#!/usr/bin/env python3
# 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 contextlib
import functools
import json
import os
import sys
import threading
import time
import traceback
import urllib.request

import detect_host_arch
import gclient_utils
import metrics_utils
import subprocess2

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')

DEFAULT_COUNTDOWN = 10

# TODO(b/265929888): Remove this variable when dogfood is over.
DEPOT_TOOLS_ENV = ['DOGFOOD_STACKED_CHANGES']

INVALID_CONFIG_WARNING = (
    'WARNING: Your metrics.cfg file was invalid or nonexistent. A new one will '
    'be created.')
PERMISSION_DENIED_WARNING = (
    'Could not write the metrics collection config:\n\t%s\n'
    'Metrics collection will be disabled.')


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

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

        # Metrics collection is disabled, so don't collect any metrics.
        if not metrics_utils.COLLECT_METRICS:
            self._config = {
                'is-googler': False,
                'countdown': 0,
                'opt-in': False,
                'version': metrics_utils.CURRENT_VERSION,
            }
            self._initialized = True
            return

        # We are running on a bot. Ignore config and collect metrics.
        if metrics_utils.REPORT_BUILD:
            self._config = {
                'is-googler': True,
                'countdown': 0,
                'opt-in': True,
                'version': metrics_utils.CURRENT_VERSION,
            }
            self._initialized = True
            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 = urllib.request.urlopen(metrics_utils.APP_URL +
                                             '/should-upload')
                self._config['is-googler'] = req.getcode() == 200
            except (urllib.request.URLError, urllib.request.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)
        self._config.setdefault('version', metrics_utils.CURRENT_VERSION)

        if config != self._config:
            print(INVALID_CONFIG_WARNING, file=sys.stderr)
            self._write_config()

        self._initialized = True

    def _write_config(self):
        try:
            gclient_utils.FileWrite(CONFIG_FILE, json.dumps(self._config))
        except IOError as e:
            print(PERMISSION_DENIED_WARNING % e, file=sys.stderr)
            self._config['opt-in'] = False

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

    @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._config['version'] = metrics_utils.CURRENT_VERSION
        self._write_config()

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

    @property
    def should_collect_metrics(self):
        # Don't report metrics if user is not a Googler.
        if not self.is_googler:
            return False
        # Don't report metrics if user has opted out.
        if self.opted_in is False:
            return False
        # Don't report metrics if countdown hasn't reached 0.
        if self.opted_in is None and self.countdown > 0:
            return False
        return True

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

    def reset_config(self):
        # Only reset countdown if we're already collecting metrics.
        if self.should_collect_metrics:
            self._ensure_initialized()
            self._config['countdown'] = DEFAULT_COUNTDOWN
            self._config['opt-in'] = None


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

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

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

    def add(self, name, value):
        if self._collect_custom_metrics:
            with self._metrics_lock:
                self._reported_metrics[name] = value

    def add_repeated(self, name, value):
        if self._collect_custom_metrics:
            with self._metrics_lock:
                self._reported_metrics.setdefault(name, []).append(value)

    @contextlib.contextmanager
    def pause_metrics_collection(self):
        collect_custom_metrics = self._collect_custom_metrics
        self._collect_custom_metrics = False
        try:
            yield
        finally:
            self._collect_custom_metrics = collect_custom_metrics

    def _upload_metrics_data(self):
        """Upload the metrics data to the AppEngine app."""
        p = subprocess2.Popen(['vpython3', UPLOAD_SCRIPT],
                              stdin=subprocess2.PIPE)
        # 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.stdin.write(json.dumps(self._reported_metrics).encode('utf-8'))
        # ... but if we're running on a bot, wait until upload has completed.
        if metrics_utils.REPORT_BUILD:
            p.communicate()

    def _collect_metrics(self, func, command_name, *args, **kwargs):
        # If we're already collecting metrics, just execute the function.
        # e.g. git-cl split invokes git-cl upload several times to upload each
        # split CL.
        if self.collecting_metrics:
            # Don't collect metrics for this function.
            # e.g. Don't record the arguments git-cl split passes to git-cl
            # upload.
            with self.pause_metrics_collection():
                return func(*args, **kwargs)

        self._collecting_metrics = True
        self.add('metrics_version', metrics_utils.CURRENT_VERSION)
        self.add('command', command_name)
        for env in DEPOT_TOOLS_ENV:
            if env in os.environ:
                self.add_repeated('env_vars', {
                    'name': env,
                    'value': os.environ.get(env)
                })

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

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

        # Add metrics regarding environment information.
        self.add('timestamp', int(time.time()))
        self.add('python_version', metrics_utils.get_python_version())
        self.add('host_os', gclient_utils.GetOperatingSystem())
        self.add('host_arch', detect_host_arch.HostArch())

        depot_tools_age = metrics_utils.get_repo_timestamp(DEPOT_TOOLS)
        if depot_tools_age is not None:
            self.add('depot_tools_age', int(depot_tools_age))

        git_version = metrics_utils.get_git_version()
        if git_version:
            self.add('git_version', git_version)

        bot_metrics = metrics_utils.get_bot_metrics()
        if bot_metrics:
            self.add('bot_metrics', bot_metrics)

        self._upload_metrics_data()
        if exception:
            gclient_utils.reraise(exception[0], exception[1], exception[2])
        return result

    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.
        """
        def _decorator(func):
            if not self.config.should_collect_metrics:
                return func
            # Needed to preserve the __name__ and __doc__ attributes of func.
            @functools.wraps(func)
            def _inner(*args, **kwargs):
                return self._collect_metrics(func, command_name, *args,
                                             **kwargs)

            return _inner

        return _decorator

    @contextlib.contextmanager
    def print_notice_and_exit(self):
        """A context manager used to print the notice and terminate execution.

        This decorator executes the function and prints the monitoring notice if
        necessary. If an exception is raised, we will catch it, and print it
        before printing the metrics collection notice.
        This will call sys.exit() with an appropriate exit code to ensure the
        notice is the last thing printed.
        """
        # Needed to preserve the __name__ and __doc__ attributes of func.
        try:
            yield
            exception = None
        # pylint: disable=bare-except
        except:
            exception = sys.exc_info()

        # Print the exception before the metrics notice, so that the notice is
        # clearly visible even if gclient fails.
        if exception:
            if isinstance(exception[1], KeyboardInterrupt):
                sys.stderr.write('Interrupted\n')
            elif not isinstance(exception[1], SystemExit):
                traceback.print_exception(*exception)

        # Check if the version has changed
        if (self.config.is_googler and self.config.opted_in is not False
                and self.config.version != metrics_utils.CURRENT_VERSION):
            metrics_utils.print_version_change(self.config.version)
            self.config.reset_config()

        # Print the notice
        if self.config.is_googler and self.config.opted_in is None:
            metrics_utils.print_notice(self.config.countdown)
            self.config.decrease_countdown()

        sys.exit(metrics_utils.return_code_from_exception(exception))


collector = MetricsCollector()
