src/app.py

import os
import logging
from dotenv import load_dotenv
import streamlit as st
from langchain_chroma import Chroma
from langchain_huggingface import HuggingFaceEmbeddings
from langchain_openai import ChatOpenAI

# Get a logger for this module
logger = logging.getLogger(__name__)

logger.info("Design Page...")
# -------------------------------
# PAGE CONFIG (MUST BE FIRST)
# -------------------------------
PORT = int(os.environ.get("PORT", 8501))

st.markdown("""
<style>
.main-title {
    font-size: 52px;
    font-weight: 800;
    text-align: center;
    color: #0B5ED7;
    margin-bottom: 5px;
}

.sub-title {
    font-size: 20px;
    text-align: center;
    color: #555555;
    margin-bottom: 30px;
}
</style>
""", unsafe_allow_html=True)

st.markdown(
    '<div class="main-title">💊 AI Medical Labelling System</div>',
    unsafe_allow_html=True
)

st.markdown(
    '<div class="sub-title">Simplifying FDA Drug Safety Information using Generative AI & RAG</div>',
    unsafe_allow_html=True
)

# -------------------------------
# CUSTOM CSS (FANCY DESIGN)
# -------------------------------
st.markdown("""
<style>
.main {
    background-color: #f7f9fc;
}

.big-title {
    font-size:40px;
    font-weight:700;
    color:#1f4e79;
}

.subtitle {
    font-size:18px;
    color:#555;
}

.result-card {
    background-color:white;
    padding:20px;
    border-radius:12px;
    box-shadow:0px 2px 10px rgba(0,0,0,0.08);
    margin-top:15px;
}
</style>
""", unsafe_allow_html=True)

# -------------------------------
# HEADER
# -------------------------------

st.divider()

# -------------------------------
# SIDEBAR CONTROLS
# -------------------------------
with st.sidebar:
    st.header("⚙️ Search Options")

    drug_name = st.text_input(
        "Drug Name",
        placeholder="PHENYTOIN SODIUM"
    )

    selected_results = st.radio(
        "Information Type",
        ["Side Effects", "Warnings", "Both"]
    )

    run_button = st.button("🔍 Generate Explanation")

# -------------------------------
# LOAD ENV + MODELS
# -------------------------------

logger.info("Loading HuggingFace embedding model...")

load_dotenv()

working_dir = os.path.dirname(os.path.abspath(__file__))

embeddings = HuggingFaceEmbeddings(
    model_name="sentence-transformers/all-MiniLM-L6-v2"
)

vectordb = Chroma(
    persist_directory=os.path.join(working_dir, "Chroma_db"),
    embedding_function=embeddings
)

logger.info("Calling OpenAI model gpt-4o-mini...")

llm = ChatOpenAI(
    model="gpt-4o-mini",
    temperature=0
)

# -------------------------------
# RAG FUNCTION
# -------------------------------
def generate_section(drug_name, section, rules):

    results = vectordb.get(
        where={
            "$and": [
                {"generic_name": drug_name},
                {"section": section}
            ]
        }
    )

    documents = results.get("documents", [])

    if not documents:
        st.warning(f"No data found for {section}")
        return

    context = "\n".join(set(documents))

    prompt = f"""
You are a medical assistant.

Rewrite the FDA drug information into simplified,
easy-to-understand language.

Rules:
{rules}

Drug: {drug_name}

FDA TEXT:
{context}
"""

    with st.spinner("🧠 AI is analysing FDA data..."):
        response = llm.invoke(prompt)

    st.markdown(
        f'<div class="result-card">{response.content}</div>',
        unsafe_allow_html=True
    )

logger.info("Configuring prompt..")
# -------------------------------
# RULES
# -------------------------------
SIDE_EFFECT_RULES = """
- Use simple English
- Bullet points (max 7)
- Group similar side effects
- Separate common vs serious
"""

WARNING_RULES = """
- Use simple English
- Bullet points (max 7)
- Group warnings clearly
"""

SECTION_MAP = {
    "Side Effects": [("adverse_reactions", SIDE_EFFECT_RULES)],
    "Warnings": [("warnings_and_cautions", WARNING_RULES)],
    "Both": [
        ("adverse_reactions", SIDE_EFFECT_RULES),
        ("warnings_and_cautions", WARNING_RULES),
    ],
}

# -------------------------------
# MAIN ACTION
# -------------------------------
if run_button and drug_name:

    st.subheader(f"Results for: {drug_name.upper()}")

    for section, rules in SECTION_MAP[selected_results]:
        generate_section(drug_name, section, rules)

elif run_button:
    st.warning("Please enter a drug name.")