//! Precomputed per-outcode and per-postcode-sector average crime rates.
//!
//! The right pane shows each crime metric's national average (the global
//! feature-histogram mean). To let users see how an area compares with its
//! immediate surroundings, we also precompute the mean headline crime rate
//! (`"X (avg/yr)"`) across every property in the selection's outcode (e.g.
//! `"E14"`) and postcode sector (e.g. `"E14 2"`).
//!
//! Crime figures are constant within a postcode (the pipeline merges them on
//! the postcode key), so each postcode's value is read once — from its first
//! row — and property-weighted by the postcode's row count. That keeps these
//! averages on the same property-weighted basis as the national average, so the
//! four numbers (this area / sector / outcode / nation) are directly comparable.

use rustc_hash::FxHashMap;

/// Crime-feature name suffix that marks an annualised headline-rate column
/// (e.g. `"Burglary (avg/yr)"`). Stripped to derive the bare type name.
pub const AVG_YR_SUFFIX: &str = " (avg/yr)";

pub struct AreaCrimeAverages {
    /// Bare crime-type names (suffix stripped, e.g. `"Burglary"`), index-aligned
    /// with the per-area mean vectors. Matches `CrimeYearStats.name`.
    pub crime_types: Vec<String>,
    /// National mean headline rate per crime type (index-aligned with
    /// `crime_types`). An EXACT property-weighted mean over every postcode, so it
    /// shares a basis with `by_outcode`/`by_sector` and the per-selection mean —
    /// unlike the histogram-bin national average, which is biased upward for the
    /// right-skewed crime densities. `NaN` where no postcode has data.
    pub national: Vec<f32>,
    /// Outcode (e.g. `"E14"`) → mean headline rate per crime type. `NaN` where
    /// the outcode has no data for that type.
    pub by_outcode: FxHashMap<String, Vec<f32>>,
    /// Postcode sector (e.g. `"E14 2"`) → mean headline rate per crime type.
    pub by_sector: FxHashMap<String, Vec<f32>>,
}

impl AreaCrimeAverages {
    pub fn empty() -> Self {
        Self {
            crime_types: Vec::new(),
            national: Vec::new(),
            by_outcode: FxHashMap::default(),
            by_sector: FxHashMap::default(),
        }
    }
}