app.py

import gradio as gr
from transformers import pipeline
from sentence_transformers import SentenceTransformer
import pandas as pd
import numpy as np
import zipfile
import os
import torch

# -----------------------------
# Load Mistral pipeline
# -----------------------------
llm = pipeline(
    "text-generation",
    model="mistralai/Mistral-7B-Instruct-v0.2",
    torch_dtype=torch.float16,
    device_map="auto"
)

# -----------------------------
# Load SentenceTransformer embeddings
# -----------------------------
embedding_model = SentenceTransformer("nlpaueb/legal-bert-base-uncased")

# -----------------------------
# Extract Yukon ZIP
# -----------------------------
zip_path = "/app/yukon.zip"  # make sure you uploaded here
extract_folder = "/app/yukon_texts"

# Remove old folder if exists
if os.path.exists(extract_folder):
    import shutil
    shutil.rmtree(extract_folder)

with zipfile.ZipFile(zip_path, "r") as zip_ref:
    zip_ref.extractall(extract_folder)

# -----------------------------
# Parse TXT files and create dataframe
# -----------------------------
def parse_metadata_and_content(raw):
    metadata = {}
    content = raw

    for line in raw.split("\n"):
        if ":" in line:
            key, value = line.split(":", 1)
            metadata[key.strip().upper()] = value.strip()

    content_lines = [
        line for line in raw.split("\n") if not any(k in line.upper() for k in metadata.keys())
    ]
    content = "\n".join(content_lines)
    return metadata, content


documents = []

for root, dirs, files in os.walk(extract_folder):
    for filename in files:
        if filename.startswith("._"):
            continue
        if filename.endswith(".txt"):
            filepath = os.path.join(root, filename)
            with open(filepath, "r", encoding="latin-1") as f:
                raw = f.read()
            metadata, content = parse_metadata_and_content(raw)
            paragraphs = [p.strip() for p in content.split("\n\n") if p.strip()]
            for p in paragraphs:
                documents.append({
                    "source_title": metadata.get("SOURCE_TITLE", "Unknown"),
                    "province": metadata.get("PROVINCE", "Unknown"),
                    "last_updated": metadata.get("LAST_UPDATED", "Unknown"),
                    "url": metadata.get("URL", "N/A"),
                    "pdf_links": metadata.get("PDF_LINKS", ""),
                    "text": p
                })

texts = [d["text"] for d in documents]
embeddings = embedding_model.encode(texts).astype("float32")

df = pd.DataFrame(documents)
df["Embedding"] = list(embeddings)

print("Loaded documents:", len(df))

# -----------------------------
# Retrieval function
# -----------------------------
def retrieve_with_pandas(query, top_k=2):
    query_emb = embedding_model.encode([query])[0]
    df["Similarity"] = df["Embedding"].apply(
        lambda x: np.dot(query_emb, x) / (np.linalg.norm(query_emb) * np.linalg.norm(x))
    )
    return df.sort_values("Similarity", ascending=False).head(top_k)

# -----------------------------
# RAG generation
# -----------------------------
def generate_with_rag(query, top_k=2):
    top_docs = retrieve_with_pandas(query, top_k)
    context = " ".join(top_docs["text"].tolist())

    input_text = f"""
Use ONLY the following context to answer the question briefly (2–3 sentences).
Do NOT guess. Do NOT add external information.

Context:
{context}

Question: {query}
"""

    response = llm(input_text, max_new_tokens=150, num_return_sequences=1)[0]['generated_text']

    meta = []
    for _, row in top_docs.iterrows():
        meta.append(
            f"- Province: {row['province']}\n"
            f"  Source: {row['source_title']}\n"
            f"  Updated: {row['last_updated']}\n"
            f"  URL: {row['url']}\n"
        )
    metadata_block = "\n".join(meta)
    final = f"{response.strip()}\n\nSources Used:\n{metadata_block}"
    return final

# -----------------------------
# Gradio Chat
# -----------------------------
def respond(message, history):
    answer = generate_with_rag(message)
    history.append((message, answer))
    return history, history

with gr.Blocks() as demo:
    chatbot = gr.Chatbot()
    msg = gr.Textbox(label="Your question")
    msg.submit(respond, [msg, chatbot], [chatbot, chatbot])
    gr.Markdown("Ask questions about Yukon rental rules and landlord responsibilities.")

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