app/components/event_input.py

"""Event input panel."""

from __future__ import annotations

from datetime import date

import streamlit as st

EUROPEAN_COUNTRIES = {
    "AUT": "Austria", "BEL": "Belgium", "BGR": "Bulgaria", "HRV": "Croatia",
    "CZE": "Czech Republic", "DNK": "Denmark", "EST": "Estonia", "FIN": "Finland",
    "FRA": "France", "DEU": "Germany", "GRC": "Greece", "HUN": "Hungary",
    "ISL": "Iceland", "IRL": "Ireland", "ITA": "Italy", "LVA": "Latvia",
    "LTU": "Lithuania", "NLD": "Netherlands", "NOR": "Norway", "POL": "Poland",
    "PRT": "Portugal", "ROU": "Romania", "SVK": "Slovakia", "SVN": "Slovenia",
    "ESP": "Spain", "SWE": "Sweden", "CHE": "Switzerland", "GBR": "United Kingdom",
    "SRB": "Serbia", "UKR": "Ukraine", "MDA": "Moldova", "BIH": "Bosnia and Herzegovina",
    "ALB": "Albania", "MKD": "North Macedonia", "MNE": "Montenegro",
}
COUNTRY_TO_ISO = {v: k for k, v in EUROPEAN_COUNTRIES.items()}


def render_event_input() -> dict | None:
    """Render the event input form. Returns input dict on submit."""
    country_names = sorted(EUROPEAN_COUNTRIES.values())
    country = st.selectbox(
        "Country",
        country_names,
        index=country_names.index("United Kingdom"),
    )
    iso = COUNTRY_TO_ISO.get(country, "GBR")

    location = st.text_input(
        "Region / Location",
        placeholder="e.g. Greater Manchester",
    )

    col_a, col_b = st.columns(2)
    with col_a:
        event_date = st.date_input("Event date", value=date.today())
    with col_b:
        severity = st.select_slider(
            "Severity",
            options=["low", "medium", "high", "critical"],
            value="high",
        )

    description = st.text_area(
        "Event description",
        placeholder=(
            "Cause, scale, affected area — e.g. heavy rain, river overflow, "
            "damaged embankments, affected population…"
        ),
        height=140,
    )

    submit = st.button(
        "Run Cascade Forecast  →",
        type="primary",
        use_container_width=True,
    )

    if submit:
        if not location or not description:
            st.warning("Location and description are both required.")
            return None
        return {
            "country": country,
            "iso": iso,
            "location": location,
            "date": str(event_date),
            "severity": severity,
            "description": description,
        }
    return None