/**
 * Diagnostic tile-border markers (the contract's additive `TileMarker`
 * presentation field) → the inline outline the renderer draws. Pure
 * decision logic — the .svelte tile components just apply the returned
 * style value.
 *
 * INLINE STYLES, deliberately: a marker value arrives in TREE DATA at
 * runtime, and Tailwind only generates classes it sees in source files — a
 * dynamic class from tree data would silently render nothing. An outline
 * (not a border) is used so the diagnostic draws WITHOUT changing any
 * tile's layout/size (4px solid, clearly visible).
 *
 * The outline is INSET (`outline-offset: -4px`) so it draws INSIDE the
 * tile's box: tiles span their containers edge-to-edge, so the default
 * (outside) outline overflows the visible area and is clipped away at the
 * screen edges. The views inside the tiles have no opaque full-bleed
 * background, so the inset ring stays on top of the tile's content.
 *
 * The marker is purely presentational: unknown/absent → no outline
 * (existing trees render exactly as before), and no other behavior is
 * attached to it anywhere in the renderer.
 */

import type { TileMarker } from "@dispatch/layout-contract";

/** The diagnostic outline style for a marker — `undefined` = draw nothing. */
export function markerOutline(marker: TileMarker | undefined): string | undefined {
  if (marker === "main") return "4px solid red";
  if (marker === "side") return "4px solid green";
  return undefined;
}

/** The inset that keeps the outline INSIDE the tile's box (see the header note). */
export const MARKER_OUTLINE_OFFSET = "-4px";

/**
 * The COMPLETE inline style for a marked element — outline + inset offset in
 * one declaration — or `undefined` when unmarked/unknown, so unmarked nodes
 * carry no outline CSS at all (existing trees render exactly as before).
 */
export function markerStyle(marker: TileMarker | undefined): string | undefined {
  const outline = markerOutline(marker);
  return outline === undefined
    ? undefined
    : `outline: ${outline}; outline-offset: ${MARKER_OUTLINE_OFFSET}`;
}