/**
 * Per-viewer memory of the live wall's map view (server-26#234): the last
 * overlays, basemap and viewport this browser used. A convenience only —
 * every access is wrapped, and a blocked/empty store (private window, cleared
 * site data) simply yields {} so the wall falls back to its defaults.
 *
 * Precedence when the wall opens: URL hash > this store > defaults
 * (resolveWallView below). Nothing here is shared with other viewers.
 */
import {
  DEFAULT_BASE, DEFAULT_LAYERS, isBaseKey, normaliseLayers, parseViewport,
  type WallView,
} from "@/lib/liveWall";

const KEY = "drb.wall.view.v1";

export function loadWallPrefs(): WallView {
  try {
    const raw = window.localStorage.getItem(KEY);
    if (!raw) return {};
    const v: unknown = JSON.parse(raw);
    if (!v || typeof v !== "object") return {};
    const o = v as Record<string, unknown>;
    const out: WallView = {};
    if (Array.isArray(o.layers)) out.layers = normaliseLayers(o.layers.filter((x): x is string => typeof x === "string"));
    if (typeof o.base === "string" && isBaseKey(o.base)) out.base = o.base;
    const view = o.view && typeof o.view === "object" ? (o.view as Record<string, unknown>) : null;
    const vp = view ? parseViewport(view.z, view.lat, view.lon) : undefined;
    if (vp) out.view = vp;
    return out;
  } catch {
    return {};
  }
}

export function saveWallPrefs(v: WallView): void {
  try {
    window.localStorage.setItem(KEY, JSON.stringify({ layers: v.layers, base: v.base, view: v.view }));
  } catch {
    /* storage blocked or full — the URL hash still carries the view */
  }
}

/** Field-by-field: hash wins, then what this browser remembers, then defaults. */
export function resolveWallView(hash: WallView, stored: WallView): Required<Pick<WallView, "layers" | "base">> & Pick<WallView, "view"> {
  return {
    layers: hash.layers ?? stored.layers ?? DEFAULT_LAYERS,
    base: hash.base ?? stored.base ?? DEFAULT_BASE,
    view: hash.view ?? stored.view,
  };
}