export const NIANCODE_APP_PROTOCOL = 'niancode';

export type NianCodeDeepLink = {
  type: 'desktop-auth-callback';
  requestId: string;
  url: string;
} | { type: 'cloud-agent'; slug: string; url: string }
  | { type: 'teacher-preview'; draftRevision: number; url: string };

let pendingTeacherPreviewRevision: number | null = null;
export function queueTeacherPreviewRevision(revision: number): void { pendingTeacherPreviewRevision = revision; }
export function takeTeacherPreviewRevision(): number | null {
  const revision = pendingTeacherPreviewRevision; pendingTeacherPreviewRevision = null; return revision;
}

let pendingCloudAgentRoute: string | null = null;
export function queueCloudAgentLink(slug: string): void {
  pendingCloudAgentRoute = '/cloud-agents/shared/' + slug;
}
export function takeCloudAgentRoute(): string | null {
  const route = pendingCloudAgentRoute;
  pendingCloudAgentRoute = null;
  return route;
}

const SENSITIVE_QUERY_KEYS = new Set([
  'access_token',
  'refresh_token',
  'device_secret',
  'token',
]);

export function parseNianCodeDeepLinkUrl(rawUrl: string): NianCodeDeepLink | null {
  let url: URL;
  try {
    url = new URL(rawUrl);
  } catch {
    return null;
  }

  if (url.protocol === `${NIANCODE_APP_PROTOCOL}:` && url.hostname === 'agents'
    && /^\/ml-[a-f0-9]{32}$/.test(url.pathname) && !url.username && !url.password && !url.port && !url.search && !url.hash) {
    return { type: 'cloud-agent', slug: url.pathname.slice(1), url: rawUrl };
  }
  if (url.protocol !== `${NIANCODE_APP_PROTOCOL}:`) {
    return null;
  }

  if (url.hostname === 'coding-teacher' && url.pathname === '/preview'
    && !url.username && !url.password && !url.port && !url.hash
    && [...url.searchParams.keys()].length === 1 && url.searchParams.has('draft_revision')) {
    const value = url.searchParams.get('draft_revision')!;
    const draftRevision = Number(value);
    if (/^[1-9][0-9]*$/.test(value) && Number.isSafeInteger(draftRevision)) {
      return { type: 'teacher-preview', draftRevision, url: rawUrl };
    }
    return null;
  }

  if (url.hostname !== 'auth' || url.pathname !== '/callback') {
    return null;
  }

  for (const key of SENSITIVE_QUERY_KEYS) {
    if (url.searchParams.has(key)) {
      return null;
    }
  }

  const requestId = url.searchParams.get('request_id')?.trim();
  if (!requestId || requestId.length > 128) {
    return null;
  }

  return {
    type: 'desktop-auth-callback',
    requestId,
    url: rawUrl,
  };
}

export function findNianCodeDeepLinkUrl(args: readonly string[]): string | null {
  return args.find((arg) => parseNianCodeDeepLinkUrl(arg) !== null) ?? null;
}