import sys
import os

# Add the cloned nanoVLM directory to Python's system path
NANOVLM_REPO_PATH = "/app/nanoVLM"
if NANOVLM_REPO_PATH not in sys.path:
    sys.path.insert(0, NANOVLM_REPO_PATH)

import gradio as gr
from PIL import Image
import torch
from transformers import CLIPImageProcessor, GPT2TokenizerFast

try:
    from models.vision_language_model import VisionLanguageModel
    print("Successfully imported VisionLanguageModel from nanoVLM clone.")
except ImportError as e:
    print(f"Error importing VisionLanguageModel from nanoVLM clone: {e}.")
    VisionLanguageModel = None

device_choice = os.environ.get("DEVICE", "auto")
if device_choice == "auto":
    device = "cuda" if torch.cuda.is_available() else "cpu"
else:
    device = device_choice
print(f"Using device: {device}")

model_id_for_weights = "lusxvr/nanoVLM-222M"
image_processor_id = "openai/clip-vit-base-patch32"
tokenizer_id = "gpt2"

image_processor = None
tokenizer = None
model = None

if VisionLanguageModel:
    try:
        print(f"Attempting to load CLIPImageProcessor from: {image_processor_id}")
        image_processor = CLIPImageProcessor.from_pretrained(image_processor_id) # Removed trust_remote_code if not strictly needed by processor
        print("CLIPImageProcessor loaded.")
        
        print(f"Attempting to load GPT2TokenizerFast from: {tokenizer_id}")
        tokenizer = GPT2TokenizerFast.from_pretrained(tokenizer_id) # Removed trust_remote_code if not strictly needed by tokenizer
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token
            print("Set tokenizer pad_token to eos_token.")
        print("GPT2TokenizerFast loaded.")
        
        print(f"Attempting to load model weights from {model_id_for_weights} using VisionLanguageModel.from_pretrained")
        model = VisionLanguageModel.from_pretrained(model_id_for_weights).to(device)
        print("Model loaded successfully.")
        model.eval()

    except Exception as e:
        print(f"Error loading model or processor components: {e}")
        import traceback
        traceback.print_exc()
        image_processor = None; tokenizer = None; model = None
else:
    print("Custom VisionLanguageModel class not imported, cannot load model.")

def prepare_inputs(text_list, image_input, image_processor_instance, tokenizer_instance, device_to_use):
    if image_processor_instance is None or tokenizer_instance is None:
        raise ValueError("Image processor or tokenizer not initialized.")
    processed_image = image_processor_instance(images=image_input, return_tensors="pt").pixel_values.to(device_to_use)
    processed_text = tokenizer_instance(
        text=text_list, return_tensors="pt", padding=True, truncation=True, max_length=getattr(tokenizer_instance, 'model_max_length', 512)
    )
    input_ids = processed_text.input_ids.to(device_to_use)
    attention_mask = processed_text.attention_mask.to(device_to_use)
    return {"pixel_values": processed_image, "input_ids": input_ids, "attention_mask": attention_mask}

def generate_text_for_image(image_input, prompt_input):
    if model is None or image_processor is None or tokenizer is None:
        return "Error: Model or processor components not loaded correctly. Check logs."
    if image_input is None: return "Please upload an image."
    if not prompt_input: return "Please provide a prompt."

    try:
        if not isinstance(image_input, Image.Image):
            pil_image = Image.fromarray(image_input)
        else:
            pil_image = image_input
        if pil_image.mode != "RGB": pil_image = pil_image.convert("RGB")

        inputs = prepare_inputs(
            text_list=[prompt_input], image_input=pil_image,
            image_processor_instance=image_processor, tokenizer_instance=tokenizer, device_to_use=device
        )
        
        generated_ids = model.generate(
            pixel_values=inputs['pixel_values'], input_ids=inputs['input_ids'],
            attention_mask=inputs['attention_mask'], max_new_tokens=150, num_beams=3,
            no_repeat_ngram_size=2, early_stopping=True, pad_token_id=tokenizer.pad_token_id
        )
        
        generated_text_list = tokenizer.batch_decode(generated_ids, skip_special_tokens=True)
        generated_text = generated_text_list[0] if generated_text_list else ""

        if prompt_input and generated_text.startswith(prompt_input):
             cleaned_text = generated_text[len(prompt_input):].lstrip(" ,.:")
        else:
            cleaned_text = generated_text
        return cleaned_text.strip()
    except Exception as e:
        print(f"Error during generation: {e}")
        import traceback; traceback.print_exc()
        return f"An error occurred during text generation: {str(e)}"

description = "Interactive demo for lusxvr/nanoVLM-222M."
# example_image_url = "http://images.cocodataset.org/val2017/000000039769.jpg" # Not used for now

print("Defining Gradio interface...")
try:
    iface = gr.Interface(
        fn=generate_text_for_image,
        inputs=[
            gr.Image(type="pil", label="Upload Image"),
            gr.Textbox(label="Your Prompt/Question")
        ],
        outputs=gr.Textbox(label="Generated Text", show_copy_button=True),
        title="Interactive nanoVLM-222M Demo",
        description=description,
        # examples=[  # <<<< REMOVED EXAMPLES
        #     [example_image_url, "a photo of a"],
        #     [example_image_url, "Describe the image in detail."],
        # ],
        allow_flagging="never"
    )
    print("Gradio interface defined.")
except Exception as e:
    print(f"Error defining Gradio interface: {e}")
    import traceback; traceback.print_exc()
    iface = None


if __name__ == "__main__":
    if model is None or image_processor is None or tokenizer is None:
        print("CRITICAL: Model or processor components failed to load. Gradio might not work.")
    
    if iface is not None:
        print("Launching Gradio interface...")
        try:
            iface.launch(server_name="0.0.0.0", server_port=7860)
        except Exception as e:
            print(f"Error launching Gradio interface: {e}")
            import traceback; traceback.print_exc()
            # This is where the ValueError: When localhost is not accessible... usually comes from
            # if the underlying TypeError has already happened during iface setup.
    else:
        print("Gradio interface could not be defined due to earlier errors.")