import time
import logging
import urllib
import sqlite3
from datetime import datetime

log = logging.getLogger('milter.greylist')

class Greylist(object):

  def __init__(self,dbname,grey_time=10,grey_expire=4,grey_retain=36):
    self.ignoreLastByte = False
    self.greylist_time = grey_time * 60         # minutes
    self.greylist_expire = grey_expire * 3600   # hours
    self.greylist_retain = grey_retain * 24 * 3600   # days
    self.conn = sqlite3.connect(dbname)
    self.conn.row_factory = sqlite3.Row
    try:
      self.conn.execute('''create table greylist(
        ip text , sender text, recipient text,
        firstseen timestamp, lastseen timestamp, cnt integer, umis text,
        primary key (ip,sender,recipient))''')
    except: pass

  def clean(self,timeinc=0):
    "Delete records past the retention limit."
    now = time.time() + timeinc - self.greylist_retain
    cur = self.conn.cursor()
    cur.execute('delete from greylist where lastseen < ?',(now,))
    cnt = cur.rowcount
    self.conn.commit()
    return cnt

  def check(self,ip,sender,recipient,timeinc=0):
    "Return number of allowed messages for greylist triple."
    cur = self.conn.cursor()
    cur.execute('''select firstseen,lastseen,cnt,umis from greylist where
      ip=? and sender=? and recipient=?''',(ip,sender,recipient))
    r = cur.fetchone()
    now = time.time() + timeinc
    cnt = 0
    if not r:
      cur.execute('''insert into 
        greylist(ip,sender,recipient,firstseen,lastseen,cnt,umis)
        values(?,?,?,?,?,?,?)''', (ip,sender,recipient,now,now,0,None))
    elif now > r['lastseen'] + self.greylist_retain:
      # expired
      log.debug('Expired greylist: %s:%s:%s',ip,sender,recipient)
      cur.execute('''update greylist set firstseen=?,lastseen=?,cnt=?,umis=?
        where ip=? and sender=? and recipient=?''',
        (now,now,0,None,ip,sender,recipient))
    elif now < r['firstseen'] + self.greylist_time + 5:
      # still greylisted
      log.debug('Early greylist: %s:%s:%s',ip,sender,recipient)
      #r = Record()
      cur.execute('''update greylist set lastseen=?
        where ip=? and sender=? and recipient=?''',
        (now,ip,sender,recipient))
    elif r['cnt'] or now < r['firstseen'] + self.greylist_expire:
      # in greylist window or active
      cnt = r['cnt'] + 1
      cur.execute('''update greylist set lastseen=?,cnt=?
        where ip=? and sender=? and recipient=?''',
        (now,cnt,ip,sender,recipient))
      log.debug('Active greylist(%d): %s:%s:%s',cnt,ip,sender,recipient)
    else:
      # passed greylist window
      log.debug('Late greylist: %s:%s:%s',ip,sender,recipient)
      cur.execute('''update greylist set firstseen=?,lastseen=?,cnt=?,umis=?
        where ip=? and sender=? and recipient=?''',
        (now,now,0,None,ip,sender,recipient))
    self.conn.commit()
    return cnt

  def close(self):
    self.conn.close()