import asyncio
import inspect
import os
import re
import time

instance = object()

def init():
    global instance
    instance = Debugger()


class Debugger(object):
    """A socket based debugger  """

    """ a list of tags to debug """
    tags = {}
    knownTags = []
    selectedTags = []

    # subscribed = {}

    def __init__(self):
        self.socket_file = '/tmp/._my_debug_socket'
        print('\nStarting the debugger on socket file \'{}\'.\nRequest help with \n  echo help | nc -U {}\'\n '.format(
            self.socket_file,
            self.socket_file
        ))

    def cleanup(self):
        if os.path.exists(self.socket_file):
            os.remove(self.socket_file)


    def add_known_tags(self, tags):
        if isinstance(tags, str):
            tags = [tags]
        self.tags = set(list(self.tags) + tags)

    def add_selected_tags(self, tags):
        if isinstance(tags, str):
            tags = [tags]
        self.selectedTags = set(list(self.selectedTags)).union(set(tags))

    def debug(self, tags, message):
        if isinstance(tags, str):
            tags = [tags]
        self.add_known_tags(tags)
        if len(set(tags) & set(self.selectedTags)):
            print(message)
        # else :
        # print( "skipping message %s vs. %s" % (self.selectedTags, tags ))

    async def server(self):

        async def handler(reader, writer):
            data = await reader.read(100)
            if data:
                msg = ""
                req = data.split()
                if not len(req):
                    msg = "Error: empty request"
                else:
                    cmd = "cmd_" + str(req.pop(0), "utf-8")
                    print("Debugger server command: %s" % (cmd))
                    if not hasattr(self, cmd):
                        msg = "Error: Invalid command '%s'" % (cmd)
                    else:
                        method = getattr(self, cmd)
                        if not callable(method):
                            msg = "Error: Called a property"
                        else:
                            try:
                                req = [str(i, 'utf-8') for i in req]
                                msg = method(req)
                            except Exception as e:
                                msg = "Error : %s " % (e)
                print("Response:\n%s" % (msg))
                writer.write(bytes(msg, "utf-8"))
                await writer.drain()
            writer.close()

        self.cleanup()
        return await asyncio.start_unix_server(handler, path=self.socket_file)

    def cmd_help(self, params):
        """
    request general help
    """
        members = inspect.getmembers(self)
        out = []
        for name, obj in members:
            if not re.match("^cmd_", name):
                continue
            out.append(
                "- " + re.sub("^cmd_(.*)", lambda m: m.group(1), name) + (str(obj.__doc__) if obj.__doc__ else ""))

        return "\n".join(out) + "\n"

    def cmd_list_tags(self, params):
        """
    List available debug tags
    """
        msg = ""
        if not len(self.tags):
            msg += "No tags yet\n"
        else:
            msg += "Tags:"
            for flag in  sorted(self.tags):
                msg += "\n - %s" % (flag)
        msg += "\n"
        return msg

    def cmd_add_tags(self, params):
        """
    Add a debug tag
    """
        msg = ""
        if not len(params):
            msg = "No flag provided"
        else:
            for flag in params:
                if flag in self.selectedTags:
                    msg += "Noop: flag '%s' already added" % (flag)
                else:
                    self.add_selected_tags([flag])
                    msg += "Added flag '%s'" % (flag)
        return msg

    def cmd_del_tags(self, params):
        """
    Removes a tag
    """
        msg = ""
        if not len(params):
            msg = "No flag provided"
        else:
            for flag in params:
                if flag not in self.selectedTags:
                    msg += "Noop: flag '%s' not added" % (flag)
                else:
                    self.selectedTags.remove(flag)
                    msg += "Removed flag '%s'" % (flag)
        return msg

    # def cmd_list_objs(self, params):
    #   """
    #   List available objects
    #   """
    #   if not len(self.subscribed ):
    #     msg += "No subscribed object yet\n"
    #   else:
    #     msg += "Subscribed objects:"
    #     for i, (oid, obj) in enumerate(self.subscribed.items()) :
    #       msg+="\n - %s\t%s" % (oid,obj)
    #
    #   return "\n".msg
    #
    #
    # def cmd_add_objs(self, params):
    #   """
    #   Debug a precise object
    #   """
    #   oid = params[0]
    #   msg = "Unknown error"
    #   if not self.subscribed[oid]:
    #
    #     msg = "No such object"
    #   else :
    #     obj = self.subscribed[oid]
    #     msg = obj.debugSelf()
    #   return msg

    # def subscribe( self, oid, obj ):
    #   self.subscribed[ oid ] = obj