/** A profile popup stays in its existing managed view only after native input. */
export interface ProfilePopupDetails {
  url: string;
  postBody?: unknown;
}

export interface ProfilePopupDiagnostic {
  taskId: string;
  category: 'xhs_profile' | 'other';
  action: 'deny' | 'deny_no_native_input' | 'deny_context' | 'deny_busy'
    | 'open_same_view' | 'opened_same_view' | 'cancel_stale' | 'open_failed';
}

interface PopupPage {
  getURL(): string;
  isDestroyed(): boolean;
  loadURL(url: string): Promise<unknown>;
}

interface ProfilePopupOptions {
  taskId: string;
  isCurrent(): boolean;
  allowed(url: string): boolean;
  diagnose(value: ProfilePopupDiagnostic): void;
  now?: () => number;
  defer?: (callback: () => void) => void;
}

const NATIVE_INPUT_WINDOW_MS = 750;

function siteURL(value: string): URL | null {
  try {
    const url = new URL(value);
    return url.protocol === 'https:' && url.hostname === 'www.xiaohongshu.com'
      && !url.username && !url.password && !url.port ? url : null;
  } catch { return null; }
}

function isNote(value: string): boolean {
  const url = siteURL(value);
  return Boolean(url && /^\/(?:explore|discovery\/item)\/[a-f0-9]{24}\/?$/i.test(url.pathname));
}

function isProfile(value: string): boolean {
  const url = siteURL(value);
  return Boolean(url && /^\/user\/profile\/[a-f0-9]{24}\/?$/i.test(url.pathname));
}

export function createProfilePopupHandler(page: PopupPage, options: ProfilePopupOptions): {
  input(type: string): void;
  open(details: ProfilePopupDetails): { action: 'deny' };
} {
  const now = options.now ?? (() => performance.now());
  const defer = options.defer ?? (callback => { setImmediate(callback); });
  let nativeInput: { url: string; at: number } | null = null;
  let pressed: { url: string; at: number } | null = null;
  let pending = false;

  return {
    input(type): void {
      // An earlier click cannot authorize a later mouse press or popup. The
      // host event is independent of scripts in the untrusted page.
      if (type === 'mouseDown') {
        nativeInput = null;
        pressed = null;
        if (!page.isDestroyed() && isNote(page.getURL())) pressed = { url: page.getURL(), at: now() };
        return;
      }
      if (type !== 'mouseUp') return;
      const down = pressed;
      pressed = null;
      if (page.isDestroyed()) { nativeInput = null; return; }
      const url = page.getURL();
      const elapsed = down ? now() - down.at : -1;
      nativeInput = down && down.url === url && isNote(url) && elapsed >= 0 && elapsed <= NATIVE_INPUT_WINDOW_MS
        ? { url, at: now() } : null;
    },
    open(details): { action: 'deny' } {
      const category = isProfile(details.url) ? 'xhs_profile' : 'other';
      const log = (action: ProfilePopupDiagnostic['action']): void => {
        // Never spread Electron's details or exceptions into diagnostics.
        options.diagnose({ taskId: options.taskId, category, action });
      };
      const clicked = nativeInput;
      nativeInput = null; // One actual input can route at most one popup.
      if (category !== 'xhs_profile') {
        log('deny');
        return { action: 'deny' };
      }
      if (pending) {
        log('deny_busy');
        return { action: 'deny' };
      }
      const elapsed = clicked ? now() - clicked.at : -1;
      if (!clicked || elapsed < 0 || elapsed > NATIVE_INPUT_WINDOW_MS) {
        log('deny_no_native_input');
        return { action: 'deny' };
      }
      if (page.isDestroyed() || !options.isCurrent() || !isNote(page.getURL())
          || page.getURL() !== clicked.url || Boolean(details.postBody) || !options.allowed(details.url)) {
        log('deny_context');
        return { action: 'deny' };
      }
      pending = true;
      const target = details.url;
      const source = clicked.url;
      log('open_same_view');
      defer(() => {
        if (page.isDestroyed() || !options.isCurrent() || page.getURL() !== source || !options.allowed(target)) {
          pending = false;
          log('cancel_stale');
          return;
        }
        // Use the actual resolved popup URL unchanged. loadURL adds a normal
        // history entry in this view; no new window or history reset is used.
        void page.loadURL(target).then(() => {
          pending = false;
          log('opened_same_view');
        }).catch(() => {
          pending = false;
          log('open_failed');
        });
      });
      // Electron must never create a separate BrowserWindow, including for an
      // accepted profile. Routing happens only on the next main-process turn.
      return { action: 'deny' };
    },
  };
}