{ config, pkgs, ... }:

with pkgs.lib;

let
  inherit (pkgs) sitecopy;

  stateDir = "/var/spool/sitecopy";

  sitecopyCron = backup : ''
    ${if backup ? period then backup.period else config.services.sitecopy.period} root ${sitecopy}/bin/sitecopy --storepath=${stateDir} --rcfile=${stateDir}/${backup.name}.conf --update ${backup.name}
  ''; 
in

{

  options = {
  
    services.sitecopy = {

      enable = mkOption {
        default = false;
        description = ''
          Whether to enable sitecopy backups of specified directories.
        '';
      };

      period = mkOption {
        default = "15 04 * * *";
        description = ''
          This option defines (in the format used by cron) when the
          sitecopy backup are being run.
          The default is to update at 04:15 (at night) every day.
        '';
      };

      backups = mkOption {
        example = [
          { name = "test"; 
            local = "/tmp/backup"; 
            remote = "/staff-groups/ewi/st/strategoxt/backup/test";
            server = "webdata.tudelft.nl";
            protocol = "webdav";
            https = true ;
            symlinks = "maintain" ;
          }
        ];
        default = [];
        description = ''
           List of attributesets describing the backups. 

           Username/password are extracted from <filename>${stateDir}/sitecopy.secrets</filename> at activation 
           time. The secrets file lines should have the following structure:
           <screen>
             server username password
           </screen>
        '';
      }; 

    };

  };

  config = mkIf config.services.sitecopy.enable {
    environment.systemPackages = [ sitecopy ];

    services.cron.systemCronJobs = map sitecopyCron config.services.sitecopy.backups;

    system.activationScripts.sitecopyBackup = stringAfter [ "stdio" "users" ]
      ''  
        mkdir -m 0700 -p ${stateDir}
        chown root ${stateDir}
        touch ${stateDir}/sitecopy.secrets
        chown root ${stateDir}/sitecopy.secrets

        ${pkgs.lib.concatStrings (map ( b: ''
            unset secrets
            unset secret
            secrets=`grep '^${b.server}' ${stateDir}/sitecopy.secrets | head -1`
            secret=($secrets)
            cat > ${stateDir}/${b.name}.conf << EOF
              site ${b.name}
              server ${b.server}
              protocol ${b.protocol}
              username ''${secret[1]}
              password ''${secret[2]}
              local ${b.local}
              remote ${b.remote}
              symlinks ${b.symlinks}
              ${if b.https then "http secure" else ""}
            EOF
            chmod 0600 ${stateDir}/${b.name}.conf
            if ! test -e ${stateDir}/${b.name} ; then
              echo " * Initializing sitecopy '${b.name}'"
              ${sitecopy}/bin/sitecopy --storepath=${stateDir} --rcfile=${stateDir}/${b.name}.conf --initialize ${b.name}
            else
              echo " * Sitecopy '${b.name}' already initialized"
            fi
          '' ) config.services.sitecopy.backups 
        )}
      '';
  };
  
}