// Telegram Mini App SDK access. The official telegram-web-app.js (loaded dynamically with a
// timeout by loadTelegramSDK — not a render-blocking <script> in index.html, so a network that
// blocks telegram.org cannot hang the page) exposes window.Telegram.WebApp; this wraps the subset
// the app uses: launch detection, initData (for auth.telegram), the deep-link start parameter,
// theme params, and ready()/expand(). Every helper is safe to call outside Telegram.

import type { TelegramThemeParams } from './theme';

/** TelegramPopupButton is one button of a native showPopup (Bot API 6.2). */
export interface TelegramPopupButton {
  id?: string;
  type?: 'default' | 'ok' | 'close' | 'cancel' | 'destructive';
  text?: string;
}

/** TelegramPopupParams configures a native showPopup (title optional, message required, up to 3 buttons). */
export interface TelegramPopupParams {
  title?: string;
  message: string;
  buttons?: TelegramPopupButton[];
}

interface TelegramWebApp {
  initData: string;
  initDataUnsafe?: { start_param?: string };
  platform?: string;
  version?: string;
  themeParams?: TelegramThemeParams;
  colorScheme?: 'light' | 'dark';
  isFullscreen?: boolean;
  isExpanded?: boolean;
  viewportHeight?: number;
  viewportStableHeight?: number;
  exitFullscreen?: () => void;
  safeAreaInset?: { top: number; bottom: number; left: number; right: number };
  contentSafeAreaInset?: { top: number; bottom: number; left: number; right: number };
  ready?: () => void;
  expand?: () => void;
  close?: () => void;
  openTelegramLink?: (url: string) => void;
  openLink?: (url: string) => void;
  onEvent?: (event: string, handler: () => void) => void;
  setHeaderColor?: (color: string) => void;
  setBackgroundColor?: (color: string) => void;
  setBottomBarColor?: (color: string) => void;
  disableVerticalSwipes?: () => void;
  HapticFeedback?: {
    impactOccurred?: (style: string) => void;
    notificationOccurred?: (type: string) => void;
    selectionChanged?: () => void;
  };
  BackButton?: {
    isVisible?: boolean;
    show?: () => void;
    hide?: () => void;
    onClick?: (cb: () => void) => void;
    offClick?: (cb: () => void) => void;
  };
  SettingsButton?: {
    show?: () => void;
    hide?: () => void;
    onClick?: (cb: () => void) => void;
    offClick?: (cb: () => void) => void;
  };
  CloudStorage?: {
    getItem?: (key: string, cb: (err: string | null, value?: string) => void) => void;
    setItem?: (key: string, value: string, cb?: (err: string | null, ok?: boolean) => void) => void;
  };
  showConfirm?: (message: string, cb?: (ok: boolean) => void) => void;
  showPopup?: (params: TelegramPopupParams, cb?: (buttonId: string) => void) => void;
  downloadFile?: (params: { url: string; file_name: string }, cb?: (accepted: boolean) => void) => void;
}

function webApp(): TelegramWebApp | undefined {
  if (typeof window === 'undefined') return undefined;
  return (window as unknown as { Telegram?: { WebApp?: TelegramWebApp } }).Telegram?.WebApp;
}

/**
 * insideTelegram reports whether the app launched as a Telegram Mini App — the SDK
 * is present and carries non-empty initData (an ordinary browser tab has neither).
 */
export function insideTelegram(): boolean {
  const w = webApp();
  return !!w && typeof w.initData === 'string' && w.initData.length > 0;
}

/** telegramClose closes the Mini App (Telegram.WebApp.close), used on the terminal
 *  account-deleted screen. A no-op outside Telegram. */
export function telegramClose(): void {
  webApp()?.close?.();
}

// The ?NN suffix pins the Bot API SDK version Telegram serves (and busts the cache); keep it at the
// version the official Mini Apps page currently recommends so newer client features (fullscreen,
// safe-area insets, vertical-swipe guard, …) are available. Bump it when Telegram bumps theirs.
const sdkScriptSrc = 'https://telegram.org/js/telegram-web-app.js?62';

/**
 * TelegramSdkOutcome records how the dynamic telegram-web-app.js load resolved, surfaced on the
 * launch-error screen to tell the failure modes apart — notably 'error' / 'timeout', which mean the
 * network could not reach telegram.org (the script blocked or hung):
 *
 *   not-attempted — loadTelegramSDK was never called (a plain web / native entry)
 *   present       — window.Telegram.WebApp was already there (a cached load or native injection)
 *   loaded        — the script loaded and defined window.Telegram.WebApp
 *   no-webapp     — the script loaded (HTTP 200) but did not define window.Telegram.WebApp
 *   error         — the script failed to load (telegram.org unreachable / blocked, a fast failure)
 *   timeout       — the script neither loaded nor failed within the timeout (a blocked, hanging fetch)
 */
export type TelegramSdkOutcome = 'not-attempted' | 'present' | 'loaded' | 'no-webapp' | 'error' | 'timeout';

let sdkLoadOutcome: TelegramSdkOutcome = 'not-attempted';

/** telegramSdkOutcome returns how the last loadTelegramSDK attempt resolved (see TelegramSdkOutcome). */
export function telegramSdkOutcome(): TelegramSdkOutcome {
  return sdkLoadOutcome;
}

/**
 * loadTelegramSDK injects the official telegram-web-app.js and resolves true once
 * window.Telegram.WebApp is available, or false if the script errors or does not load within
 * timeoutMs. It is loaded dynamically — not a render-blocking <script> in index.html — so a network
 * that blocks telegram.org (common where Telegram itself reaches users only over a proxy) cannot
 * hang the page and strand the app or the launch-error screen. Resolves true immediately when the
 * SDK is already present (a cached load, or a future native injection); a fast connection failure
 * resolves via the error event without waiting out the timeout, so the timeout only bounds a true
 * hang.
 */
export function loadTelegramSDK(timeoutMs: number): Promise<boolean> {
  if (typeof document === 'undefined') return Promise.resolve(false);
  if (webApp()) {
    sdkLoadOutcome = 'present';
    return Promise.resolve(true);
  }
  return new Promise<boolean>((resolve) => {
    let done = false;
    const finish = (outcome: TelegramSdkOutcome): void => {
      if (done) return;
      done = true;
      sdkLoadOutcome = outcome;
      resolve(outcome === 'loaded');
    };
    const timer = setTimeout(() => finish(webApp() ? 'loaded' : 'timeout'), timeoutMs);
    const s = document.createElement('script');
    s.src = sdkScriptSrc;
    s.async = true;
    s.onload = () => {
      clearTimeout(timer);
      finish(webApp() ? 'loaded' : 'no-webapp');
    };
    s.onerror = () => {
      clearTimeout(timer);
      finish('error');
    };
    document.head.appendChild(s);
  });
}

/**
 * telegramOpenLink opens a t.me link through the Mini App SDK, so Telegram navigates to
 * it natively (e.g. a bot chat) rather than spawning an in-app browser tab. Returns false
 * outside Telegram or when the SDK lacks the method, so the caller can fall back to a plain
 * window.open.
 */
export function telegramOpenLink(url: string): boolean {
  const w = webApp();
  if (!w?.openTelegramLink) return false;
  w.openTelegramLink(url);
  return true;
}

/**
 * telegramOpenExternalLink opens an arbitrary external URL through the Mini App SDK's openLink,
 * so Telegram opens it directly in its in-app browser instead of the WebView's generic "open
 * this link?" confirmation that a plain target=_blank navigation triggers. Returns false
 * outside Telegram or when the SDK lacks the method, so the caller can fall back to a normal
 * anchor.
 */
export function telegramOpenExternalLink(url: string): boolean {
  const w = webApp();
  if (!w?.openLink) return false;
  w.openLink(url);
  return true;
}

/**
 * isExternalHttpUrl reports whether href is an absolute http(s) URL on a different origin than the
 * app — so a same-origin or root-relative in-app (SPA) link is left to normal navigation, only a
 * genuinely external link is routed through the host platform's browser (the Telegram router here
 * and the VK router in vk.ts share it).
 */
export function isExternalHttpUrl(href: string): boolean {
  try {
    const u = new URL(href, typeof location === 'undefined' ? undefined : location.href);
    if (u.protocol !== 'http:' && u.protocol !== 'https:') return false;
    return typeof location === 'undefined' || u.origin !== location.origin;
  } catch {
    return false;
  }
}

/**
 * routeExternalLinkInTelegram decides whether a clicked anchor should be opened through the Mini
 * App SDK rather than the WebView's default navigation: only inside Telegram, and only for an
 * external http(s) link opened in a new tab (target=_blank) that is not a t.me link (those use
 * telegramOpenLink/openTelegramLink). Returns true when it opened the link through openLink — the
 * caller should then preventDefault — and false to let the browser handle the click normally.
 */
export function routeExternalLinkInTelegram(anchor: { href: string; target: string }): boolean {
  if (!insideTelegram()) return false;
  if (anchor.target !== '_blank') return false;
  if (anchor.href.startsWith('https://t.me/')) return false;
  if (!isExternalHttpUrl(anchor.href)) return false;
  return telegramOpenExternalLink(anchor.href);
}

/**
 * shareTelegramLink opens Telegram's native "share to a chat" picker for url with a
 * caption, through the Mini App SDK (https://t.me/share/url). Returns false outside
 * Telegram or when the SDK lacks the method, so the caller can fall back to the Web
 * Share API. Works consistently on iOS and Android within Telegram.
 */
export function shareTelegramLink(url: string, text: string): boolean {
  return telegramOpenLink(`https://t.me/share/url?url=${encodeURIComponent(url)}&text=${encodeURIComponent(text)}`);
}

/** TelegramLaunch is the data a Mini App launch carries. */
export interface TelegramLaunch {
  initData: string;
  startParam: string;
  theme: TelegramThemeParams | undefined;
}

/**
 * telegramLaunch readies the Mini App (full-height, ready signal) and returns its
 * launch data: the raw initData (for auth.telegram), the deep-link start parameter
 * (from the SDK or, for a bot web_app button, the page URL), and the theme params.
 */
export function telegramLaunch(): TelegramLaunch {
  const w = webApp();
  if (!w) return { initData: '', startParam: startParamFromURL(), theme: undefined };
  w.ready?.();
  w.expand?.();
  const startParam = w.initDataUnsafe?.start_param ?? startParamFromURL();
  return { initData: w.initData, startParam, theme: w.themeParams };
}

/**
 * telegramOnEvent subscribes to a Telegram WebApp lifecycle event (e.g. 'activated' /
 * 'deactivated', added in Bot API 8.0). It is a no-op outside Telegram or on a client
 * that predates the event, so callers can register defensively.
 */
export function telegramOnEvent(event: string, handler: () => void): void {
  webApp()?.onEvent?.(event, handler);
}

/**
 * telegramColorScheme returns Telegram's active colour scheme ('light' | 'dark'),
 * or undefined outside Telegram. Inside the Mini App this — not the OS
 * prefers-color-scheme — is the authoritative theme: on some clients (Telegram
 * Desktop) the OS scheme leaks into the webview and fights Telegram's own setting,
 * so the app forces this value on launch.
 */
export function telegramColorScheme(): 'light' | 'dark' | undefined {
  return webApp()?.colorScheme;
}

/**
 * telegramThemeParams returns Telegram's current theme palette (WebApp.themeParams), or undefined
 * outside Telegram. It reads the live value rather than a launch snapshot, so the themeChanged
 * event can re-apply the palette when the user switches Telegram's light/dark theme mid-session.
 */
export function telegramThemeParams(): TelegramThemeParams | undefined {
  return webApp()?.themeParams;
}

/**
 * telegramSetChrome paints Telegram's own header, background and bottom bar to match the
 * app's colours, so the surrounding Telegram chrome does not clash with the UI. No-op
 * outside Telegram or on a client predating a given setter.
 */
export function telegramSetChrome(header: string, background: string, bottom: string): void {
  const w = webApp();
  if (header) w?.setHeaderColor?.(header);
  if (background) w?.setBackgroundColor?.(background);
  if (bottom) w?.setBottomBarColor?.(bottom);
}

/**
 * telegramContentSafeAreaTop returns the height (px) Telegram's own UI overlays at the top of
 * the viewport in fullscreen (its nav band; the content-safe area, Bot API 8.0). It is 0
 * outside Telegram or on clients predating it, so callers can pad/position defensively.
 */
export function telegramContentSafeAreaTop(): number {
  return webApp()?.contentSafeAreaInset?.top ?? 0;
}

/**
 * telegramSafeAreaInset returns the device safe-area insets (px) — the notch / status bar (top),
 * the home indicator (bottom) and, in landscape, the notch sides (left / right) — from the SDK's
 * safeAreaInset (Bot API 8.0). All 0 outside Telegram or on a client predating it, so callers can
 * pad defensively. Telegram's own nav controls sit in the band between the top inset and
 * telegramContentSafeAreaTop, so aligning our header to that band lines it up with them.
 */
export function telegramSafeAreaInset(): { top: number; bottom: number; left: number; right: number } {
  const i = webApp()?.safeAreaInset;
  return { top: i?.top ?? 0, bottom: i?.bottom ?? 0, left: i?.left ?? 0, right: i?.right ?? 0 };
}

/**
 * telegramDisableVerticalSwipes turns off Telegram's swipe-down-to-minimise gesture so
 * it does not fight tile drag-and-drop or the board's vertical scroll.
 */
export function telegramDisableVerticalSwipes(): void {
  webApp()?.disableVerticalSwipes?.();
}

/**
 * telegramShowSettingsButton reveals Telegram's native Settings button (in the Mini App's ⋮ menu,
 * Bot API 7.0) and routes its taps to handler. A no-op outside Telegram or on a client predating
 * the button, so the app's own in-app settings entry stays the primary path. The app registers it
 * once per launch (Telegram hides the button when the Mini App closes), so there is no offClick.
 */
export function telegramShowSettingsButton(handler: () => void): void {
  const b = webApp()?.SettingsButton;
  if (!b?.show) return;
  b.onClick?.(handler);
  b.show();
}

/** telegramCloudAvailable reports whether Telegram CloudStorage (Bot API 6.9) is usable. */
export function telegramCloudAvailable(): boolean {
  return !!webApp()?.CloudStorage?.getItem;
}

/**
 * telegramCloudGet reads a value from Telegram CloudStorage, resolving null when the key is absent,
 * CloudStorage is unavailable (outside Telegram / a client predating Bot API 6.9), or the read
 * errors — so the caller can fall back to the local value.
 */
export function telegramCloudGet(key: string): Promise<string | null> {
  const cs = webApp()?.CloudStorage;
  if (!cs?.getItem) return Promise.resolve(null);
  return new Promise((resolve) => {
    cs.getItem!(key, (err, value) => resolve(err ? null : (value ?? null)));
  });
}

/**
 * telegramCloudSet writes a value to Telegram CloudStorage, resolving once the write settles. It is
 * best-effort: a no-op outside Telegram / on an older client, and it swallows write errors, since
 * the local store remains the source of truth.
 */
export function telegramCloudSet(key: string, value: string): Promise<void> {
  const cs = webApp()?.CloudStorage;
  if (!cs?.setItem) return Promise.resolve();
  return new Promise((resolve) => {
    cs.setItem!(key, value, () => resolve());
  });
}

/** telegramDialogsAvailable reports whether Telegram's native dialogs (showConfirm / showPopup, Bot
 *  API 6.2) are usable, so a caller can choose the native path over its own modal. */
export function telegramDialogsAvailable(): boolean {
  return !!webApp()?.showPopup;
}

/**
 * telegramShowConfirm shows Telegram's native confirm dialog and resolves true when the user
 * accepts. Resolves false outside Telegram or on a client predating the dialog, so callers should
 * gate on telegramDialogsAvailable and fall back to their own modal otherwise.
 */
export function telegramShowConfirm(message: string): Promise<boolean> {
  const w = webApp();
  if (!w?.showConfirm) return Promise.resolve(false);
  return new Promise((resolve) => w.showConfirm!(message, (ok) => resolve(!!ok)));
}

/**
 * telegramShowPopup shows Telegram's native popup and resolves the pressed button id (the empty
 * string when dismissed without pressing a button). Resolves null outside Telegram or on a client
 * predating the popup, so callers can fall back to their own modal. NOTE: the callback runs with
 * no user activation — never lead from it into navigator.share or a clipboard write.
 */
export function telegramShowPopup(params: TelegramPopupParams): Promise<string | null> {
  const w = webApp();
  if (!w?.showPopup) return Promise.resolve(null);
  return new Promise((resolve) => w.showPopup!(params, (id) => resolve(id ?? '')));
}

/** telegramCanDownloadFile reports whether the native download dialog exists (Bot API 8.0). */
export function telegramCanDownloadFile(): boolean {
  return !!webApp()?.downloadFile;
}

/** telegramPlatform returns the SDK's platform tag ('ios', 'android', 'tdesktop', …) or ''
 *  outside Telegram — the export delivery branches on it (iOS gets the OS share sheet). */
export function telegramPlatform(): string {
  return webApp()?.platform ?? '';
}

/**
 * telegramDownloadFile asks Telegram to download url as fileName through its native
 * dialog — the Mini App file delivery that works on every Telegram platform (a webview
 * <a download> does not). Returns false outside Telegram or on a client predating it.
 */
export function telegramDownloadFile(url: string, fileName: string): boolean {
  const w = webApp();
  if (!w?.downloadFile) return false;
  w.downloadFile({ url, file_name: fileName });
  return true;
}

/** Haptic is the set of feedbacks the app triggers. */
export type Haptic = 'select' | 'success' | 'error' | 'warning' | 'light' | 'medium' | 'heavy';

/** telegramHaptic fires a Telegram haptic; a no-op outside Telegram or on older clients. */
export function telegramHaptic(kind: Haptic): void {
  const h = webApp()?.HapticFeedback;
  if (!h) return;
  if (kind === 'select') h.selectionChanged?.();
  else if (kind === 'success' || kind === 'error' || kind === 'warning') h.notificationOccurred?.(kind);
  else h.impactOccurred?.(kind);
}

/**
 * startParamFromURL reads a startapp parameter from the page URL — a bot web_app
 * launch button carries the deep-link there rather than in initDataUnsafe.
 */
function startParamFromURL(): string {
  if (typeof location === 'undefined') return '';
  return new URLSearchParams(location.search).get('startapp') ?? '';
}

/**
 * onTelegramPath reports whether the app is served under the dedicated Telegram
 * entry path (/telegram/); outside Telegram on that path the app refuses to render.
 */
export function onTelegramPath(): boolean {
  if (typeof location === 'undefined') return false;
  return location.pathname.startsWith('/telegram/');
}

/** hasLaunchFragment reports whether the URL fragment carries Telegram launch params (tgWebApp…),
 *  the form Telegram appends when opening a Mini App — so the SDK is loaded for a Mini App opened
 *  at the site root too, not only the /telegram/ path. */
export function hasLaunchFragment(): boolean {
  if (typeof location === 'undefined') return false;
  return location.hash.includes('tgWebApp');
}

// --- Launch diagnostics (the /telegram/ entry without sign-in data) ---

/** The initData fields a valid Telegram launch is expected to carry; their absence is the signal
 *  the launch-error screen reports. Only field names are ever inspected, never their values. */
const expectedInitDataFields = ['user', 'auth_date', 'hash', 'signature'];

interface uaBrand {
  brand: string;
  version: string;
}

interface uaDataValue {
  platform?: string;
  mobile?: boolean;
  brands?: uaBrand[];
}

/** uaData returns the User-Agent Client Hints object (Chromium only — notably the Android Telegram
 *  webview), or undefined where it is unavailable (iOS / Safari / Firefox). */
function uaData(): uaDataValue | undefined {
  if (typeof navigator === 'undefined') return undefined;
  return (navigator as unknown as { userAgentData?: uaDataValue }).userAgentData;
}

/** launchFragmentData returns the raw tgWebAppData carried in the URL fragment (the form Telegram
 *  appends on launch), or '' when absent. With no SDK present a non-empty value means Telegram
 *  delivered the data but telegram-web-app.js never ran to parse it. */
function launchFragmentData(): string {
  if (typeof location === 'undefined') return '';
  const frag = location.hash.replace(/^#/, '');
  if (!frag) return '';
  try {
    return new URLSearchParams(frag).get('tgWebAppData') ?? '';
  } catch {
    return '';
  }
}

/** initDataFieldNames parses a Telegram initData (or raw fragment data) query string and returns
 *  only its field NAMES — never the values, since the hash / signature are auth material. */
function initDataFieldNames(raw: string): string[] {
  if (!raw) return [];
  try {
    return [...new URLSearchParams(raw).keys()];
  } catch {
    return [];
  }
}

/**
 * TelegramDiag is a privacy-safe snapshot of why a Mini App launch lacked sign-in data, taken at
 * the moment of failure and rendered on the launch-error screen so a stuck user can share it with
 * the developer. It carries no secret values — only presence flags, client / OS identification and
 * the field NAMES of the launch data, never the signed initData itself, and never an IP.
 */
export interface TelegramDiag {
  /** Whether window.Telegram (the telegram-web-app.js script) is present at all. */
  hasSDK: boolean;
  /** Whether window.Telegram.WebApp is present. */
  hasWebApp: boolean;
  /** How the dynamic telegram-web-app.js load resolved (see TelegramSdkOutcome) — 'error' /
   *  'timeout' mean telegram.org was unreachable, the prime suspect for an empty launch. */
  sdkLoad: TelegramSdkOutcome;
  /** Telegram's own platform string (ios | android | android_x | tdesktop | web | …), or ''. */
  platform: string;
  /** The Bot API version the client reports, or ''. */
  version: string;
  /** The length of WebApp.initData — 0 is the failure this screen reports. */
  initDataLen: number;
  /** Whether the URL fragment still carried tgWebAppData at launch; true with hasSDK false means
   *  Telegram delivered the data but the SDK script did not load to parse it. */
  hashHadTgData: boolean;
  /** The field names present in the launch data (from initData, or the raw fragment when the SDK
   *  left initData empty); values are never included. */
  fieldsPresent: string[];
  /** The expected field names absent from the launch data (a subset of expectedInitDataFields). */
  fieldsMissing: string[];
  /** The OS / platform per User-Agent Client Hints (else navigator.platform), e.g. 'Android', ''. */
  osPlatform: string;
  /** Whether the client reports itself mobile per Client Hints: 'yes' | 'no' | '' (unknown). */
  mobile: string;
  /** The browser brands + major versions per Client Hints (Chromium only), or ''. */
  browser: string;
  /** The full User-Agent string — the catch-all that also carries the OS version and webview build. */
  userAgent: string;
}

/**
 * collectTelegramDiag captures a TelegramDiag snapshot of the current launch state. Call it at the
 * point a /telegram/ launch is found to lack sign-in data, so the snapshot reflects that moment —
 * sign-in data arriving late would otherwise mask the failure.
 */
export function collectTelegramDiag(): TelegramDiag {
  const w = webApp();
  const sdk = typeof window !== 'undefined' && !!(window as unknown as { Telegram?: unknown }).Telegram;
  const initData = w?.initData ?? '';
  const fragData = initData ? '' : launchFragmentData();
  const present = initDataFieldNames(initData || fragData);
  const ua = uaData();
  const navPlatform =
    typeof navigator === 'undefined' ? '' : (navigator as unknown as { platform?: string }).platform ?? '';
  return {
    hasSDK: sdk,
    hasWebApp: !!w,
    sdkLoad: sdkLoadOutcome,
    platform: w?.platform ?? '',
    version: w?.version ?? '',
    initDataLen: initData.length,
    hashHadTgData: fragData.length > 0,
    fieldsPresent: present,
    fieldsMissing: expectedInitDataFields.filter((f) => !present.includes(f)),
    osPlatform: ua?.platform ?? navPlatform,
    mobile: ua?.mobile === undefined ? '' : ua.mobile ? 'yes' : 'no',
    browser: (ua?.brands ?? []).map((b) => `${b.brand} ${b.version}`).join(', '),
    userAgent: typeof navigator === 'undefined' ? '' : navigator.userAgent,
  };
}

/**
 * telegramChromeDiag returns a compact, privacy-safe readout of Telegram's viewport / chrome state
 * (platform, version, fullscreen/expanded, viewport geometry, safe-area insets, SDK-load outcome,
 * back-button state, UA). It feeds the hidden debug panel (components/DebugPanel), opened by tapping
 * the header title ten times. No secrets: no initData values, no IP.
 */
export function telegramChromeDiag(): string {
  const w = webApp();
  if (!w) return 'no telegram';
  const win = typeof window === 'undefined' ? undefined : window;
  const scr = typeof screen === 'undefined' ? undefined : screen;
  const vv = win?.visualViewport ?? undefined;
  const bar = typeof document === 'undefined' ? null : (document.querySelector('.bar')?.getBoundingClientRect() ?? null);
  const sa = w.safeAreaInset;
  const csa = w.contentSafeAreaInset;
  const n = (v: number | undefined): string => (v === undefined ? '—' : String(Math.round(v)));
  return [
    `platform: ${w.platform ?? '—'}  version: ${w.version ?? '—'}  scheme: ${w.colorScheme ?? '—'}`,
    `isFullscreen: ${w.isFullscreen}  isExpanded: ${w.isExpanded}`,
    `inTG: ${insideTelegram()}  sdkLoad: ${sdkLoadOutcome}  backPresent: ${!!w.BackButton}  backVisible: ${w.BackButton?.isVisible}`,
    `innerH: ${n(win?.innerHeight)}  outerH: ${n(win?.outerHeight)}  screenH: ${n(scr?.height)}  availH: ${n(scr?.availHeight)}`,
    `screenY: ${n(win?.screenY)}  vv.offTop: ${n(vv?.offsetTop)}  vv.h: ${n(vv?.height)}`,
    `tgViewportH: ${n(w.viewportHeight)}  stableH: ${n(w.viewportStableHeight)}`,
    `safeArea T/B: ${n(sa?.top)}/${n(sa?.bottom)}  contentSafe T/B: ${n(csa?.top)}/${n(csa?.bottom)}`,
    `appHeader top/h: ${bar ? Math.round(bar.top) : '—'}/${bar ? Math.round(bar.height) : '—'}`,
  ].join('\n');
}

// --- Login Widget (web sign-in for account linking) ---

// The Login Widget is the web (non-Mini-App) Telegram sign-in. It is used only to
// attach a Telegram identity to an existing account from a browser; inside the Mini
// App the session is already a Telegram identity. It needs the bot id (numeric,
// VITE_TELEGRAM_BOT_ID) and, in production, the site domain registered with BotFather
// (/setdomain) — without that Telegram refuses to render. The connector validates the
// returned data (HMAC under SHA-256(bot_token)).

const widgetScriptSrc = 'https://telegram.org/js/telegram-widget.js?22';

interface telegramAuthUser {
  id: number;
  first_name?: string;
  last_name?: string;
  username?: string;
  photo_url?: string;
  auth_date: number;
  hash: string;
}

interface telegramLoginSDK {
  auth(opts: { bot_id: string; request_access?: string }, cb: (user: telegramAuthUser | false) => void): void;
}

function isMock(): boolean {
  return import.meta.env.MODE === 'mock';
}

function botID(): string {
  return (import.meta.env.VITE_TELEGRAM_BOT_ID as string | undefined) ?? '';
}

/**
 * loginWidgetAvailable reports whether the "Link Telegram" control should be shown:
 * not already inside the Mini App, and either the mock build or a configured bot id.
 */
export function loginWidgetAvailable(): boolean {
  if (insideTelegram()) return false;
  return isMock() || botID() !== '';
}

let widgetLoad: Promise<void> | null = null;

function loadWidget(): Promise<void> {
  if (typeof document === 'undefined') return Promise.reject(new Error('telegram: no document'));
  const sdk = (window as unknown as { Telegram?: { Login?: telegramLoginSDK } }).Telegram?.Login;
  if (sdk) return Promise.resolve();
  if (!widgetLoad) {
    widgetLoad = new Promise<void>((resolve, reject) => {
      const s = document.createElement('script');
      s.src = widgetScriptSrc;
      s.async = true;
      s.onload = () => resolve();
      s.onerror = () => reject(new Error('telegram: widget load failed'));
      document.head.appendChild(s);
    });
  }
  return widgetLoad;
}

/**
 * requestTelegramLogin drives the Login Widget popup and resolves with the auth data
 * serialized as a URL query string (id=...&auth_date=...&hash=...) — the form the
 * connector validates — or null when the user cancels. In the mock build it returns
 * a fixed payload without loading the real widget (telegram.org is blocked in tests).
 */
export async function requestTelegramLogin(): Promise<string | null> {
  if (isMock()) {
    return `id=42&first_name=Telegram&auth_date=${Math.floor(Date.now() / 1000)}&hash=mock`;
  }
  await loadWidget();
  const login = (window as unknown as { Telegram?: { Login?: telegramLoginSDK } }).Telegram?.Login;
  if (!login) throw new Error('telegram: login unavailable');
  const user = await new Promise<telegramAuthUser | false>((resolve) => {
    login.auth({ bot_id: botID(), request_access: 'write' }, resolve);
  });
  if (!user) return null;
  return serializeTelegramAuth(user);
}

function serializeTelegramAuth(u: telegramAuthUser): string {
  const params = new URLSearchParams();
  params.set('id', String(u.id));
  if (u.first_name) params.set('first_name', u.first_name);
  if (u.last_name) params.set('last_name', u.last_name);
  if (u.username) params.set('username', u.username);
  if (u.photo_url) params.set('photo_url', u.photo_url);
  params.set('auth_date', String(u.auth_date));
  params.set('hash', u.hash);
  return params.toString();
}