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import { computeHash, hmacSign, splitBy } from "../shared/util.ts";import { SessionImpl } from "./session.ts";import type { ConnInfo, Context, HTMLRewriterHandlers, Session, SessionOptions } from "./types.ts";
type ContextOptions = {  connInfo?: ConnInfo;  session?: SessionOptions;};
/** create a context object */export function createContext(  req: Request,  next: () => Promise<Response> | Response,  options?: ContextOptions,): Context {  let cookies: Map<string, string> | null = null;  let session: Session<Record<string, unknown>> | null = null;  const ctx: Context = {    connInfo: options?.connInfo,    params: {},    headers: new Headers(),    cookies: {      get(name: string) {        if (cookies === null) {          cookies = new Map<string, string>();          const cookieHeader = req.headers.get("Cookie");          if (cookieHeader) {            for (const cookie of cookieHeader.split(";")) {              const [key, value] = splitBy(cookie, "=");              cookies.set(key.trim(), value);            }          }        }        return cookies.get(name);      },    },    // deno-lint-ignore ban-ts-comment    // @ts-ignore    async getSession(): Promise<Session<Record<string, unknown>>> {      if (session !== null) {        return session;      }
      const cookieName = options?.session?.cookie?.name ?? "session";      const secret = options?.session?.secret ?? "-";      let sid = ctx.cookies.get(cookieName);      let skipInit = false;      if (sid) {        const [rid, signature] = splitBy(sid, ".");        if (!signature || signature !== await hmacSign(rid, secret, "SHA-256")) {          sid = undefined;        }      }      if (!sid) {        const rid = await computeHash("SHA-1", crypto.randomUUID());        sid = rid + "." + hmacSign(rid, secret);        skipInit = true;      }
      const sessionImpl = new SessionImpl<Record<string, unknown>>(        sid,        options?.session,      );      session = sessionImpl;      if (!skipInit) {        await sessionImpl.init();      }      return session;    },    __htmlRewriterHandlers: [],    htmlRewriter: {      on: (selector: string, handlers: HTMLRewriterHandlers) => {        (ctx.__htmlRewriterHandlers as unknown[]).push([selector, handlers]);      },    },    next,  };  return ctx;}