# tz.py - example of datetime objects with time zones
# -*- encoding: utf8 -*-
#
# Copyright (C) 2004-2010 Federico Di Gregorio  <fog@debian.org>
#
# psycopg2 is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# psycopg2 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 Lesser General Public
# License for more details.

## put in DSN your DSN string

DSN = 'dbname=test'

## don't modify anything below this line (except for experimenting)

import sys
import psycopg2
import datetime

from psycopg2.tz import ZERO, LOCAL, FixedOffsetTimezone

if len(sys.argv) > 1:
    DSN = sys.argv[1]

print("Opening connection using dsn:", DSN)
conn = psycopg2.connect(DSN)
curs = conn.cursor()

try:
    curs.execute("CREATE TABLE test_tz (t timestamp with time zone)")
except:
    conn.rollback()
    curs.execute("DROP TABLE test_tz")
    curs.execute("CREATE TABLE test_tz (t timestamp with time zone)")
conn.commit()

d = datetime.datetime(1971, 10, 19, 22, 30, 0, tzinfo=LOCAL)
curs.execute("INSERT INTO test_tz VALUES (%s)", (d,))
print("Inserted timestamp with timezone:", d)
print("Time zone:", d.tzinfo.tzname(d), "offset:", d.tzinfo.utcoffset(d))

tz = FixedOffsetTimezone(-5*60, "EST")
d = datetime.datetime(1971, 10, 19, 22, 30, 0, tzinfo=tz)
curs.execute("INSERT INTO test_tz VALUES (%s)", (d,))
print("Inserted timestamp with timezone:", d)
print("Time zone:", d.tzinfo.tzname(d), "offset:", d.tzinfo.utcoffset(d))

curs.execute("SELECT * FROM test_tz")
d = curs.fetchone()[0]
curs.execute("INSERT INTO test_tz VALUES (%s)", (d,))
print("Inserted SELECTed timestamp:", d)
print("Time zone:", d.tzinfo.tzname(d), "offset:", d.tzinfo.utcoffset(d))

curs.execute("SELECT * FROM test_tz")
for d in curs:
    u = d[0].utcoffset() or ZERO
    print("UTC time:  ", d[0] - u)
    print("Local time:", d[0])
    print("Time zone:", d[0].tzinfo.tzname(d[0]), d[0].tzinfo.utcoffset(d[0]))


curs.execute("DROP TABLE test_tz")
conn.commit()