import datetime
from DIRAC.DataManagementSystem.private.FTS3Utilities import FTS3Serializable


class FTS3File(FTS3Serializable):
  """ This class represents an a File on which a given Operation
      (Transfer, Staging) should be executed
   """

  ALL_STATES = ['New',  # Nothing was attempted yet on this file
                'Submitted',  # From FTS: Initial state of a file as soon it's dropped into the database
                'Ready',  # From FTS: File is ready to become active
                'Active',  # From FTS: File went active
                'Finished',  # From FTS: File finished gracefully
                'Canceled',  # From FTS: Canceled by the user
                'Staging',  # From FTS: When staging of a file is requested
                'Failed',  # From FTS: File failure
                'Defunct',  # Totally fail, no more attempt will be made
                'Started',  # From FTS: File transfer has started
                ]

  # These are the states that we consider final.
  # No new attempts will be done on our side for
  # FTS3Files reaching one of these
  # Note that Canceled is not final state, because
  # FTS fails some transfers as "Canceled" (gsiftp timeout)

  FINAL_STATES = ['Finished', 'Defunct']

  FTS_SUCCESS_STATES = ['Finished']
  FTS_FAILED_STATES = ['Canceled', 'Failed']

  # These are the states that the fts servers consider final.
  # No new attempts will be done on their side, but we can
  # still retry.
  FTS_FINAL_STATES = FTS_SUCCESS_STATES + FTS_FAILED_STATES
  INIT_STATE = 'New'

  _attrToSerialize = ['fileID', 'operationID', 'status', 'attempt', 'creationTime',
                      'lastUpdate', 'rmsFileID', 'checksum', 'size', 'lfn', 'error', 'targetSE']

  def __init__(self):

    self.status = FTS3File.INIT_STATE
    self.attempt = 0

    now = datetime.datetime.utcnow().replace(microsecond=0)

    self.creationTime = now
    self.lastUpdate = now

    self.rmsFileID = 0
    self.checksum = None
    self.size = 0

    self.lfn = None
    self.error = None

    self.targetSE = None

  @staticmethod
  def fromRMSFile(rmsFile, targetSE):
    """ Returns an FTS3File constructed from an RMS File.
        It takes the value of LFN, rmsFileID, checksum and Size

        :param rmsFile: the RMS File to use as source
        :param targetSE: the SE target

        :returns: an FTS3File instance
    """
    ftsFile = FTS3File()
    ftsFile.lfn = rmsFile.LFN
    ftsFile.rmsFileID = rmsFile.FileID
    ftsFile.checksum = rmsFile.Checksum
    ftsFile.size = rmsFile.Size
    ftsFile.targetSE = targetSE

    return ftsFile
