from transformers import NougatProcessor, VisionEncoderDecoderModel
import gradio as gr
import torch
from PIL import Image
from pathlib import Path
from pdf2image import convert_from_path

# Load the model and processor
processor = NougatProcessor.from_pretrained("MohamedRashad/arabic-small-nougat")
model = VisionEncoderDecoderModel.from_pretrained("MohamedRashad/arabic-small-nougat")
device = "cuda" if torch.cuda.is_available() else "cpu"
model.to(device)

print(f"Using {device} device")
context_length = 2048

def extract_text_from_image(image):
    """
    Extract text from PIL image

    Args:
    image (PIL.Image): Input image

    Returns:
    str: Extracted text from the image
    """

    # prepare PDF image for the model
    pixel_values = processor(image, return_tensors="pt").pixel_values

    # generate transcription
    outputs = model.generate(
        pixel_values.to(device),
        min_length=1,
        max_new_tokens=context_length,
        bad_words_ids=[[processor.tokenizer.unk_token_id]],
    )
    page_sequence = processor.batch_decode(outputs, skip_special_tokens=True)[0]
    page_sequence = processor.post_process_generation(page_sequence, fix_markdown=False)
    return page_sequence

def extract_text_from_pdf(pdf_path, progress=gr.Progress()):
    """
    Extract text from PDF
    
    Args:
    pdf_path (str): Path to the PDF file
    progress (gr.Progress): Progress bar
    
    Returns:
    str: Extracted text from the PDF
    """
    
    progress(0, desc="Starting...")
    images = convert_from_path(pdf_path)
    texts = []
    for image in progress.tqdm(images):
        extracted_text = extract_text_from_image(image)
        texts.append(extracted_text)

    return "\n".join(texts)

model_description = """
This is a demo for the Arabic Small Nougat model. It is an end-to-end OCR model that can extract text from images and PDFs.

- The model is trained on the [Khatt dataset](https://huggingface.co/datasets/Fakhraddin/khatt) and custom made dataset.
- The model is a finetune of [facebook/nougat-small](https://huggingface.co/facebook/nougat-small) model.

**Note**: The model is a prototype in my book and may not work well on all types of images and PDFs. **Check the output carefully before using it for any serious work.**
"""

example_images = [Image.open(Path(__file__).parent / "book_page.jpeg")]

with gr.Blocks(title="Arabic Small Nougat") as demo:
    gr.HTML("<h1 style='text-align: center'>Arabic End-to-End Structured OCR for textbooks</h1>")
    gr.Markdown(model_description)

    with gr.Tab("Extract Text from Image"):
        with gr.Row():
            with gr.Column():
                input_image = gr.Image(label="Input Image", type="pil")
                image_submit_button = gr.Button(value="Submit", variant="primary")
            output = gr.Markdown(label="Output Markdown", rtl=True)    
        image_submit_button.click(extract_text_from_image, inputs=[input_image], outputs=output)
        gr.Examples(example_images, [input_image], output, extract_text_from_image, cache_examples=True)
    
    with gr.Tab("Extract Text from PDF"):
        with gr.Row():
            with gr.Column():
                pdf = gr.File(label="Input PDF", type="filepath")
                pdf_submit_button = gr.Button(value="Submit", variant="primary")
            output = gr.Markdown(label="Output Markdown", rtl=True)    
        pdf_submit_button.click(extract_text_from_pdf, inputs=[pdf], outputs=output)

demo.queue().launch(share=False)