#!/usr/bin/env python
# Copyright (c) 2018 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 functools
import json
import os
import subprocess
import sys
import tempfile
import threading
import time
import traceback
import urllib2

import detect_host_arch
import gclient_utils
import metrics_utils


DEPOT_TOOLS = os.path.dirname(os.path.abspath(__file__))
CONFIG_FILE = os.path.join(DEPOT_TOOLS, 'metrics.cfg')
UPLOAD_SCRIPT = os.path.join(DEPOT_TOOLS, 'upload_metrics.py')

APP_URL = 'https://cit-cli-metrics.appspot.com'

DISABLE_METRICS_COLLECTION = os.environ.get('DEPOT_TOOLS_METRICS') == '0'
DEFAULT_COUNTDOWN = 10

INVALID_CONFIG_WARNING = (
    'WARNING: Your metrics.cfg file was invalid or nonexistent. A new one has '
    'been created'
)


class _Config(object):
  def __init__(self):
    self._initialized = False
    self._config = {}

  def _ensure_initialized(self):
    if self._initialized:
      return

    try:
      config = json.loads(gclient_utils.FileRead(CONFIG_FILE))
    except (IOError, ValueError):
      config = {}

    self._config = config.copy()

    if 'is-googler' not in self._config:
      # /should-upload is only accessible from Google IPs, so we only need to
      # check if we can reach the page. An external developer would get access
      # denied.
      try:
        req = urllib2.urlopen(APP_URL + '/should-upload')
        self._config['is-googler'] = req.getcode() == 200
      except (urllib2.URLError, urllib2.HTTPError):
        self._config['is-googler'] = False

    # Make sure the config variables we need are present, and initialize them to
    # safe values otherwise.
    self._config.setdefault('countdown', DEFAULT_COUNTDOWN)
    self._config.setdefault('opt-in', None)

    if config != self._config:
      print INVALID_CONFIG_WARNING
      self._write_config()

    self._initialized = True

  def _write_config(self):
    gclient_utils.FileWrite(CONFIG_FILE, json.dumps(self._config))

  @property
  def is_googler(self):
    self._ensure_initialized()
    return self._config['is-googler']

  @property
  def opted_in(self):
    self._ensure_initialized()
    return self._config['opt-in']

  @opted_in.setter
  def opted_in(self, value):
    self._ensure_initialized()
    self._config['opt-in'] = value
    self._write_config()

  @property
  def countdown(self):
    self._ensure_initialized()
    return self._config['countdown']

  def decrease_countdown(self):
    self._ensure_initialized()
    if self.countdown == 0:
      return
    self._config['countdown'] -= 1
    self._write_config()


class MetricsCollector(object):
  def __init__(self):
    self._metrics_lock = threading.Lock()
    self._reported_metrics = {}
    self._config = _Config()
    self._collecting_metrics = False

  @property
  def config(self):
    return self._config

  @property
  def collecting_metrics(self):
    return self._collecting_metrics

  def add(self, name, value):
    if not self.collecting_metrics:
      return
    with self._metrics_lock:
      self._reported_metrics[name] = value

  def _upload_metrics_data(self):
    """Upload the metrics data to the AppEngine app."""
    # We invoke a subprocess, and use stdin.write instead of communicate(),
    # so that we are able to return immediately, leaving the upload running in
    # the background.
    p = subprocess.Popen([sys.executable, UPLOAD_SCRIPT], stdin=subprocess.PIPE)
    p.stdin.write(json.dumps(self._reported_metrics))

  def _collect_metrics(self, func, command_name, *args, **kwargs):
    # If the user hasn't opted in or out, and the countdown is not yet 0, just
    # display the notice.
    if self.config.opted_in == None and self.config.countdown > 0:
      metrics_utils.print_notice(self.config.countdown)
      self.config.decrease_countdown()
      func(*args, **kwargs)
      return

    self._collecting_metrics = True
    self.add('command', command_name)
    try:
      start = time.time()
      func(*args, **kwargs)
      exception = None
    # pylint: disable=bare-except
    except:
      exception = sys.exc_info()
    finally:
      self.add('execution_time', time.time() - start)

    # Print the exception before the metrics notice, so that the notice is
    # clearly visible even if gclient fails.
    if exception and not isinstance(exception[1], SystemExit):
      traceback.print_exception(*exception)

    exit_code = metrics_utils.return_code_from_exception(exception)
    self.add('exit_code', exit_code)

    # Print the metrics notice only if the user has not explicitly opted in
    # or out.
    if self.config.opted_in is None:
      metrics_utils.print_notice(self.config.countdown)

    # Add metrics regarding environment information.
    self.add('timestamp', metrics_utils.seconds_to_weeks(time.time()))
    self.add('python_version', metrics_utils.get_python_version())
    self.add('host_os', gclient_utils.GetMacWinOrLinux())
    self.add('host_arch', detect_host_arch.HostArch())
    self.add('depot_tools_age', metrics_utils.get_repo_timestamp(DEPOT_TOOLS))

    self._upload_metrics_data()
    sys.exit(exit_code)

  def collect_metrics(self, command_name):
    """A decorator used to collect metrics over the life of a function.

    This decorator executes the function and collects metrics about the system
    environment and the function performance. It also catches all the Exceptions
    and invokes sys.exit once the function is done executing.
    """
    def _decorator(func):
      # Do this first so we don't have to read, and possibly create a config
      # file.
      if DISABLE_METRICS_COLLECTION:
        return func
      # If the user has opted out or the user is not a googler, then there is no
      # need to do anything.
      if self.config.opted_in == False or not self.config.is_googler:
        return func
      # Otherwise, collect the metrics.
      # Needed to preserve the __name__ and __doc__ attributes of func.
      @functools.wraps(func)
      def _inner(*args, **kwargs):
        self._collect_metrics(func, command_name, *args, **kwargs)
      return _inner
    return _decorator


collector = MetricsCollector()