app.py

# app.py

import streamlit as st
import spacy
import subprocess
from neo4j import GraphDatabase
import matplotlib.pyplot as plt
import networkx as nx
from sklearn.feature_extraction.text import TfidfVectorizer

# === Ensure spaCy model is installed ===
def install_spacy_model():
    try:
        spacy.load("en_core_web_sm")
    except OSError:
        subprocess.run(["python", "-m", "spacy", "download", "en_core_web_sm"])
        spacy.load("en_core_web_sm")

install_spacy_model()

# Load spaCy model
nlp = spacy.load("en_core_web_sm")

# === Neo4j credentials ===
NEO4J_URI = "neo4j+s://ff701b1c.databases.neo4j.io"
NEO4J_USERNAME = "neo4j"
NEO4J_PASSWORD = "BfZM7YRKpFz1b_V7acAmOtaSQHPU9xK03rJlfPep88g"  

def get_neo4j_driver():
    try:
        driver = GraphDatabase.driver(NEO4J_URI, auth=(NEO4J_USERNAME, NEO4J_PASSWORD))
        return driver
    except Exception as e:
        st.error(f"Failed to connect to Neo4j: {e}")
        return None

# === TF-IDF Filtering (Optional for noise reduction) ===
def compute_tfidf_keywords(text: str, top_n=100):
    vectorizer = TfidfVectorizer(stop_words='english')
    X = vectorizer.fit_transform([text])
    scores = zip(vectorizer.get_feature_names_out(), X.toarray()[0])
    sorted_scores = sorted(scores, key=lambda x: x[1], reverse=True)
    return {word for word, _ in sorted_scores[:top_n]}

# === Triple Extraction ===
def extract_triples(text, use_tfidf=False):
    doc = nlp(text)
    tfidf_keywords = compute_tfidf_keywords(text) if use_tfidf else None
    triples = []

    for sent in doc.sents:
        subject = ""
        obj = ""
        verb = ""

        noun_chunks = list(sent.noun_chunks)
        root = [token for token in sent if token.dep_ == "ROOT"]
        if root:
            verb = root[0].lemma_

        for chunk in noun_chunks:
            if chunk.root.dep_ in ("nsubj", "nsubjpass") and not subject:
                subject = chunk.text
            elif chunk.root.dep_ in ("dobj", "pobj", "attr") and not obj:
                obj = chunk.text

        if subject and verb and obj:
            if tfidf_keywords:
                if subject.lower() in tfidf_keywords or obj.lower() in tfidf_keywords:
                    triples.append((subject.strip(), verb.strip(), obj.strip()))
            else:
                triples.append((subject.strip(), verb.strip(), obj.strip()))

    return triples

# === Visualization Function ===
def show_graph(triples):
    if not triples:
        st.warning("No triples found to visualize.")
        return

    G = nx.DiGraph()
    for s, p, o in triples:
        G.add_node(s)
        G.add_node(o)
        G.add_edge(s, o, label=p)

    pos = nx.spring_layout(G, seed=42)  # fixed layout
    plt.figure(figsize=(10, 8))
    nx.draw(G, pos, with_labels=True, node_color='skyblue', node_size=2000, font_size=10, edge_color='gray')
    nx.draw_networkx_edge_labels(G, pos, edge_labels={(u, v): d['label'] for u, v, d in G.edges(data=True)})
    st.pyplot(plt.gcf())
    plt.clf()

# === Streamlit UI ===
st.title("🧠 Knowledge Graph Generator")

text_input = st.text_area("Paste your text here:", height=200)
use_tfidf = st.checkbox("Use TF-IDF filtering (Optional: Recommended for large texts)")

if st.button("Generate Graph"):
    if text_input:
        all_triples = extract_triples(text_input, use_tfidf=use_tfidf)

        if all_triples:
            st.subheader("🔗 Extracted Triples:")
            for triple in all_triples:
                st.markdown(f"- **({triple[0]} → {triple[1]} → {triple[2]})**")

            show_graph(all_triples)
        else:
            st.warning("No valid triples could be extracted. Try different text.")
    else:
        st.warning("Please enter some text.")