# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# Copyright (C) 2021 Nicolargo <nicolas@nicolargo.com>
#
# Glances is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Glances is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

import os

from glances.compat import iterkeys
from glances.globals import BSD, LINUX, MACOS, WINDOWS
from glances.timer import Timer, getTimeSinceLastUpdate
from glances.filter import GlancesFilter
from glances.logger import logger

import psutil

# This constant defines the list of available processes sort key
sort_processes_key_list = ['cpu_percent',
                           'memory_percent',
                           'username',
                           'cpu_times',
                           'io_counters',
                           'name']


class GlancesProcesses(object):
    """Get processed stats using the psutil library."""

    def __init__(self, cache_timeout=60):
        """Init the class to collect stats about processes."""
        # Add internals caches because psutil do not cache all the stats
        # See: https://code.google.com/p/psutil/issues/detail?id=462
        self.username_cache = {}
        self.cmdline_cache = {}

        # The internals caches will be cleaned each 'cache_timeout' seconds
        self.cache_timeout = cache_timeout
        # First iteration, no cache
        self.cache_timer = Timer(0)

        # Init the io dict
        # key = pid
        # value = [ read_bytes_old, write_bytes_old ]
        self.io_old = {}

        # Init stats
        self.auto_sort = None
        self._sort_key = None
        # Default processes sort key is 'auto'
        # Can be overwrite from the configuration file (issue#1536) => See glances_processlist.py init
        self.set_sort_key('auto', auto=True)
        self.processlist = []
        self.reset_processcount()

        # Cache is a dict with key=pid and value = dict of cached value
        self.processlist_cache = {}

        # Tag to enable/disable the processes stats (to reduce the Glances CPU consumption)
        # Default is to enable the processes stats
        self.disable_tag = False

        # Extended stats for top process is enable by default
        self.disable_extended_tag = False

        # Test if the system can grab io_counters
        try:
            p = psutil.Process()
            p.io_counters()
        except Exception as e:
            logger.warning('PsUtil can not grab processes io_counters ({})'.format(e))
            self.disable_io_counters = True
        else:
            logger.debug('PsUtil can grab processes io_counters')
            self.disable_io_counters = False

        # Test if the system can grab gids
        try:
            p = psutil.Process()
            p.gids()
        except Exception as e:
            logger.warning('PsUtil can not grab processes gids ({})'.format(e))
            self.disable_gids = True
        else:
            logger.debug('PsUtil can grab processes gids')
            self.disable_gids = False

        # Maximum number of processes showed in the UI (None if no limit)
        self._max_processes = None

        # Process filter is a regular expression
        self._filter = GlancesFilter()

        # Whether or not to hide kernel threads
        self.no_kernel_threads = False

        # Store maximums values in a dict
        # Used in the UI to highlight the maximum value
        self._max_values_list = ('cpu_percent', 'memory_percent')
        # { 'cpu_percent': 0.0, 'memory_percent': 0.0 }
        self._max_values = {}
        self.reset_max_values()

    def reset_processcount(self):
        """Reset the global process count"""
        self.processcount = {'total': 0,
                             'running': 0,
                             'sleeping': 0,
                             'thread': 0,
                             'pid_max': None}

    def update_processcount(self, plist):
        """Update the global process count from the current processes list"""
        # Update the maximum process ID (pid) number
        self.processcount['pid_max'] = self.pid_max
        # For each key in the processcount dict
        # count the number of processes with the same status
        for k in iterkeys(self.processcount):
            self.processcount[k] = len(list(filter(lambda v: v['status'] is k,
                                                   plist)))
        # Compute thread
        self.processcount['thread'] = sum(i['num_threads'] for i in plist
                                          if i['num_threads'] is not None)
        # Compute total
        self.processcount['total'] = len(plist)

    def enable(self):
        """Enable process stats."""
        self.disable_tag = False
        self.update()

    def disable(self):
        """Disable process stats."""
        self.disable_tag = True

    def enable_extended(self):
        """Enable extended process stats."""
        self.disable_extended_tag = False
        self.update()

    def disable_extended(self):
        """Disable extended process stats."""
        self.disable_extended_tag = True

    @property
    def pid_max(self):
        """
        Get the maximum PID value.

        On Linux, the value is read from the `/proc/sys/kernel/pid_max` file.

        From `man 5 proc`:
        The default value for this file, 32768, results in the same range of
        PIDs as on earlier kernels. On 32-bit platfroms, 32768 is the maximum
        value for pid_max. On 64-bit systems, pid_max can be set to any value
        up to 2^22 (PID_MAX_LIMIT, approximately 4 million).

        If the file is unreadable or not available for whatever reason,
        returns None.

        Some other OSes:
        - On FreeBSD and macOS the maximum is 99999.
        - On OpenBSD >= 6.0 the maximum is 99999 (was 32766).
        - On NetBSD the maximum is 30000.

        :returns: int or None
        """
        if LINUX:
            # XXX: waiting for https://github.com/giampaolo/psutil/issues/720
            try:
                with open('/proc/sys/kernel/pid_max', 'rb') as f:
                    return int(f.read())
            except (OSError, IOError):
                return None
        else:
            return None

    @property
    def processes_count(self):
        """Get the current number of processes showed in the UI."""
        return min(self._max_processes - 2, glances_processes.processcount['total'] - 1)

    @property
    def max_processes(self):
        """Get the maximum number of processes showed in the UI."""
        return self._max_processes

    @max_processes.setter
    def max_processes(self, value):
        """Set the maximum number of processes showed in the UI."""
        self._max_processes = value

    @property
    def process_filter_input(self):
        """Get the process filter (given by the user)."""
        return self._filter.filter_input

    @property
    def process_filter(self):
        """Get the process filter (current apply filter)."""
        return self._filter.filter

    @process_filter.setter
    def process_filter(self, value):
        """Set the process filter."""
        self._filter.filter = value

    @property
    def process_filter_key(self):
        """Get the process filter key."""
        return self._filter.filter_key

    @property
    def process_filter_re(self):
        """Get the process regular expression compiled."""
        return self._filter.filter_re

    def disable_kernel_threads(self):
        """Ignore kernel threads in process list."""
        self.no_kernel_threads = True

    @property
    def sort_reverse(self):
        """Return True to sort processes in reverse 'key' order, False instead."""
        if self.sort_key == 'name' or self.sort_key == 'username':
            return False

        return True

    def max_values(self):
        """Return the max values dict."""
        return self._max_values

    def get_max_values(self, key):
        """Get the maximum values of the given stat (key)."""
        return self._max_values[key]

    def set_max_values(self, key, value):
        """Set the maximum value for a specific stat (key)."""
        self._max_values[key] = value

    def reset_max_values(self):
        """Reset the maximum values dict."""
        self._max_values = {}
        for k in self._max_values_list:
            self._max_values[k] = 0.0

    def update(self):
        """Update the processes stats."""
        # Reset the stats
        self.processlist = []
        self.reset_processcount()

        # Do not process if disable tag is set
        if self.disable_tag:
            return

        # Time since last update (for disk_io rate computation)
        time_since_update = getTimeSinceLastUpdate('process_disk')

        # Grab standard stats
        #####################
        sorted_attrs = ['cpu_percent', 'cpu_times',
                          'memory_percent', 'name',
                          'status', 'status', 'num_threads']
        displayed_attr = ['memory_info', 'nice', 'pid', 'ppid']
        cached_attrs = ['cmdline', 'username']

        # Some stats are optionals
        if not self.disable_io_counters:
            sorted_attrs.append('io_counters')
        if not self.disable_gids:
            displayed_attr.append('gids')
        # Some stats are not sort key
        # An optimisation can be done be only grabed displayed_attr
        # for displayed processes (but only in standalone mode...)
        sorted_attrs.extend(displayed_attr)
        # Some stats are cached (not necessary to be refreshed every time)
        if self.cache_timer.finished():
            sorted_attrs += cached_attrs
            self.cache_timer.set(self.cache_timeout)
            self.cache_timer.reset()
            is_cached = False
        else:
            is_cached = True

        # Build the processes stats list (it is why we need psutil>=5.3.0)
        self.processlist = [p.info
                            for p in psutil.process_iter(attrs=sorted_attrs,
                                                         ad_value=None)
                            # OS-related processes filter
                            if not (BSD and p.info['name'] == 'idle') and
                            not (WINDOWS and p.info['name'] == 'System Idle Process') and
                            not (MACOS and p.info['name'] == 'kernel_task') and
                            # Kernel threads filter
                            not (self.no_kernel_threads and LINUX and p.info['gids'].real == 0)]

        # Sort the processes list by the current sort_key
        self.processlist = sort_stats(self.processlist,
                                      sortedby=self.sort_key,
                                      reverse=True)

        # Update the processcount
        self.update_processcount(self.processlist)

        # Loop over processes and add metadata
        first = True
        for proc in self.processlist:
            # Get extended stats, only for top processes (see issue #403).
            if first and not self.disable_extended_tag:
                # - cpu_affinity (Linux, Windows, FreeBSD)
                # - ionice (Linux and Windows > Vista)
                # - num_ctx_switches (not available on Illumos/Solaris)
                # - num_fds (Unix-like)
                # - num_handles (Windows)
                # - memory_maps (only swap, Linux)
                #   https://www.cyberciti.biz/faq/linux-which-process-is-using-swap/
                # - connections (TCP and UDP)
                extended = {}
                try:
                    top_process = psutil.Process(proc['pid'])
                    extended_stats = ['cpu_affinity', 'ionice',
                                      'num_ctx_switches']
                    if LINUX:
                        # num_fds only avalable on Unix system (see issue #1351)
                        extended_stats += ['num_fds']
                    if WINDOWS:
                        extended_stats += ['num_handles']

                    # Get the extended stats
                    extended = top_process.as_dict(attrs=extended_stats,
                                                   ad_value=None)

                    if LINUX:
                        try:
                            extended['memory_swap'] = sum([v.swap for v in top_process.memory_maps()])
                        except (psutil.NoSuchProcess, KeyError):
                            # (KeyError catch for issue #1551)
                            pass
                        except (psutil.AccessDenied, NotImplementedError):
                            # NotImplementedError: /proc/${PID}/smaps file doesn't exist
                            # on kernel < 2.6.14 or CONFIG_MMU kernel configuration option
                            # is not enabled (see psutil #533/glances #413).
                            extended['memory_swap'] = None
                    try:
                        extended['tcp'] = len(top_process.connections(kind="tcp"))
                        extended['udp'] = len(top_process.connections(kind="udp"))
                    except (psutil.AccessDenied, psutil.NoSuchProcess):
                        # Manage issue1283 (psutil.AccessDenied)
                        extended['tcp'] = None
                        extended['udp'] = None
                except (psutil.NoSuchProcess, ValueError, AttributeError) as e:
                    logger.error('Can not grab extended stats ({})'.format(e))
                    extended['extended_stats'] = False
                else:
                    logger.debug('Grab extended stats for process {}'.format(proc['pid']))
                    extended['extended_stats'] = True
                proc.update(extended)
            first = False
            # /End of extended stats

            # PID is the key
            proc['key'] = 'pid'

            # Time since last update (for disk_io rate computation)
            proc['time_since_update'] = time_since_update

            # Process status (only keep the first char)
            proc['status'] = str(proc['status'])[:1].upper()

            # Process IO
            # procstat['io_counters'] is a list:
            # [read_bytes, write_bytes, read_bytes_old, write_bytes_old, io_tag]
            # If io_tag = 0 > Access denied or first time (display "?")
            # If io_tag = 1 > No access denied (display the IO rate)
            if 'io_counters' in proc and proc['io_counters'] is not None:
                io_new = [proc['io_counters'].read_bytes,
                          proc['io_counters'].write_bytes]
                # For IO rate computation
                # Append saved IO r/w bytes
                try:
                    proc['io_counters'] = io_new + self.io_old[proc['pid']]
                    io_tag = 1
                except KeyError:
                    proc['io_counters'] = io_new + [0, 0]
                    io_tag = 0
                # then save the IO r/w bytes
                self.io_old[proc['pid']] = io_new
            else:
                proc['io_counters'] = [0, 0] + [0, 0]
                io_tag = 0
            # Append the IO tag (for display)
            proc['io_counters'] += [io_tag]

            # Manage cached information
            if is_cached:
                # Grab cached values (in case of a new incoming process)
                if proc['pid'] not in self.processlist_cache:
                    try:
                        self.processlist_cache[proc['pid']]= psutil.Process(pid=proc['pid']).as_dict(attrs=cached_attrs,
                                                                                                    ad_value=None)
                    except psutil.NoSuchProcess:
                        pass
                # Add cached value to current stat
                try:
                    proc.update(self.processlist_cache[proc['pid']])
                except KeyError:
                    pass
            else:
                # Save values to cache
                self.processlist_cache[proc['pid']] = { cached: proc[cached] for cached in cached_attrs }

        # Apply filter
        self.processlist = [p for p in self.processlist if not (self._filter.is_filtered(p))]

        # Compute the maximum value for keys in self._max_values_list: CPU, MEM
        # Usefull to highlight the processes with maximum values
        for k in self._max_values_list:
            values_list = [i[k] for i in self.processlist if i[k] is not None]
            if values_list != []:
                self.set_max_values(k, max(values_list))

    def getcount(self):
        """Get the number of processes."""
        return self.processcount

    def getlist(self, sortedby=None):
        """Get the processlist."""
        return self.processlist

    @property
    def sort_key(self):
        """Get the current sort key."""
        return self._sort_key

    def set_sort_key(self, key, auto=True):
        """Set the current sort key."""
        if key == 'auto':
            self.auto_sort = True
            self._sort_key = 'cpu_percent'
        else:
            self.auto_sort = auto
            self._sort_key = key

    def kill(self, pid, timeout=3):
        """Kill process with pid"""
        assert pid != os.getpid(), "Glances can kill itself..."
        p = psutil.Process(pid)
        logger.debug('Send kill signal to process: {}'.format(p))
        p.kill()
        return p.wait(timeout)


def weighted(value):
    """Manage None value in dict value."""
    return -float('inf') if value is None else value


def _sort_io_counters(process,
                      sortedby='io_counters',
                      sortedby_secondary='memory_percent'):
    """Specific case for io_counters
    Sum of io_r + io_w"""
    return process[sortedby][0] - process[sortedby][2] + process[sortedby][1] - process[sortedby][3]


def _sort_cpu_times(process,
                    sortedby='cpu_times',
                    sortedby_secondary='memory_percent'):
    """ Specific case for cpu_times
    Patch for "Sorting by process time works not as expected #1321"
    By default PsUtil only takes user time into account
    see (https://github.com/giampaolo/psutil/issues/1339)
    The following implementation takes user and system time into account"""
    return process[sortedby][0] + process[sortedby][1]


def _sort_lambda(sortedby='cpu_percent',
                 sortedby_secondary='memory_percent'):
    """Return a sort lambda function for the sortedbykey"""
    ret = None
    if sortedby == 'io_counters':
        ret = _sort_io_counters
    elif sortedby == 'cpu_times':
        ret = _sort_cpu_times
    return ret


def sort_stats(stats,
               sortedby='cpu_percent',
               sortedby_secondary='memory_percent',
               reverse=True):
    """Return the stats (dict) sorted by (sortedby).

    Reverse the sort if reverse is True.
    """
    if sortedby is None and sortedby_secondary is None:
        # No need to sort...
        return stats

    # Check if a specific sort should be done
    sort_lambda = _sort_lambda(sortedby=sortedby,
                               sortedby_secondary=sortedby_secondary)

    if sort_lambda is not None:
        # Specific sort
        try:
            stats.sort(key=sort_lambda, reverse=reverse)
        except Exception:
            # If an error is detected, fallback to cpu_percent
            stats.sort(key=lambda process: (weighted(process['cpu_percent']),
                                            weighted(process[sortedby_secondary])),
                       reverse=reverse)
    else:
        # Standard sort
        try:
            stats.sort(key=lambda process: (weighted(process[sortedby]),
                                            weighted(process[sortedby_secondary])),
                       reverse=reverse)
        except (KeyError, TypeError):
            # Fallback to name
            stats.sort(key=lambda process: process['name'] if process['name'] is not None else '~',
                       reverse=False)

    return stats


glances_processes = GlancesProcesses()