#!/usr/bin/env python
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import hmac
from hashlib import sha1
from os.path import basename
from sys import argv, exit
from time import time


if __name__ == '__main__':
    if len(argv) != 5:
        prog = basename(argv[0])
        print 'Syntax: %s <method> <seconds> <path> <key>' % prog
        print
        print 'Where:'
        print '  <method>   The method to allow; GET for example.'
        print '  <seconds>  The number of seconds from now to allow requests.'
        print '  <path>     The full path to the resource.'
        print '             Example: /v1/AUTH_account/c/o'
        print '  <key>      The X-Account-Meta-Temp-URL-Key for the account.'
        print
        print 'Example output:'
        print '    /v1/AUTH_account/c/o?temp_url_sig=34d49efc32fe6e3082e411e' \
              'eeb85bd8a&temp_url_expires=1323482948'
        print
        print 'This can be used to form a URL to give out for the access '
        print 'allowed. For example:'
        print '    echo https://swift-cluster.example.com`%s GET 60 ' \
              '/v1/AUTH_account/c/o mykey`' % prog
        print
        print 'Might output:'
        print '    https://swift-cluster.example.com/v1/AUTH_account/c/o?' \
              'temp_url_sig=34d49efc32fe6e3082e411eeeb85bd8a&' \
              'temp_url_expires=1323482948'
        exit(1)
    method, seconds, path, key = argv[1:]
    try:
        expires = int(time() + int(seconds))
    except ValueError:
        expires = 0
    if expires < 1:
        print 'Please use a positive <seconds> value.'
        exit(1)
    parts = path.split('/', 4)
    # Must be five parts, ['', 'v1', 'a', 'c', 'o'], must be a v1 request, have
    # account, container, and object values, and the object value can't just
    # have '/'s.
    if len(parts) != 5 or parts[0] or parts[1] != 'v1' or not parts[2] or \
            not parts[3] or not parts[4].strip('/'):
        print '<path> must point to an object.'
        print 'For example: /v1/account/container/object'
        exit(1)
    sig = hmac.new(key, '%s\n%s\n%s' % (method, expires, path),
                   sha1).hexdigest()
    print '%s?temp_url_sig=%s&temp_url_expires=%s' % (path, sig, expires)