src/streamlit_app.py

import os
import math
import streamlit as st
import pandas as pd
from pathlib import Path
from dotenv import load_dotenv

load_dotenv()

st.set_page_config(page_title="GridCoin Calculator", layout="wide", page_icon="⚡")


st.markdown("""
<style>
    .stNumberInput, .stSelectbox, .stSlider {
        margin-bottom: -1rem;
    }
    div[data-testid="stVerticalBlock"] > div {
        gap: 0.5rem;
    }
    .stSubheader {
        margin-top: 0.5rem;
        margin-bottom: 0.5rem;
    }
</style>
""", unsafe_allow_html=True)

st.title("GridCoin — DER vs Non-DER Dashboard")


left_col, right_col = st.columns([1, 1])


with left_col:
    st.subheader("⚙️ System Configuration")
    
    c1, c2 = st.columns(2)
    with c1:
        owner = st.selectbox("Household type", ["DER Homeowner", "Non-DER Homeowner"])
        pv_kw = st.number_input("Solar size (kW)", 0.0, 50.0, 7.0, step=0.5)
        batt_kwh = st.number_input("Battery (kWh)", 0.0, 40.0, 0.0, step=0.5)
    with c2:
        annual_load = st.number_input("Annual use (kWh)", 500, 30000, 12000)
        retail_rate = st.number_input("Retail rate ($/kWh)", 0.01, 1.0, 0.13, format="%.3f")
        upfront = st.number_input("System cost ($)", 0, 100000, 25000)
    
    st.markdown("---")
    st.subheader("💰 Policy & GridCoin Settings")
    
    c3, c4 = st.columns(2)
    with c3:
        exp_actual = st.number_input("Export credit ($/kWh)", 0.0, 1.0, 0.075, format="%.3f")
        exp_evc = st.number_input("EVC Bonus ($/kWh)", 0.0, 1.0, 0.123, format="%.3f")
        grid_fee = st.number_input("Grid fee ($/kW-mo)", 0.0, 20.0, 4.0)
    with c4:
        peak_start = st.number_input("Peak start (hr)", 0, 23, 17)
        peak_end = st.number_input("Peak end (hr)", 0, 23, 21)
        coin_value = st.number_input("GridCoin value ($)", 0.0, 1.0, 0.05, format="%.3f")
    
    st.markdown("---")
    st.subheader("🔋 GridCoin Calculator")
    c5, c6 = st.columns(2)
    with c5:
        peak_fraction = st.slider("Peak export share", 0.0, 1.0, 0.30, 0.05)
    with c6:
        dr_kwh = st.number_input("DR savings (kWh)", 0.0, 5000.0, 0.0)


pv_yield = pv_kw * 1250
self_use_ratio = 0.65
self_used = pv_yield * self_use_ratio
exports = max(0, pv_yield - self_used - batt_kwh * 200)

peak_exports = exports * peak_fraction
coins_peak = peak_exports * 1.0
coins_dr = dr_kwh * 0.5
coins_total = coins_peak + coins_dr
coin_dollars = coins_total * coin_value

bill_nonder = annual_load * retail_rate
imports_der = max(0, annual_load - self_used)
exp_credit = exports * exp_actual
fee_der = grid_fee * pv_kw * 12
bill_der = imports_der * retail_rate + fee_der - exp_credit - coin_dollars

savings = max(0, bill_nonder - bill_der)
payback = upfront / savings if savings > 0 else math.inf


with right_col:
    st.subheader("📊 Results Dashboard")
    

    m1, m2 = st.columns(2)
    m1.metric("GridCoins Earned", f"{coins_total:,.1f}")
    m2.metric("GridCoin Value", f"${coin_dollars:,.2f}")
    
    st.markdown("---")
    

    st.markdown("### 💵 Annual Bill Comparison")
    b1, b2, b3 = st.columns(3)
    b1.metric("Non-DER Bill", f"${bill_nonder:,.0f}")
    b2.metric("DER Bill", f"${bill_der:,.0f}", delta=f"${bill_der-bill_nonder:,.0f}")
    b3.metric("Payback Period", f"{payback:.1f} yrs" if payback != math.inf else "N/A")