import os
import shutil
import datetime
import settings

def backuppath(date = None):
    '''Return backup file name for datetime.date instance date, or if date is None, for today.'''
    if not date:
        date = datetime.date.today()
    
    filename = date.strftime("backup-%Y-%m-%d.db")
    backupdir = settings.parser.get('DEFAULT', 'backupdir')
    return os.path.join(backupdir, filename)

def cleanbackups():
    '''Clean old backups. Get backupdir and the number of backups to keep from ConfigParser.'''
    backupdir = settings.parser.get('DEFAULT', 'backupdir')
    count = settings.parser.get('DEFAULT', 'keepbackups')
    
    files = os.listdir(backupdir)
    files = [f for f in files if f.startswith('backup-') and f.endswith('.db')]
    files.sort() # Oldest first
    
    if len(files) <= count:
        return
    
    removefiles = files[:(len(files) - count)]
    for f in removefiles:
        os.remove(f)

def dobackup():
    '''Backup database. Get database location and backupdir from ConfigParser.'''
    backupdir = settings.parser.get('DEFAULT', 'backupdir')
    if not os.path.isdir(backupdir):
        os.mkdir(backupdir)
    
    dst = backuppath()
    src = settings.parser.get('DEFAULT', 'dbfile')
    
    if os.path.isfile(dst):
        return # We already have a backup for today

    shutil.copyfile(src, dst)