main() {
  #### metadata examples ####

  # before version 4.2.7 several microservices(functions) are required achieve metadata manipulation
  # generally data structures of key pairs are created, applied or removed from the data-object/collection/resource
  # from version 4.2.7 the msiModAVUMetadata microservice greatly simplifies metadata transformation
  # for any version - retrieve metadata with sql like queries against the iRODS database, this is equivalent to the 'imeta ls' command

  ### metadata structures

  # sample metadata in the % delimted format for msiString2KeyValPair
  *str = "a=10%zebra=horse%hula=dance"

  # load kvp structure from string
  msiString2KeyValPair(*str, *kvp);

  # add some keys with values
  msiAddKeyVal(*kvp, "art", "crayon");
  msiGetSystemTime(*Time, "human");
  msiAddKeyVal(*kvp, "timestamp", *Time);
  
  # print all keys and values
  msiPrintKeyValPair("stdout", *kvp);
  writeKeyValPairs("stdout", *kvp, " || ")

  # print all keys
  foreach(*kvp) {
    writeLine("stdout", *kvp);
  }

  # print all keys with values
  foreach(*i in *kvp) {
    msiGetValByKey(*kvp,*i,*result);
    writeLine("stdout", "1: *i = *result"); 
  }

  # print key=value where key like zeb*
  # print key=value where value matches *Time (set with msiGetSystemTime above)   
  # print key=value where string value matches 10, convert to int and divide
  foreach(*i in *kvp) {
    msiGetValByKey(*kvp,*i,*result);
    if (*i like "zeb*") then {
      writeLine("stdout","2: *i = *result")
    } else if (*result == *Time) then {
      writeLine("stdout","2: *i = *result")
    } else if (*result == "10") then {
      *number=int("*result")/2
      writeLine("stdout","2: *i = *number")
    } else {
      writeLine("stdout","2: no match")
    }
  }

  # more conditional behaviour
  foreach(*i in *kvp) {
    msiGetValByKey(*kvp,*i,*result);
    #if (*result == "dance" || *i == "art" || *i == "zebra") then { # this is a valid condition, however multiple OR with != / "not like" operators are not pre-evaluated correctly
    if (*i == "a" && *result == str(10)) then { # must preceed the else statement or will not be matched
      writeLine("stdout","3: AND *i = *result")
    } else if (*result not like "dance") then {
      writeLine("stdout","3: *i = *result")
    }
  } 

  ## Add/Remove metadata for files(data objects) or directories(collections) ##
 
  # print all session variables (rei) with msiGetSessionVarValue, when running the rule locally without script parameters the only useful variables are userNameClient= / rodsZoneClient=
  # when run from the server rules engine, there are many more useful session variables
  #msiGetSessionVarValue("all", "client");

  # access the variables as $<variable name>
  *testpath = "/$rodsZoneClient/home/$userNameClient"
  *newfile = "/$rodsZoneClient/home/$userNameClient/test.txt"
  
  # test for valid path, errorcode microservice is used to ensure the script does not exit on failure instead return boolean
  *a = errorcode(msiObjStat(*testpath,*status)) >=0
  writeLine("stdout","4: collection exists: *testpath *a")

  # if path exists add/remove metadata
  if (errorcode(msiObjStat(*testpath,*status)) >=0) then {
    # remove file without sending to trash and unregister from database
    if (errorcode(msiObjStat(*newfile,*status)) >=0) then {
      msiDataObjUnlink("objPath=*newfile++++forceFlag=++++unreg=",*status)
      writeLine("stdout","4: file removed: *newfile")
    }

    # create a file, forceFlag attribute required to overwrite file, resource can be specified here, note the field delimiter "destRescName=demoResc++++forceFlag="
    *content = "test.txt content"
    msiDataObjCreate(*newfile,"forceFlag=",*file_descriptor)
    msiDataObjWrite(*file_descriptor,*content,*write_length)
    msiDataObjClose(*file_descriptor,*status)
    writeLine("stdout","4: file created: *newfile")

    # apply metadata to object from kvp structure
    msiAssociateKeyValuePairsToObj(*kvp,*newfile,"-d")

    # get data object and collection from a full path string
    #*filepath_element = ( size( (split(*newfile,"/")) ) )
    #*file = (elem((split(*newfile,"/")), (*filepath_element - 1) ))
    #*data_object = (elem( (split(*newfile,"/")), ( (size((split(*newfile,"/")))) - 1) ))
    msiSplitPath(*newfile,*collection,*file)
    
    # query iRODS db for metadata of file, load into a new key pair structure
    *query = SELECT META_DATA_ATTR_NAME,META_DATA_ATTR_VALUE WHERE DATA_NAME = '*file' AND COLL_NAME = '*collection'
    foreach(*row in *query) {
      #msiPrintKeyValPair("stdout",*row)
      #writeLine("stdout","next row")
      msiGetValByKey(*row,"META_DATA_ATTR_NAME",*key);
      msiGetValByKey(*row,"META_DATA_ATTR_VALUE",*value);
      msiAddKeyVal(*query_kvp, *key, *value);
    }

    # create a new 'trimmed' metadata structure including the key pairs to be removed
    foreach(*i in *query_kvp) {
      #writeLine("stdout", "key is *i")
      if (*i == "a" || *i == "art") then {
        msiGetValByKey(*query_kvp,*i,*result)
        writeLine("stdout","4: metadata to keep on *newfile, *i=*result")
      } else {
        msiGetValByKey(*query_kvp,*i,*result)
        writeLine("stdout","4: metadata to remove from *newfile, *i=*result")
        msiAddKeyVal(*new_kvp, *i, *result)        
      }
    }
    # remove key pairs listed in the new metadata structure from the data object 
    msiRemoveKeyValuePairsFromObj(*new_kvp,*newfile,"-d")

    # create a new kvp structure, add key pairs
    msiAddKeyVal(*kvp2, "company", "OCF");
    msiAddKeyVal(*kvp2, "department", "Cloud");
    msiGetSystemTime(*created_epoc, "unix")
    msiAddKeyVal(*kvp2, "create_date_epoc", *created_epoc );

    # get system time, load into list and grab elements based on position
    msiGetFormattedSystemTime(*created,"human","%d-%02d-%02d-%02d-%02d-%02d")
    writeLine("stdout", "4: year:" ++ " " ++ (elem((split(*created,"-")),0)) )
    *year = elem((split(*created,"-")),0)
    *month = elem((split(*created,"-")),1)
    *day = elem((split(*created,"-")),2)
    msiAddKeyVal(*kvp2, "create_year", *year );
    msiAddKeyVal(*kvp2, "create_month", *month );
    msiAddKeyVal(*kvp2, "create_day", *day );

    # add meta data to the data object; -d file(data object), -C directory(collection)
    msiAssociateKeyValuePairsToObj(*kvp2,*newfile,"-d");

    # find files with metadata between an epoc date range
    # supported operators
    #>=
    #<=
    #=
    #<
    #>
    #'1' '100'
    #
    # 2020(1575072000) - 2030(1890691200)
    *query = SELECT DATA_NAME WHERE COLL_NAME = '*collection' AND META_DATA_ATTR_NAME = 'create_date_epoc' AND META_DATA_ATTR_VALUE BETWEEN '01575072000' '01890691200'
    foreach(*row in *query) {
      msiGetValByKey(*row,"DATA_NAME",*data_name)
      writeLine("stdout", "4: file: " ++ "*data_name" ++ " created between 2020 - 2030" )
    }

  }

  ### msiModAVUMetadata - change metadata directly on the object/collection/resource ###

  # this is new microservice as of version 4.2.7 and easy to use
  # msiModAVUMetadata allows key, value and unit (AVU) manipulation, much like the imeta icommand
  # assigning an additional attribute 'unit' to the key pair is useful and can be treated as a secondary value or left empty ""
  
  # remove all key pairs directly from the data object
  msiModAVUMetadata("-d","*newfile","rmw", "%", "%", "%")

  # add new key pair directly to the data object
  msiModAVUMetadata("-d","*newfile","add", "car", "ford", "string")

  # change value for key directly on the data object
  msiModAVUMetadata("-d","*newfile","set", "car", "toyoda", "string")

  # remove key pair directly on the data object
  msiModAVUMetadata("-d","*newfile","rm", "car", "toyoda", "string")

  # wildcard remove key pairs directly on the data object
  msiModAVUMetadata("-d","*newfile","add", "car", "subaru", "string")
  msiModAVUMetadata("-d","*newfile","add", "car", "suzuki", "string")
  msiModAVUMetadata("-d","*newfile","add", "car", "saab", "string")
  msiModAVUMetadata("-d","*newfile","rmw", "car", "su%", "%")
  #msiModAVUMetadata("-d","*newfile","rmw", "ca%", "%", "%")

  # add some meta data with arbitrary unit types
  msiModAVUMetadata("-d","*newfile","add", "catC", "yes", "damage")
  msiModAVUMetadata("-d","*newfile","add", "price", "1200", "sterling")

  ## searching with metadata

  # search for files in a collection where the key unit matches damage and the key value matches yes, return the filename key value key name with value yes and unit damage 
  *query = SELECT DATA_NAME,META_DATA_ATTR_NAME WHERE COLL_NAME = '*collection' AND META_DATA_ATTR_UNITS = 'damage' AND META_DATA_ATTR_VALUE like 'y%'
  foreach(*row in *query) {
    msiGetValByKey(*row,"DATA_NAME",*target_file)
    msiGetValByKey(*row,"META_DATA_ATTR_NAME",*damage_type)
    # search for car key value using the file name 
    *sub_query = SELECT META_DATA_ATTR_VALUE WHERE COLL_NAME = '*collection' AND DATA_NAME = '*target_file' AND META_DATA_ATTR_NAME = 'car'
    foreach(*sub_row in *sub_query) {
      msiGetValByKey(*sub_row,"META_DATA_ATTR_VALUE",*car)
      # search for the price key value under threshold (string is dynamically evaluated as numeric)
      *sub_query = SELECT META_DATA_ATTR_VALUE WHERE COLL_NAME = '*collection' AND DATA_NAME = '*target_file' AND META_DATA_ATTR_NAME = 'price' AND META_DATA_ATTR_VALUE < '1201'
      foreach(*sub_row in *sub_query) {
        msiGetValByKey(*sub_row,"META_DATA_ATTR_VALUE",*price)
        #writeLine("stdout", *price)
      }
      # if price variable set, its value below 1201
      if (errorcode(*price) >=0) then {
        writeLine("stdout","5: writeoff: *damage_type *car £*price")
      }
    }
  }

}
INPUT null
OUTPUT ruleExecOut