## Amazon S3 manager
 ## Author: Michal Ludvig <michal@logix.cz>
 ##         http://www.logix.cz/michal
 ## License: GPL Version 2

 ## Copyright: TGRMN Software and contributors

 import logging

 from SortedDict import SortedDict
 import Utils

 import Config

 zero_length_md5 = "d41d8cd98f00b204e9800998ecf8427e"

 cfg = Config.Config()

 class FileDict(SortedDict):
     def __init__(self, mapping = {}, ignore_case = True, **kwargs):
         SortedDict.__init__(self, mapping = mapping, ignore_case = ignore_case, **kwargs)
         self.hardlinks = dict() # { dev: { inode : {'md5':, 'relative_files':}}}
         self.by_md5 = dict() # {md5: set(relative_files)}
 
     def record_md5(self, relative_file, md5):

         if md5 is None: return

         if md5 == zero_length_md5: return

         if md5 not in self.by_md5:
             self.by_md5[md5] = set()
         self.by_md5[md5].add(relative_file)
 
     def find_md5_one(self, md5):

         if md5 is None: return None

         try:
             return list(self.by_md5.get(md5, set()))[0]
         except:
             return None
 
     def get_md5(self, relative_file):
         """returns md5 if it can, or raises IOError if file is unreadable"""
         md5 = None
         if 'md5' in self[relative_file]:
             return self[relative_file]['md5']
         md5 = self.get_hardlink_md5(relative_file)

         if md5 is None and 'md5' in cfg.sync_checks:
             logging.debug(u"doing file I/O to read md5 of %s" % relative_file)

             md5 = Utils.hash_file_md5(self[relative_file]['full_name'])
         self.record_md5(relative_file, md5)
         self[relative_file]['md5'] = md5
         return md5
 

     def record_hardlink(self, relative_file, dev, inode, md5, size):

         if md5 is None: return

         if size == 0: return # don't record 0-length files

         if dev == 0 or inode == 0: return # Windows

         if dev not in self.hardlinks:
             self.hardlinks[dev] = dict()
         if inode not in self.hardlinks[dev]:
             self.hardlinks[dev][inode] = dict(md5=md5, relative_files=set())
         self.hardlinks[dev][inode]['relative_files'].add(relative_file)
 
     def get_hardlink_md5(self, relative_file):
         md5 = None
         dev = self[relative_file]['dev']
         inode = self[relative_file]['inode']
         try:
             md5 = self.hardlinks[dev][inode]['md5']
         except:
             pass
         return md5