import torch
from transformers import AutoModelForCausalLM, AutoProcessor, VisionEncoderDecoderModel
from huggingface_hub import snapshot_download
from qwen_vl_utils import process_vision_info

def load_model(model_name):
    """
    Load the specified model and its processor based on the model name.
    
    Args:
        model_name (str): Name of the model ("dots.ocr" or "Dolphin").
    
    Returns:
        tuple: (model, processor) for the specified model.
    """
    if model_name == "dots.ocr":
        model_id = "rednote-hilab/dots.ocr"
        model_path = "./models/dots-ocr-local"
        snapshot_download(
            repo_id=model_id,
            local_dir=model_path,
            local_dir_use_symlinks=False,
        )
        model = AutoModelForCausalLM.from_pretrained(
            model_path,
            attn_implementation="flash_attention_2",
            torch_dtype=torch.bfloat16,
            device_map="auto",
            trust_remote_code=True
        )
        processor = AutoProcessor.from_pretrained(model_path, trust_remote_code=True)
    elif model_name == "Dolphin":
        model_id = "ByteDance/Dolphin"
        processor = AutoProcessor.from_pretrained(model_id)
        model = VisionEncoderDecoderModel.from_pretrained(model_id)
        model.eval()
        device = "cuda" if torch.cuda.is_available() else "cpu"
        model.to(device)
        model = model.half()  # Use half precision
    else:
        raise ValueError(f"Unknown model: {model_name}")
    return model, processor

def inference_dots_ocr(model, processor, image, prompt, max_new_tokens):
    """
    Perform inference using the dots.ocr model.
    
    Args:
        model: The loaded dots.ocr model.
        processor: The corresponding processor.
        image (PIL.Image): Input image.
        prompt (str): Prompt for inference.
        max_new_tokens (int): Maximum number of tokens to generate.
    
    Returns:
        str: Generated text output.
    """
    messages = [
        {
            "role": "user",
            "content": [
                {"type": "image", "image": image},
                {"type": "text", "text": prompt}
            ]
        }
    ]
    text = processor.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
    image_inputs, video_inputs = process_vision_info(messages)
    inputs = processor(
        text=[text],
        images=image_inputs,
        videos=video_inputs,
        padding=True,
        return_tensors="pt",
    )
    inputs = inputs.to(model.device)
    with torch.no_grad():
        generated_ids = model.generate(
            **inputs,
            max_new_tokens=max_new_tokens,
            do_sample=False,
            temperature=0.1
        )
    generated_ids_trimmed = [out_ids[len(in_ids):] for in_ids, out_ids in zip(inputs.input_ids, generated_ids)]
    output_text = processor.batch_decode(
        generated_ids_trimmed,
        skip_special_tokens=True,
        clean_up_tokenization_spaces=False
    )
    return output_text[0] if output_text else ""

def inference_dolphin(model, processor, image):
    """
    Perform inference using the Dolphin model.
    
    Args:
        model: The loaded Dolphin model.
        processor: The corresponding processor.
        image (PIL.Image): Input image.
    
    Returns:
        str: Generated text output.
    """
    pixel_values = processor(image, return_tensors="pt").pixel_values.to(model.device).half()
    generated_ids = model.generate(pixel_values)
    generated_text = processor.tokenizer.batch_decode(generated_ids, skip_special_tokens=True)[0]
    return generated_text