        image: PIL Image of a chart or table.

    Returns:
        CSV-formatted text extracted from the chart.
    """
    if use_api_mode():
        from infer_api import extract_csv_api
        return extract_csv_api(image)

    if use_mlx_mode():
        from infer_mlx import extract_csv_mlx
        return extract_csv_mlx(image)

    processor, model = load_model()

    if processor is None or model is None:
        return "col1,col2,col3\nvalue1,value2,value3\nvalue4,value5,value6"

    try:
        import torch

        image = image.convert("RGB")
        conversation = [{"role": "user", "content": [
            {"type": "image"},
            {"type": "text", "text": "<chart2csv>"},
        ]}]
        text = processor.apply_chat_template(conversation, tokenize=False, add_generation_prompt=True)
        inputs = processor(text=text, images=image, return_tensors="pt").to(model.device)

        max_new_tokens = 4096
        with torch.inference_mode():
            outputs = model.generate(**inputs, max_new_tokens=max_new_tokens, use_cache=True)

        gen = outputs[0, inputs["input_ids"].shape[1]:]
        result = processor.decode(gen, skip_special_tokens=True)
        if len(gen) >= max_new_tokens:
            result += "\n\n[Max token limit reached — response may be truncated]"
        return result

    except Exception as e:  # noqa: BLE001
        import traceback

        traceback.print_exc()
        return f"Error: {e!s}"


def _run_generate(model: Any, generation_kwargs: dict[str, Any]) -> None:
    """Run model.generate in a thread (used by the streaming variant)."""
    with torch.inference_mode():
        model.generate(**generation_kwargs)


def extract_csv_stream(image: Image.Image) -> Generator[str, None, None]:
    """Stream CSV extraction token-by-token from a chart image.
    Same interface as extract_csv() but yields tokens incrementally.
    Args:
        image: PIL Image of a chart or table.
    Yields:
        Token strings as they are generated by the model.
    """
    if use_api_mode():
        from infer_api import extract_csv_stream_api
        yield from extract_csv_stream_api(image)
        return

    if use_mlx_mode():
        from infer_mlx import extract_csv_stream_mlx
        yield from extract_csv_stream_mlx(image)
        return

    processor, model = load_model()

    if processor is None or model is None:
        yield "col1,col2,col3\nvalue1,value2,value3\nvalue4,value5,value6"
        return

    try:
        image = image.convert("RGB")
        conversation = [{"role": "user", "content": [
            {"type": "image"},
            {"type": "text", "text": "<chart2csv>"},
        ]}]
        text = processor.apply_chat_template(conversation, tokenize=False, add_generation_prompt=True)
        inputs = processor(text=text, images=image, return_tensors="pt").to(model.device)

        streamer = TextIteratorStreamer(
            processor.tokenizer, skip_prompt=True, skip_special_tokens=True,
        )
        generation_kwargs = {
            **inputs,
            "max_new_tokens": 4096,
            "use_cache": True,
            "streamer": streamer,
        }

        thread = threading.Thread(target=_run_generate, args=(model, generation_kwargs))
        thread.start()

        for token_text in streamer:
            if token_text:
                yield token_text

        thread.join()

    except Exception as e:  # noqa: BLE001
        import traceback

        traceback.print_exc()
        yield f"Error: {e!s}"