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/** Custom messages sent between clients and DocSync via y-partyserver's custom message channel. */
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export type PageMetadataRefresh = {
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  type: "page-metadata-refresh";
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};
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export type PageMetadataUpdated = {
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  type: "page-metadata-updated";
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  pageId: string;
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  icon: string | null;
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  cover_url: string | null;
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};
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export type DocCustomMessage = PageMetadataRefresh | PageMetadataUpdated;
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function isRecord(value: unknown): value is Record<string, unknown> {
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  return !!value && typeof value === "object" && !Array.isArray(value);
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}
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function isStringOrNull(value: unknown): value is string | null {
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  return typeof value === "string" || value === null;
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}
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export function parseDocMessage(raw: string): DocCustomMessage | null {
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  try {
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    const parsed = JSON.parse(raw);
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    if (!isRecord(parsed) || typeof parsed.type !== "string") {
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      return null;
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    }
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    if (parsed.type === "page-metadata-refresh") {
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      return { type: "page-metadata-refresh" };
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    }
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    if (
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      parsed.type === "page-metadata-updated" &&
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      typeof parsed.pageId === "string" &&
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      isStringOrNull(parsed.icon) &&
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      isStringOrNull(parsed.cover_url)
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    ) {
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      return {
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        type: "page-metadata-updated",
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        pageId: parsed.pageId,
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        icon: parsed.icon,
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        cover_url: parsed.cover_url,
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      };
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    }
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    return null;
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  } catch {
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    return null;
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  }
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}