import * as Data from "effect/Data";
import * as Effect from "effect/Effect";
import type { InstallationConfig } from "../configuration/customer.ts";
import type { Secret } from "../configuration/secrets.ts";
import { bodyJson, withResponse } from "../server/http.ts";
import { verifyOwnerSession } from "./session.ts";

const TIMEOUT_MS = 2_500;
const MAX_BODY_BYTES = 8_192;
class UpdateUnavailable extends Data.TaggedError("UpdateUnavailable") {}

function isHtmlNavigation(request: Request) {
  if (request.method !== "GET") return false;
  const url = new URL(request.url);
  if (
    url.pathname === "/flarebot-health.txt" ||
    url.pathname.startsWith("/api") ||
    url.pathname.startsWith("/agents/") ||
    url.pathname.startsWith("/auth/") ||
    request.headers.get("Upgrade")?.toLowerCase() === "websocket"
  )
    return false;
  const destination = request.headers.get("Sec-Fetch-Dest");
  return (
    destination === "document" ||
    (!destination && request.headers.get("Accept")?.includes("text/html"))
  );
}
const digest = (value: unknown): value is string =>
  typeof value === "string" && /^[a-f0-9]{64}$/.test(value);

/** Redirect only when a bounded publisher reply proves a newer release. */
export function updateOnOwnerVisit(
  request: Request,
  installation: InstallationConfig,
  secret: Secret,
  production: boolean,
  network: typeof fetch = fetch,
): Effect.Effect<Response | null> {
  return Effect.gen(function* () {
    const release = installation.release;
    if (
      !production ||
      !installation.bridge ||
      !release ||
      new URL(request.url).origin !== installation.runtimeOrigin ||
      !isHtmlNavigation(request) ||
      !(yield* verifyOwnerSession(request, secret, installation))
    )
      return null;
    return yield* withResponse(
      network,
      new URL("/api/releases/latest", installation.controlPlaneOrigin),
      { headers: { Accept: "application/json" }, signal: request.signal },
      TIMEOUT_MS,
      new UpdateUnavailable(),
      (response) =>
        Effect.gen(function* () {
          if (!response.ok) return null;
          const data = yield* bodyJson(
            response,
            MAX_BODY_BYTES,
            new UpdateUnavailable(),
          );
          if (
            !data ||
            typeof data !== "object" ||
            !("artifactDigest" in data) ||
            !digest(data.artifactDigest) ||
            !("version" in data) ||
            typeof data.version !== "string" ||
            !("sourceRevision" in data) ||
            typeof data.sourceRevision !== "string" ||
            data.artifactDigest === release.artifactDigest
          )
            return null;
          const destination = new URL(
            "/connect",
            installation.controlPlaneOrigin,
          );
          destination.searchParams.set(
            "updateInstallation",
            installation.installationId,
          );
          return new Response(null, {
            status: 303,
            headers: {
              Location: destination.href,
              "Cache-Control": "no-store",
            },
          });
        }),
    ).pipe(Effect.catchTag("UpdateUnavailable", () => Effect.succeed(null)));
  });
}