#
# This file is part of Glances.
#
# SPDX-FileCopyrightText: 2022 Nicolas Hennion <nicolas@nicolargo.com>
#
# SPDX-License-Identifier: LGPL-3.0-only
#

"""CPU plugin."""

import psutil

from glances.cpu_percent import cpu_percent
from glances.globals import LINUX, SUNOS, WINDOWS
from glances.plugins.core import CorePlugin
from glances.plugins.plugin.model import GlancesPluginModel

# Fields description
# https://github.com/nicolargo/glances/wiki/How-to-create-a-new-plugin-%3F#create-the-plugin-script
fields_description = {
    'total': {'description': 'Sum of all CPU percentages (except idle).', 'unit': 'percent', 'log': True},
    'system': {
        'description': 'Percent time spent in kernel space. System CPU time is the \
time spent running code in the Operating System kernel.',
        'unit': 'percent',
        'log': True,
    },
    'user': {
        'description': 'CPU percent time spent in user space. \
User CPU time is the time spent on the processor running your program\'s code (or code in libraries).',
        'unit': 'percent',
        'log': True,
    },
    'iowait': {
        'description': '*(Linux)*: percent time spent by the CPU waiting for I/O \
operations to complete.',
        'unit': 'percent',
        'log': True,
    },
    'dpc': {
        'description': '*(Windows)*: time spent servicing deferred procedure calls (DPCs)',
        'unit': 'percent',
        'log': True,
    },
    'idle': {
        'description': 'percent of CPU used by any program. Every program or task \
that runs on a computer system occupies a certain amount of processing \
time on the CPU. If the CPU has completed all tasks it is idle.',
        'unit': 'percent',
        'optional': True,
    },
    'irq': {
        'description': '*(Linux and BSD)*: percent time spent servicing/handling \
hardware/software interrupts. Time servicing interrupts (hardware + \
software).',
        'unit': 'percent',
        'optional': True,
    },
    'nice': {
        'description': '*(Unix)*: percent time occupied by user level processes with \
a positive nice value. The time the CPU has spent running users\' \
processes that have been *niced*.',
        'unit': 'percent',
        'optional': True,
    },
    'steal': {
        'description': '*(Linux)*: percentage of time a virtual CPU waits for a real \
CPU while the hypervisor is servicing another virtual processor.',
        'unit': 'percent',
        'alert': True,
        'optional': True,
    },
    'guest': {
        'description': '*(Linux)*: time spent running a virtual CPU for guest operating \
systems under the control of the Linux kernel.',
        'unit': 'percent',
        'optional': True,
    },
    'ctx_switches': {
        'description': 'number of context switches (voluntary + involuntary) per \
second. A context switch is a procedure that a computer\'s CPU (central \
processing unit) follows to change from one task (or process) to \
another while ensuring that the tasks do not conflict.',
        'unit': 'number',
        'rate': True,
        'min_symbol': 'K',
        'short_name': 'ctx_sw',
        'optional': True,
    },
    'interrupts': {
        'description': 'number of interrupts per second.',
        'unit': 'number',
        'rate': True,
        'min_symbol': 'K',
        'short_name': 'inter',
        'optional': True,
    },
    'soft_interrupts': {
        'description': 'number of software interrupts per second. Always set to \
0 on Windows and SunOS.',
        'unit': 'number',
        'rate': True,
        'min_symbol': 'K',
        'short_name': 'sw_int',
        'optional': True,
    },
    'syscalls': {
        'description': 'number of system calls per second. Always 0 on Linux OS.',
        'unit': 'number',
        'rate': True,
        'min_symbol': 'K',
        'short_name': 'sys_call',
        'optional': True,
    },
    'cpucore': {'description': 'Total number of CPU core.', 'unit': 'number'},
    'time_since_update': {'description': 'Number of seconds since last update.', 'unit': 'seconds'},
}

# SNMP OID
# percentage of user CPU time: .1.3.6.1.4.1.2021.11.9.0
# percentages of system CPU time: .1.3.6.1.4.1.2021.11.10.0
# percentages of idle CPU time: .1.3.6.1.4.1.2021.11.11.0
snmp_oid = {
    'default': {
        'user': '1.3.6.1.4.1.2021.11.9.0',
        'system': '1.3.6.1.4.1.2021.11.10.0',
        'idle': '1.3.6.1.4.1.2021.11.11.0',
    },
    'windows': {'percent': '1.3.6.1.2.1.25.3.3.1.2'},
    'esxi': {'percent': '1.3.6.1.2.1.25.3.3.1.2'},
    'netapp': {
        'system': '1.3.6.1.4.1.789.1.2.1.3.0',
        'idle': '1.3.6.1.4.1.789.1.2.1.5.0',
        'cpucore': '1.3.6.1.4.1.789.1.2.1.6.0',
    },
}

# Define the history items list
# - 'name' define the stat identifier
# - 'y_unit' define the Y label
items_history_list = [
    {'name': 'user', 'description': 'User CPU usage', 'y_unit': '%'},
    {'name': 'system', 'description': 'System CPU usage', 'y_unit': '%'},
]


class CpuPlugin(GlancesPluginModel):
    """Glances CPU plugin.

    'stats' is a dictionary that contains the system-wide CPU utilization as a
    percentage.
    """

    def __init__(self, args=None, config=None):
        """Init the CPU plugin."""
        super().__init__(
            args=args, config=config, items_history_list=items_history_list, fields_description=fields_description
        )

        # We want to display the stat in the curse interface
        self.display_curse = True

        # Call CorePlugin in order to display the core number
        try:
            self.nb_log_core = CorePlugin(args=self.args).update()["log"]
        except Exception:
            self.nb_log_core = 1

    @GlancesPluginModel._check_decorator
    @GlancesPluginModel._log_result_decorator
    def update(self):
        """Update CPU stats using the input method."""
        # Grab stats into self.stats
        if self.input_method == 'local':
            stats = self.update_local()
        elif self.input_method == 'snmp':
            stats = self.update_snmp()

        # Update the stats
        self.stats = stats

        return self.stats

    @GlancesPluginModel._manage_rate
    def update_local(self):
        """Update CPU stats using psutil."""
        # Grab CPU stats using psutil's cpu_percent and cpu_times_percent
        # Get all possible values for CPU stats: user, system, idle,
        # nice (UNIX), iowait (Linux), irq (Linux, FreeBSD), steal (Linux 2.6.11+)
        # The following stats are returned by the API but not displayed in the UI:
        # softirq (Linux), guest (Linux 2.6.24+), guest_nice (Linux 3.2.0+)

        # Init new stats
        stats = self.get_init_value()

        stats['total'] = cpu_percent.get_cpu()

        # Standards stats
        # - user: time spent by normal processes executing in user mode; on Linux this also includes guest time
        # - system: time spent by processes executing in kernel mode
        # - idle: time spent doing nothing
        # - nice (UNIX): time spent by niced (prioritized) processes executing in user mode
        #                on Linux this also includes guest_nice time
        # - iowait (Linux): time spent waiting for I/O to complete.
        #                   This is not accounted in idle time counter.
        # - irq (Linux, BSD): time spent for servicing hardware interrupts
        # - softirq (Linux): time spent for servicing software interrupts
        # - steal (Linux 2.6.11+): time spent by other operating systems running in a virtualized environment
        # - guest (Linux 2.6.24+): time spent running a virtual CPU for guest operating systems under
        #                          the control of the Linux kernel
        # - guest_nice (Linux 3.2.0+): time spent running a niced guest (virtual CPU for guest operating systems
        #                              under the control of the Linux kernel)
        # - interrupt (Windows): time spent for servicing hardware interrupts ( similar to “irq” on UNIX)
        # - dpc (Windows): time spent servicing deferred procedure calls (DPCs)
        cpu_times_percent = psutil.cpu_times_percent(interval=0.0)
        # Filter stats to keep only the fields we want (define in fields_description)
        # It will also convert psutil objects to a standard Python dict
        stats.update(self.filter_stats(cpu_times_percent))

        # Additional CPU stats (number of events not as a %; psutil>=4.1.0)
        # - ctx_switches: number of context switches (voluntary + involuntary) since boot.
        # - interrupts: number of interrupts since boot.
        # - soft_interrupts: number of software interrupts since boot. Always set to 0 on Windows and SunOS.
        # - syscalls: number of system calls since boot. Always set to 0 on Linux.
        cpu_stats = psutil.cpu_stats()
        # Filter stats to keep only the fields we want (define in fields_description)
        # It will also convert psutil objects to a standard Python dict
        stats.update(self.filter_stats(cpu_stats))
        # Core number is needed to compute the CTX switch limit
        stats['cpucore'] = self.nb_log_core

        return stats

    def update_snmp(self):
        """Update CPU stats using SNMP."""

        # Init new stats
        stats = self.get_init_value()

        # Update stats using SNMP
        if self.short_system_name in ('windows', 'esxi'):
            # Windows or VMWare ESXi
            # You can find the CPU utilization of windows system by querying the oid
            # Give also the number of core (number of element in the table)
            try:
                cpu_stats = self.get_stats_snmp(snmp_oid=snmp_oid[self.short_system_name], bulk=True)
            except KeyError:
                self.reset()

            # Iter through CPU and compute the idle CPU stats
            stats['nb_log_core'] = 0
            stats['idle'] = 0
            for c in cpu_stats:
                if c.startswith('percent'):
                    stats['idle'] += float(cpu_stats['percent.3'])
                    stats['nb_log_core'] += 1
            if stats['nb_log_core'] > 0:
                stats['idle'] = stats['idle'] / stats['nb_log_core']
            stats['idle'] = 100 - stats['idle']
            stats['total'] = 100 - stats['idle']

        else:
            # Default behavior
            try:
                stats = self.get_stats_snmp(snmp_oid=snmp_oid[self.short_system_name])
            except KeyError:
                stats = self.get_stats_snmp(snmp_oid=snmp_oid['default'])

            if stats['idle'] == '':
                self.reset()
                return self.stats

            # Convert SNMP stats to float
            for key in stats:
                stats[key] = float(stats[key])
            stats['total'] = 100 - stats['idle']

        return stats

    def update_views(self):
        """Update stats views."""
        # Call the father's method
        super().update_views()

        # Add specifics information
        for key in ['ctx_switches']:
            # Skip alert if no timespan to measure
            if self.stats.get('time_since_update', 0) == 0:
                continue
            if key in self.stats:
                self.views[key]['decoration'] = self.get_alert(
                    self.stats[key], maximum=100 * self.stats['cpucore'], header=key
                )

    def msg_curse(self, args=None, max_width=None):
        """Return the list to display in the UI."""
        # Init the return message
        ret = []

        # Only process if stats exist and plugin not disable
        if not self.stats or self.args.percpu or self.is_disabled():
            return ret

        # Some tag to enable/disable stats (example: idle_tag triggered on Windows OS)
        idle_tag = 'user' not in self.stats

        # First line
        # Total + (idle) + ctx_sw
        msg = '{:8}'.format('CPU')
        ret.append(self.curse_add_line(msg, "TITLE"))
        # Total CPU usage
        msg = '{:5.1f}%'.format(self.stats['total'])
        ret.append(self.curse_add_line(msg, self.get_views(key='total', option='decoration')))
        # Idle CPU
        if 'idle' in self.stats and not idle_tag:
            msg = '  {:8}'.format('idle')
            ret.append(self.curse_add_line(msg, optional=self.get_views(key='idle', option='optional')))
            msg = '{:4.1f}%'.format(self.stats['idle'])
            ret.append(self.curse_add_line(msg, optional=self.get_views(key='idle', option='optional')))
        # ctx_switches
        # On WINDOWS/SUNOS the ctx_switches is displayed in the third line
        if not WINDOWS and not SUNOS:
            ret.extend(self.curse_add_stat('ctx_switches', width=15, header='  '))

        # Second line
        # user|idle + irq + interrupts
        ret.append(self.curse_new_line())
        # User CPU
        if not idle_tag:
            ret.extend(self.curse_add_stat('user', width=15))
        elif 'idle' in self.stats:
            ret.extend(self.curse_add_stat('idle', width=15))
        # IRQ CPU
        ret.extend(self.curse_add_stat('irq', width=14, header='  '))
        # interrupts
        ret.extend(self.curse_add_stat('interrupts', width=15, header='  '))

        # Third line
        # system|core + nice + sw_int
        ret.append(self.curse_new_line())
        # System CPU
        if not idle_tag:
            ret.extend(self.curse_add_stat('system', width=15))
        else:
            ret.extend(self.curse_add_stat('core', width=15))
        # Nice CPU
        ret.extend(self.curse_add_stat('nice', width=14, header='  '))
        # soft_interrupts
        if not WINDOWS and not SUNOS:
            ret.extend(self.curse_add_stat('soft_interrupts', width=15, header='  '))
        else:
            ret.extend(self.curse_add_stat('ctx_switches', width=15, header='  '))

        # Fourth line
        # iowait + steal + (syscalls or guest)
        ret.append(self.curse_new_line())
        if 'iowait' in self.stats:
            # IOWait CPU
            ret.extend(self.curse_add_stat('iowait', width=15))
        elif 'dpc' in self.stats:
            # DPC CPU
            ret.extend(self.curse_add_stat('dpc', width=15))
        # Steal CPU usage
        ret.extend(self.curse_add_stat('steal', width=14, header='  '))
        if not LINUX:
            # syscalls: number of system calls since boot. Always set to 0 on Linux. (do not display)
            ret.extend(self.curse_add_stat('syscalls', width=15, header='  '))
        else:
            # So instead on Linux we display the guest CPU usage (see #2667)
            # guest: time spent running a virtual CPU for guest operating systems under
            ret.extend(self.curse_add_stat('guest', width=14, header='  '))

        # Return the message with decoration
        return ret
