wrongmove/frontend/src/utils/format.ts

/**
 * Shared formatting utility functions.
 *
 * Consolidates duplicated formatters that were previously defined inline in
 * PropertyCard, ListingDetail, MobileBottomSheet, and StatsBar.
 */

/** Em-dash placeholder used at render boundaries for missing/invalid values. */
export const EM_DASH = '—';

/** Returns true when v is a finite number — i.e. safe to render directly. */
export function isFiniteNumber(v: unknown): v is number {
    return typeof v === 'number' && Number.isFinite(v);
}

/**
 * Format an integer GBP price with thousands separators, e.g. "£2,500".
 * Returns the em-dash sentinel for null / undefined / non-finite inputs.
 * Use at the JSX leaf to distinguish "missing data" from "£0".
 */
export function formatPrice(value: number | null | undefined): string {
    if (!isFiniteNumber(value)) return EM_DASH;
    return `£${Math.round(value).toLocaleString()}`;
}

/**
 * Format a price-per-square-metre integer, e.g. "£42/m²".
 * Returns the em-dash sentinel for null / undefined / non-finite / zero / negative inputs.
 * (Zero / negative qmprice values come from missing-data rows, not real listings.)
 */
export function formatPricePerSqmShort(value: number | null | undefined): string {
    if (!isFiniteNumber(value) || value <= 0) return EM_DASH;
    return `£${Math.round(value)}/m²`;
}

/**
 * Format an integer count (bedrooms, square metres, etc).
 * Returns the em-dash sentinel for null / undefined / non-finite inputs.
 */
export function formatInteger(value: number | null | undefined): string {
    if (!isFiniteNumber(value)) return EM_DASH;
    return `${Math.round(value)}`;
}

/** Format a number as a compact GBP string, e.g. "£1.2k" or "£950". */
export function formatCurrency(value: number): string {
    if (value >= 1000) return `£${(value / 1000).toFixed(1)}k`;
    return `£${Math.round(value)}`;
}

/**
 * Format a duration in seconds as a human-readable string, e.g. "12m" or "1h30m".
 *
 * Returns the em-dash sentinel for non-finite or negative inputs (null, NaN, -120…).
 * Caps absurdly large values (> 24h) as ">24h" to avoid rendering nonsense like
 * "8760h" when a backend bug produces year-scale values.
 */
export function formatDuration(seconds: number | null | undefined): string {
    if (typeof seconds !== 'number' || !Number.isFinite(seconds) || seconds < 0) {
        return EM_DASH;
    }
    // Cap at 24 hours — beyond this it's almost certainly bad data.
    if (seconds > 24 * 3600) return '>24h';
    const minutes = Math.round(seconds / 60);
    if (minutes < 60) return `${minutes}m`;
    const hours = Math.floor(minutes / 60);
    const mins = minutes % 60;
    return mins > 0 ? `${hours}h${mins}m` : `${hours}h`;
}

/** Format an ISO date string as a localised short date (e.g. "3 Jan 2025"). */
export function formatDate(value: string): string {
    const date = new Date(value);
    if (isNaN(date.getTime())) return value;
    return date.toLocaleDateString('en-GB', { day: 'numeric', month: 'short', year: 'numeric' });
}

/**
 * Compute the price per square metre as a formatted string, e.g. "£4,500/m²".
 * Returns null when square metres data is unavailable.
 */
export function formatPricePerSqm(price: number, sqm: number | null | undefined): string | null {
    if (sqm == null || sqm <= 0) return null;
    return `£${Math.round(price / sqm).toLocaleString()}/m²`;
}