#!/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>
####################################################################################################
import ROOT
import rat
from rat import ratdb
import pgdb as psql
from sys import exc_info

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 = ratdb.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 psql.Error as e:
    print "PgSQL error:"
    print e
  except:
    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)