from signal import SIGUSR1, SIGUSR2
from secrets import token_urlsafe
from kthread import KThread
import re, os
from ctypes import CDLL, POINTER, c_char_p, c_int, c_ushort, CFUNCTYPE, c_void_p, byref

#c++ -o proxy proxy.cpp

class Filter:
    def __init__(self, regex, is_case_sensitive=True, is_blacklist=True, c_to_s=False, s_to_c=False, blocked_packets=0, code=None):
        self.regex = regex
        self.is_case_sensitive = is_case_sensitive
        self.is_blacklist = is_blacklist
        if c_to_s == s_to_c: c_to_s = s_to_c = True # (False, False) == (True, True)
        self.c_to_s = c_to_s
        self.s_to_c = s_to_c
        self.blocked = blocked_packets
        self.code = code
    
    def compile(self):
        if isinstance(self.regex, str): self.regex = self.regex.encode()
        if not isinstance(self.regex, bytes): raise Exception("Invalid Regex Paramether")
        re.compile(self.regex) # raise re.error if is invalid!
        case_sensitive = "1" if self.is_case_sensitive else "0"
        if self.c_to_s:
            yield case_sensitive + "C" + self.regex.hex() if self.is_blacklist else case_sensitive + "c"+ self.regex.hex()
        if self.s_to_c:
            yield case_sensitive + "S" + self.regex.hex() if self.is_blacklist else case_sensitive + "s"+ self.regex.hex()

class Proxy:
    def __init__(self, internal_port, public_port, callback_blocked_update=None, filters=None, public_host="0.0.0.0", internal_host="127.0.0.1"):
        self.public_host = public_host
        self.public_port = public_port
        self.internal_host = internal_host
        self.internal_port = internal_port
        self.filters = set(filters) if filters else set([])
        self.process = None
        self.callback_blocked_update = callback_blocked_update
        self.config_file_path = None
        while self.config_file_path is None:
            config_file_path = os.path.join("/tmp/" + token_urlsafe(16))
            if not os.path.exists(config_file_path):
                self.config_file_path = config_file_path
        self.lib = CDLL(os.path.join(os.path.dirname(os.path.abspath(__file__)),"./proxy.so"))
        self.lib.start_proxy.restype = c_int
        #char* local_host_p, unsigned short local_port, char* forward_host_p,  unsigned short forward_port, char* config_file_p, void (*incrementCallback_p)(const char *)
        self.lib.start_proxy.argtypes = [c_char_p, c_ushort, c_char_p, c_ushort, c_char_p, POINTER(c_int), c_void_p]

    
    def start(self, in_pause=False):
        if self.process is None:
            self.filter_map = self.compile_filters()
            filters_codes = list(self.filter_map.keys()) if not in_pause else []
            self.__write_config(filters_codes)
            
            @CFUNCTYPE(None, c_char_p)
            def callback_wrap(regex):
                filter = self.filter_map[regex.decode()]
                filter.blocked+=1
                print(self.filter_map)
                if self.callback_blocked_update:
                    self.callback_blocked_update(self.filter_map[regex.decode()])
            
            status_code = c_int(1)
            self.process = KThread(
                target=self.lib.start_proxy, 
                args=(self.public_host.encode(), self.public_port,
                    self.internal_host.encode(), self.internal_port,
                    self.config_file_path.encode(),
                    byref(status_code), callback_wrap
                ),
            )
            self.process.start()
            self.process.join()
            self.__delete_config()
            return status_code.value
    
    def stop(self):
        if self.process:
            if self.process.is_alive():
                os.kill(self.process.native_id,SIGUSR2)
        self.process = None
        return True

    def restart(self, in_pause=False):
        status = self.stop()
        self.start(in_pause=in_pause)
        return status
    
    def __write_config(self, filters_codes):
        with open(self.config_file_path,'w') as config_file:
            for line in filters_codes:
                config_file.write(line + '\n')
    
    def __delete_config(self):
        os.remove(self.config_file_path)
    
    def reload(self):
        if self.isactive():
            filter_map = self.compile_filters()
            filters_codes = list(filter_map.keys())
            self.__write_config(filters_codes)
            self.trigger_reload_config()

    def isactive(self):
        if self.process and not self.process.is_alive():
            self.process = None
        return not self.process is None

    def trigger_reload_config(self):
        os.kill(self.process.native_id, SIGUSR1)

    def pause(self):
        if self.isactive():
            self.__write_config([])
            self.trigger_reload_config()
        else:
            self.start(in_pause=True)

    def compile_filters(self):
        res = {}
        for filter_obj in self.filters:
            try:
                raw_filters = filter_obj.compile()
                for filter in raw_filters:
                    res[filter] = filter_obj
            except Exception: pass
        return res