export default class BoundingBox {
	x1: number = null;
	x2: number = null;
	y1: number = null;
	y2: number = null;

	/**
	 * QA_AT-11: round a GPS coordinate to 6 decimal places (~11 cm precision).
	 * Single source of truth for client-side coordinate rounding — shared by
	 * `GpsInput` (map right-click / typed-blur paths) and `GpsBoundingBoxInput`
	 * (typed-blur path) so a coordinate stored from ANY path is normalised to 6
	 * decimals IMMEDIATELY, not only at server persist time.
	 *
	 * Mirrors the server-side `GpsHelper.roundCoord` exactly (numeric rounding,
	 * not string truncation) — `null` / `undefined` pass through unchanged.
	 */
	static roundCoord(value: number | null | undefined): number | null {
		if (value == null) {
			return null;
		}

		return Math.round(value * 1e6) / 1e6;
	}

	/**
	 * QA_AT-8: build a ~3 km square bbox centred on a GPS point. Used by
	 * the Resort modal's auto-fill (and Reset-bbox-from-GPS button) plus
	 * the dummy-resort seed so both call sites stay in lock-step.
	 *
	 * - half-width = 0.042 longitude degrees (~3 km at SK/CZ latitudes)
	 * - half-height = 0.031 latitude degrees (~3.4 km)
	 */
	static fromGpsPoint(latitude: number, longitude: number): BoundingBox {
		const bbox = new BoundingBox();
		bbox.x1 = longitude - 0.042;
		bbox.x2 = longitude + 0.042;
		bbox.y1 = latitude - 0.031;
		bbox.y2 = latitude + 0.031;

		return bbox;
	}

	/**
	 * QA_AT-8: shared bbox save-time validation predicate used by every modal
	 * that surfaces a `GpsBoundingBoxInput` (Resort + Location today; future
	 * consumers go through the same helper). Returns the list of localised
	 * error strings the caller should render inline.
	 *
	 * Rules:
	 *   - all four corners must be set OR all four must be null (mixed →
	 *     `gpsBboxIncompleteError`).
	 *   - `x1 < x2` (west longitude < east longitude); otherwise
	 *     `gpsBboxWestEastError`.
	 *   - `y1 < y2` (south latitude < north latitude); otherwise
	 *     `gpsBboxSouthNorthError`.
	 *
	 * Callers pass the already-localised strings from their `resources` so the
	 * helper stays in `_common/` (no i18n coupling).
	 *
	 * Extracted from the previously-duplicated `validateBbox()` methods on
	 * `ResortManagementModal` + `LocationManagementModal` + the qa-at-8 spec
	 * mirror — per `feedback_no_parallel_code_path.md`.
	 */
	static validate(bbox: BoundingBox | null | undefined, resources: {
		gpsBboxIncompleteError: string;
		gpsBboxWestEastError: string;
		gpsBboxSouthNorthError: string;
	}): string[] {
		const errors: string[] = [];

		if (!bbox) {
			return errors;
		}

		const corners = [
			bbox.x1,
			bbox.x2,
			bbox.y1,
			bbox.y2,
		];
		const filled = corners.filter(v => v != null).length;

		if (filled > 0 && filled < 4) {
			errors.push(resources.gpsBboxIncompleteError);

			return errors;
		}

		if (filled === 0) {
			return errors;
		}

		if (bbox.x1 >= bbox.x2) {
			errors.push(resources.gpsBboxWestEastError);
		}

		if (bbox.y1 >= bbox.y2) {
			errors.push(resources.gpsBboxSouthNorthError);
		}

		return errors;
	}
}