#!/usr/bin/env python3
# Copyright 2020 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Prints expanded histograms."""

import argparse
import re
import sys
import xml.dom.minidom

import setup_modules  # pylint: disable=unused-import

import chromium_src.tools.metrics.common.utf8_encoding as utf8_encoding
import chromium_src.tools.metrics.histograms.extract_histograms as extract_histograms
import chromium_src.tools.metrics.histograms.histogram_configuration_model as histogram_configuration_model
import chromium_src.tools.metrics.histograms.histogram_paths as histogram_paths
import chromium_src.tools.metrics.histograms.merge_xml as merge_xml


def _ConstructHistogram(doc, name, histogram_dict):
  """Constructs a histogram node based on the |histogram_dict|."""
  histogram = doc.createElement('histogram')
  # Set histogram node attributes.
  histogram.setAttribute('name', name)
  if 'enumDetails' in histogram_dict:
    histogram.setAttribute('enum', histogram_dict['enumDetails']['name'])
  elif 'units' in histogram_dict:
    histogram.setAttribute('units', histogram_dict['units'])
  if 'expires_after' in histogram_dict:
    histogram.setAttribute('expires_after', histogram_dict['expires_after'])
  # Populate owner nodes.
  for owner in histogram_dict.get('owners', []):
    owner_node = doc.createElement('owner')
    owner_node.appendChild(doc.createTextNode(owner))
    histogram.appendChild(owner_node)
  # Populate the summary node - stored as description.
  if 'description' in histogram_dict:
    summary_node = doc.createElement('summary')
    summary_node.appendChild(doc.createTextNode(histogram_dict['description']))
    histogram.appendChild(summary_node)
  return histogram


def main(argv=sys.argv[1:]):
  """Prints expanded histograms."""
  parser = argparse.ArgumentParser(description='Print expanded histograms.')
  parser.add_argument(
    '--pattern',
    type=str,
    default='.*',
    help='The histogram name regex for histograms to be printed.',
  )
  parser.add_argument(
    '--print-names-only',
    action='store_true',
    help='If set, only prints the histogram names.',
  )
  parser.add_argument(
    '--histograms-xml-file',
    type=str,
    default=None,
    help=(
      'Path to histograms.xml file. If omitted, all Chromium '
      'histograms.xml files are processed.'
    ),
  )
  args = parser.parse_args(argv)

  utf8_encoding.setup_stdout_and_stderr_utf8_encoding()

  try:
    pattern = re.compile(args.pattern)
  except re.error:
    print('Non valid regex pattern.')
    return 1

  if args.histograms_xml_file:
    files = [args.histograms_xml_file]
    # If a file is provided, don't do expansion as the file may not
    # be in Chromium.
    expand_owners_and_extract_components = False
  else:
    files = histogram_paths.ALL_XMLS
    # No owner expansion is needed if we're printing names only.
    expand_owners_and_extract_components = not args.print_names_only

  # Extract all histograms into a dict. This is the expensive part that
  # handles expansion of suffixes and variants.
  doc = merge_xml.MergeFiles(
    filenames=files,
    expand_owners_and_extract_components=expand_owners_and_extract_components,
  )
  histograms, had_errors = extract_histograms.ExtractHistogramsFromDom(doc)
  if had_errors:
    raise ValueError('Error parsing inputs.')

  # If only names are requested, print them and exit. This is much faster as
  # it skips the expensive XML construction and pretty-printing.
  if args.print_names_only:
    for name in sorted(histograms.keys()):
      if re.match(pattern, name):
        print(name)
    return 0

  # Construct a dom tree that is similar to the normal histograms.xml so that
  # we can use histogram_configuration_model to pretty print it.
  doc = xml.dom.minidom.Document()
  configuration = doc.createElement('histogram-configuration')
  histograms_node = doc.createElement('histograms')
  for name, histogram in sorted(histograms.items()):
    if re.match(pattern, name):
      histograms_node.appendChild(_ConstructHistogram(doc, name, histogram))
  configuration.appendChild(histograms_node)
  doc.appendChild(configuration)
  print(histogram_configuration_model.PrettifyTree(doc))
  return 0


if __name__ == '__main__':
  sys.exit(main())