#!/usr/bin/env python3
# Copyright (C) 2023 Rudra Saraswat
# 
# This file is part of blend.
# 
# blend is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# blend 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 blend.  If not, see <http://www.gnu.org/licenses/>.


import os, re, sys, time
import argparse
import subprocess

__version = '2.0.0'

### Colors
class colors:
    reset = '\033[0m'
    bold = '\033[01m'
    disable = '\033[02m'
    underline = '\033[04m'
    reverse = '\033[07m'
    strikethrough = '\033[09m'
    invisible = '\033[08m'

    class fg:
        black = '\033[30m'
        red = '\033[31m'
        green = '\033[32m'
        orange = '\033[33m'
        blue = '\033[34m'
        purple = '\033[35m'
        cyan = '\033[36m'
        lightgrey = '\033[37m'
        darkgrey = '\033[90m'
        lightred = '\033[91m'
        lightgreen = '\033[92m'
        yellow = '\033[93m'
        lightblue = '\033[94m'
        pink = '\033[95m'
        lightcyan = '\033[96m'

    class bg:
        black = '\033[40m'
        red = '\033[41m'
        green = '\033[42m'
        orange = '\033[43m'
        blue = '\033[44m'
        purple = '\033[45m'
        cyan = '\033[46m'
        lightgrey = '\033[47m'

### END

### Helper functions

def info(msg):
    print (colors.bold + colors.fg.cyan + '>> i: ' + colors.reset + colors.bold + msg + colors.reset)

def error(err):
    print (colors.bold + colors.fg.red + '>> e: ' + colors.reset + colors.bold + err + colors.reset)

def load_prev_state():
    subprocess.call(['rm', '-rf', '/blend/overlay/current'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    subprocess.call(['mkdir', '-p', '/blend/overlay/current/usr'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    subprocess.call(['tar', '-xvpzf', f'/blend/states/state{current_state()}.tar.gz', '-C', '/blend/overlay/current/usr', '--numeric-owner'],
                        stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    subprocess.call(['rm', '-f', f'/blend/states/state{current_state()}.tar.gz'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)

### END

def current_state():
    _state = -1
    for s in os.listdir('/blend/states'):
        if re.match(r'^state([0-9]+)\.tar\.gz$', s):
            if int(s[5:-7]) > _state:
                _state = int(s[5:-7])
    return _state

def save_state():
    subprocess.call(['mkdir', '-p', '/blend/states'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    state = current_state() + 1

    subprocess.call(r"find /blend/states/ -type f -not -name 'state" + str(state - 1) + ".tar.gz' -print0 | xargs -0 -I {} rm {}", stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, shell=True)
    subprocess.call(['tar', '-C', '/blend/overlay/current/usr', '-cpzf', f'/blend/states/state{state}.tar.gz', '.'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    info(f'saved state {state}')

def autosave_state():
    while True:
        if not os.path.isfile('/blend/states/.disable_states'):
            save_state()
        time.sleep(6*60*60) # XXX: make this configurable

def toggle_states():
    if os.path.isfile('/blend/states/.disable_states'):
        os.remove('/blend/states/.disable_states')
        info('enabled saving states automatically (every 6 hours; this will be configurable in future releases)')
    else:
        subprocess.call(['touch', '/blend/states/.disable_states'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        info('disabled saving states automatically')

def rollback():
    if current_state() == -1:
        error('no states present')
        exit(1)
    subprocess.call(['touch', '/blend/states/.load_prev_state'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    info(f'will rollback to the previous state on the next boot')

description = f'''
{colors.bold}{colors.fg.purple}Usage:{colors.reset}
  blend-system [command] [options] [arguments]

{colors.bold}{colors.fg.purple}Version:{colors.reset} {__version}{colors.bold}

{colors.bold}{colors.fg.purple}available commands{colors.reset}:
  {colors.bold}help{colors.reset}                  Show this help message and exit.
  {colors.bold}version{colors.reset}               Show version information and exit.
  {colors.bold}load-overlay{colors.reset}          Load the current overlay.
  {colors.bold}save-state{colors.reset}            Save the current state (backup).
  {colors.bold}toggle-states{colors.reset}         Enable/disable automatic state creation (you can still manually save states).
  {colors.bold}rollback{colors.reset}              Rollback to previous state.

{colors.bold}{colors.fg.purple}options for commands{colors.reset}:
  {colors.bold}-v, --version{colors.reset}         show version information and exit
'''

epilog = f'''
{colors.bold}Made with {colors.fg.red}\u2764{colors.reset}{colors.bold} by Rudra Saraswat.{colors.reset}
'''

parser = argparse.ArgumentParser(description=description, usage=argparse.SUPPRESS,
                                 epilog=epilog, formatter_class=argparse.RawTextHelpFormatter)
command_map = { 'help': 'help',
                'version': 'version',
                'load-overlay': load_overlay,
                'save-state': save_state,
                'toggle-states': toggle_states,
                'autosave-state': autosave_state,
                'rollback': rollback }
parser.add_argument('command', choices=command_map.keys(), help=argparse.SUPPRESS)
parser.add_argument('-v', '--version', action='version', version=f'%(prog)s {__version}', help=argparse.SUPPRESS)

if len(sys.argv) == 1:
    parser.print_help()
    exit()

if os.geteuid() != 0:
    error('requires root')
    exit(1)

args = parser.parse_intermixed_args()

command = command_map[args.command]

if command == 'help':
    parser.print_help()
elif command == 'version':
    parser.parse_args(['--version'])
else:
    command()