"""Stress Tests tab — bank run sweep."""

import streamlit as st

from src.composed.simulator import scenario_bank_run
from dashboard.charts import fig_bank_run_sweep


def render():
    st.header("Stress Tests")

    config = st.session_state.get("myco_config")
    n_assets = config.n_reserve_assets if config else 3

    col1, col2 = st.columns(2)
    with col1:
        fractions_str = st.text_input(
            "Redemption fractions (comma-separated)",
            "0.02, 0.05, 0.10, 0.20",
        )
    with col2:
        initial_reserve = st.number_input(
            "Initial reserve ($)", 10_000, 1_000_000, 100_000, step=10_000,
        )

    st.caption(f"Using **{n_assets}** reserve assets from System Config.")

    if st.button("Run Stress Test", key="stress_run"):
        fractions = [float(f.strip()) for f in fractions_str.split(",")]
        results = {}

        progress = st.progress(0)
        for i, frac in enumerate(fractions):
            with st.spinner(f"Running {frac:.0%} redemption..."):
                results[frac] = scenario_bank_run(
                    initial_reserve=float(initial_reserve),
                    n_assets=n_assets,
                    redemption_fraction=frac,
                )
            progress.progress((i + 1) / len(fractions))

        st.session_state["stress_results"] = results

    if "stress_results" in st.session_state:
        results = st.session_state["stress_results"]

        # Summary table
        cols = st.columns(len(results))
        for i, (frac, result) in enumerate(results.items()):
            final_ratio = result.backing_ratio[-1]
            with cols[i]:
                st.metric(
                    f"{frac:.0%} Redemption",
                    f"Backing: {final_ratio:.4f}",
                    delta="Survived" if final_ratio > 0.5 else "Failed",
                    delta_color="normal" if final_ratio > 0.5 else "inverse",
                )

        st.plotly_chart(fig_bank_run_sweep(results), use_container_width=True)