PolyMPR/routes/login.tsx

import { Handlers } from "$fresh/server.ts";
import { State } from "$root/routes/_middleware.ts";
import {
  parse,
  type RegularTagNode,
  type TextNode,
} from "@melvdouc/xml-parser";
import { createJwt } from "@popov/jwt";
import { setCookie } from "$std/http/cookie.ts";
import { getKey } from "$root/routes/_middleware.ts";

const SERVICE = "https://localhost/login";
const CAS = "https://ident.univ-amu.fr/cas";

interface CasTagNode extends RegularTagNode {
  children: [TextNode];
}

interface CasGroupNode extends RegularTagNode {
  children: CasTagNode[];
}

interface CasResponse extends RegularTagNode {
  children: [TextNode, CasGroupNode];
}

export interface LoginJWT {
  iss: "PolyMPR";
  iat: number;
  exp: number;
  aud: "PolyMPR";
  user: Record<string, string | string[]>;
}

function getTag(tag: CasTagNode): [string, string] {
  return [
    tag.tagName.replace("cas:", ""),
    tag.children[0].value,
  ];
}

function createUserJWT(casResponse: CasResponse): Promise<string> {
  const nodes = casResponse.children[1].children.map(getTag);
  const fullUserInfos: Record<string, string | string[]> = {};

  nodes.forEach(([key, value]) => {
    if (fullUserInfos[key] && Array.isArray(fullUserInfos[key])) {
      fullUserInfos[key].push(value);
    } else if (fullUserInfos[key]) {
      fullUserInfos[key] = [fullUserInfos[key], value];
    } else {
      fullUserInfos[key] = value;
    }
  });

  const now = Math.floor(Date.now() / 1000);
  const oneHour = 60 * 60;

  const payload = {
    iss: "PolyMPR",
    iat: now,
    exp: now + oneHour,
    aud: "PolyMPR",
    user: fullUserInfos,
  };

  const key = getKey(fullUserInfos.uid as string);
  return createJwt(payload, key);
}

// deno-lint-ignore no-explicit-any
export const handler: Handlers<any, State> = {
  async GET(request, context) {
    const url = new URL(request.url);
    const ticket = url.searchParams.get("ticket");

    if (ticket) {
      const response = await fetch(
        `${CAS}/serviceValidate?service=${SERVICE}&ticket=${ticket}`,
      );
      const body = parse(await response.text()) as [RegularTagNode];
      const casResponse = body[0].children[0] as CasResponse;

      if (casResponse.tagName != "cas:authenticationSuccess") {
        return new Response(null, {
          status: 302,
          headers: {
            Location: `${CAS}/login?service=${SERVICE}`,
          },
        });
      }

      const headers = new Headers();

      setCookie(headers, {
        name: "sessionToken",
        value: await createUserJWT(casResponse),
      });
      headers.set("Location", "/apps");

      return new Response(null, {
        status: 302,
        headers,
      });
    }

    if (context.state.isAuthenticated) {
      return new Response(null, {
        status: 302,
        headers: {
          Location: "/apps",
        },
      });
    } else {
      return new Response(null, {
        status: 302,
        headers: {
          Location: `${CAS}/login?service=${SERVICE}`,
        },
      });
    }
  },
};