proxy/intermediate/nginx.nix

let
  lib = import <nixpkgs/lib>;
  servicesConfig = import ../config/services.nix;
  endpointsConfig = (import ../validation/endpoints.nix).getEndpointsConfig (import ../config/endpoints.nix);

  tunnelOffset = 10000;
  proxyOffset = servicesConfig.nginxProxyOffset;

  forwardingEndpoints = builtins.filter (endpoint: endpoint.type == "forwarding") endpointsConfig;
  proxyEndpoints = builtins.filter (endpoint: endpoint.type == "proxy") endpointsConfig;

  forwardingTlsEndpoints = builtins.filter (endpoint: endpoint.content.tls or false) forwardingEndpoints;
  forwardingHttpEndpoints = builtins.filter (endpoint: !(endpoint.content.tls or false)) forwardingEndpoints;
  proxyTlsEndpoints = builtins.filter (endpoint: endpoint.force_ssl or false) proxyEndpoints;

  forwardingTarget = endpoint: "127.0.0.1:${toString endpoint.content.port}";
  proxyBackendPort = endpoint: proxyOffset + endpoint.listenPort;
  proxyBackendTarget = endpoint: "127.0.0.1:${toString (proxyBackendPort endpoint)}";

  mkTlsRouteEntryForForwarding = endpoint: {
    domain = endpoint.domain;
    listenPort = endpoint.listenPort;
    upstream = forwardingTarget endpoint;
  };

  mkTlsRouteEntryForProxy = endpoint: {
    domain = endpoint.domain;
    listenPort = endpoint.listenPort;
    upstream = proxyBackendTarget endpoint;
  };

  tlsRouteEntriesRaw =
    map mkTlsRouteEntryForForwarding forwardingTlsEndpoints
    ++ map mkTlsRouteEntryForProxy proxyTlsEndpoints;

  groupedTlsRoutes =
    lib.foldl'
      (acc: entry:
        let
          key = toString entry.listenPort;
          previous = acc.${key} or [];
        in
          acc // {
            ${key} = previous ++ [ entry ];
          }
      )
      {}
      tlsRouteEntriesRaw;

  dedupeRouteEntriesByDomain = entries:
    builtins.attrValues (builtins.listToAttrs (map (entry: {
      name = entry.domain;
      value = entry;
    }) entries));

  mkTlsRouteMapForListenPort = listenPort:
    let
      routesForPort = groupedTlsRoutes.${toString listenPort} or [];
      routeEntries = dedupeRouteEntriesByDomain routesForPort;
      defaultRoute = if routeEntries == [] then null else (builtins.head routeEntries).upstream;
    in
      if defaultRoute == null then null else {
        inherit listenPort routeEntries defaultRoute;
      };

  tlsListenPorts = lib.unique (map (entry: entry.listenPort) tlsRouteEntriesRaw);
  tlsRouteMaps = builtins.filter (mapDef: mapDef != null) (map mkTlsRouteMapForListenPort tlsListenPorts);

  renderTlsServer = tlsRouteMap:
    let
      portString = toString tlsRouteMap.listenPort;
    in
    ''
    map $ssl_preread_server_name $proxy_upstream_${portString} {
      ${lib.concatStringsSep "\n" (map (entry: "${entry.domain} ${entry.upstream};") tlsRouteMap.routeEntries)}
      default ${tlsRouteMap.defaultRoute};
    }

    server {
      listen ${portString};
      proxy_pass $proxy_upstream_${portString};
      ssl_preread on;
    }
  '';

  groupedProxyEndpoints =
    lib.foldl'
      (acc: endpoint:
        let
          key = "${endpoint.domain}:${toString endpoint.listenPort}";
          previous = acc.${key} or {
            domain = endpoint.domain;
            publicListenPort = endpoint.listenPort;
            listenPort = proxyBackendPort endpoint;
            locations = {};
            forceSSL = false;
          };
          location = {
            proxyPass = "http://${endpoint.content.host}:${toString endpoint.content.port}";
          } // lib.optionalAttrs (endpoint.content ? websocket && endpoint.content.websocket) {
            proxyWebsockets = true;
          };
        in
          acc // {
            ${key} = previous // {
              listenPort = proxyBackendPort endpoint;
              forceSSL = previous.forceSSL || (endpoint.force_ssl or false);
              locations = previous.locations // {
                ${endpoint.endpoint} = location;
              };
            };
          }
      )
      {}
      proxyEndpoints;

  proxyBackendVirtualHosts = lib.mapAttrs (_: hostConfig: {
    serverName = hostConfig.domain;
    listen = [
      {
        addr = "127.0.0.1";
        port = hostConfig.listenPort;
        ssl = true;
      }
    ];
    onlySSL = true;
    extraConfig = ''
      absolute_redirect off;
      port_in_redirect off;
    '';
    locations = hostConfig.locations;
  } // lib.optionalAttrs (hostConfig.forceSSL && servicesConfig.nginx.acmeEmail != null) {
    useACMEHost = hostConfig.domain;
  }) groupedProxyEndpoints;

  forwardingHttpVirtualHosts = builtins.listToAttrs (map (endpoint: {
    name = "forward-http-${endpoint.domain}-${toString endpoint.listenPort}";
    value = {
      serverName = endpoint.domain;
      listen = [
        {
          addr = "0.0.0.0";
          port = endpoint.listenPort;
        }
      ];
      locations."/".proxyPass = "http://${forwardingTarget endpoint}";
    };
  }) forwardingHttpEndpoints);

  forwardingHttpDomains = lib.unique (map (endpoint: endpoint.domain) forwardingHttpEndpoints);

  localServiceAcmeDomains =
    lib.unique
      (map
        (hostConfig: hostConfig.domain)
        (builtins.attrValues (lib.filterAttrs (_: hostConfig: hostConfig.forceSSL) groupedProxyEndpoints)));

  localAcmeHttpVirtualHosts = builtins.listToAttrs (map (domain: {
    name = "acme-http-${domain}-80";
    value = {
      serverName = domain;
      listen = [
        {
          addr = "0.0.0.0";
          port = 80;
        }
      ];
      locations."^~ /.well-known/acme-challenge/" = {
        root = "/var/lib/acme/acme-challenge";
        extraConfig = ''
          auth_basic off;
          auth_request off;
        '';
      };
      locations."/" = {
        return = "301 https://$host$request_uri";
      };
    };
  }) (builtins.filter (domain: !(builtins.elem domain forwardingHttpDomains)) localServiceAcmeDomains));

  virtualHosts = forwardingHttpVirtualHosts // localAcmeHttpVirtualHosts // proxyBackendVirtualHosts;

  streamConfig = lib.concatStringsSep "\n\n" (map renderTlsServer tlsRouteMaps);
  publicListenPorts = lib.unique (map (endpoint: endpoint.listenPort) endpointsConfig);
in
{
  inherit endpointsConfig forwardingEndpoints proxyEndpoints streamConfig virtualHosts proxyOffset publicListenPorts localServiceAcmeDomains;
}