"""Financial summary dashboard tab."""

from __future__ import annotations

import streamlit as st

from app.components import charts
from app.pages._helpers import report_meta, safe
from core.export import build_report_data
from core.tei_client import AthenaAPIError, TEIClient


def render(client: TEIClient, tool: dict) -> None:
    st.header("📊 Financial Summary")
    public_id = tool["id"]
    report = report_meta(client, tool)

    try:
        summary = client.get_summary(public_id)
    except AthenaAPIError as e:
        if e.status_code == 404:
            st.info(
                "No summary yet — click **Recalculate** in the sidebar after "
                "filling in benefits and costs."
            )
            return
        st.error(f"Athena API error: {e.detail}")
        return

    npv = float(summary.get("net_present_value") or summary.get("npv") or 0)
    roi = float(
        summary.get("roi_percentage")
        or summary.get("roi")
        or summary.get("roi_pct")
        or 0
    )
    payback = summary.get("payback_period_months", summary.get("payback_months"))
    bpv = float(summary.get("total_benefits_pv") or 0)
    cpv = float(summary.get("total_costs_pv") or 0)

    cols = st.columns(5)
    cols[0].metric("NPV", f"${npv/1_000_000:,.1f}M")
    cols[1].metric("ROI", f"{roi:,.0f}%")
    cols[2].metric(
        "Payback",
        f"{float(payback):.1f} months" if payback is not None else "N/A",
    )
    cols[3].metric("Benefits PV", f"${bpv/1_000_000:,.1f}M")
    cols[4].metric("Costs PV", f"${cpv/1_000_000:,.1f}M")

    st.divider()

    # Build the yearly breakdown from the documented per-year summary keys
    # (benefits_year_N / costs_year_N) when no pre-built breakdown exists.
    yb = summary.get("yearly_breakdown") or []
    if not yb:
        n = 1
        while f"benefits_year_{n}" in summary or f"costs_year_{n}" in summary:
            b = float(summary.get(f"benefits_year_{n}") or 0)
            c = float(summary.get(f"costs_year_{n}") or 0)
            yb.append({"year": n, "benefits": b, "costs": c, "net": b - c})
            n += 1
    initial = float(summary.get("initial_costs") or 0)
    if yb:
        charts.cashflow(yb, initial_cost=initial)
        with st.expander("Cash flow table"):
            st.dataframe(yb, use_container_width=True, hide_index=True)
    else:
        st.caption("No yearly breakdown in this summary.")

    # Scenario comparison — computed locally from current values
    with st.expander("Scenario analysis (conservative / moderate / aggressive)"):
        envelope = safe(
            build_report_data,
            client,
            public_id,
            include_scenarios=True,
            study_slug=report.get("name", ""),
        )
        if envelope and envelope.get("scenarios"):
            charts.scenario_bars(envelope["scenarios"])
            rows = [
                {
                    "Scenario": k,
                    "Benefits PV": float(v.get("total_benefits_pv") or 0),
                    "Costs PV": float(v.get("total_costs_pv") or 0),
                    "NPV": float(v.get("npv") or 0),
                    "ROI %": float(v.get("roi_pct") or 0),
                    "Payback (months)": (
                        round(float(v.get("payback_months") or 0), 1)
                        if v.get("payback_months") is not None
                        else None
                    ),
                }
                for k, v in envelope["scenarios"].items()
            ]
            st.dataframe(rows, use_container_width=True, hide_index=True)

    # Export button
    st.divider()
    if st.button("📦 Build export envelope (JSON)"):
        envelope = safe(
            build_report_data,
            client,
            public_id,
            include_scenarios=True,
            study_slug=report.get("name", ""),
        )
        if envelope:
            import json

            data = json.dumps(envelope, indent=2, default=str)
            st.download_button(
                "Download export.json",
                data=data,
                file_name=f"{public_id}_export.json",
                mime="application/json",
            )