"""
This is a module that contains basic timer facilities. It's useful for profiling
the performance of a script in "chunks".
"""

from time import time
from os import linesep as ls

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class Timer(object):
   """ Timer class. It adds new timers and keeps track of how much time has been
       spent. """

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   def __init__(self):
      """ Declares the global timer """
      self.timers = {'global' : -time()}
      self.descriptions = {'global' : 'Total time taken:'}
      self.active_timers = ['global']
      self.timer_names = ['global']
      self.units = 'sec.'

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   def add_timer(self, timer_name, description):
      """ Add a new timer """
      # Check to make sure it doesn't already exist. Then add it if it doesn't
      if timer_name in self.timer_names:
         return

      self.timers[timer_name] = 0
      self.timer_names.append(timer_name)
      self.descriptions[timer_name] = description

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   def start_timer(self, timer_name):
      """ Start the specified timer """
      # Make sure the timer is not on already
      if timer_name in self.active_timers:
         return
      
      # Check to make sure we've added the timer or not. If not, then add it
      if not timer_name in self.timer_names:
         self.add_timer(timer_name, '%s timer' % timer_name)

      self.timers[timer_name] -= time()

      # This timer is now on
      self.active_timers.append(timer_name)

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   def stop_timer(self, timer_name):
      """ End the specified timer """
      # First make sure that it is a timer to begin with
      if not timer_name in self.timer_names:
         return

      # Next make sure that the timer is on in the first place
      if not timer_name in self.active_timers:
         return

      # Now if it's on, end it and remove it from the list of active timers
      self.timers[timer_name] += time()
      self.active_timers.pop(self.active_timers.index(timer_name))

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   def end_all(self):
      """ End all of the timers """
      while len(self.active_timers) > 0:
         self.stop_timer(self.active_timers[0])

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   def done(self):
      """ Tell Timer we are done, and we can convert units to best 
          human-readable option 
      """

      # Make sure all timers are ended
      self.end_all()
      
      tfactor = 1
      # Now test the magnitude of the global timer so we can decide what the 
      # reported units should be
      if self.timers['global'] > 60 * 60 * 48:
         self.units = 'days'
         tfactor = 60 * 60 * 24
      elif self.timers['global'] > 60 * 60:
         self.units = 'hr.'
         tfactor = 60 * 60
      elif self.timers['global'] > 60:
         self.units = 'min.'
         tfactor = 60

      for timer in self.timer_names:
         self.timers[timer] /= tfactor

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   def print_(self, timer, outfile, newline=True):
      """ Prints the value of the timer """
      outfile.write("%-40s %8.3f %s" % (self.descriptions[timer], 
                                        self.timers[timer], self.units))
      if newline:
         outfile.write(ls)

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