# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# Copyright (C) 2014 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/>.
"""
Glances DiskIO plugin
"""

import psutil

# Import Glances libs
from glances.core.glances_timer import getTimeSinceLastUpdate
from glances.plugins.glances_plugin import GlancesPlugin


class Plugin(GlancesPlugin):
    """
    Glances's disks IO Plugin

    stats is a list
    """

    def __init__(self, args=None):
        GlancesPlugin.__init__(self, args=args)

        # We want to display the stat in the curse interface
        self.display_curse = True
        # Set the message position
        # It is NOT the curse position but the Glances column/line
        # Enter -1 to right align
        self.column_curse = 0
        # Enter -1 to diplay bottom
        self.line_curse = 3

        # Init the stats
        self.reset()        

    def reset(self):
        """
        Reset/init the stats
        """
        self.stats = []

    def update(self):
        """
        Update disk IO stats using the input method
        """

        # Reset stats
        self.reset()

        if self.get_input() == 'local':
            # Update stats using the standard system lib
            # Grab the stat using the PsUtil disk_io_counters method
            # read_count: number of reads
            # write_count: number of writes
            # read_bytes: number of bytes read
            # write_bytes: number of bytes written
            # read_time: time spent reading from disk (in milliseconds)
            # write_time: time spent writing to disk (in milliseconds)
            try:
                diskiocounters = psutil.disk_io_counters(perdisk=True)
            except:
                return self.stats

            # Previous disk IO stats are stored in the diskio_old variable
            if not hasattr(self, 'diskio_old'):
                # First call, we init the network_old var
                try:
                    self.diskio_old = diskiocounters
                except (IOError, UnboundLocalError):
                    pass
            else:
                # By storing time data we enable Rx/s and Tx/s calculations in the
                # XML/RPC API, which would otherwise be overly difficult work
                # for users of the API
                time_since_update = getTimeSinceLastUpdate('disk')

                diskio_new = diskiocounters
                for disk in diskio_new:
                    try:
                        # Try necessary to manage dynamic disk creation/del
                        diskstat = {}
                        diskstat['time_since_update'] = time_since_update
                        diskstat['disk_name'] = disk
                        diskstat['read_bytes'] = (
                            diskio_new[disk].read_bytes -
                            self.diskio_old[disk].read_bytes)
                        diskstat['write_bytes'] = (
                            diskio_new[disk].write_bytes -
                            self.diskio_old[disk].write_bytes)
                    except KeyError:
                        continue
                    else:
                        self.stats.append(diskstat)
                
                # Save stats to compute next bitrate
                self.diskio_old = diskio_new
        elif self.get_input() == 'snmp':
            # Update stats using SNMP
            # !!! TODO: no standard way for the moment
            pass

        return self.stats

    def msg_curse(self, args=None):
        """
        Return the dict to display in the curse interface
        """

        # Init the return message
        ret = []

        # Only process if stats exist and display plugin enable...
        if self.stats == [] or args.disable_diskio:
            return ret

        # Build the string message
        # Header
        msg = "{0:9}".format(_("DISK I/O"))
        ret.append(self.curse_add_line(msg, "TITLE"))
        msg = "{0:>7}".format(_("R/s"))
        ret.append(self.curse_add_line(msg))
        msg = "{0:>7}".format(_("W/s"))
        ret.append(self.curse_add_line(msg))
        # Disk list (sorted by name)
        for i in sorted(self.stats, key=lambda diskio: diskio['disk_name']):
            # Do not display hidden interfaces
            if self.is_hide(i['disk_name']):
                continue
            # New line
            ret.append(self.curse_new_line())
            msg = "{0:9}".format(i['disk_name'])
            ret.append(self.curse_add_line(msg))
            txps = self.auto_unit(int(i['read_bytes'] // i['time_since_update']))
            rxps = self.auto_unit(int(i['write_bytes'] // i['time_since_update']))
            msg = "{0:>7}".format(txps)
            ret.append(self.curse_add_line(msg))
            msg = "{0:>7}".format(rxps)
            ret.append(self.curse_add_line(msg))

        return ret