#Read last line from large log files by bits and
#savie it to a single line CSV to be monitored in QGIS
#SeaIT - rev 190224a


# required
import os

#The file to read from - use a small one to test in case it shits itself
#readfile = "Z:/10030530 Borssele III&IV_SBP/21 NHP/21 Survey Online/01 [100XXXXX - Online Project]/LogFiles/Output to QGIS - Logfile 24Feb19.txt"
readfile = "Z:/10030530 Borssele III&IV_SBP/21 NHP/21 Survey Online/01 [100XXXXX - Online Project]/LogFiles/BLACKBOX Borssele III IV SBP.txt"

#Your CSV to write to - will be created if non existing
writefile = "Z:/10030530 Borssele III&IV_SBP/21 NHP/29 Reporting/20 Ops QGIS/Ops QGIS Layers/07 SBP Phase/vessel.csv"

#Do the magic
with open(readfile, 'rb') as fr:
  fr.seek(-2, os.SEEK_END)
  while fr.read(1) != b'\n':
    fr.seek(-2, os.SEEK_CUR)
  with open(writefile, 'w+') as fw:
    fw.writelines(fr.readline().decode())