Jyrä

# -*- coding: utf-8 -*-
"The database update main procedure."

__copyright__ = """
Database updater script.
Copyright (C) 2010, 2011  Jyrki Launonen

This file is part of slavemaster.

Slavemaster is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Slavemaster is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with Slavemaster.  If not, see <http://www.gnu.org/licenses/>.
"""

# Must be run from project root with command:
#  python -m update.updater
from update import uc


def findFromVersion():
   "Try to find current version number."
   try:
      verinfo = __import__("version", globals(), locals(), ['VERSION'])
      return verinfo.VERSION
   except ImportError:
      print "updater: Current db-version information (../version.py) could not be found!"
      print "         Please write following information in mentioned file:"
      print "  VERSION=\"xxx.yyy\""
      print "         xxx.yyy is version number of installed database/software, like \"0.2\"."
      print "         Then run this tool again..."
   return None


def getMod(start, what):
   "Search 'what'-version starting from uc'start'-module."
   while True:
      try:
         module = __import__("update.uc%i" % start, [], [], ['MAP'])
      except ImportError, ex:
         # No module that had this version. Error?
         print ex
         return start, None

      if what in module.MAP:
         return start + 1, module
      start += 1
   #


def findLast(module_index):
   "Find last existing version number or None if it is not in this module."
   module = __import__("update.uc%i" % module_index, [], [], ['MAP'])
   for key, value in module.MAP.iteritems():
      if value is None:
         # Reached end.
         return key
      if value is uc.NEXT:
         # Reached tag "Next module"
         return None
   
   raise KeyError, "Erroneous line of updates - "\
      "could not find latest version number."


def execSQL(sql):
   "Exec given sql statements (separately) and commit them."
   from django.db import connection, transaction
   cursor = connection.cursor() #@UndefinedVariable

   # Data modifying operation - commit required
   for statement in sql.split(";"):
      statement = statement.strip()
      if statement == "":
         continue
      print("## %s;" % statement) #DEBUG :)
      cursor.execute("%s;" % statement)
   transaction.commit_unless_managed()
#


def main():
   "Main entry point."
   import os
   
   # Declare settings module..
   if "DJANGO_SETTINGS_MODULE" not in os.environ:
      os.environ["DJANGO_SETTINGS_MODULE"] = "slavemaster.settings"
   
   # Keep deleted tables so update can do its job
   os.environ["KEEP_DJANGO_TABLES"] = "1"
   
   import sys
   if len(sys.argv) == 2 and sys.argv[1] == "--generate-version":
      module_index = 0
      name = findLast(module_index)
      
      while name is None:
         module_index += 1
         name = findLast(module_index)
      
      print "VERSION=\"%s\"" % name
      exit(0)
   

   fromversion = findFromVersion()
   if fromversion is None:
      exit(1)

   module_index, detmod = getMod(0, fromversion)
   if detmod is None:
      print "updater: No update information found. Probably in latest state..."
      exit(0)

   
   anyUpdate = False
   current = fromversion
   while True:
      tgt = detmod.MAP[current]
      if tgt is None:
         if anyUpdate:
            print " * Reached %s. Updating 'current version'..." % current
            try:
               vdb = open("version.py", "w")
               vdb.write("VERSION=\"%s\"\n" % current)
               vdb.close()
            except IOError:
               print "updater: Failed to write 'version.py'. Please replace its"
               print "         contents with following line:"
               print "VERSION=\"%s\"" % current
            #
         break

      if tgt is not uc.NEXT:
         mod = tgt[0]
         modi = mod()

         if not modi.preCondition():
            print " * Skipping %s.%s" % (mod.__module__, mod.__name__)

         else:
            print " * Updating from %s to %s with %s" % (
               current,
               tgt[1],
               "%s.%s" % (mod.__module__, mod.__name__)
            )

            modi.preCommands()

            for cmdblob in modi.getCommands():
               execSQL(cmdblob)

            modi.postCommands()
            anyUpdate = True

         current = tgt[1]

      else:
         # Import different module.
         module_index, detmod = getMod(module_index, current)
         if detmod is None:
            print "updater: Lost track of versions!"
            exit(1)
         #
      #

   if not anyUpdate:
      print "updater: Already in latest state. No update performed."
   else:
      print "updater: All done."
   #

if __name__ == "__main__":
   main()