import numpy as np
import torch
from torch import nn
import streamlit as st
import os

from PIL import Image
from io import BytesIO
from transformers import VisionEncoderDecoderModel, VisionEncoderDecoderConfig, DonutProcessor, DonutImageProcessor, AutoTokenizer

def run_prediction(sample, model, processor):

    pixel_values = processor(np.array(
                    sample,
                    np.float32,
                ), return_tensors="pt").pixel_values

    with torch.no_grad():
        outputs = model.generate(
            pixel_values.to(device),
            decoder_input_ids=processor.tokenizer("<s><s_plain>", add_special_tokens=False, return_tensors="pt").input_ids.to(device),
            do_sample=True,
            top_p=0.92,
            top_k=5,
            no_repeat_ngram_size=10,
            num_beams=3
        )

    # process output
    prediction = processor.batch_decode(outputs)[0]
    print(prediction)
    
    return prediction
    

logo = Image.open("./rsz_unstructured_logo.png")
st.image(logo)

st.markdown('''
### Chipper
Chipper is an OCR-free Document Understanding Transformer. It was pre-trained with over 1M documents from public sources and fine-tuned on a large range of documents. 

At [Unstructured.io](https://github.com/Unstructured-IO/unstructured) we are on a mission to build custom preprocessing pipelines for labeling, training, or production ML-ready pipelines. 
Come and join us in our public repos and contribute! Each of your contributions and feedback holds great value and is very significant to the community.
''')

image_upload = None
photo = None
with st.sidebar:
    # file upload
    uploaded_file = st.file_uploader("Upload a document")
    if uploaded_file is not None:
        # To read file as bytes:
        image_bytes_data = uploaded_file.getvalue()
        image_upload = Image.open(BytesIO(image_bytes_data)) 

if image_upload:
    image = image_upload
else:
    image = Image.open(f"./document.png")

st.image(image, caption='Your target document')

with st.spinner(f'Processing the document ...'):
        pre_trained_model = "unstructuredio/chipper-fast-fine-tuning"
        processor = DonutProcessor.from_pretrained(pre_trained_model)
        model = VisionEncoderDecoderModel.from_pretrained(pre_trained_model)

        from huggingface_hub import hf_hub_download

        lm_head_file = hf_hub_download(
            repo_id=pre_trained_model, filename="lm_head.pth"
        )

        rank = 128
        model.decoder.lm_head = nn.Sequential(
            nn.Linear(model.decoder.lm_head.weight.shape[1], rank, bias=False),
            nn.Linear(rank, rank, bias=False),
            nn.Linear(rank, model.decoder.lm_head.weight.shape[0], bias=True),
        )

        model.decoder.lm_head.load_state_dict(torch.load(lm_head_file))

        device = "cuda" if torch.cuda.is_available() else "cpu"

        model.eval()
        model.to(device)

st.info(f'Parsing document')
parsed_info = run_prediction(image.convert("RGB"), model, processor)
st.text(f'\nDocument:')
st.text_area('Output text', value=parsed_info, height=800)