#!/usr/bin/env python3

import configparser
import dbus
import glob
import os
import psutil
import struct
import subprocess
import sys

from collections import defaultdict
from dbus.mainloop.glib import DBusGMainLoop
from errno import EACCES, EPERM
from mmio import MMIO, MMIOError
from multiprocessing import cpu_count
from threading import Event, Thread

try:
    from gi.repository import GObject
except ImportError:
    import gobject as GObject

SYSFS_POWER_PATH = '/sys/class/power_supply/AC/online'
CONFIG_PATH = '/etc/lenovo_fix.conf'

VOLTAGE_PLANES = {
    'CORE': 0,
    'GPU': 1,
    'CACHE': 2,
    'UNCORE': 3,
    'ANALOGIO': 4,
}

TRIP_TEMP_RANGE = (40, 97)

power = {'source': None, 'method': 'polling'}


def writemsr(msr, val):
    n = ['/dev/cpu/{:d}/msr'.format(x) for x in range(cpu_count())]
    if not os.path.exists(n[0]):
        try:
            subprocess.check_call(('modprobe', 'msr'))
        except subprocess.CalledProcessError:
            print('[E] Unable to load the msr module.')
            sys.exit(1)
    try:
        for c in n:
            f = os.open(c, os.O_WRONLY)
            os.lseek(f, msr, os.SEEK_SET)
            os.write(f, struct.pack('Q', val))
            os.close(f)
    except (IOError, OSError) as e:
        if e.errno == EPERM or e.errno == EACCES:
            print('[E] Unable to write to MSR. Try to disable Secure Boot.')
            sys.exit(1)
        else:
            raise e


def is_on_battery():
    with open(SYSFS_POWER_PATH) as f:
        return not bool(int(f.read()))


def calc_time_window_vars(t):
    for Y in range(2**5):
        for Z in range(2**2):
            if t <= (2**Y) * (1. + Z / 4.) * 0.000977:
                return (Y, Z)
    raise ValueError('Unable to find a good combination!')


def undervolt(config):
    for plane in VOLTAGE_PLANES:
        writemsr(0x150, calc_undervolt_msr(plane, config.getfloat('UNDERVOLT', plane)))


def calc_undervolt_msr(plane, offset):
    assert offset <= 0
    assert plane in VOLTAGE_PLANES
    offset = int(round(offset * 1.024))
    offset = 0xFFE00000 & ((offset & 0xFFF) << 21)
    return 0x8000001100000000 | (VOLTAGE_PLANES[plane] << 40) | offset


def load_config():
    config = configparser.ConfigParser()
    config.read(CONFIG_PATH)

    # config values sanity check
    for power_source in ('AC', 'BATTERY'):
        for option in (
                'Update_Rate_s',
                'PL1_Tdp_W',
                'PL1_Duration_s',
                'PL2_Tdp_W',
                'PL2_Duration_S',
        ):
            config.set(power_source, option, str(max(0.1, config.getfloat(power_source, option))))

        trip_temp = config.getfloat(power_source, 'Trip_Temp_C')
        valid_trip_temp = min(TRIP_TEMP_RANGE[1], max(TRIP_TEMP_RANGE[0], trip_temp))
        if trip_temp != valid_trip_temp:
            config.set(power_source, 'Trip_Temp_C', str(valid_trip_temp))
            print('[!] Overriding invalid "Trip_Temp_C" value in "{:s}": {:.1f} -> {:.1f}'.format(
                power_source, trip_temp, valid_trip_temp))

    for plane in VOLTAGE_PLANES:
        value = config.getfloat('UNDERVOLT', plane)
        valid_value = min(0, value)
        if value != valid_value:
            config.set('UNDERVOLT', plane, str(valid_value))
            print('[!] Overriding invalid "UNDERVOLT" value in "{:s}" voltage plane: {:.0f} -> {:.0f}'.format(
                plane, value, valid_value))

    return config


def calc_reg_values(config):
    regs = defaultdict(dict)
    for power_source in ('AC', 'BATTERY'):
        # the critical temperature for this CPU is 100 C
        trip_offset = int(round(100 - config.getfloat(power_source, 'Trip_Temp_C')))
        regs[power_source]['MSR_TEMPERATURE_TARGET'] = trip_offset << 24

        # 0.125 is the power unit of this CPU
        PL1 = int(round(config.getfloat(power_source, 'PL1_Tdp_W') / 0.125))
        Y, Z = calc_time_window_vars(config.getfloat(power_source, 'PL1_Duration_s'))
        TW1 = Y | (Z << 5)

        PL2 = int(round(config.getfloat(power_source, 'PL2_Tdp_W') / 0.125))
        Y, Z = calc_time_window_vars(config.getfloat(power_source, 'PL2_Duration_s'))
        TW2 = Y | (Z << 5)

        regs[power_source]['MSR_PKG_POWER_LIMIT'] = PL1 | (1 << 15) | (TW1 << 17) | (PL2 << 32) | (1 << 47) | (
            TW2 << 49)

    return regs


def set_hwp(pref):
    # set HWP energy performance hints
    assert pref in ('performance', 'balance_performance', 'default', 'balance_power', 'power')
    n = glob.glob('/sys/devices/system/cpu/cpu[0-9]*/cpufreq/energy_performance_preference')
    for c in n:
        with open(c, 'wb') as f:
            f.write(pref.encode())


def power_thread(config, regs, exit_event):
    try:
        mchbar_mmio = MMIO(0xfed159a0, 8)
    except MMIOError:
        print('[E] Unable to open /dev/mem. Try to disable Secure Boot.')
        sys.exit(1)

    while not exit_event.is_set():
        #
        if power['method'] == 'polling':
            power['source'] = 'BATTERY' if is_on_battery() else 'AC'

        # set temperature trip point
        writemsr(0x1a2, regs[power['source']]['MSR_TEMPERATURE_TARGET'])

        # set PL1/2 on MSR
        writemsr(0x610, regs[power['source']]['MSR_PKG_POWER_LIMIT'])
        # set MCHBAR register to the same PL1/2 values
        mchbar_mmio.write32(0, regs[power['source']]['MSR_PKG_POWER_LIMIT'] & 0xffffffff)
        mchbar_mmio.write32(4, regs[power['source']]['MSR_PKG_POWER_LIMIT'] >> 32)

        wait_t = config.getfloat(power['source'], 'Update_Rate_s')
        enable_hwp_mode = config.getboolean('AC', 'HWP_Mode', fallback=False)
        if power['source'] == 'AC' and enable_hwp_mode:
            cpu_usage = float(psutil.cpu_percent(interval=wait_t))
            # set full performance mode only when load is greater than this threshold (~ at least 1 core full speed)
            performance_mode = cpu_usage > 100. / (cpu_count() * 1.25)
            # check again if we are on AC, since in the meantime we might have switched to BATTERY
            if not is_on_battery():
                set_hwp('performance' if performance_mode else 'balance_performance')
        else:
            exit_event.wait(wait_t)


def main():
    if os.geteuid() != 0:
        print('[E] No root no party. Try again with sudo.')
        sys.exit(1)

    power['source'] = 'BATTERY' if is_on_battery() else 'AC'

    config = load_config()
    regs = calc_reg_values(config)

    if not config.getboolean('GENERAL', 'Enabled'):
        return

    exit_event = Event()
    thread = Thread(target=power_thread, args=(config, regs, exit_event))
    thread.daemon = True
    thread.start()

    undervolt(config)

    # handle dbus events for applying undervolt on resume from sleep/hybernate
    def handle_sleep_callback(sleeping):
        if not sleeping:
            undervolt(config)

    def handle_ac_callback(*args):
        try:
            power['source'] = 'BATTERY' if args[1]['Online'] == 0 else 'AC'
            power['method'] = 'dbus'
        except:
            power['method'] = 'polling'

    DBusGMainLoop(set_as_default=True)
    bus = dbus.SystemBus()

    # add dbus receiver only if undervolt is enabled in config
    if any(config.getfloat('UNDERVOLT', plane) != 0 for plane in VOLTAGE_PLANES):
        bus.add_signal_receiver(handle_sleep_callback, 'PrepareForSleep', 'org.freedesktop.login1.Manager',
                                'org.freedesktop.login1')
    bus.add_signal_receiver(
        handle_ac_callback,
        signal_name="PropertiesChanged",
        dbus_interface="org.freedesktop.DBus.Properties",
        path="/org/freedesktop/UPower/devices/line_power_AC")

    try:
        GObject.threads_init()
        loop = GObject.MainLoop()
        loop.run()
    except (KeyboardInterrupt, SystemExit):
        pass

    exit_event.set()
    loop.quit()
    thread.join(timeout=1)


if __name__ == '__main__':
    main()