保存与恢复

import type { Editor, JSONContent } from "@quirekit/core";
import type { DocumentSnapshot } from "./types";

/**
 * Saves explicitly; storage failure propagates so callers cannot report false success.
 * @param editor - The current document authority.
 * @param storage - Host-selected browser or test storage.
 * @param key - Document-specific storage key.
 */
export function saveDocument(editor: Pick<Editor, "getJSON">, storage: Pick<Storage, "setItem">, key: string): void {
  const snapshot: DocumentSnapshot = { version: 1, content: editor.getJSON() };
  storage.setItem(key, JSON.stringify(snapshot));
}

/**
 * Reads the versioned envelope; the editor schema remains responsible for content admission.
 * @param storage - The same host storage used for saving.
 * @param key - Document-specific storage key.
 * @returns Saved canonical JSON, or null when this document has not been saved.
 */
export function readDocument(storage: Pick<Storage, "getItem">, key: string): JSONContent | null {
  const source = storage.getItem(key);
  if (source === null) return null;
  const value: unknown = JSON.parse(source);
  if (!value || typeof value !== "object" || !("version" in value) || value.version !== 1 || !("content" in value)) {
    throw new Error("Unsupported document snapshot version");
  }
  const content = value.content;
  if (!content || typeof content !== "object" || !("type" in content) || content.type !== "doc") {
    throw new Error("Invalid document snapshot");
  }
  return content as JSONContent;
}