#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# TODO:
# - check if everything is filled in (computers, params, preparation)
# - improve scoring
# - test
# - switch to a real SSH/SFTP client to properly handle filenames

instructions = {
    'si': u'''
Postavite dva navidezna računalnika - SimpleArbiter in Student.
Oba naj bosta povezana na internet. Poleg tega mora biti
Student na naslovu {student_IP} dostopen s SimpleArbiter.

Računajte, da se na Student ob zagonu zažene program {net_prog_name},
ki vam spreminja nastavitve mrežne kartice.

V domačem imeniku uporabnika student obstaja program {P_c} v programskem jeziku C.
Prevedite ga v program z imenom {P_executable}.
Izvorna koda je namenoma pokvarjena tako, da so vanjo vrinjeni nepotrebni znaki.
Pred prevajanjem jo morate popraviti.

Napišite skripto ali program {P_script} v domačem imeniku uporabnika student, ki:
- požene {P_executable} z argumentom "{arg_c}" in mu na standardni vhod pripelje vrednost spremenljivke {env_c}
- vse, kar {P_executable} izpiše na stderr, spravi v datoteko {out_stderr_c}.
- vse vrstice, ki jih {P_executable} izpiše na stdout in vsebujejo zaporedje znakov "ma", zapiše v {out_stdout_c}.

Lastnik vseh ustvarjenih datotek mora biti uporabnik student. 
Gesla uporabnika student (vaje) ne smete spreminjati.''',
    'en': u'''Set up two virtual machines - SimpleArbiter and Student.
Both should be connected to the Internet. Student should also be accessible
from SimpleArbiter at the address {student_IP}.

Keep in mind that a program called {net_prog_name} starts on Student
whenever Student boots. This program may change your network settings.

There is a program called {P_c} in the home directory of student. Compile it
into a program called {P_executable}. The source code is intentionally broken
so that unneccessarry characters are inserted into the file. You have to fix
the file before compiling.

Also, write a script or program called {P_script} in the home directory of student.
The script should:
- run {P_executable} with the argument {arg_c} and pipe the value of the environment variable {env_c} into {P_executable}'s standard input.
- redirect stderr of {P_executable} into a file called {out_stderr_c}.
- save each line which {P_executable} outputs and which contains the character sequence "ma" into {out_stdout_c}.

The owner of all created files should be student. You are not allowed to change student's password (vaje).
''',
}

computers = {
    'SimpleArbiter': {
        'disks': [
            {
                'name': 'simpleArbiter',
            },
        ],
        'network_interfaces': [
            {'network': 'net1'},
            {'network': 'net2'},
        ],
        'flavor': 'm1.tiny',
        'config_drive': True,
    },
    'Student': {
        'disks': [
            {'name': 'student-entrance'}
        ],
        'flavor': 'm1.tiny',
        'network_interfaces': [{'network': 'net1'}, {'network': 'net3'}],
        'config_drive': True,
    }
}

networks = {
    'net1': {
        'public': False,
    },
    'net2': {
        'public': True,
    },
    'net3': {
        'public': True,
    }
}

params_meta = {
    'student_IP': {
        'descriptions': { 'si': 'IP naslov SimpleStudent', 'en': 'IP address of SimpleStudent',
        }, 'w': False, 'public': True, 'type': 'IP', 'generated': True,
    },
    'net_prog_name': {
        'descriptions': { 'si': 'Ime programa, ki ponastalvlja naslov', 'en': 'The name of the program resetting the network'
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'P_c': {
        'descriptions': { 'si': 'Datoteka s programom v C', 'en': 'Filename of the program in C',
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'P_executable': { 'descriptions': { 'si': 'Ime prevedenega programa v C', 'en': 'Filename of the compiled C program'
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'arg_c': {
        'descriptions': { 'si': 'Vrednost argumenta', 'en': 'Argument value',
        }, 'w': False, 'public': True, 'type': 'short_text', 'generated': True,
    },
    'env_c': {
        'descriptions': { 'si': 'Ime okoljske spremenljivke', 'en': 'The name of the environment environment',
        }, 'w': False, 'public': True, 'type': 'short_text', 'generated': True,
    },
    'out_stderr_c': {
        'descriptions': { 'si': 'Datoteka z napakami', 'en': 'File to store errors',
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'P_script': {
        'descriptions': { 'si': 'Ime skripte', 'en': 'Filename of the script',
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'out_stdout_c': {
        'descriptions': { 'si': 'Datoteka z izhodom', 'en': 'File to store the output',
        }, 'w': False, 'public': True, 'type': 'filename', 'generated': True,
    },
    'param_gen_seed': {
        'descriptions': { 'si': 'Nakljucno seme', 'en': 'Random seed',
        }, 'w': False, 'public': True, 'type': None, 'generated': True,
    },
    'c_destroy_gen_seed': {
        'descriptions': { 'si': 'Nakljucno seme za kvarjenje kode v C', 'en': 'Random seed for destroying the C code',
        }, 'w': False, 'public': False, 'type': None, 'generated': True,
    }

}

def task(student_IP, net_prog_name, 
        P_c, P_executable, arg_c, env_c, out_stderr_c, out_stdout_c, P_script,
        param_gen_seed):
    from pexpect import pxssh
    import random
    conn = pxssh.pxssh()
    conn.login(student_IP, 'student', 'vaje')
    results = dict()
    r = random.Random(int(param_gen_seed))
    env_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(11)])
    
    arg_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(13)])
    stdin_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(17)])
    conn.sendline('ls -l {}'.format(P_script))
    conn.prompt()
    results['script_ls'] = conn.before
    conn.sendline('ls -l {}'.format(P_executable))
    conn.prompt()
    results['executable_ls'] = conn.before
    conn.sendline('export {}={}; {}'.format(env_c, env_val, P_script))
    conn.prompt()
    results['script_run'] = conn.before
    conn.sendline('cat {}'.format(out_stderr_c))
    conn.prompt()
    results['script_stderr'] = conn.before
    conn.sendline('cat {}'.format(out_stdout_c))
    conn.prompt()
    results['script_stdout'] = conn.before
    conn.sendline('echo "{}" | {} "{}" 2> /dev/null'.format(stdin_val, P_executable, arg_val))
    conn.prompt()
    results['prog_stdout'] = conn.before
    conn.sendline('echo "{}" | {} "{}" > /dev/null'.format(stdin_val, P_executable, arg_val))
    conn.prompt()
    results['prog_stderr'] = conn.before
    conn.logout()
    return results

def gen_params(user_id, params_meta):
    import random
    r = random.Random(user_id+'evil cornholio')
    params = kpov_random_helpers.default_gen(user_id, params_meta)
    homedir = '/home/student/'
    params['env_c'] = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ') for i in xrange(5)])
    params['P_c'] = "".join([r.choice('abcdefghijklmnoprst') for i in xrange(5)]) + ".c"
    params['param_gen_seed'] = str(r.randint(0, 2**24))
    params['c_destroy_gen_seed'] = str(r.randint(0, 2**24))
    dest_net = kpov_random_helpers.IPv4_subnet_gen(r, '10.0.2.128/26', 26)
    params['student_IP'] = kpov_random_helpers.IPv4_addr_gen(r, dest_net)[0]
    for k in ['P_c', 'P_executable', 'out_stderr_c', 'P_script', 'out_stdout_c']:
        params[k] = homedir + params[k]
    return params

def task_check(results, params):
    import os
    def test_out_gen(arg, var):
        s_out = ""
        s_err = ""
        r = 0
        arg_len = len(arg)
        env_len = len(var)
        for i in xrange(100):
            s_out += chr(32 + ((ord(arg[i % arg_len]) ^ ord(var[i % env_len])) % 64))
            r += ord(arg[i % arg_len]) + ord(var[i % env_len]) + i;
            if (i % 17 == 0):
                s_out += "RAUS\r\n";
            if (i % 29 == 0):
                s_out += 'ma'
            s_err += chr((r % 31) + ord('A'));
            if (i % 23 == 0):
                s_err += "PATACIS\r\n"
        retval = r % 16
        s_err += '\r\n'
        s_out += '\r\n'
        return(s_out, s_err, retval)
    score = 0
    hints = []
    r = random.Random(int(params['param_gen_seed']))
    env_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(11)])
    arg_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(13)])
    stdin_val = "".join([r.choice('ABCDEFGHIJKLMNPRSTUVZ012345') for i in xrange(17)])
    expected_script_stdout, expected_script_stderr, rval = test_out_gen(
        params['arg_c'], env_val 
        )
    expected_script_stderr = 'cat {}\r\n'.format(params['out_stderr_c']) + expected_script_stderr
    # hints += [expected_script_stderr, results['script_run'], results['script_stderr'], params['arg_c'], env_val]
    if expected_script_stderr != results['script_stderr']:
        hints += ['wrong script stderr']
    else:
        score += 2
    split_stdout = expected_script_stdout.split('\r\n')
    expected_script_stdout = "\r\n".join([ i for i in split_stdout if i.find('ma') >= 0])
    expected_script_stdout = 'cat {}\r\n'.format(params['out_stdout_c']) + expected_script_stdout + "\r\n"
    if expected_script_stdout != results['script_stdout']:
        hints += ['wrong script stdout']
    else:
        score += 2
    expected_prog_stdout, expected_prog_stderr, rval = test_out_gen(
        arg_val, stdin_val
        )
    if expected_prog_stderr != results['prog_stderr'][-len(expected_prog_stderr):]:
        hints += ['wrong program stderr']
    else:
        score += 2
    if expected_prog_stdout != results['prog_stdout'][-len(expected_prog_stdout):]:
        hints += ['wrong program stdout']
    else:
        score += 2
    if results['script_ls'].find('-r') < 0:
        hints += ['script not found']
    else:
        score += 1
    if results['executable_ls'].find('xr') < 0:
        hints += ['C executable not found']
    else:
        score += 1
    return score, hints

def prepare_disks(templates, task_params, global_params):
    c_source = '''#include<stdio.h>
#include<stdlib.h>
#include<string.h>
/* Odstranite vse odvecne velike crke Q, W ali X in program se bo prevedel. */

int main(int argc, char **argv){
    unsigned char *arg;
    unsigned char var[255];
    int i, arg_len, env_len, r;
    scanf("%s", var);
    arg = argv[1];
    arg_len = strlen(argv[1]);
    env_len = strlen(var);
    r = 0;
    for (i = 0; i<100; i++){
        printf("%c", 32 + (arg[i % arg_len] ^ var[i % env_len]) % 64);
        r += (int)arg[i % arg_len] + (int)var[i % env_len] + i;
        if (i % 17 == 0){
            printf("RAUS\\n");
        }
        if (i % 29 == 0){
            printf("ma");
        }
        fprintf(stderr, "%c", (r % 31) + 'A');
        if (i % 23 == 0){
            fprintf(stderr, "PATACIS\\n");
        }
    }
    printf("\\n");
    fprintf(stderr, "\\n");
    return r % 16;
}
'''
    evil_shell_source = """#!/bin/bash -e

while true; do
    /sbin/ifconfig eth1 10.0.4.19 2> /dev/null;
    /sbin/ifconfig eth0 10.0.4.20 2> /dev/null;
    /sbin/ifconfig eth2 10.0.4.21 2> /dev/null;
    /sbin/ifconfig en0p3 10.0.4.19 2> /dev/null;
    /sbin/ifconfig en0p8 10.0.4.20 2> /dev/null;
    /sbin/ifconfig enp0s3 10.0.4.21 2> /dev/null;
    /sbin/ifconfig enp0s8 10.0.4.21 2> /dev/null;
    sleep 10;
done;
"""
    import random
    d = templates['student-entrance']
    r = random.Random(task_params['c_destroy_gen_seed'])
    destroyed_c_source = c_source[:110]
    for c in c_source[110:]:
        i = r.randint(0, 5) 
        if i == 1:
            destroyed_c_source += 'QW'
        if i == 2:
            destroyed_c_source += 'XW'
        if i == 3:
            destroyed_c_source += 'QX'
        destroyed_c_source += c
    d.write(task_params['P_c'], destroyed_c_source)
    d.chown(1000, 1000, task_params['P_c'])
    sh_path = r.choice(['/usr/share/doc', '/var/lib', '/usr/local/share', '/etc/alternatives'])
    sh_file = sh_path + '/' + task_params['net_prog_name']
    d.write(sh_file, evil_shell_source)
    d.chmod(0775, sh_file)
    d.write("/etc/rc.local", """#!/bin/sh -e
export PATH=$PATH:{}
nohup {} &

exit 0
""".format(sh_path, task_params['net_prog_name']))