import os
import sys
import argparse
import importlib
import inspect
import re
import pickle
import asyncio
from argparse import ArgumentParser
from typing import Optional

import jwutils
from jwutils.log import *

class Cmds: # export

    def __instantiate(self, cls):
        try:
            r = cls()
        except Exception as e:
            slog(ERR, f'Failed to instantiate command of type {cls}: {e}')
            raise
        r.cmds = self # TODO: Rename Cmds class to App, "Cmds" isn't very self-explanatory
        r.app = self
        return r

    def __add_cmd_to_parser(self, cmd, parsers):
        parser = cmd.add_parser(parsers)
        cmd.add_arguments(parser)
        if len(cmd.child_classes) > len(cmd.children):
            for c in cmd.child_classes:
                cmd.children.append(self.__instantiate(c))
        if len(cmd.children) > 0:
            subparsers = parser.add_subparsers(title='Available subcommands of ' + cmd.name, metavar='')
            for sub_cmd in cmd.children:
                self.__add_cmd_to_parser(sub_cmd, subparsers)

    def __init__(self, description: str = '', filter: str = '^Cmd.*', modules: None=None, eloop: None=None) -> None:
        self.__description = description
        self.__filter = filter
        self.__modules = modules
        self.__cmds = []
        self.eloop = eloop
        self.__own_eloop = False
        if eloop is None:
            self.eloop = asyncio.get_event_loop()
            self.__own_eloop = True

        log_level = "notice"
        log_flags = 'stderr,position,prio,color'
        # poor man's parsing in the absence of a complete command-line definition
        for i in range(1, len(sys.argv)):
            if i >= len(sys.argv) - 1:
                break
            arg = sys.argv[i]
            if arg == '--log-level':
                i += 1
                log_level = sys.argv[i]
                continue
            if arg == '--log-flags':
                log_flags = sys.argv[i]
                continue
        set_flags(log_flags)
        set_level(log_level)
        slog(DEBUG, "set log level to {}".format(log_level))
        self.__parser = argparse.ArgumentParser(usage=os.path.basename(sys.argv[0]) + ' [options]',
            formatter_class=argparse.ArgumentDefaultsHelpFormatter, description=self.__description)
        self.__parser.add_argument('--log-flags', help='Log flags', default=log_flags)
        self.__parser.add_argument('--log-level', help='Log level', default=log_level)
        self.__parser.add_argument('--backtrace', help='Show exception backtraces', action='store_true', default=False)
        if self.__modules == None:
            self.__modules = [ '__main__' ]
        subcmds = set()
        slog(DEBUG, '-- searching for commands')
        for m in self.__modules: # type: ignore
            if m != '__main__':
                importlib.import_module(m)
            for name, c in inspect.getmembers(sys.modules[m], inspect.isclass):
                if not re.match(self.__filter, name):
                    slog(DEBUG, 'o "{}.{}" has wrong name'.format(m, name))
                    continue
                if inspect.isabstract(c):
                    slog(DEBUG, 'o "{}.{}" is abstract'.format(m, name))
                    continue
                slog(DEBUG, 'o "{}.{}" is fine, instantiating'.format(m, name))
                cmd = self.__instantiate(c)
                #cmd.add_parser(subparsers)
                self.__cmds.append(cmd)
                subcmds.update(cmd.child_classes)

        cmds = [cmd for cmd in self.__cmds if type(cmd) not in subcmds]
        subparsers = self.__parser.add_subparsers(title='Available commands', metavar='')
        for cmd in cmds:
            slog(DEBUG, f'Adding top-level command {cmd} to parser')
            self.__add_cmd_to_parser(cmd, subparsers)

    async def __run(self, argv=None):
        self.args = self.__parser.parse_args(args=argv)
        set_flags(self.args.log_flags)
        set_level(self.args.log_level)
        self.__back_trace = self.args.backtrace

        # This is the toplevel parser, i.e. no func member has been added to the args via
        #
        #    Cmds.__init__()
        #    Cmds.__add_cmd_to_parser(cmd, subparsers)
        #    CmdXXX.add_parser(parsers)
        #    super().add_parser(parsers)
        #    Cmd.__parser.set_defaults(func=self.run)
        #
        if not hasattr(self.args, 'func'):
            self.__parser.print_help()
            return None

        if self.__back_trace:
            ret = await self.args.func(self.args)
        else:
            try:
                ret = await self.args.func(self.args)
            except Exception as e:
                if hasattr(e, 'message'):
                    slog(ERR, e.message)
                else:
                    slog(ERR, f'Exception: {type(e)}: {e}')
                sys.exit(1)

    def __del__(self):
        if self.__own_eloop:
            if self.eloop is not None:
                self.eloop.close()
                self.eloop = None
            self.__own_eloop = False

    def parser(self) -> ArgumentParser:
        return self.__parser

    def run(self, argv=None) -> None:
        #return self.__run()
        return self.eloop.run_until_complete(self.__run(argv)) # type: ignore

def run_sub_commands(description = '', filter = '^Cmd.*', modules=None, argv=None): # export
    cmds = Cmds(description, filter, modules)
    return cmds.run(argv=argv)