app.py

import json
import random
from pathlib import Path
import gradio as gr
import numpy as np
from transformers import AutoTokenizer, AutoModelForSequenceClassification, pipeline

# Constants
MIN_WORDS = 50
MAX_WORDS = 500
SAMPLE_JSON_PATH = Path('samples.json')

# Load models
def load_model(model_name):
    tokenizer = AutoTokenizer.from_pretrained(model_name)
    model = AutoModelForSequenceClassification.from_pretrained(model_name)
    return pipeline('text-classification', model=model, tokenizer=tokenizer, truncation=True, max_length=512, top_k=4)

classifier = load_model("./fine_tuned_roberta-base")

# Load sample essays
with open(SAMPLE_JSON_PATH, 'r') as f:
    demo_essays = json.load(f)

# Global variable to store the current essay index
current_essay_index = None

TEXT_CLASS_MAPPING = {
    'LABEL_2': 'Machine-Generated',
    'LABEL_0': 'Human-Written',
    'LABEL_3': 'Machine-Written, Machine-Humanized',
    'LABEL_1': 'Human-Written, Machine-Polished'
}

def process_result_detection_tab(text): 

    result = classifier(text)[0]

    labels = [TEXT_CLASS_MAPPING[x['label']] for x in result]
    scores = list(np.array([x['score'] for x in result]))

    final_results = dict(zip(labels, scores))

    # Return only the label with the highest score
    return max(final_results, key=final_results.get)

def update_detection_tab(name):
    if name == '':
        return "" 
    return process_result_detection_tab(name)
   
def active_button_detection_tab(input_text):
    if not (50 <= len(input_text.split()) <= 500):
        return gr.Button("Check Origin", variant="primary", interactive=False) 
    return gr.Button("Check Origin", variant="primary", interactive=True)

def clear_detection_tab():
    return "", gr.Button("Check Origin", variant="primary", interactive=False)

def count_words_detection_tab(text): 
    return f'{len(text.split())}/500 words (Minimum 50 words)'

def generate_text_challenge_tab(): 
    global index

    mg = gr.Button("Machine-Generated", variant="secondary", interactive=True)
    hw = gr.Button("Human-Written", variant="secondary", interactive=True)
    mh = gr.Button("Machine-Humanized", variant="secondary", interactive=True)    
    mp = gr.Button("Machine-Polished", variant="secondary", interactive=True)

    index = random.choice(range(80))
    essay = demo_essays[index][0]
    return essay, mg, hw, mh, mp, '' 

def correct_label_challenge_tab(): 
    if 0 <= index < 20 : 
        return 'Human-Written'
    elif 20 <= index < 40:
        return 'Machine-Generated'
    elif 40 <= index < 60:
        return 'Machine-Polished'
    elif 60 <= index < 80:
        return 'Machine-Humanized'
        
def show_result_challenge_tab(button): 
    correct_btn = correct_label_challenge_tab() 
    mg = gr.Button("Machine-Generated", variant="secondary")
    hw = gr.Button("Human-Written", variant="secondary")
    mh = gr.Button("Machine-Humanized", variant="secondary")
    mp = gr.Button("Machine-Polished", variant="secondary")
    
    if button == 'Machine-Generated':
        mg = gr.Button("Machine-Generated", variant="stop")
    elif button == 'Human-Written':
        hw = gr.Button("Human-Written", variant="stop")
    elif button == 'Machine-Humanized':
        mh = gr.Button("Machine-Humanized", variant="stop")
    elif button == 'Machine-Polished':
        mp = gr.Button("Machine-Polished", variant="stop")

    if correct_btn == 'Machine-Generated':
        mg = gr.Button("Machine-Generated", variant="primary")
    elif correct_btn == 'Human-Written':
        hw = gr.Button("Human-Written", variant="primary")
    elif correct_btn == 'Machine-Humanized':
        mh = gr.Button("Machine-Humanized", variant="primary")  
    elif correct_btn == 'Machine-Polished':
        mp = gr.Button("Machine-Polished", variant="primary")

    outcome = 'Correct' if button == correct_btn else 'Incorrect'

    return outcome, mg, hw, mh, mp

css = """
body, .gradio-container {
    font-family: Arial, sans-serif;
}

.gr-input, .gr-textarea {
}

.class-intro {
    padding: 15px;
    margin-bottom: 20px;
    border-radius: 5px;
}
.class-intro h2 {
    margin-top: 0;
}
.class-intro p {
    margin-bottom: 5px;
}
"""

class_intro_html = """
<div class="class-intro">
    <h2>Text Classes</h2>
    <p><strong>Human-Written:</strong> Original text created by humans.</p>
    <p><strong>Machine-Generated:</strong> Text created by AI from basic prompts, without style instructions.</p>
    <p><strong>Human-Written, Machine-Polished:</strong> Human text refined by AI for grammar and flow, without new content.</p>
    <p><strong>Machine-Written, Machine-Humanized:</strong> AI-generated text modified to mimic human writing style.</p>
</div>
"""

with gr.Blocks(css=css) as demo:
    gr.Markdown("""<h1><centre>LLM-DetectAIve</center></h1>""")
    with gr.Tab('Try it!'): 
        gr.HTML(class_intro_html)
        
        with gr.Row():
            input_text = gr.Textbox(placeholder="Paste your text here...", label="Text", lines=10, max_lines=15)

        with gr.Row(): 
            wc = gr.Markdown("0/500 words (Minimum 50 words)")
        with gr.Row():
            check_button = gr.Button("Check Origin", variant="primary", interactive=False)
            clear_button = gr.ClearButton([input_text], variant="stop")
        
        out = gr.Label(label='Result')
        clear_button.add(out)
        
        check_button.click(fn=update_detection_tab, inputs=[input_text], outputs=out)

        input_text.change(count_words_detection_tab, input_text, wc, show_progress=False)
        input_text.input(
            active_button_detection_tab,
            [input_text],
            [check_button],
        )

        clear_button.click(
            clear_detection_tab,
            inputs=[],
            outputs=[input_text, check_button],
        )

    with gr.Tab('Challenge Yourself!'): 
        with gr.Row(): 
            generate = gr.Button("Generate Sample Text", variant="primary")
            clear = gr.ClearButton([], variant="stop")

        with gr.Row(): 
            text = gr.Textbox(value="", label="Text", lines=20, interactive=False)
        
        with gr.Row():
            mg = gr.Button("Machine-Generated", variant="secondary", interactive=False)
            hw = gr.Button("Human-Written", variant="secondary", interactive=False)
            mh = gr.Button("Machine-Humanized", variant="secondary", interactive=False)    
            mp = gr.Button("Machine-Polished", variant="secondary", interactive=False)

        with gr.Row(): 
            result = gr.Label(label="Result", value="") 

        clear.add([result, text])
        generate.click(generate_text_challenge_tab, [], [text, mg, hw, mh, mp, result])
        for button in [mg, hw, mh, mp]: 
            button.click(show_result_challenge_tab, [button], [result, mg, hw, mh, mp])

        clear.click(lambda: ("", 
                             gr.Button("Machine-Generated", variant="secondary", interactive=False),
                             gr.Button("Human-Written", variant="secondary", interactive=False),
                             gr.Button("Machine-Humanized", variant="secondary", interactive=False),
                             gr.Button("Machine-Polished", variant="secondary", interactive=False),
                             ""), 
                    outputs=[text, mg, hw, mh, mp, result])

demo.launch(share=False)