#!/usr/bin/env python
#
# Shows how to use the ratdb module to access the database and browse for an object
#
# Author N. Barros <nfbarros@hep.upenn.edu>
####################################################################################################

from __future__ import print_function
from __future__ import absolute_import
from __future__ import division

from sys import exc_info

from rat.ratdb import RATDBConnector

def calculate_run_duration(run):
    """
    Calculate the duration of a run based ont he contents of the respective RUN table

    Args:
      run (`int`): Run number
    """
    # By default it connects to the remote database
    db = RATDBConnector(server="postgres://snoplus@pgsql.snopl.us:5400/ratdb")
    try:
        result = db.fetch(obj_type="RUN", run=run)
        if len(result) == 0:
            # Nothing was found. Just exit
            print("Didn't find a run table for run {0}".format(run))
            return

        # We should now have a table
        # Grab the start and end times and calculate
        # Keep in mind that the return of the query is an array (there could be multiple objects matching
        # the query, depending on how it is formulated

        table = result[0]['data']
        ns_in_a_day = 24 * 3600 * 1e9
        elapsed_time = (table['stop_day'] - table['start_day']) * ns_in_a_day
        elapsed_time += (table['stop_sec'] - table['start_sec']) * 1e9
        elapsed_time += (table['stop_nsc'] - table['start_nsc'])
        print("")
        print("Run {0} lasted {1} ns ({2} h) ".format(run, elapsed_time, elapsed_time / (3600 * 1e9)))
        print("")

    except Exception:
        e = exc_info()[1]
        print("==> Database Exception: {0}".format(e))

    finally:
        if db is not None:
            db.close_ratdb_connection()


if __name__ == "__main__":
    calculate_run_duration(102220)