import type { MarginPreset, PageId } from "../engine/geometry";

/** Page and template choices frozen with an invoice at issue (stored as JSON). */
export interface RenderPrefsV1 {
  version: 1;
  templateId: string;
  pageSize: PageId;
  margins: MarginPreset;
  logo?: {
    /** The logo already contains the business name, so a template drops its own name lockup. */
    useWordmark?: boolean;
  };
}

export const DEFAULT_PREFS: RenderPrefsV1 = {
  version: 1,
  templateId: "classic",
  pageSize: "A4",
  margins: "template",
};

const PAGE_SIZE_IDS: readonly PageId[] = ["A4", "LETTER"];
const MARGIN_IDS: readonly MarginPreset[] = ["template", "narrow", "normal"];

/** Tolerant: anything unreadable or out of range falls back to the default for that field. */
export function parsePrefs(json: string | null | undefined): RenderPrefsV1 {
  if (!json) return { ...DEFAULT_PREFS };
  let raw: unknown;
  try {
    raw = JSON.parse(json);
  } catch {
    return { ...DEFAULT_PREFS };
  }
  if (typeof raw !== "object" || raw === null) return { ...DEFAULT_PREFS };
  const o = raw as Record<string, unknown>;
  const prefs: RenderPrefsV1 = {
    version: 1,
    templateId: typeof o.templateId === "string" && o.templateId ? o.templateId : DEFAULT_PREFS.templateId,
    pageSize: PAGE_SIZE_IDS.includes(o.pageSize as PageId) ? (o.pageSize as PageId) : DEFAULT_PREFS.pageSize,
    margins: MARGIN_IDS.includes(o.margins as MarginPreset) ? (o.margins as MarginPreset) : DEFAULT_PREFS.margins,
  };
  const logo = o.logo;
  if (typeof logo === "object" && logo !== null && typeof (logo as { useWordmark?: unknown }).useWordmark === "boolean") {
    prefs.logo = { useWordmark: (logo as { useWordmark: boolean }).useWordmark };
  }
  return prefs;
}

export const prefsToJson = (prefs: RenderPrefsV1): string => JSON.stringify(prefs);