{ pkgs, config, ... }:
let

  hostAddress = "192.168.100.10";
  containerAddress = "192.168.100.11";
  #syncthingGid = config.users.groups.syncthing.gid;

in {

  #  Nextcloud 19 is still supported, but CVE-2020-8259 & CVE-2020-8152 are unfixed!
  nixpkgs.config.permittedInsecurePackages = [ "nextcloud-19.0.6" ];

  containers.nextcloud = {

    # mount host folders
    bindMounts = {
      rootpassword = {
        hostPath = toString <secrets/nextcloud/root_password>;
        mountPoint = toString <secrets/nextcloud/root_password>;
        isReadOnly = true;
      };
      databasepassword = {
        hostPath = toString <secrets/nextcloud/database_password>;
        mountPoint = toString <secrets/nextcloud/database_password>;
        isReadOnly = true;
      };
      home = {
        # make sure this folder exist on the host
        hostPath = toString "/home/nextcloud";
        mountPoint = "/var/lib/nextcloud";
        isReadOnly = false;
      };
      db = {
        # make sure this folder exist on the host
        hostPath = toString "/home/nextcloud_db";
        mountPoint = "/var/lib/mysql";
        isReadOnly = false;
      };
      krops-lib = {
        mountPoint = toString <krops-lib>;
        hostPath = toString <krops-lib>;
        isReadOnly = true;
      };
      modules = {
        mountPoint = toString <modules>;
        hostPath = toString <modules>;
        isReadOnly = true;
      };
      # shared folders
      samples = {
        mountPoint =
          toString config.services.syncthing.declarative.folders.samples.path;
        hostPath =
          toString config.services.syncthing.declarative.folders.samples.path;
        isReadOnly = true;
      };
      movies = {
        mountPoint =
          toString config.services.syncthing.declarative.folders.movies.path;
        hostPath =
          toString config.services.syncthing.declarative.folders.movies.path;
        isReadOnly = true;
      };
      music = {
        mountPoint = toString
          config.services.syncthing.declarative.folders.music-library.path;
        hostPath = toString
          config.services.syncthing.declarative.folders.music-library.path;
        isReadOnly = true;
      };
      series = {
        mountPoint =
          toString config.services.syncthing.declarative.folders.series.path;
        hostPath =
          toString config.services.syncthing.declarative.folders.series.path;
        isReadOnly = true;
      };
    };

    # container network setup
    # see also nating on host system.
    privateNetwork = true;
    hostAddress = hostAddress;
    localAddress = containerAddress;

    autoStart = true;

    config = { config, pkgs, lib, ... }: {

      imports = [ <modules> <krops-lib> ];

      services.nginx = {

        # Use recommended settings
        recommendedGzipSettings = lib.mkDefault true;
        recommendedOptimisation = lib.mkDefault true;
        recommendedProxySettings = lib.mkDefault true;
        recommendedTlsSettings = lib.mkDefault true;

        # for graylog logging
        commonHttpConfig = let
          access_log_sink = "${hostAddress}:12304";
          error_log_sink = "${hostAddress}:12305";
        in ''
          log_format graylog2_json escape=json '{ "timestamp": "$time_iso8601", '
            '"facility": "nginx", '
            '"src_addr": "$remote_addr", '
            '"body_bytes_sent": $body_bytes_sent, '
            '"request_time": $request_time, '
            '"response_status": $status, '
            '"request": "$request", '
            '"request_method": "$request_method", '
            '"host": "$host",'
            '"upstream_cache_status": "$upstream_cache_status",'
            '"upstream_addr": "$upstream_addr",'
            '"http_x_forwarded_for": "$http_x_forwarded_for",'
            '"http_referrer": "$http_referer", '
            '"http_user_agent": "$http_user_agent" }';

          access_log syslog:server=${access_log_sink} graylog2_json;
          error_log syslog:server=${error_log_sink};
        '';
      };

      # don't forget the database backup before doing this
      # https://docs.nextcloud.com/server/stable/admin_manual/maintenance/backup.html
      # https://docs.nextcloud.com/server/stable/admin_manual/maintenance/upgrade.html
      # use snapshots in case of a rollback
      #nixpkgs.config.packageOverrides = super: {
      #  nextcloud = super.nextcloud.overrideAttrs (old: rec {
      #    name = "nextcloud-${version}";
      #    version = "18.0.1";
      #    src = super.fetchurl {
      #      url =
      #        "https://download.nextcloud.com/server/releases/nextcloud-18.0.1.tar.bz2";
      #      sha256 = "1h0rxpdssn1hc65k41zbvww9r4f79vbd9bixc9ri5n7hp0say3vp";
      #    };
      #  });
      #};

      networking.firewall.allowedTCPPorts = [ 80 ];
      networking.firewall.allowedUDPPorts = [ 80 ];

      # nextcloud database
      # ==================
      #
      # set user password:
      # -----------------
      # #> mysql
      # mysql> ALTER USER 'nextcloud'@'localhost' IDENTIFIED BY 'nextcloud-password';
      #
      # recreate database:
      # ------------------
      # mysql> DROP DATABASE nextcloud;
      # mysql> CREATE DATABASE nextcloud;
      #
      # migration:
      # ----------
      # nextcloud-occ db:convert-type --all-apps mysql nextcloud 127.0.0.1 nextcloud
      #
      # 4-byte stuff:
      # -------------
      # https://docs.nextcloud.com/server/18/admin_manual/configuration_database/mysql_4byte_support.html
      # if you do this don't forget --default-character-set=utf8mb4 for mysqldump
      services.mysql = {
        enable = true;
        package = pkgs.mysql;
        # https://nixos.org/manual/nixos/stable/release-notes.html#sec-release-20.09-incompatibilities
        ensureDatabases = [ "nextcloud" ];
        ensureUsers = [{
          name = "nextcloud";
          ensurePermissions = { "nextcloud.*" = "ALL PRIVILEGES"; };
        }];
        extraOptions = ''
          innodb_large_prefix=true
          innodb_file_format=barracuda
          innodb_file_per_table=1
        '';
      };

      # nextcloud setup
      services.nextcloud = {
        enable = true;
        #package = pkgs.nextcloud18;
        #package = pkgs.nextcloud.overrideAttrs (old: rec {
        #  name = "nextcloud-${version}";
        #  version = "18.0.1";
        #  src = pkgs.fetchurl {
        #    url =
        #      "https://download.nextcloud.com/server/releases/nextcloud-18.0.1.tar.bz2";
        #    sha256 = "1h0rxpdssn1hc65k41zbvww9r4f79vbd9bixc9ri5n7hp0say3vp";
        #  };
        #});
        autoUpdateApps.enable = true;
        #nginx.enable = true;
        hostName = "nextcloud.ingolf-wagner.de";
        #logLevel = 0;
        https = true;
        config = {
          adminpassFile = toString <secrets/nextcloud/root_password>;
          overwriteProtocol = "https";
          trustedProxies = [ "195.201.134.247" hostAddress ];
          dbtype = "mysql";
          dbpassFile = toString config.krops.userKeys."nextcloud".target;
          dbport = 3306;
        };
      };

      # provide password file for database with proper rights
      krops.userKeys."nextcloud" = {
        user = "nextcloud";
        source = toString <secrets/nextcloud/database_password>;
        requiredBy = [ "nginx.service" ];
      };

      environment.systemPackages = [ pkgs.smbclient ];

      # send log to host systems graylog (use tinc or wireguard if host is not graylog)
      services.SystemdJournal2Gelf.enable = true;
      services.SystemdJournal2Gelf.graylogServer = "${hostAddress}:11201";
    };
  };

  # give containers internet access
  networking.nat.enable = true;
  networking.nat.internalInterfaces = [ "ve-nextcloud" ];
  networking.nat.externalInterface = "enp2s0f1";

  # don't let networkmanager manger container network
  networking.networkmanager.unmanaged = [ "interface-name:ve-*" ];

  # open ports for logging
  networking.firewall.interfaces."ve-nextcloud".allowedTCPPorts =
    [ 11201 12304 12305 ];
  networking.firewall.interfaces."ve-nextcloud".allowedUDPPorts =
    [ 11201 12304 12305 ];

  # host nginx setup
  services.nginx = {
    enable = true;
    recommendedProxySettings = true;
    virtualHosts = {
      "nextcloud.workhorse.private" = {
        serverAliases = [
          "nextcloud.ingolf-wagner.de"
          # "nextcloud.gaykraft.com"
        ];
        locations."/" = {
          proxyPass = "http://${containerAddress}";
          extraConfig = ''
            # allow big uploads
            # -----------------
            client_max_body_size 0;
          '';
        };
      };
    };
  };

}