#!/usr/bin/env python
# Copyright 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import os.path
import requests
import sys

_MOJO_DEBUGGER_PORT = 7777


def _send_request(request, payload=None):
  """Sends a request to mojo:debugger."""
  try:
    url = 'http://localhost:%s/%s' % (_MOJO_DEBUGGER_PORT, request)
    if payload:
      return requests.post(url, payload)
    else:
      return requests.get(url)
  except requests.exceptions.ConnectionError:
    print 'Failed to connect to mojo:debugger, make sure the shell is running.'
    return None


def _tracing_start(_):
  """Starts tracing."""
  if not _send_request('start_tracing'):
    return 1
  print "Started tracing."
  return 0


def _tracing_stop(args):
  """Stops tracing and writes trace to file."""
  if args.file_name:
    file_name = args.file_name
  else:
    for i in xrange(1000):
      candidate_file_name = 'mojo_trace_%03d.json' % i
      if not os.path.exists(candidate_file_name):
        file_name = candidate_file_name
        break
    else:
      print 'Failed to pick a name for the trace output file.'
      return 1

  response = _send_request('stop_tracing')
  if not response:
    return 1

  with open(file_name, "wb") as trace_file:
    trace_file.write('{"traceEvents":[')
    trace_file.write(response.content)
    trace_file.write(']}')
  print "Trace saved in %s" % file_name
  return 0


def _add_tracing_command(subparsers):
  """Sets up the command line parser to manage tracing."""
  tracing_parser = subparsers.add_parser('tracing',
      help='trace event profiler')
  tracing_subparser = tracing_parser.add_subparsers(
      help='the command to run')

  start_tracing_parser = tracing_subparser.add_parser('start',
      help='start tracing')
  start_tracing_parser.set_defaults(func=_tracing_start)

  stop_tracing_parser = tracing_subparser.add_parser('stop',
      help='stop tracing and retrieve the result')
  stop_tracing_parser.add_argument('file_name', type=str, nargs='?',
      help='name of the output file (optional)')
  stop_tracing_parser.set_defaults(func=_tracing_stop)


def _wm_load(args):
  """Loads (embeds) the given url in the window manager."""
  if not _send_request('load', args.url):
    return 1
  return 0


def _add_wm_command(subparsers):
  """Sets up the parser for the 'wm' command."""
  wm_parser = subparsers.add_parser('wm', help='window manager')
  wm_subparser = wm_parser.add_subparsers(
      help='the command to run')

  wm_load_parser = wm_subparser.add_parser('load',
      help='load (embed) the given url')
  wm_load_parser.add_argument('url', type=str,
      help='the url to load')
  wm_load_parser.set_defaults(func=_wm_load)


def main():
  parser = argparse.ArgumentParser(description='Command-line interface for '
                                                'mojo:debugger')
  subparsers = parser.add_subparsers(help='the tool to run')
  _add_tracing_command(subparsers)
  _add_wm_command(subparsers)

  args = parser.parse_args()
  return args.func(args)

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