# -*- coding: utf-8 -*-

""" License

    Copyright (C) 2013 YunoHost

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program; if not, see http://www.gnu.org/licenses

"""

""" yunohost_monitor.py

    Monitoring functions
"""
import re
import json
import psutil
import subprocess
import xmlrpclib
from urllib import urlopen
from datetime import datetime, timedelta
from yunohost import YunoHostError

glances_uri = 'http://127.0.0.1:61209'

def monitor_disk(units=None, mountpoint=None, human_readable=False):
    """
    Monitor disk space and usage

    Keyword argument:
        units -- Unit(s) to monitor
        mountpoint -- Device mountpoint
        human_readable -- Print sizes in human readable format

    """
    glances = _get_glances_api()
    result_dname = None
    result = {}

    if units is None:
        units = ['io', 'filesystem']

    # Get mounted block devices
    devices = {}
    output = subprocess.check_output('lsblk -o NAME,MOUNTPOINT -l -n'.split())
    for d in output.split('\n'):
        m = re.search(r'([a-z]+[0-9]*)[ ]+(\/\S*)', d) # Extract device name (1) and its mountpoint (2)
        if m and (mountpoint is None or m.group(2) == mountpoint):
            (dn, dm) = (m.group(1), m.group(2))
            devices[dn] = dm
            result[dn] = {} if len(units) > 1 else []
            result_dname = dn if mountpoint is not None else None
    if len(devices) == 0:
        if mountpoint is None:
            raise YunoHostError(1, _("No mounted block device found"))
        raise YunoHostError(1, _("Unknown mountpoint '%s'") % mountpoint)

    # Retrieve monitoring for unit(s)
    for u in units:
        if u == 'io':
            for d in json.loads(glances.getDiskIO()):
                dname = d['disk_name']
                if dname in devices.keys():
                    del d['disk_name']
                    if len(units) > 1:
                        result[dname][u] = d
                    else:
                        d['mnt_point'] = devices[dname]
                        result[dname] = d
            for dname in devices.keys():
                if len(units) > 1 and u not in result[dname]:
                    result[dname][u] = 'not-available'
                elif len(result[dname]) == 0:
                    result[dname] = 'not-available'
        elif u == 'filesystem':
            for d in json.loads(glances.getFs()):
                dmount = d['mnt_point']
                for (dn, dm) in devices.items():
                    # TODO: Show non-block filesystems?
                    if dm != dmount:
                        continue
                    del d['device_name']
                    if human_readable:
                        for i in ['used', 'avail', 'size']:
                            d[i] = _binary_to_human(d[i]) + 'B'
                    if len(units) > 1:
                        result[dn][u] = d
                    else:
                        result[dn] = d
        else:
            raise YunoHostError(1, _("Unknown unit '%s'") % u)

    if result_dname is not None:
        return result[result_dname]
    return result


def monitor_network(units=None, human_readable=False):
    """
    Monitor network interfaces

    Keyword argument:
        units -- Unit(s) to monitor
        human_readable -- Print sizes in human readable format

    """
    glances = _get_glances_api()
    result = {}

    if units is None:
        units = ['usage', 'infos']

    # Get network devices and their addresses
    devices = {}
    output = subprocess.check_output('ip addr show'.split())
    for d in re.split('^(?:[0-9]+: )', output, flags=re.MULTILINE):
        d = re.sub('\n[ ]+', ' % ', d)          # Replace new lines by %
        m = re.match('([a-z]+[0-9]?): (.*)', d) # Extract device name (1) and its addresses (2)
        if m:
            devices[m.group(1)] = m.group(2)

    # Retrieve monitoring for unit(s)
    for u in units:
        if u == 'usage':
            result[u] = {}
            for i in json.loads(glances.getNetwork()):
                iname = i['interface_name']
                if iname in devices.keys():
                    del i['interface_name']
                    if human_readable:
                        for k in i.keys():
                            if k != 'time_since_update':
                                i[k] = _binary_to_human(i[k]) + 'B'
                    result[u][iname] = i
        elif u == 'infos':
            try:
                p_ip = str(urlopen('http://ip.yunohost.org').read())
            except:
                raise YunoHostError(1, _("Public IP resolution failed"))

            l_ip = None
            for name, addrs in devices.items():
                if name == 'lo':
                    continue
                if len(devices) == 2:
                    l_ip = _extract_inet(addrs)
                else:
                    if l_ip is None:
                        l_ip = {}
                    l_ip[name] = _extract_inet(addrs)

            gateway = None
            output = subprocess.check_output('ip route show'.split())
            m = re.search('default via (.*) dev ([a-z]+[0-9]?)', output)
            if m:
                gateway = _extract_inet(m.group(1), True)

            result[u] = {
                'public_ip': p_ip,
                'local_ip': l_ip,
                'gateway': gateway
            }
        else:
            raise YunoHostError(1, _("Unknown unit '%s'") % u)

    if len(units) == 1:
        return result[units[0]]
    return result


def monitor_system(units=None, human_readable=False):
    """
    Monitor system informations and usage

    Keyword argument:
        units -- Unit(s) to monitor
        human_readable -- Print sizes in human readable format

    """
    glances = _get_glances_api()
    result = {}

    if units is None:
        units = ['memory', 'cpu', 'process', 'uptime', 'infos']

    # Retrieve monitoring for unit(s)
    for u in units:
        if u == 'memory':
            ram = json.loads(glances.getMem())
            swap = json.loads(glances.getMemSwap())
            if human_readable:
                for i in ram.keys():
                    if i != 'percent':
                        ram[i] = _binary_to_human(ram[i]) + 'B'
                for i in swap.keys():
                    if i != 'percent':
                        swap[i] = _binary_to_human(swap[i]) + 'B'
            result[u] = {
                'ram': ram,
                'swap': swap
            }
        elif u == 'cpu':
            result[u] = {
                'load': json.loads(glances.getLoad()),
                'usage': json.loads(glances.getCpu())
            }
        elif u == 'process':
            result[u] = json.loads(glances.getProcessCount())
        elif u == 'uptime':
            result[u] = (str(datetime.now() - datetime.fromtimestamp(psutil.BOOT_TIME)).split('.')[0])
        elif u == 'infos':
            result[u] = json.loads(glances.getSystem())
        else:
            raise YunoHostError(1, _("Unknown unit '%s'") % u)

    if len(units) == 1 and type(result[units[0]]) is not str:
        return result[units[0]]
    return result


def _get_glances_api():
    """
    Retrieve Glances API running on the local server

    """
    try:
        p = xmlrpclib.ServerProxy(glances_uri)
        p.system.methodHelp('getAll')
    except (xmlrpclib.ProtocolError, IOError):
        # TODO: Try to start Glances service
        raise YunoHostError(1, _("Connection to Glances server failed"))

    return p


def _extract_inet(string, skip_netmask=False):
    """
    Extract IP address (v4 or v6) from a string

    Keyword argument:
        string -- String to search in

    """
    # TODO: Return IPv4 and IPv6?
    ip4 = '((25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}'
    ip6 = '((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?'
    ip4 += '/[0-9]{1,2})' if not skip_netmask else ')'
    ip6 += '/[0-9]{1,2})' if not skip_netmask else ')'

    ip4_prog = re.compile(ip4)
    ip6_prog = re.compile(ip6)

    m = ip4_prog.search(string)
    if m:
        return m.group(1)

    m = ip6_prog.search(string)
    if m:
        return m.group(1)

    return None


def _binary_to_human(n, customary=False):
    """
    Convert bytes or bits into human readable format with binary prefix

    Keyword argument:
        n -- Number to convert
        customary -- Use customary symbol instead of IEC standard

    """
    symbols = ('Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi', 'Yi')
    if customary:
        symbols = ('K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
    prefix = {}
    for i, s in enumerate(symbols):
        prefix[s] = 1 << (i+1)*10
    for s in reversed(symbols):
        if n >= prefix[s]:
            value = float(n) / prefix[s]
            return '%.1f%s' % (value, s)
    return "%s" % n