{pkgs, config, ...}:

###### interface
let
  inherit (pkgs.lib) mkOption mkIf;

  options = {
    services = {
      tomcat = {
        enable = mkOption {
          default = false;
          description = "Whether to enable Apache Tomcat";
        };
        
        baseDir = mkOption {
          default = "/var/tomcat";
          description = "Location where Tomcat stores configuration files, webapplications and logfiles";
        };
        
        user = mkOption {
          default = "tomcat";
          description = "User account under which Apache Tomcat runs.";
        };      
        
        deployFrom = mkOption {
          default = "";
          description = "Location where webapplications are stored. Leave empty to use the baseDir.";
        };
        
        javaOpts = mkOption {
          default = "";
          description = "Parameters to pass to the Java Virtual Machine which spawns Apache Tomcat";
        };
        
        catalinaOpts = mkOption {
          default = "";
          description = "Parameters to pass to the Java Virtual Machine which spawns the Catalina servlet container";
        };
        
        sharedLibFrom = mkOption {
          default = "";
          description = "Location where shared libraries are stored. Leave empty to use the baseDir.";
        };
        
        commonLibFrom = mkOption {
          default = "";
          description = "Location where common libraries are stored. Leave empty to use the baseDir.";
        };
        
        contextXML = mkOption {
          default = "";
          description = "Location of the context.xml to use. Leave empty to use the default.";
        };
      };
    };
  };
in

###### implementation

let
  cfg = config.services.tomcat;
in

mkIf config.services.tomcat.enable {
  require = [
    options
  ];

  services = {
    extraJobs = [{
      name = "tomcat";
      
      groups = [
        { name = "tomcat";
          gid = config.ids.gids.tomcat;
        }
      ];
      
      users = [
        { name = "tomcat";
          uid = config.ids.uids.tomcat;
          description = "Tomcat user";
          home = "/homeless-shelter";
        }
      ];
      
      job = ''
        description "Apache Tomcat server"

        start on network-interface/started
        stop on network-interfaces/stop
        
        start script
            # Create initial state data
            
            if ! test -d ${cfg.baseDir}
            then    
                mkdir -p ${cfg.baseDir}/webapps
                mkdir -p ${cfg.baseDir}/shared
                mkdir -p ${cfg.baseDir}/lib
                cp -av ${pkgs.tomcat6}/{conf,temp,logs} ${cfg.baseDir}
            fi
            
            # Deploy context.xml
            
            if test "${cfg.contextXML}" = ""
            then
                cp ${pkgs.tomcat6}/conf/context.xml.default ${cfg.baseDir}/conf/context.xml
            else
                cp ${cfg.contextXML} ${cfg.baseDir}/conf/context.xml
            fi
                    
            # Deploy all webapplications
            
            if ! test "${cfg.deployFrom}" = ""
            then
                rm -rf ${cfg.baseDir}/webapps
                mkdir -p ${cfg.baseDir}/webapps
                for i in ${cfg.deployFrom}/*
                do
                    cp -rL $i ${cfg.baseDir}/webapps
                done
            fi
            
            # Fix permissions
            
            chown -R ${cfg.user} ${cfg.baseDir}
            
            for i in `find ${cfg.baseDir} -type d`
            do
                chmod -v 755 $i
            done
            
            for i in `find ${cfg.baseDir} -type f`
            do
                chmod -v 644 $i
            done

            # Deploy all common libraries
                    
            rm -rf ${cfg.baseDir}/lib/*
            
            if test "${cfg.commonLibFrom}" = ""
            then
                commonLibFrom="${pkgs.tomcat6}/lib";
            else
                commonLibFrom="${cfg.commonLibFrom}";
            fi
            
            for i in $commonLibFrom/*.jar
            do
                ln -s $i ${cfg.baseDir}/lib
            done

            # Deploy all shared libraries
            
            if ! test "${cfg.sharedLibFrom}" = ""
            then
                rm -f ${cfg.baseDir}/shared/lib
                ln -s ${cfg.sharedLibFrom} ${cfg.baseDir}/shared/lib
            fi

        end script
        
        respawn ${pkgs.su}/bin/su -s ${pkgs.bash}/bin/sh ${cfg.user} -c 'CATALINA_BASE=${cfg.baseDir} JAVA_HOME=${pkgs.jdk} JAVA_OPTS="${cfg.javaOpts}" CATALINA_OPTS="${cfg.catalinaOpts}" ${pkgs.tomcat6}/bin/startup.sh; sleep 1000d'
        
        stop script
            echo "Stopping tomcat..."
            CATALINA_BASE=${cfg.baseDir} JAVA_HOME=${pkgs.jdk} ${pkgs.su}/bin/su -s ${pkgs.bash}/bin/sh ${cfg.user} -c ${pkgs.tomcat6}/bin/shutdown.sh
        end script
      '';
    }];
  };
}