#!/usr/bin/env python3
#
# Copyright (C) 2022 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

import os
import re
import sys
import glob
import json
import typing
from datetime import datetime
from tabulate import tabulate

import vyos.opmode
from vyos.ifconfig import Section
from vyos.ifconfig import Interface
from vyos.ifconfig import VRRP
from vyos.util import cmd, rc_cmd, call

def catch_broken_pipe(func):
    def wrapped(*args, **kwargs):
        try:
            func(*args, **kwargs)
        except (BrokenPipeError, KeyboardInterrupt):
            # Flush output to /dev/null and bail out.
            os.dup2(os.open(os.devnull, os.O_WRONLY), sys.stdout.fileno())
    return wrapped

# The original implementation of filtered_interfaces has signature:
# (ifnames: list, iftypes: typing.Union[str, list], vif: bool, vrrp: bool) -> intf: Interface:
# Arg types allowed in CLI (ifnames: str, iftypes: str) were manually
# re-typed from argparse args.
# We include the function in a general form, however op-mode standard
# functions will restrict to the CLI-allowed arg types, wrapped in Optional.
def filtered_interfaces(ifnames: typing.Union[str, list],
                        iftypes: typing.Union[str, list],
                        vif: bool, vrrp: bool) -> Interface:
    """
    get all interfaces from the OS and return them; ifnames can be used to
    filter which interfaces should be considered

    ifnames: a list of interface names to consider, empty do not filter

    return an instance of the Interface class
    """
    if isinstance(ifnames, str):
        ifnames = [ifnames] if ifnames else []
    if isinstance(iftypes, list):
        for iftype in iftypes:
            yield from filtered_interfaces(ifnames, iftype, vif, vrrp)

    for ifname in Section.interfaces(iftypes):
        # Bail out early if interface name not part of our search list
        if ifnames and ifname not in ifnames:
            continue

        # As we are only "reading" from the interface - we must use the
        # generic base class which exposes all the data via a common API
        interface = Interface(ifname, create=False, debug=False)

        # VLAN interfaces have a '.' in their name by convention
        if vif and not '.' in ifname:
            continue

        if vrrp:
            vrrp_interfaces = VRRP.active_interfaces()
            if ifname not in vrrp_interfaces:
                continue

        yield interface

def _split_text(text, used=0):
    """
    take a string and attempt to split it to fit with the width of the screen

    text: the string to split
    used: number of characted already used in the screen
    """
    no_tty = call('tty -s')

    returned = cmd('stty size') if not no_tty else ''
    returned = returned.split()
    if len(returned) == 2:
        _, columns = tuple(int(_) for _ in returned)
    else:
        _, columns = (40, 80)

    desc_len = columns - used

    line = ''
    for word in text.split():
        if len(line) + len(word) < desc_len:
            line = f'{line} {word}'
            continue
        if line:
            yield line[1:]
        else:
            line = f'{line} {word}'

    yield line[1:]

def _get_counter_val(prev, now):
    """
    attempt to correct a counter if it wrapped, copied from perl

    prev: previous counter
    now:  the current counter
    """
    # This function has to deal with both 32 and 64 bit counters
    if prev == 0:
        return now

    # device is using 64 bit values assume they never wrap
    value = now - prev
    if (now >> 32) != 0:
        return value

    # The counter has rolled.  If the counter has rolled
    # multiple times since the prev value, then this math
    # is meaningless.
    if value < 0:
        value = (4294967296 - prev) + now

    return value

def _pppoe(ifname):
    out = cmd('ps -C pppd -f')
    if ifname in out:
        return 'C'
    if ifname in [_.split('/')[-1] for _ in glob.glob('/etc/ppp/peers/pppoe*')]:
        return 'D'
    return ''

def _find_intf_by_ifname(intf_l: list, name: str):
    for d in intf_l:
        if d['ifname'] == name:
            return d
    return {}

# lifted out of operational.py to separate formatting from data
def _format_stats(stats, indent=4):
    stat_names = {
        'rx': ['bytes', 'packets', 'errors', 'dropped', 'overrun', 'mcast'],
        'tx': ['bytes', 'packets', 'errors', 'dropped', 'carrier', 'collisions'],
    }

    stats_dir = {
        'rx': ['rx_bytes', 'rx_packets', 'rx_errors', 'rx_dropped', 'rx_over_errors', 'multicast'],
        'tx': ['tx_bytes', 'tx_packets', 'tx_errors', 'tx_dropped', 'tx_carrier_errors', 'collisions'],
    }
    tabs = []
    for rtx in list(stats_dir):
        tabs.append([f'{rtx.upper()}:', ] + stat_names[rtx])
        tabs.append(['', ] + [stats[_] for _ in stats_dir[rtx]])

    s = tabulate(
        tabs,
        stralign="right",
        numalign="right",
        tablefmt="plain"
    )

    p = ' '*indent
    return f'{p}' + s.replace('\n', f'\n{p}')

def _get_raw_data(ifname: typing.Optional[str],
                  iftype: typing.Optional[str],
                  vif: bool, vrrp: bool) -> list:
    if ifname is None:
        ifname = ''
    if iftype is None:
        iftype = ''
    ret =[]
    for interface in filtered_interfaces(ifname, iftype, vif, vrrp):
        res_intf = {}
        cache = interface.operational.load_counters()

        out = cmd(f'ip -json addr show {interface.ifname}')
        res_intf_l = json.loads(out)
        res_intf = res_intf_l[0]

        if res_intf['link_type'] == 'tunnel6':
            # Note that 'ip -6 tun show {interface.ifname}' is not json
            # aware, so find in list
            out = cmd('ip -json -6 tun show')
            tunnel = json.loads(out)
            res_intf['tunnel6'] = _find_intf_by_ifname(tunnel,
                                                       interface.ifname)
            if 'ip6_tnl_f_use_orig_tclass' in res_intf['tunnel6']:
                res_intf['tunnel6']['tclass'] = 'inherit'
                del res_intf['tunnel6']['ip6_tnl_f_use_orig_tclass']

        res_intf['counters_last_clear'] = int(cache.get('timestamp', 0))

        res_intf['description'] = interface.get_alias()

        stats = interface.operational.get_stats()
        for k in list(stats):
            stats[k] = _get_counter_val(cache[k], stats[k])

        res_intf['stats'] = stats

        ret.append(res_intf)

    # find pppoe interfaces that are in a transitional/dead state
    if ifname.startswith('pppoe') and not _find_intf_by_ifname(ret, ifname):
        pppoe_intf = {}
        pppoe_intf['unhandled'] = None
        pppoe_intf['ifname'] = ifname
        pppoe_intf['state'] = _pppoe(ifname)
        ret.append(pppoe_intf)

    return ret

def _get_summary_data(ifname: typing.Optional[str],
                      iftype: typing.Optional[str],
                      vif: bool, vrrp: bool) -> list:
    if ifname is None:
        ifname = ''
    if iftype is None:
        iftype = ''
    ret = []
    for interface in filtered_interfaces(ifname, iftype, vif, vrrp):
        res_intf = {}

        res_intf['ifname'] = interface.ifname
        res_intf['oper_state'] = interface.operational.get_state()
        res_intf['admin_state'] = interface.get_admin_state()
        res_intf['addr'] = [_ for _ in interface.get_addr() if not _.startswith('fe80::')]
        res_intf['description'] = interface.get_alias()

        ret.append(res_intf)

    # find pppoe interfaces that are in a transitional/dead state
    if ifname.startswith('pppoe') and not _find_intf_by_ifname(ret, ifname):
        pppoe_intf = {}
        pppoe_intf['unhandled'] = None
        pppoe_intf['ifname'] = ifname
        pppoe_intf['state'] = _pppoe(ifname)
        ret.append(pppoe_intf)

    return ret

def _get_counter_data(ifname: typing.Optional[str],
                      iftype: typing.Optional[str],
                      vif: bool, vrrp: bool) -> list:
    if ifname is None:
        ifname = ''
    if iftype is None:
        iftype = ''
    ret = []
    for interface in filtered_interfaces(ifname, iftype, vif, vrrp):
        res_intf = {}

        oper = interface.operational.get_state()

        if oper not in ('up','unknown'):
            continue

        stats = interface.operational.get_stats()
        cache = interface.operational.load_counters()
        res_intf['ifname'] = interface.ifname
        res_intf['rx_packets'] = _get_counter_val(cache['rx_packets'], stats['rx_packets'])
        res_intf['rx_bytes'] = _get_counter_val(cache['rx_bytes'], stats['rx_bytes'])
        res_intf['tx_packets'] = _get_counter_val(cache['tx_packets'], stats['tx_packets'])
        res_intf['tx_bytes'] = _get_counter_val(cache['tx_bytes'], stats['tx_bytes'])
        res_intf['rx_dropped'] = _get_counter_val(cache['rx_dropped'], stats['rx_dropped'])
        res_intf['tx_dropped'] = _get_counter_val(cache['tx_dropped'], stats['tx_dropped'])
        res_intf['rx_over_errors'] = _get_counter_val(cache['rx_over_errors'], stats['rx_over_errors'])
        res_intf['tx_carrier_errors'] = _get_counter_val(cache['tx_carrier_errors'], stats['tx_carrier_errors'])

        ret.append(res_intf)

    return ret

@catch_broken_pipe
def _format_show_data(data: list):
    unhandled = []
    for intf in data:
        if 'unhandled' in intf:
            unhandled.append(intf)
            continue
        # instead of reformatting data, call non-json output:
        rc, out = rc_cmd(f"ip addr show {intf['ifname']}")
        if rc != 0:
            continue
        out = re.sub('^\d+:\s+','',out)
        # add additional data already collected
        if 'tunnel6' in intf:
            t6_d = intf['tunnel6']
            t6_str = 'encaplimit %s hoplimit %s tclass %s flowlabel %s (flowinfo %s)' % (
                    t6_d.get('encap_limit', ''), t6_d.get('hoplimit', ''),
                    t6_d.get('tclass', ''), t6_d.get('flowlabel', ''),
                    t6_d.get('flowinfo', ''))
            out = re.sub('(\n\s+)(link/tunnel6)', f'\g<1>{t6_str}\g<1>\g<2>', out)
        print(out)
        ts = intf.get('counters_last_clear', 0)
        if ts:
            when = datetime.fromtimestamp(ts).strftime("%a %b %d %R:%S %Z %Y")
            print(f'    Last clear: {when}')
        description = intf.get('description', '')
        if description:
            print(f'    Description: {description}')

        stats = intf.get('stats', {})
        if stats:
            print()
            print(_format_stats(stats))

    for intf in unhandled:
        string = {
            'C': 'Coming up',
            'D': 'Link down'
        }[intf['state']]
        print(f"{intf['ifname']}: {string}")

    return 0

@catch_broken_pipe
def _format_show_summary(data):
    format1 = '%-16s %-33s %-4s %s'
    format2 = '%-16s %s'

    print('Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down')
    print(format1 % ("Interface", "IP Address", "S/L", "Description"))
    print(format1 % ("---------", "----------", "---", "-----------"))

    unhandled = []
    for intf in data:
        if 'unhandled' in intf:
            unhandled.append(intf)
            continue
        ifname = [intf['ifname'],]
        oper = ['u',] if intf['oper_state'] in ('up', 'unknown') else ['D',]
        admin = ['u',] if intf['admin_state'] in ('up', 'unknown') else ['A',]
        addrs = intf['addr'] or ['-',]
        descs = list(_split_text(intf['description'], 0))

        while ifname or oper or admin or addrs or descs:
            i = ifname.pop(0) if ifname else ''
            a = addrs.pop(0) if addrs else ''
            d = descs.pop(0) if descs else ''
            s = [admin.pop(0)] if admin else []
            l = [oper.pop(0)] if oper else []
            if len(a) < 33:
                print(format1 % (i, a, '/'.join(s+l), d))
            else:
                print(format2 % (i, a))
                print(format1 % ('', '', '/'.join(s+l), d))

    for intf in unhandled:
        string = {
            'C': 'u/D',
            'D': 'A/D'
        }[intf['state']]
        print(format1 % (ifname, '', string, ''))

    return 0

@catch_broken_pipe
def _format_show_counters(data: list):
    data_entries = []
    for entry in data:
            interface = entry.get('ifname')
            rx_packets = entry.get('rx_packets')
            rx_bytes = entry.get('rx_bytes')
            tx_packets = entry.get('tx_packets')
            tx_bytes = entry.get('tx_bytes')
            rx_dropped = entry.get('rx_dropped')
            tx_dropped = entry.get('tx_dropped')
            rx_errors = entry.get('rx_over_errors')
            tx_errors = entry.get('tx_carrier_errors')
            data_entries.append([interface, rx_packets, rx_bytes, tx_packets, tx_bytes, rx_dropped, tx_dropped, rx_errors, tx_errors])
    
    headers = ['Interface', 'Rx Packets', 'Rx Bytes', 'Tx Packets', 'Tx Bytes', 'Rx Dropped', 'Tx Dropped', 'Rx Errors', 'Tx Errors']
    output = tabulate(data_entries, headers, numalign="left")
    print (output)
    return output

def show(raw: bool, intf_name: typing.Optional[str],
                    intf_type: typing.Optional[str],
                    vif: bool, vrrp: bool):
    data = _get_raw_data(intf_name, intf_type, vif, vrrp)
    if raw:
        return data
    return _format_show_data(data)

def show_summary(raw: bool, intf_name: typing.Optional[str],
                            intf_type: typing.Optional[str],
                            vif: bool, vrrp: bool):
    data = _get_summary_data(intf_name, intf_type, vif, vrrp)
    if raw:
        return data
    return _format_show_summary(data)

def show_counters(raw: bool, intf_name: typing.Optional[str],
                             intf_type: typing.Optional[str],
                             vif: bool, vrrp: bool):
    data = _get_counter_data(intf_name, intf_type, vif, vrrp)
    if raw:
        return data
    return _format_show_counters(data)

def clear_counters(intf_name: typing.Optional[str],
                   intf_type: typing.Optional[str],
                   vif: bool, vrrp: bool):
    for interface in filtered_interfaces(intf_name, intf_type, vif, vrrp):
        interface.operational.clear_counters()

def reset_counters(intf_name: typing.Optional[str],
                   intf_type: typing.Optional[str],
                   vif: bool, vrrp: bool):
    for interface in filtered_interfaces(intf_name, intf_type, vif, vrrp):
        interface.operational.reset_counters()

if __name__ == '__main__':
    try:
        res = vyos.opmode.run(sys.modules[__name__])
        if res:
            print(res)
    except (ValueError, vyos.opmode.Error) as e:
        print(e)
        sys.exit(1)