app.py

from transformers import pipeline
import gradio as gr
import re

# ============ MODEL ============
MODEL_ID = "google/flan-t5-small"
simplifier = pipeline("text2text-generation", model=MODEL_ID)


# ============ HELPERS ============

def too_similar(src: str, out: str) -> bool:
    src_clean = src.lower().strip()
    out_clean = out.lower().strip()
    if out_clean.startswith(src_clean):
        return True
    if len(out_clean) < 40:
        return True
    src_words = set(src_clean.split())
    out_words = set(out_clean.split())
    if not src_words:
        return True
    overlap = len(src_words & out_words) / len(src_words)
    return overlap > 0.78


def fallback_explanation(text: str, lang: str = "en") -> str:
    txt = text.strip()

    if lang == "fr":
        return (
            "### 🗣️ Explication en français simple\n"
            f"- **Texte original :** {txt}\n"
            "- Ce texte contient une règle ou une obligation administrative/juridique.\n"
            "- Il faut bien vérifier qui doit faire quoi, dans quel délai, et quelles sont les conséquences.\n"
            "- Si le texte mentionne une *décision définitive*, cela signifie qu’on **ne peut plus la contester** après ce délai.\n"
            "\n**En résumé :** ce texte décrit ce qu’il faut faire et les conséquences si on ne le fait pas."
        )

    return (
        "### 🗣️ Explanation in simple English\n"
        f"- **Original clause:** {txt}\n"
        "- This text contains a rule or an obligation.\n"
        "- Check who must act, what must be done, and when.\n"
        "- If it says a decision becomes *final*, that means it **cannot be challenged later**.\n"
        "\n**In short:** this tells you what must be done and what happens if you don’t."
    )


# ============ MAIN FUNCTION ============

def simplify_legal(text, lang):
    text = (text or "").strip()
    if not text:
        return "Veuillez coller un texte juridique ou administratif." if lang == "fr" else "Please paste a legal or administrative text."

    if lang == "fr":
        prompt = f"""
Tu es un assistant juridique qui explique les textes administratifs ou juridiques en français simple.
Réécris, simplifie ET explique le texte suivant pour qu'une personne sans formation juridique puisse le comprendre.
Conserve les chiffres, les délais et les conditions importants.
Utilise des puces si utile.
Termine par une phrase commençant par "En résumé :"

Texte :
{text}

Explication en français simple :
"""
    else:
        prompt = f"""
You are a legal communication assistant.
Rewrite, simplify AND explain the following legal or administrative clause for a non-lawyer.
Keep all numbers, dates, deadlines, and conditions correct.
If there are legal or Latin terms, explain them briefly.
Use bullet points to make it readable.
End with a one-sentence summary starting with "In short:".

Clause:
{text}

Explanation in simple English:
"""

    result = simplifier(prompt, max_new_tokens=320, do_sample=False, temperature=0.0)[0]["generated_text"].strip()

    if too_similar(text, result):
        return fallback_explanation(text, lang)

    return result


# ============ INTERFACE ============

with gr.Blocks(
    title="Talk2Law — Legal Text Explainer",
    theme=gr.themes.Soft(primary_hue="indigo", secondary_hue="blue")
) as demo:

    # --- HEADER ---
    gr.HTML(
        """
        <div style="text-align: center; margin-bottom: 25px;">
            <h1 style="color:#283593; font-size: 2.2em;">⚖️ Talk2Law</h1>
            <h3 style="color:#455A64;">Explain complex legal texts in simple French or English</h3>
            <p style="color:#607D8B; font-size: 0.95em;">
                Paste a clause below — the app will simplify, reformulate, and explain it clearly.
            </p>
        </div>
        """
    )

    # --- INPUT AREA ---
    with gr.Row():
        with gr.Column(scale=1):
            lang = gr.Radio(
                ["English", "Français"],
                value="English",
                label="🌐 Language / Langue",
                interactive=True,
            )

            inp = gr.Textbox(
                lines=8,
                placeholder="Paste your legal or administrative text here...",
                label="📜 Legal / Administrative Text",
            )

            btn = gr.Button("🧩 Explain / Expliquer", variant="primary")
            clear_btn = gr.Button("🧹 Clear / Effacer")

            gr.Markdown("### 💡 Example Texts / Exemples")
            gr.Examples(
                examples=[
                    ["The appeal must be filed within thirty days from the notification of this decision; otherwise, the decision becomes final."],
                    ["This contract is concluded intuitu personae and may not be assigned without the other party’s prior written consent."],
                    ["Toute réclamation doit être introduite dans un délai de trente jours suivant la notification de la décision."],
                ],
                inputs=[inp]
            )

        with gr.Column(scale=1):
            out = gr.Markdown(label="✅ Explanation / Explication")

    # --- BUTTON ACTIONS ---
    btn.click(fn=simplify_legal, inputs=[inp, lang], outputs=out)
    clear_btn.click(fn=lambda: "", inputs=None, outputs=inp)

    # --- FOOTER ---
    gr.HTML(
        """
        <hr>
        <p style="text-align:center; color:gray; font-size:0.85em;">
            ⚠️ Talk2Law simplifies and explains texts for educational purposes only.<br>
            Cette application ne fournit pas de conseils juridiques.
        </p>
        """
    )

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