/*
 * webview.ts — source 2: navigator.geolocation inside the WebView, and the
 * Android freshness nudge's reading hand (D-04, D-05).
 * -------------------------------------------------------------------
 * maximumAge: 0 is load-bearing — D-05 requires the freshest fix, and a
 * cached position would silently defeat the freshness axis (the whole
 * point of the nudge is to force a NEW read, not to re-read a cache).
 * Success AND timeout both resolve; the error callback resolves null so
 * the chain advances instead of rejecting. Timeout present for the same
 * reason as the telegram wrapper: wedging ACQUIRING is never acceptable.
 */
import type { Fix } from "./types.ts";

export function webviewLocationSupported(): boolean {
  return typeof navigator !== "undefined" && typeof navigator.geolocation?.getCurrentPosition === "function";
}

export function readWebviewFix(options: { timeoutMs?: number; nowMs?: () => number } = {}): Promise<Fix | null> {
  const timeoutMs = options.timeoutMs ?? 8000;
  if (!webviewLocationSupported()) return Promise.resolve(null); // Desktop Telegram, plain browsers without permission
  return new Promise((resolve) => {
    let settled = false;
    const done = (fix: Fix | null): void => {
      if (settled) return;
      settled = true;
      clearTimeout(timer);
      resolve(fix);
    };
    const timer = setTimeout(() => done(null), timeoutMs);
    navigator.geolocation.getCurrentPosition(
      (pos) =>
        done({
          lat: pos.coords.latitude,
          lng: pos.coords.longitude,
          accuracyM: pos.coords.accuracy ?? null,
          headingDeg: pos.coords.heading ?? null,
          ts: (options.nowMs ?? Date.now)(),
          source: "webview",
        }),
      () => done(null), // denial / unavailability = null; the chain's normal signal (no error object escapes)
      { enableHighAccuracy: true, timeout: timeoutMs, maximumAge: 0 },
    );
  });
}