# Felix server
{
  config,
  lib,
  pkgs,
  ...
}:
let

  cfg = config.services.felix;

in

{

  ###### interface

  options = {

    services.felix = {

      enable = lib.mkEnableOption "the Apache Felix OSGi service";

      bundles = lib.mkOption {
        type = lib.types.listOf lib.types.package;
        default = [ pkgs.felix_remoteshell ];
        defaultText = lib.literalExpression "[ pkgs.felix_remoteshell ]";
        description = "List of bundles that should be activated on startup";
      };

      user = lib.mkOption {
        type = lib.types.str;
        default = "osgi";
        description = "User account under which Apache Felix runs.";
      };

      group = lib.mkOption {
        type = lib.types.str;
        default = "osgi";
        description = "Group account under which Apache Felix runs.";
      };

    };

  };

  ###### implementation

  config = lib.mkIf cfg.enable {
    users.groups.osgi.gid = config.ids.gids.osgi;

    users.users.osgi = {
      uid = config.ids.uids.osgi;
      description = "OSGi user";
      home = "/homeless-shelter";
    };

    systemd.services.felix = {
      description = "Felix server";
      wantedBy = [ "multi-user.target" ];

      preStart = ''
        # Initialise felix instance on first startup
        if [ ! -d /var/felix ]
        then
          # Symlink system files

          mkdir -p /var/felix
          chown ${cfg.user}:${cfg.group} /var/felix

          for i in ${pkgs.felix}/*
          do
              if [ "$i" != "${pkgs.felix}/bundle" ]
              then
                  ln -sfn $i /var/felix/$(basename $i)
              fi
          done

          # Symlink bundles
          mkdir -p /var/felix/bundle
          chown ${cfg.user}:${cfg.group} /var/felix/bundle

          for i in ${pkgs.felix}/bundle/* ${toString cfg.bundles}
          do
              if [ -f $i ]
              then
                  ln -sfn $i /var/felix/bundle/$(basename $i)
              elif [ -d $i ]
              then
                  for j in $i/bundle/*
              do
                  ln -sfn $j /var/felix/bundle/$(basename $j)
              done
              fi
          done
        fi
      '';

      script = ''
        cd /var/felix
        ${pkgs.su}/bin/su -s ${pkgs.bash}/bin/sh ${cfg.user} -c '${pkgs.jre}/bin/java -jar bin/felix.jar'
      '';
    };
  };
}