app.py

"""
Gradio Space for Human-AI Text Attribution (HATA) Model
Detects whether text is human-written or AI-generated
Supports multiple African languages
"""

import gradio as gr
import torch
from transformers import AutoTokenizer, AutoModelForSequenceClassification
import numpy as np

# Load model and tokenizer
MODEL_NAME = "msmaje/phdhatamodel"

print("Loading model...")
tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME)
model = AutoModelForSequenceClassification.from_pretrained(MODEL_NAME)
model.eval()
print("Model loaded successfully!")

# Language examples
EXAMPLES = [
    ["Ìwé yìí jẹ́ ìwé tó dára púpọ̀ fún àwọn akẹ́kọ̀ọ́.", "Yoruba"],
    ["Wannan littafi mai kyau ne ga ɗalibai.", "Hausa"],
    ["Akwụkwọ a dị mma maka ụmụ akwụkwọ.", "Igbo"],
    ["Dis book dey very good for students wey wan learn.", "Nigerian Pidgin"],
   
]

def classify_text(text, show_probabilities=True):
    """
    Classify text as human-written or AI-generated
    
    Args:
        text: Input text to classify
        show_probabilities: Whether to show probability scores
        
    Returns:
        Classification result with confidence scores
    """
    if not text or len(text.strip()) == 0:
        return "⚠️ Please enter some text to classify.", None
    
    # Tokenize
    inputs = tokenizer(
        text,
        return_tensors="pt",
        truncation=True,
        max_length=128,
        padding=True
    )
    
    # Get prediction
    with torch.no_grad():
        outputs = model(**inputs)
        probabilities = torch.nn.functional.softmax(outputs.logits, dim=-1)
        predicted_class = torch.argmax(probabilities, dim=-1).item()
        confidence = probabilities[0][predicted_class].item()
    
    # Labels
    labels = {0: "👤 Human-written", 1: "🤖 AI-generated"}
    
    # Create result text
    result = f"## Prediction: {labels[predicted_class]}\n"
    result += f"**Confidence:** {confidence:.2%}\n\n"
    
    # Add interpretation
    if confidence > 0.9:
        result += "✅ **High confidence** - The model is very certain about this prediction."
    elif confidence > 0.7:
        result += "⚠️ **Moderate confidence** - The model is fairly certain, but there's some uncertainty."
    else:
        result += "❓ **Low confidence** - The model is uncertain. The text may have mixed characteristics."
    
    # Probability chart data
    prob_data = {
        "Human-written": float(probabilities[0][0].item()),
        "AI-generated": float(probabilities[0][1].item())
    }
    
    if show_probabilities:
        return result, prob_data
    else:
        return result, None

def batch_classify(file):
    """
    Classify multiple texts from uploaded file
    """
    if file is None:
        return "⚠️ Please upload a text file."
    
    # Read file
    try:
        with open(file.name, 'r', encoding='utf-8') as f:
            texts = f.readlines()
    except Exception as e:
        return f"❌ Error reading file: {e}"
    
    # Process each text
    results = []
    for i, text in enumerate(texts, 1):
        text = text.strip()
        if not text:
            continue
            
        inputs = tokenizer(text, return_tensors="pt", truncation=True, max_length=128)
        
        with torch.no_grad():
            outputs = model(**inputs)
            probabilities = torch.nn.functional.softmax(outputs.logits, dim=-1)
            predicted_class = torch.argmax(probabilities, dim=-1).item()
            confidence = probabilities[0][predicted_class].item()
        
        label = "Human" if predicted_class == 0 else "AI"
        results.append(f"{i}. [{label} - {confidence:.2%}] {text[:100]}...")
    
    return "\n".join(results)

# Custom CSS
custom_css = """
#title {
    text-align: center;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 2.5em;
    font-weight: bold;
    margin-bottom: 0.5em;
}

#subtitle {
    text-align: center;
    color: #666;
    font-size: 1.2em;
    margin-bottom: 1em;
}

.output-box {
    border: 2px solid #667eea;
    border-radius: 10px;
    padding: 15px;
}

.gradio-container {
    max-width: 900px;
    margin: auto;
}
"""

# Create Gradio interface
with gr.Blocks(css=custom_css, theme=gr.themes.Soft()) as demo:
    
    # Header
    gr.Markdown("<h1 id='title'>🔍 Human vs AI Text Detector</h1>")
    gr.Markdown(
        "<p id='subtitle'>Detect whether text is human-written or AI-generated | "
        "Supports African Languages 🌍</p>"
    )
    
    # Main interface
    with gr.Tabs():
        # Tab 1: Single text classification
        with gr.Tab("📝 Single Text"):
            with gr.Row():
                with gr.Column(scale=2):
                    text_input = gr.Textbox(
                        label="Enter text to classify",
                        placeholder="Type or paste your text here...",
                        lines=6,
                        max_lines=10
                    )
                    
                    show_probs = gr.Checkbox(
                        label="Show probability distribution",
                        value=True
                    )
                    
                    with gr.Row():
                        classify_btn = gr.Button("🔍 Classify Text", variant="primary")
                        clear_btn = gr.ClearButton([text_input])
                
                with gr.Column(scale=2):
                    result_output = gr.Markdown(label="Result")
                    prob_plot = gr.BarPlot(
                        x="label",
                        y="probability",
                        title="Probability Distribution",
                        y_lim=[0, 1],
                        height=300,
                        visible=True
                    )
            
            # Examples
            gr.Markdown("### 📚 Try these examples:")
            gr.Examples(
                examples=EXAMPLES,
                inputs=[text_input],
                label="Example texts in different languages"
            )
            
            # Connect classification function
            classify_btn.click(
                fn=classify_text,
                inputs=[text_input, show_probs],
                outputs=[result_output, prob_plot]
            )
        
        # Tab 2: Batch classification
        with gr.Tab("📄 Batch Processing"):
            gr.Markdown("""
            ### Upload a text file for batch classification
            
            Upload a `.txt` file with one text sample per line. 
            The app will classify each line and show the results.
            """)
            
            with gr.Row():
                with gr.Column():
                    file_input = gr.File(
                        label="Upload text file (.txt)",
                        file_types=[".txt"]
                    )
                    batch_btn = gr.Button("🔍 Classify All", variant="primary")
                
                with gr.Column():
                    batch_output = gr.Textbox(
                        label="Batch Results",
                        lines=15,
                        max_lines=20
                    )
            
            batch_btn.click(
                fn=batch_classify,
                inputs=file_input,
                outputs=batch_output
            )
        
        # Tab 3: About
        with gr.Tab("ℹ️ About"):
            gr.Markdown("""
            # About This Model
            
            ## 🎯 Purpose
            This model detects whether text is **human-written** or **AI-generated**. 
            It has been specifically trained on African languages to ensure fair and 
            accurate detection across diverse linguistic contexts.
            
            ## 🌍 Supported Languages
            - **English**
            - **Yoruba** (yo)
            - **Hausa** (ha)
            - **Igbo** (ig)
            - **Swahili** (sw)
            - **Amharic** (am)
            - **Nigerian Pidgin** (pcm)
            
            ## 📊 Performance
            - **Accuracy:** 100%
            - **F1 Score:** 100%
            - **Fairness Metrics:** EOD = 0.0, AAOD = 0.0 (Perfect fairness)
            
            ## 🔬 Model Details
            - **Base Model:** [AfroXLMR-base](https://huggingface.co/davlan/afro-xlmr-base)
            - **Parameters:** ~270M (0.3B)
            - **Max Sequence Length:** 128 tokens
            - **Training Dataset:** PhD HATA African Dataset
            
            ## ⚖️ Fairness & Ethics
            This model has been trained with explicit fairness constraints to ensure:
            - Equal performance across all supported languages
            - No bias toward high-resource languages
            - Fair treatment of diverse linguistic communities
            
            ## ⚠️ Limitations
            - Performance may vary on languages outside the training distribution
            - AI detection capabilities are tied to the AI systems present in training data
            - Should be used as one component in content verification, not sole determinant
            - Text length and domain may affect accuracy
            
            ## 📚 Citation
            ```bibtex
            @misc{msmaje2025hata,
              author = {Maje, M.S.},
              title = {AfroXLMR for Human-AI Text Attribution},
              year = {2025},
              publisher = {HuggingFace},
              url = {https://huggingface.co/msmaje/phdhatamodel}
            }
            ```
            
            ## 🔗 Links
            - [Model on HuggingFace](https://huggingface.co/msmaje/phdhatamodel)
            - [Training Visualizations](https://huggingface.co/msmaje/phdhatamodel/tree/main/visualizations)
            - [Dataset](https://huggingface.co/datasets/msmaje/phd-hata-african-dataset)
            
            ## 👤 Contact
            For questions or feedback, please open an issue on the model repository.
            """)
    
    # Footer
    gr.Markdown("""
    ---
    <div style='text-align: center; color: #666; padding: 20px;'>
        <p>Built with 💜 for African Language NLP | Powered by AfroXLMR</p>
        <p>Model: <a href='https://huggingface.co/msmaje/phdhatamodel'>msmaje/phdhatamodel</a></p>
    </div>
    """)

# Launch
if __name__ == "__main__":
    demo.launch()