import streamlit as st
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM
import torch

# -------------------------
# PAGE CONFIG
# -------------------------
st.set_page_config(page_title="FitPlan-AI", page_icon="💪")

st.title("💪 FitPlan-AI: Personalized Fitness Profile")

# -------------------------
# BMI FUNCTIONS
# -------------------------
def calculate_bmi(weight, height_cm):
    height_m = height_cm / 100
    return round(weight / (height_m ** 2), 2)

def get_category(bmi):
    if bmi < 18.5:
        return "Underweight"
    elif bmi < 24.9:
        return "Normal"
    elif bmi < 29.9:
        return "Overweight"
    else:
        return "Obese"

# -------------------------
# LOAD MODEL
# -------------------------
@st.cache_resource
def load_model():
    tokenizer = AutoTokenizer.from_pretrained("google/flan-t5-base")
    model = AutoModelForSeq2SeqLM.from_pretrained("google/flan-t5-base")
    return tokenizer, model

tokenizer, model = load_model()

# -------------------------
# FORM
# -------------------------
with st.form("fitness_form"):

    st.subheader("Personal Information")

    name = st.text_input("Full Name*", placeholder="Enter your name")

    col1, col2 = st.columns(2)
    with col1:
        height = st.number_input("Height (cm)*", min_value=1.0, step=0.1)
    with col2:
        weight = st.number_input("Weight (kg)*", min_value=1.0, step=0.1)

    st.subheader("Fitness Details")

    goal = st.selectbox(
        "Fitness Goal",
        ["Build Muscle", "Weight Loss", "Strength Gain", "Abs Building", "Flexibility"]
    )

    level = st.radio(
        "Fitness Level",
        ["Beginner", "Intermediate", "Advanced"]
    )

    equipment = st.multiselect(
        "Available Equipment",
        ["Dumbbells", "Resistance Band", "Yoga Mat", "No Equipment", 
         "Kettlebell", "Pull-up Bar"]
    )

    submit = st.form_submit_button("Submit Profile")

# -------------------------
# HANDLE SUBMISSION
# -------------------------
if submit:

    if not name:
        st.error("Please enter your name.")

    elif height <= 0 or weight <= 0:
        st.error("Please enter valid height and weight.")

    elif not equipment:
        st.error("Please select at least one equipment option.")

    else:
        st.success("Profile Submitted Successfully!")

        # Calculate BMI
        bmi = calculate_bmi(weight, height)
        bmi_status = get_category(bmi)

        st.write(f"### 📊 Your BMI: {bmi} ({bmi_status})")

        # -------------------------
        # GENERATE 5-DAY PLAN (SINGLE PROMPT METHOD)
        # -------------------------
        from prompt_builder import build_prompt

        with st.spinner("Generating your 5-day workout plan..."):

            prompt, bmi, bmi_status = build_prompt(
                name=name,
                gender="Not specified",  # You can add gender field later
                height=height,
                weight=weight,
                goal=goal,
                fitness_level=level,
                equipment=equipment
            )

            inputs = tokenizer(prompt, return_tensors="pt", truncation=True)

            outputs = model.generate(
                **inputs,
                max_new_tokens=2000,
                temperature=0.7,
                do_sample=True,
                repetition_penalty=1.1
            )

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

        # -------------------------
        # DISPLAY PLAN
        # -------------------------
        st.subheader("🏋️ Your Personalized 5-Day Workout Plan")
        st.write(full_plan)