#!/usr/bin/env python3

# Copyright 2021 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""A command to display summary statistics from runs of 'bootperf'.

Command line options allow selecting from one of four sets of
performance statistics:
 1. boot time statistics (selected by --keyset boot) measure time
    spent since kernel startup;
 2. disk statistics (selected by --keyset disk) measure total bytes
    read from the boot device since kernel startup;
 3. firmware time statistics (selected by --keyset firmware) measure
    time spent since CPU power on.
 4. reboot time statistics (selected by --keyset reboot) measure
    time spent since the shutdown request immediately preceding
    the request.

The various statistics are recorded as cumulative time (or disk read)
since kernel startup (or CPU power on), sampled when specific events
occur during boot.  Events include such things as 'startup', (the
moment when the upstart 'startup' job begins running), and 'login',
(when the Chrome OS login screen is displayed).  By default, all
recorded events are included in the output; command line options
allow restricting the view to a selected subset of events.

Separate command line options allow selecting from one of two
different display modes.  When --averages is selected, the display
shows the average value and sample standard deviation (as a percent
of the average) for all selected events.  The --averages display
also calculates the difference (in time or bytes) between adjacent
events, and shows the average and sample standard deviation of the
differences.

The --rawdata display shows the raw data value associated with each
event for each boot:  Each line of output represents the event values
for one boot iteration.
"""

import argparse
import os
import sys

import perfprinter
import resultsdir
import resultset


_USAGE = f'{os.path.basename(sys.argv[0])} [options] [results-directory ...]'
_DESCRIPTION = """\
Summarize boot time performance results.  The result directory
arguments are directories previously specified as output for the
'bootperf' script.
"""


def _SetupOptions():
  """Create an ArgumentParser for the command line.

  Returns:
    The configured ArgumentParser object.
  """
  argparser = argparse.ArgumentParser(usage=_USAGE, description=_DESCRIPTION)

  arggroup = argparser.add_argument_group(title='Statistics selection')

  keyset_help = ('Selects the set of statistics to display; '
                    'choose one of ')
  keyset_help += "'" + resultset.TestResultSet.AVAILABLE_KEYSETS[0] + "'"
  for keyset in resultset.TestResultSet.AVAILABLE_KEYSETS[1:-1]:
    keyset_help += ", '" + keyset + "'"
  keyset_help += (", or '" +
                  resultset.TestResultSet.AVAILABLE_KEYSETS[-1] + "'.")
  keyset_default = resultset.TestResultSet.BOOTTIME_KEYSET
  keyset_help += "  (Default is '" + keyset_default + "'.)"
  arggroup.add_argument(
      '-k', '--keyset', action='store', dest='keyset',
      choices=resultset.TestResultSet.AVAILABLE_KEYSETS,
      help=keyset_help)
  argparser.set_defaults(keyset=keyset_default)

  arggroup = argparser.add_argument_group('Event selection')
  arggroup.add_argument(
      '-e', '--event', action='append',
      dest='eventnames',
      help='Restrict statistics to the comma-separated list of events.')

  arggroup = argparser.add_argument_group(
      'Display mode selection (choose one)')
  arggroup.add_argument(
      '-a', '--averages', action='store_true',
      dest='print_averages',
      help='Display a summary of the averages of chosen statistics (default).')
  arggroup.add_argument(
      '-r', '--rawdata', action='store_true',
      dest='print_raw',
      help='Display raw data from all boot iterations.')
  argparser.set_defaults(print_averages=False)
  argparser.set_defaults(print_raw=False)

  # Positional arguments (results_directory)
  argparser.add_argument('results_directory',
                         help='bootperf results directory.', nargs='*')
  return argparser


def _ProcessDisplayOptions(args):
  """Determine options controlling the display format.

  Command options allow choosing either raw data format, or summary
  statistics format.  The default option is the summary format.
  It's not allowed to select both formats.

  Args:
    args: Parsed command line options data.

  Returns:
    A print function or None on invalid display options.
  """
  display_count = 0
  if args.print_averages:
    display_count += 1
    printfunc = perfprinter.PrintStatisticsSummary
  if args.print_raw:
    display_count += 1
    printfunc = perfprinter.PrintRawData
  if display_count == 0:
    printfunc = perfprinter.PrintStatisticsSummary
  elif display_count > 1:
    print("Can't use -a and -r together.\n", file=sys.stderr)
    return None
  return printfunc


def _ProcessEventlistOptions(args):
  """Determine whether we'll display all events, or a subset.

  Command options allow restricting a chosen key set to a
  list of specific events.  If the option is present, return
  the list of events.  Otherwise, return `None`.

  Args:
    args: Parsed command line options data.

  Returns:
    A list of events names.
  """
  if not args.eventnames:
    return None
  eventlist = []
  for kl in args.eventnames:
    eventlist.extend(kl.split(','))
  return eventlist


def main(argv):
  """Canonical main routine."""
  argparser = _SetupOptions()
  args = argparser.parse_args(argv)
  printfunc = _ProcessDisplayOptions(args)
  keyset_type = args.keyset
  eventlist = _ProcessEventlistOptions(args)
  if printfunc is None or keyset_type is None:
    argparser.print_help()
    sys.exit(1)
  results_dir = args.results_directory
  if not results_dir:
    results_dir = ['.']
  printfunc(resultsdir.ReadResultsDirectory,
            results_dir, keyset_type, eventlist)


if __name__ == '__main__':
  main(sys.argv[1:])