/**
 * Client-side print export for the personal report.
 *
 * Deliberately print-only: `await document.fonts.ready` then `window.print()`.
 * It never requests a server-side PDF endpoint, never launches a headless
 * browser, and never rasterizes pixels: the user's own browser and OS render
 * the PDF.
 */

export interface PrintPersonalReportOptions {
  /** Title used as the browser's default PDF filename (document.title). */
  title?: string;
}

/** Sanitize a report id into a safe PDF filename fragment (no path/query chars). */
export function safeReportFilename(reportId: string): string {
  const cleaned = String(reportId ?? "")
    .replace(/[^a-zA-Z0-9_-]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .slice(0, 64);
  return cleaned.length > 0 ? `jyotisha-report-${cleaned}` : "jyotisha-report";
}

export function isPrintSupported(): boolean {
  return typeof window !== "undefined" && typeof window.print === "function";
}

/**
 * Detect environments whose built-in browser cannot print reliably.
 * WeChat's in-app browser is the known case; it should ask users to open the
 * page in the system browser instead of producing a broken printout.
 */
export function detectPrintRestriction(userAgent?: string): {
  restricted: boolean;
  message?: string;
} {
  const ua = typeof userAgent === "string" ? userAgent : typeof navigator !== "undefined" ? navigator.userAgent : "";
  if (/MicroMessenger/i.test(ua)) {
    return {
      restricted: true,
      message: "微信内置浏览器可能无法完整打印，请在系统浏览器中打开本页后打印。",
    };
  }
  return { restricted: false };
}

/**
 * Wait for web fonts, then open the browser print dialog.
 * The page/PDF layout is computed on the user's device; nothing is uploaded.
 */
export async function printPersonalReport(options: PrintPersonalReportOptions = {}): Promise<void> {
  if (typeof window === "undefined" || typeof window.print !== "function") {
    return;
  }
  const fonts = typeof document !== "undefined" ? document.fonts : undefined;
  if (fonts && typeof fonts.ready?.then === "function") {
    await fonts.ready;
  }
  const previousTitle = typeof document !== "undefined" ? document.title : "";
  const requested = typeof options.title === "string" ? options.title.trim() : "";
  if (typeof document !== "undefined" && requested.length > 0) {
    // Browsers derive the default PDF filename from document.title.
    document.title = requested;
  }
  try {
    window.print();
  } finally {
    if (typeof document !== "undefined") {
      document.title = previousTitle;
    }
  }
}