"""This module defines a very basic store that's used by the CGI interface
to store session and one-time-key information.

Yes, it's called "sessions" - because originally it only defined a session
class. It's now also used for One Time Key handling too.
"""
__docformat__ = 'restructuredtext'
import os, time
from cgi import escape

class BasicDatabase:
    ''' Provide a nice encapsulation of an RDBMS table.

        Keys are id strings, values are automatically marshalled data.
    '''
    name = None
    def __init__(self, db):
        self.db = db
        self.cursor = self.db.cursor

    def clear(self):
        self.cursor.execute('delete from %ss'%self.name)

    def exists(self, infoid):
        n = self.name
        self.cursor.execute('select count(*) from %ss where %s_key=%s'%(n,
            n, self.db.arg), (infoid,))
        return int(self.cursor.fetchone()[0])

    _marker = []
    def get(self, infoid, value, default=_marker):
        n = self.name
        self.cursor.execute('select %s_value from %ss where %s_key=%s'%(n,
            n, n, self.db.arg), (infoid,))
        res = self.cursor.fetchone()
        if not res:
            if default != self._marker:
                return default
            raise KeyError('No such %s "%s"'%(self.name, escape(infoid)))
        values = eval(res[0])
        return values.get(value, None)

    def getall(self, infoid):
        n = self.name
        self.cursor.execute('select %s_value from %ss where %s_key=%s'%(n,
            n, n, self.db.arg), (infoid,))
        res = self.cursor.fetchone()
        if not res:
            raise KeyError('No such %s "%s"'%(self.name, escape (infoid)))
        return eval(res[0])

    def set(self, infoid, **newvalues):
        """ Store all newvalues under key infoid with a timestamp in database.

            If newvalues['__timestamp'] exists and is representable as a floating point number
            (i.e. could be generated by time.time()), that value is used for the <name>_time
            column in the database.
        """
        c = self.cursor
        n = self.name
        a = self.db.arg
        c.execute('select %s_value from %ss where %s_key=%s'%(n, n, n, a),
            (infoid,))
        res = c.fetchone()
        if res:
            values = eval(res[0])
        else:
            values = {}
        values.update(newvalues)

        if res:
            sql = 'update %ss set %s_value=%s where %s_key=%s'%(n, n,
                a, n, a)
            args = (repr(values), infoid)
        else:
            if '__timestamp' in newvalues:
                try:
                    # __timestamp must be represntable as a float. Check it.
                    timestamp = float(newvalues['__timestamp'])
                except ValueError:
                    timestamp = time.time()
            else:
                timestamp = time.time()

            sql = 'insert into %ss (%s_key, %s_time, %s_value) '\
                'values (%s, %s, %s)'%(n, n, n, n, a, a, a)
            args = (infoid, timestamp, repr(values))
        c.execute(sql, args)

    def list(self):
        c = self.cursor
        n = self.name
        c.execute('select %s_key from %ss'%(n, n))
        return [res[0] for res in c.fetchall()]

    def destroy(self, infoid):
        self.cursor.execute('delete from %ss where %s_key=%s'%(self.name,
            self.name, self.db.arg), (infoid,))

    def updateTimestamp(self, infoid):
        """ don't update every hit - once a minute should be OK """
        now = time.time()
        self.cursor.execute('''update %ss set %s_time=%s where %s_key=%s
            and %s_time < %s'''%(self.name, self.name, self.db.arg,
            self.name, self.db.arg, self.name, self.db.arg),
            (now, infoid, now-60))

    def clean(self):
        ''' Remove session records that haven't been used for a week. '''
        now = time.time()
        week = 60*60*24*7
        old = now - week
        self.cursor.execute('delete from %ss where %s_time < %s'%(self.name,
            self.name, self.db.arg), (old, ))

class Sessions(BasicDatabase):
    name = 'session'

class OneTimeKeys(BasicDatabase):
    name = 'otk'

# vim: set et sts=4 sw=4 :