# Copyright 2017 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.

"""Calculates statistics for lists of data and pretty print them."""

from __future__ import print_function

import collections
import json
import logging
import math
import os

import numpy

STATS_PREFIX = '@@'
NAN_TAG = '*'
NAN_DESCRIPTION = '%s domains contain NaN samples' % NAN_TAG

LONG_UNIT = {
    '': 'N/A',
    'mW': 'milliwatt',
    'uW': 'microwatt',
    'mV': 'millivolt',
    'uA': 'microamp',
    'uV': 'microvolt'
}


class StatsManagerError(Exception):
  """Errors in StatsManager class."""
  pass


class StatsManager(object):
  """Calculates statistics for several lists of data(float).

  Example usage:

    >>> stats = StatsManager(title='Title Banner')
    >>> stats.AddSample(TIME_KEY, 50.0)
    >>> stats.AddSample(TIME_KEY, 25.0)
    >>> stats.AddSample(TIME_KEY, 40.0)
    >>> stats.AddSample(TIME_KEY, 10.0)
    >>> stats.AddSample(TIME_KEY, 10.0)
    >>> stats.AddSample('frobnicate', 11.5)
    >>> stats.AddSample('frobnicate', 9.0)
    >>> stats.AddSample('foobar', 11111.0)
    >>> stats.AddSample('foobar', 22222.0)
    >>> stats.CalculateStats()
    >>> print(stats.SummaryToString())
  ` @@--------------------------------------------------------------
  ` @@                        Title Banner
    @@--------------------------------------------------------------
    @@            NAME  COUNT      MEAN   STDDEV       MAX       MIN
    @@   sample_msecs      4     31.25    15.16     50.00     10.00
    @@         foobar      2  16666.50  5555.50  22222.00  11111.00
    @@     frobnicate      2     10.25     1.25     11.50      9.00
  ` @@--------------------------------------------------------------

  Attributes:
    _data: dict of list of readings for each domain(key)
    _unit: dict of unit for each domain(key)
    _smid: id supplied to differentiate data output to other StatsManager
           instances that potentially save to the same directory
           if smid all output files will be named |smid|_|fname|
    _title: title to add as banner to formatted summary. If no title,
            no banner gets added
    _order: list of formatting order for domains. Domains not listed are
            displayed in sorted order
    _hide_domains: collection of domains to hide when formatting summary string
    _accept_nan: flag to indicate if NaN samples are acceptable
    _nan_domains: set to keep track of which domains contain NaN samples
    _summary: dict of stats per domain (key): min, max, count, mean, stddev
    _logger = StatsManager logger

  Note:
    _summary is empty until CalculateStats() is called, and is updated when
    CalculateStats() is called.
  """

  # pylint: disable=W0102
  def __init__(self, smid='', title='', order=[], hide_domains=[],
               accept_nan=True):
    """Initialize infrastructure for data and their statistics."""
    self._title = title
    self._data = collections.defaultdict(list)
    self._unit = collections.defaultdict(str)
    self._smid = smid
    self._order = order
    self._hide_domains = hide_domains
    self._accept_nan = accept_nan
    self._nan_domains = set()
    self._summary = {}
    self._logger = logging.getLogger('StatsManager')

  def AddSample(self, domain, sample):
    """Add one sample for a domain.

    Args:
      domain: the domain name for the sample.
      sample: one time sample for domain, expect type float.

    Raises:
      StatsManagerError: if trying to add NaN and |_accept_nan| is false
    """
    try:
      sample = float(sample)
    except ValueError:
      # if we don't accept nan this will be caught below
      self._logger.debug('sample %s for domain %s is not a number. Making NaN',
                         sample, domain)
      sample = float('NaN')
    if not self._accept_nan and math.isnan(sample):
      raise StatsManagerError('accept_nan is false. Cannot add NaN sample.')
    self._data[domain].append(sample)
    if math.isnan(sample):
      self._nan_domains.add(domain)

  def SetUnit(self, domain, unit):
    """Set the unit for a domain.

    There can be only one unit for each domain. Setting unit twice will
    overwrite the original unit.

    Args:
      domain: the domain name.
      unit: unit of the domain.
    """
    if domain in self._unit:
      self._logger.warn('overwriting the unit of %s, old unit is %s, new unit '
                        'is %s.', domain, self._unit[domain], unit)
    self._unit[domain] = unit

  def CalculateStats(self):
    """Calculate stats for all domain-data pairs.

    First erases all previous stats, then calculate stats for all data.
    """
    self._summary = {}
    for domain, data in self._data.iteritems():
      data_np = numpy.array(data)
      self._summary[domain] = {
          'mean': numpy.nanmean(data_np),
          'min': numpy.nanmin(data_np),
          'max': numpy.nanmax(data_np),
          'stddev': numpy.nanstd(data_np),
          'count': data_np.size,
      }

  def SummaryToString(self, prefix=STATS_PREFIX):
    """Format summary into a string, ready for pretty print.

    See class description for format example.

    Args:
      prefix: start every row in summary string with prefix, for easier reading.

    Returns:
      formatted summary string.
    """
    headers = ('NAME', 'COUNT', 'MEAN', 'STDDEV', 'MAX', 'MIN')
    table = [headers]
    # determine what domains to display & and the order
    domains_to_display = set(self._summary.keys()) - set(self._hide_domains)
    display_order = [key for key in self._order if key in domains_to_display]
    domains_to_display -= set(display_order)
    display_order.extend(sorted(domains_to_display))
    nan_in_output = False
    for domain in display_order:
      stats = self._summary[domain]
      if not domain.endswith(self._unit[domain]):
        domain = '%s_%s' % (domain, self._unit[domain])
      if domain in self._nan_domains:
        domain = '%s%s' % (domain, NAN_TAG)
        nan_in_output = True
      row = [domain]
      row.append(str(stats['count']))
      for entry in headers[2:]:
        row.append('%.2f' % stats[entry.lower()])
      table.append(row)

    max_col_width = []
    for col_idx in range(len(table[0])):
      col_item_widths = [len(row[col_idx]) for row in table]
      max_col_width.append(max(col_item_widths))

    formatted_lines = []
    for row in table:
      formatted_row = prefix + ' '
      for i in range(len(row)):
        formatted_row += row[i].rjust(max_col_width[i] + 2)
      formatted_lines.append(formatted_row)
    if nan_in_output:
      formatted_lines.append('%s %s' % (prefix, NAN_DESCRIPTION))

    if self._title:
      line_length = len(formatted_lines[0])
      dec_length = len(prefix)
      # trim title to be at most as long as the longest line without the prefix
      title = self._title[:(line_length - dec_length)]
      # line is a seperator line consisting of -----
      line = '%s%s' % (prefix, '-' * (line_length - dec_length))
      # prepend the prefix to the centered title
      padded_title = '%s%s' % (prefix, title.center(line_length)[dec_length:])
      formatted_lines = [line, padded_title, line] + formatted_lines + [line]
    formatted_output = '\n'.join(formatted_lines)
    return formatted_output

  def GetSummary(self):
    """Getter for summary."""
    return self._summary

  def _MakeUniqueFName(self, fname):
    """prepend |_smid| to fname & rotate fname to ensure uniqueness.

    Before saving a file through the StatsManager, make sure that the filename
    is unique, first by prepending the smid if any and otherwise by appending
    increasing integer suffixes until the filename is unique.

    If |smid| is defined /path/to/example/file.txt becomes
    /path/to/example/{smid}_file.txt.

    The rotation works by changing /path/to/example/somename.txt to
    /path/to/example/somename1.txt if the first one already exists on the
    system.

    Note: this is not thread-safe. While it makes sense to use StatsManager
    in a threaded data-collection, the data retrieval should happen in a
    single threaded environment to ensure files don't get potentially clobbered.

    Args:
      fname: filename to ensure uniqueness.

    Returns:
      {smid_}fname{tag}.ext
      the smid portion gets prepended if |smid| is defined
      the tag portion gets appended if necessary to ensure unique fname
    """
    fdir = os.path.dirname(fname)
    base, ext = os.path.splitext(os.path.basename(fname))
    if self._smid:
      base = '%s_%s' % (self._smid, base)
    unique_fname = os.path.join(fdir, '%s%s' % (base, ext))
    tag = 0
    while os.path.exists(unique_fname):
      old_fname = unique_fname
      unique_fname = os.path.join(fdir, '%s%d%s' % (base, tag, ext))
      self._logger.warn('Attempted to store stats information at %s, but file '
                        'already exists. Attempting to store at %s now.',
                        old_fname, unique_fname)
      tag += 1
    return unique_fname

  def SaveSummary(self, directory, fname='summary.txt', prefix=STATS_PREFIX):
    """Save summary to file.

    Args:
      directory: directory to save the summary in.
      fname: filename to save summary under.
      prefix: start every row in summary string with prefix, for easier reading.

    Returns:
      full path of summary save location
    """
    summary_str = self.SummaryToString(prefix=prefix) + '\n'
    if not os.path.exists(directory):
      os.makedirs(directory)
    fname = self._MakeUniqueFName(os.path.join(directory, fname))
    with open(fname, 'w') as f:
      f.write(summary_str)
    return fname

  def SaveSummaryJSON(self, directory, fname='summary.json'):
    """Save summary (only MEAN) into a JSON file.

    Args:
      directory: directory to save the JSON summary in.
      fname: filename to save summary under.

    Returns:
      full path of summary save location
    """
    data = {}
    for domain in self._summary:
      unit = LONG_UNIT.get(self._unit[domain], self._unit[domain])
      data_entry = {'mean': self._summary[domain]['mean'], 'unit': unit}
      data[domain] = data_entry
    if not os.path.exists(directory):
      os.makedirs(directory)
    fname = self._MakeUniqueFName(os.path.join(directory, fname))
    with open(fname, 'w') as f:
      json.dump(data, f)
    return fname

  def GetRawData(self):
    """Getter for all raw_data."""
    return self._data

  def SaveRawData(self, directory, dirname='raw_data'):
    """Save raw data to file.

    Args:
      directory: directory to create the raw data folder in.
      dirname: folder in which raw data live.

    Returns:
      list of full path of each domain's raw data save location
    """
    if not os.path.exists(directory):
      os.makedirs(directory)
    dirname = os.path.join(directory, dirname)
    if not os.path.exists(dirname):
      os.makedirs(dirname)
    fnames = []
    for domain, data in self._data.iteritems():
      if not domain.endswith(self._unit[domain]):
        domain = '%s_%s' % (domain, self._unit[domain])
      fname = self._MakeUniqueFName(os.path.join(dirname, '%s.txt' % domain))
      with open(fname, 'w') as f:
        f.write('\n'.join('%.2f' % sample for sample in data) + '\n')
      fnames.append(fname)
    return fnames
