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

with lib;

let
  cfg = config.services.mesos.master;
  
in {

  options.services.mesos = {
    
    master = {
      enable = mkOption {
        description = "Whether to enable the Mesos Master.";
        default = false;
        type = types.uniq types.bool;
      };

      port = mkOption {
        description = "Mesos Master port";
        default = 5050;
        type = types.int;
      };

      zk = mkOption {
        description = ''
          ZooKeeper URL (used for leader election amongst masters).
          May be one of:
            zk://host1:port1,host2:port2,.../mesos
            zk://username:password@host1:port1,host2:port2,.../mesos
        '';
        type = types.str;
      };
      
      workDir = mkOption {
        description = "The Mesos work directory.";
        default = "/var/lib/mesos/master";
        type = types.str;
      };
      
      extraCmdLineOptions = mkOption {
        description = ''
	  Extra command line options for Mesos Master.
	  
	  See https://mesos.apache.org/documentation/latest/configuration/
	'';
        default = [ "" ];
        type = types.listOf types.string;
        example = [ "--credentials=VALUE" ];
      };
      
      quorum = mkOption {
        description = ''
          The size of the quorum of replicas when using 'replicated_log' based
          registry. It is imperative to set this value to be a majority of
          masters i.e., quorum > (number of masters)/2.
          
          If 0 will fall back to --registry=in_memory.
        '';
        default = 0;
        type = types.int;
      };
      
      logLevel = mkOption {
        description = ''
          The logging level used. Possible values:
            'INFO', 'WARNING', 'ERROR'
        '';
        default = "INFO";
        type = types.str;
      };

    };


  };


  config = mkIf cfg.enable {
    systemd.services.mesos-master = {
      description = "Mesos Master";
      wantedBy = [ "multi-user.target" ];
      after = [ "network-interfaces.target" ];
      serviceConfig = {
	ExecStart = ''
	  ${pkgs.mesos}/bin/mesos-master \
	    --port=${toString cfg.port} \
	    --zk=${cfg.zk} \
	    ${if cfg.quorum == 0 then "--registry=in_memory" else "--registry=replicated_log --quorum=${cfg.quorum}"} \
	    --work_dir=${cfg.workDir} \
	    --logging_level=${cfg.logLevel} \
	    ${toString cfg.extraCmdLineOptions}
	'';
	PermissionsStartOnly = true;
      };
      preStart = ''
	mkdir -m 0700 -p ${cfg.workDir}
      '';
    };
  };
  
}