import { getCanonicalHostRedirectUrl, getHostAwareInternalUrlPath, getHostRoutingContextFromRequest } from "../apps/web/app/utils/app/HostRouting.server";

export type HostRoutingRuntimeDecision =
  | { type: "redirect"; status: 308; location: string }
  | { type: "reject"; status: 404 }
  | { type: "dispatch"; target: "api" | "web"; request: Request };

const internalWebApiProxyHeader = "x-toolctrl-internal-web-api-proxy";

export function getHostRoutingRuntimeDecision(request: Request): HostRoutingRuntimeDecision {
  const context = getHostRoutingContextFromRequest(request);
  if (isInternalWebApiProxyRequest(request, context)) {
    const requestUrl = new URL(request.url);
    const rewrittenRequest = rewriteRequestUrl(request, `${requestUrl.pathname}${requestUrl.search}${requestUrl.hash}`);
    return {
      type: "dispatch",
      target: "web",
      request: rewrittenRequest,
    };
  }

  if (isRemovedLegacyRoute(request, context)) {
    return {
      type: "reject",
      status: 404,
    };
  }

  const canonicalRedirectUrl = getCanonicalHostRedirectUrl(request);
  if (canonicalRedirectUrl) {
    return {
      type: "redirect",
      status: 308,
      location: canonicalRedirectUrl,
    };
  }

  const rewrittenRequest = rewriteRequestUrl(request, getRuntimeInternalUrlPath(request, context));
  return {
    type: "dispatch",
    target: context === "api" ? "api" : "web",
    request: rewrittenRequest,
  };
}

function isInternalWebApiProxyRequest(request: Request, context: ReturnType<typeof getHostRoutingContextFromRequest>) {
  if (context !== "app" || request.headers.get(internalWebApiProxyHeader) !== "1") {
    return false;
  }

  const pathname = new URL(request.url).pathname;
  return pathname === "/internal/api/usage" || pathname === "/internal/api/stripe.webhooks" || pathname.startsWith("/internal/api/workflows/");
}

function isRemovedLegacyRoute(request: Request, context: ReturnType<typeof getHostRoutingContextFromRequest>) {
  const pathname = new URL(request.url).pathname.replace(/\/+$/g, "") || "/";
  const isLegacyApiV1Route = pathname === "/api/v1" || pathname.startsWith("/api/v1/");
  const isAdminApiSectionRoute = context === "admin" && (pathname === "/api" || pathname.startsWith("/api/")) && !isLegacyApiV1Route;
  return (
    pathname === "/app" ||
    pathname.startsWith("/app/") ||
    pathname === "/admin" ||
    pathname.startsWith("/admin/") ||
    (!isAdminApiSectionRoute && (pathname === "/api" || (pathname.startsWith("/api/") && !isLegacyApiV1Route)))
  );
}

function getRuntimeInternalUrlPath(request: Request, context: ReturnType<typeof getHostRoutingContextFromRequest>) {
  if (context === "app") {
    const url = new URL(request.url);
    return `${url.pathname}${url.search}${url.hash}`;
  }

  return getHostAwareInternalUrlPath(request);
}

function rewriteRequestUrl(request: Request, internalUrlPath: string) {
  const url = new URL(request.url);
  url.pathname = "/";
  url.search = "";
  url.hash = "";

  const rewrittenUrl = new URL(internalUrlPath, url);
  return new Request(rewrittenUrl, request);
}