app.py

import torch
import gradio as gr
import faiss
import numpy as np

from transformers import AutoTokenizer, AutoModelForSeq2SeqLM
from sentence_transformers import SentenceTransformer

# Models
GEN_MODEL_NAME = "google/flan-t5-small"
EMB_MODEL_NAME = "sentence-transformers/all-MiniLM-L6-v2"

DEVICE = "cuda" if torch.cuda.is_available() else "cpu"

tokenizer = AutoTokenizer.from_pretrained(GEN_MODEL_NAME)
gen_model = AutoModelForSeq2SeqLM.from_pretrained(GEN_MODEL_NAME).to(DEVICE)
embedder = SentenceTransformer(EMB_MODEL_NAME, device=DEVICE)

DISCLAIMER = (
    "Disclaimer: This tool provides general health information only. "
    "It does not give medical advice, diagnosis, or prescriptions. "
    "Always speak to a qualified healthcare professional for personal medical concerns or emergencies."
)

health_facts =  [
    {
        "id": 1,
        "topic": "Hypertension",
        "text": (
            "Hypertension is a long-term condition in which the force of blood against the walls of the arteries is consistently too high. "
            "Over time, uncontrolled high blood pressure can damage blood vessels and organs such as the heart, brain, kidneys, and eyes, increasing the risk of heart disease and stroke. "
            "Many people with hypertension do not have obvious symptoms, which is why it is sometimes called a 'silent killer', so regular blood pressure checks are important. "
            "Lifestyle measures such as reducing salt intake, engaging in regular physical activity, managing stress, maintaining a healthy weight, and avoiding tobacco products play a major role in controlling blood pressure."
        )
    },
    {
        "id": 2,
        "topic": "Diabetes",
        "text": (
            "Type 2 diabetes is a chronic condition in which the body does not use insulin properly or does not produce enough insulin, leading to elevated blood sugar levels over time. "
            "If blood sugar remains high for many years, it can damage blood vessels and nerves, affecting the eyes, kidneys, heart, and feet. "
            "People with type 2 diabetes are encouraged to adopt habits such as eating balanced meals with controlled portions, staying physically active, and attending regular medical checkups to monitor blood sugar and related complications. "
            "Early detection, lifestyle changes, and appropriate medical follow-up can significantly reduce the risk of serious long-term problems."
        )
    },
    {
        "id": 3,
        "topic": "Pregnancy nutrition",
        "text": (
            "During pregnancy, good nutrition supports the health of both the mother and the developing baby. "
            "Balanced meals that include vegetables, fruits, whole grains, sources of protein, and healthy fats help supply essential vitamins and minerals. "
            "Nutrients such as folic acid and iron are especially important in pregnancy because they support the baby’s development and help prevent certain birth defects and anemia. "
            "Pregnant women are advised to avoid alcohol, smoking, and recreational drugs, and to discuss any supplements or herbal remedies with a qualified healthcare professional during antenatal visits."
        )
    },
    {
        "id": 4,
        "topic": "Vaccination",
        "text": (
            "Vaccination is a safe and effective way to train the immune system to recognize and fight specific infections without causing the actual disease. "
            "Many vaccines are given during childhood, but some are also recommended in adulthood, in pregnancy, and for people with certain health conditions. "
            "Keeping vaccination schedules up to date helps protect not only the individual but also the wider community by reducing the spread of infectious diseases. "
            "Delaying or skipping recommended vaccines can increase the risk of outbreaks and leave vulnerable groups, such as young children and older adults, unprotected."
        )
    },
    {
        "id": 5,
        "topic": "Common cold",
        "text": (
            "The common cold is usually a mild infection of the nose and throat caused by viruses, often leading to symptoms such as a runny nose, sore throat, sneezing, and mild cough. "
            "Most colds improve on their own within a week or two, and complications are uncommon in otherwise healthy people. "
            "Simple measures such as resting, drinking enough fluids, and using home remedies for comfort can help people feel better while the body fights the infection. "
            "Because the common cold is viral, antibiotics, which are designed to treat bacterial infections, do not cure it and are generally not needed."
        )
    },
    {
        "id": 6,
        "topic": "Asthma",
        "text": (
            "Asthma is a long-term condition in which the airways become inflamed and narrow, making it harder for air to move in and out of the lungs. "
            "People with asthma may experience episodes of wheezing, chest tightness, coughing, and shortness of breath, which can be mild or severe. "
            "Common triggers include dust, smoke, cold air, respiratory infections, strong smells, and sometimes exercise. "
            "Understanding personal triggers, avoiding them when possible, and following an asthma action plan from a healthcare professional helps reduce symptoms and improve quality of life."
        )
    },
    {
        "id": 7,
        "topic": "Malaria prevention",
        "text": (
            "Malaria is a potentially serious disease transmitted by the bite of infected Anopheles mosquitoes, and it is common in many tropical and subtropical regions. "
            "Early symptoms often include fever, chills, headache, and body pains, which can resemble other illnesses, so testing is important when malaria is suspected. "
            "Prevention strategies include sleeping under insecticide-treated mosquito nets, using protective clothing, and reducing mosquito breeding sites such as stagnant water around the home. "
            "Prompt testing and treatment when fever occurs in malaria-endemic areas help prevent severe illness and complications."
        )
    },
    {
        "id": 8,
        "topic": "Tuberculosis",
        "text": (
            "Tuberculosis (TB) is an infectious disease caused by bacteria that most often affect the lungs. "
            "It spreads through the air when a person with active TB in the lungs coughs, sneezes, or speaks, and someone nearby breathes in the droplets. "
            "Common symptoms include a persistent cough lasting more than a few weeks, chest pain, weight loss, night sweats, and fever. "
            "Early detection, adherence to the full course of treatment prescribed by a healthcare professional, and support from TB programs are important to cure the disease and reduce transmission."
        )
    },
    {
        "id": 9,
        "topic": "HIV basics",
        "text": (
            "HIV is a virus that weakens the immune system by attacking specific cells that help the body fight infections. "
            "Without proper treatment and care, ongoing damage to the immune system can eventually lead to AIDS, which is the advanced stage of HIV infection. "
            "HIV can be transmitted through unprotected sex, sharing needles or sharp instruments that break the skin, and from mother to child during pregnancy, birth, or breastfeeding without preventive measures. "
            "Regular HIV testing, safer sex practices, and access to appropriate medical care help people living with HIV maintain their health and reduce the risk of transmission to others."
        )
    },
    {
        "id": 10,
        "topic": "Mental health",
        "text": (
            "Mental health refers to a person’s emotional, psychological, and social well-being, influencing how they think, feel, and behave in daily life. "
            "Challenges such as prolonged sadness, strong anxiety, loss of interest in usual activities, difficulty concentrating, or major changes in sleep and appetite can signal a mental health concern. "
            "Life events, ongoing stress, physical illness, and social or economic pressures can all affect mental health. "
            "Talking to trusted people, seeking professional support, and reducing stigma around mental health conditions are important steps in promoting overall wellbeing."
        )
    },
    {
        "id": 11,
        "topic": "Healthy eating",
        "text": (
            "Healthy eating means choosing a variety of foods that provide the nutrients the body needs to function well and stay strong. "
            "Meals that include vegetables, fruits, whole grains, beans or lean animal proteins, and small amounts of healthy fats help support energy, growth, and disease prevention. "
            "Limiting foods and drinks that are very high in sugar, salt, and unhealthy fats can reduce the risk of conditions such as obesity, hypertension, and type 2 diabetes. "
            "Regular meal patterns, mindful portion sizes, and drinking enough safe water are also important parts of a healthy eating routine."
        )
    },
    {
        "id": 12,
        "topic": "Physical activity",
        "text": (
            "Physical activity includes any body movement that uses energy, from walking and household chores to structured exercise and sports. "
            "Regular movement helps maintain a healthy weight, supports heart and lung function, strengthens muscles and bones, and can improve mood and sleep quality. "
            "Even small amounts of daily activity are beneficial, especially for people who have been mostly inactive, and it can be built up gradually. "
            "Choosing activities that are enjoyable and suitable for a person’s age and health status makes it easier to stay active over the long term."
        )
    },
    {
        "id": 13,
        "topic": "Childhood fever",
        "text": (
            "Fever in children is usually a sign that the body is fighting an infection, which may be caused by viruses, bacteria, or other germs. "
            "Caregivers should pay attention to the child’s overall behavior, ability to drink fluids, and level of alertness, not just the temperature reading. "
            "Warning signs that require urgent medical attention include difficulty breathing, convulsions, persistent vomiting, inability to drink, unusual sleepiness, or a fever that lasts several days. "
            "Keeping the child comfortable, offering fluids, and seeking professional advice when worried helps ensure that serious conditions are not missed."
        )
    },
    {
        "id": 14,
        "topic": "Diarrhoea and dehydration",
        "text": (
            "Diarrhoea is the passing of loose or watery stools more often than usual and can be caused by infections, food-related issues, or other conditions. "
            "One of the main dangers of diarrhoea, especially in young children and older adults, is dehydration, which happens when the body loses too much water and salts. "
            "Signs of dehydration include dry mouth, reduced urination, unusual tiredness, dizziness, and in children, sunken eyes or a sunken soft spot on the head. "
            "Offering safe fluids, watching for warning signs, and seeking medical care when diarrhoea is severe, persistent, or accompanied by blood or high fever are important steps."
        )
    },
    {
        "id": 15,
        "topic": "Menstrual health",
        "text": (
            "Menstruation is a normal monthly process in people with a uterus, where the lining of the womb is shed if pregnancy has not occurred. "
            "Cycle length and flow can vary between individuals, but sudden major changes, very heavy bleeding, or severe pain may require medical evaluation. "
            "Using clean menstrual products, changing them regularly, and maintaining good personal hygiene help prevent irritation and infections. "
            "Open, accurate information about menstruation supports dignity, reduces shame, and enables people to manage their periods safely and confidently."
        )
    },
    {
        "id": 16,
        "topic": "Oral and dental hygiene",
        "text": (
            "Good oral hygiene helps keep the teeth, gums, and mouth healthy, which also supports overall wellbeing. "
            "Brushing teeth at least twice a day with a suitable toothbrush and fluoride toothpaste helps remove food particles and plaque, reducing the risk of tooth decay and gum disease. "
            "Cleaning between the teeth, limiting sugary snacks and drinks, and visiting a dental professional for regular checks are also important. "
            "Ignoring oral health problems can lead to pain, infection, tooth loss, and difficulties with eating and speaking."
        )
    },
    {
        "id": 17,
        "topic": "Smoking and health",
        "text": (
            "Smoking exposes the body to many harmful chemicals that damage the lungs, heart, and blood vessels, and it greatly increases the risk of several cancers. "
            "People who smoke are more likely to develop chronic respiratory diseases, heart disease, stroke, and complications from infections. "
            "Stopping smoking, even after many years, brings health benefits, such as improved breathing, circulation, and reduced risk of heart attack and some cancers over time. "
            "Support from healthcare professionals, support groups, and smoke-free environments can make it easier for people who smoke to reduce or quit."
        )
    },
    {
        "id": 18,
        "topic": "Alcohol and health",
        "text": (
            "Alcohol affects the brain, liver, heart, and many other organs, and drinking large amounts or drinking frequently can harm physical and mental health. "
            "Heavy or risky drinking is linked to liver disease, certain cancers, high blood pressure, injuries, violence, and relationship and work problems. "
            "Some people are more vulnerable to the effects of alcohol due to age, health conditions, pregnancy, or the medicines they take. "
            "Reducing alcohol intake, avoiding drinking in unsafe situations, and seeking help when alcohol use feels out of control can lower the risk of harm."
        )
    },
    {
        "id": 19,
        "topic": "Obesity and weight management",
        "text": (
            "Obesity refers to having excessive body fat that may affect health and is often related to an imbalance between energy taken in from food and energy used by the body. "
            "It increases the risk of several conditions, including type 2 diabetes, hypertension, heart disease, joint problems, and some cancers. "
            "Healthy weight management focuses on long-term habits, such as eating balanced meals, being physically active, getting enough sleep, and reducing long periods of sitting. "
            "Small, realistic changes maintained over time tend to be more sustainable than extreme short-term diets."
        )
    },
    {
        "id": 20,
        "topic": "Kidney health",
        "text": (
            "The kidneys are organs that filter waste products and excess fluid from the blood and help regulate blood pressure, mineral balance, and red blood cell production. "
            "Long-term uncontrolled hypertension, diabetes, repeated kidney infections, and some medications or toxins can gradually damage the kidneys. "
            "Early kidney problems often cause few or no symptoms, so regular checkups are important for people at higher risk. "
            "Protecting kidney health includes managing chronic conditions with professional guidance, staying hydrated with safe fluids, and avoiding unnecessary use of substances that can harm the kidneys."
        )
    },
]

corpus_texts = [item["text"] for item in health_facts]
corpus_embeddings = embedder.encode(corpus_texts, convert_to_numpy=True)

dimension = corpus_embeddings.shape[1]
index = faiss.IndexFlatL2(dimension)
index.add(corpus_embeddings)

unsafe_keywords = [
    "dose", "dosage", "mg", "milligram", "tablet", "capsule",
    "prescribe", "prescription", "how many times", "self medicate",
    "diagnose", "diagnosis"
]

def is_potentially_unsafe(question: str) -> bool:
    q_lower = question.lower()
    return any(keyword in q_lower for keyword in unsafe_keywords)

def retrieve_facts(query: str, k: int = 3):
    query_embedding = embedder.encode([query], convert_to_numpy=True)
    distances, indices = index.search(query_embedding, k)
    results = []
    for idx in indices[0]:
        results.append(health_facts[idx]["text"])
    return results

def generate_answer_from_context(question: str, contexts, max_tokens: int = 200) -> str:
    context_str = "\n\n".join(contexts)
    prompt = f"""
You are a healthcare information assistant. Use ONLY the information in the context below to answer the user's question in simple language.

Context:
{context_str}

Rules:
- Do not make a diagnosis.
- Do not give medication doses or prescriptions.
- Encourage the user to talk to a qualified healthcare professional for personal decisions.
- If the answer is not in the context, say you are not sure and ask them to speak to a professional.

Question: {question}

Answer:
"""
    inputs = tokenizer(
        prompt,
        return_tensors="pt",
        truncation=True,
        max_length=1024
    ).to(DEVICE)

    with torch.no_grad():
        outputs = gen_model.generate(
            **inputs,
            max_new_tokens=max_tokens,
            num_beams=4,
            early_stopping=True
        )

    answer = tokenizer.decode(outputs[0], skip_special_tokens=True)
    return answer.strip()

def health_qa_pipeline(question: str) -> str:
    question = question.strip()
    if len(question) == 0:
        return "Please type a question."

    if is_potentially_unsafe(question):
        safe_msg = (
            "I cannot provide medication doses, prescriptions, or make diagnoses. "
            "Please consult a qualified healthcare professional for that. "
            "I can help with general information only."
        )
        return f"{safe_msg}\n\n{DISCLAIMER}"

    contexts = retrieve_facts(question, k=3)
    answer = generate_answer_from_context(question, contexts)
    return f"{answer}\n\n{DISCLAIMER}"

def qa_interface(question: str) -> str:
    return health_qa_pipeline(question)

with gr.Blocks() as demo:
    gr.Markdown("# 🧠 Health Facts Q&A Bot (Educational Only)")
    gr.Markdown(
        "Ask general health questions covered by the internal facts. "
        "The bot uses retrieval augmented generation and will not give doses or diagnoses."
    )

    question_box = gr.Textbox(
        label="Your question",
        placeholder="e.g. How can I reduce my risk of hypertension?",
        lines=2
    )
    answer_box = gr.Textbox(
        label="Answer",
        lines=10
    )
    ask_button = gr.Button("Ask")

    ask_button.click(
        qa_interface,
        inputs=question_box,
        outputs=answer_box,
    )

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