"""
The purpose of this script to create enough traffic in config datastore
to trigger creation of Snapshot.
This script uses PATCH http method for handling "moving segment" of cars.
The car data is minimal, containing only an ID (car-<num>).
This script is tailored to behavior of Berylium-SR2,
if the behavior changes, new script will be needed.
"""


import argparse
import string
import sys
import requests


def main():
    """
    The main function that does it all.

    TODO: Move argument parsing to a separate function,
    so allow the main logic to be started programmatically?
    """

    # Constants
    car_entry_template = string.Template('''      {
       "id": "car-$NUM"
      }''')

    patch_data_template = string.Template('''{
 "ietf-restconf:yang-patch": {
  "patch-id": "$ID",
  "edit": [
   {
    "edit-id": "0",
    "operation": "replace",
    "target": "/car:car-entry[car:id='0']",
    "value": {
     "car:car-entry": [
$ENTRIES
     ]
    }
   }
  ]
 }
}''')

    # Arguments
    parser = argparse.ArgumentParser(description="Config datastore"
                                                 "scale test script")
    parser.add_argument("--host", default="127.0.0.1",
                        help="Host where odl controller is running."
                             "(default: 127.0.0.1)")
    parser.add_argument("--port", default="8181",
                        help="Port on which odl's RESTCONF is listening"
                             "(default: 8181)")
    parser.add_argument("--start-id", type=int, default=1,
                        help="ID number of the first car. (default:1)")
    parser.add_argument("--segment-size", type=int, default=1,
                        help="Number of cars in segment. (default:1)")
    parser.add_argument("--iterations", type=int, default=1,
                        help="How many times the segment sent. (default:1)")
    parser.add_argument("--move-per-iter", type=int, default=1,
                        help="Each segment has IDs moved by this. (default:1)")
    parser.add_argument("--user", help="Restconf user name", default="admin")
    parser.add_argument("--password", help="Restconf password", default="admin")

    args = parser.parse_args()

    # Logic
    url = "http://" + args.host + ':' + args.port + "/restconf/config/car:cars"
    auth = (args.user, args.password)
    headers = {"Content-Type": "application/yang.patch+json"}
    session = requests.Session()
    for iteration in range(args.iterations):
        entry_list = []
        for num_entry in range(args.segment_size):
            num_id = args.start_id + iteration * args.move_per_iter + num_entry
            entry_list.append(car_entry_template.substitute({"NUM": str(num_id)}))
        mapping = {"ID": str(iteration), "ENTRIES": ",\n".join(entry_list)}
        data = patch_data_template.substitute(mapping)
        response = session.patch(url=url, auth=auth, headers=headers, data=data)
        if response.status_code not in [200, 201, 204]:
            print "status:", response.status_code
            print "text:", response.text
            sys.exit(1)


if __name__ == "__main__":
    main()