# maubot - A plugin-based Matrix bot system.
# Copyright (C) 2022 Tulir Asokan
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
from typing import (
    Any,
    Awaitable,
    Callable,
    Dict,
    Iterable,
    List,
    NewType,
    Optional,
    Pattern,
    Sequence,
    Set,
    Tuple,
    Union,
)
from abc import ABC, abstractmethod
import asyncio
import functools
import inspect
import re

from mautrix.types import EventType, MessageType

from ..matrix import MaubotMessageEvent
from . import event

PrefixType = Optional[Union[str, Callable[[], str], Callable[[Any], str]]]
AliasesType = Union[
    List[str], Tuple[str, ...], Set[str], Callable[[str], bool], Callable[[Any, str], bool]
]
CommandHandlerFunc = NewType(
    "CommandHandlerFunc", Callable[[MaubotMessageEvent, Any], Awaitable[Any]]
)
CommandHandlerDecorator = NewType(
    "CommandHandlerDecorator",
    Callable[[Union["CommandHandler", CommandHandlerFunc]], "CommandHandler"],
)
PassiveCommandHandlerDecorator = NewType(
    "PassiveCommandHandlerDecorator", Callable[[CommandHandlerFunc], CommandHandlerFunc]
)


def _split_in_two(val: str, split_by: str) -> List[str]:
    return val.split(split_by, 1) if split_by in val else [val, ""]


class CommandHandler:
    def __init__(self, func: CommandHandlerFunc) -> None:
        self.__mb_func__: CommandHandlerFunc = func
        self.__mb_parent__: Optional[CommandHandler] = None
        self.__mb_subcommands__: List[CommandHandler] = []
        self.__mb_arguments__: List[Argument] = []
        self.__mb_help__: Optional[str] = None
        self.__mb_get_name__: Callable[[Any], str] = lambda s: "noname"
        self.__mb_is_command_match__: Callable[[Any, str], bool] = self.__command_match_unset
        self.__mb_require_subcommand__: bool = True
        self.__mb_must_consume_args__: bool = True
        self.__mb_arg_fallthrough__: bool = True
        self.__mb_event_handler__: bool = True
        self.__mb_event_types__: set[EventType] = {EventType.ROOM_MESSAGE}
        self.__mb_msgtypes__: Iterable[MessageType] = (MessageType.TEXT,)
        self.__bound_copies__: Dict[Any, CommandHandler] = {}
        self.__bound_instance__: Any = None

    def __get__(self, instance, instancetype):
        if not instance or self.__bound_instance__:
            return self
        try:
            return self.__bound_copies__[instance]
        except KeyError:
            new_ch = type(self)(self.__mb_func__)
            keys = [
                "parent",
                "subcommands",
                "arguments",
                "help",
                "get_name",
                "is_command_match",
                "require_subcommand",
                "must_consume_args",
                "arg_fallthrough",
                "event_handler",
                "event_types",
                "msgtypes",
            ]
            for key in keys:
                key = f"__mb_{key}__"
                setattr(new_ch, key, getattr(self, key))
            new_ch.__bound_instance__ = instance
            new_ch.__mb_subcommands__ = [
                subcmd.__get__(instance, instancetype) for subcmd in self.__mb_subcommands__
            ]
            self.__bound_copies__[instance] = new_ch
            return new_ch

    @staticmethod
    def __command_match_unset(self, val: str) -> bool:
        raise NotImplementedError("Hmm")

    async def __call__(
        self,
        evt: MaubotMessageEvent,
        *,
        _existing_args: Dict[str, Any] = None,
        remaining_val: str = None,
    ) -> Any:
        if evt.sender == evt.client.mxid or evt.content.msgtype not in self.__mb_msgtypes__:
            return
        if remaining_val is None:
            if not evt.content.body or evt.content.body[0] != "!":
                return
            command, remaining_val = _split_in_two(evt.content.body[1:], " ")
            command = command.lower()
            if not self.__mb_is_command_match__(self.__bound_instance__, command):
                return
        call_args: Dict[str, Any] = {**_existing_args} if _existing_args else {}

        if not self.__mb_arg_fallthrough__ and len(self.__mb_subcommands__) > 0:
            ok, res = await self.__call_subcommand__(evt, call_args, remaining_val)
            if ok:
                return res

        ok, remaining_val = await self.__parse_args__(evt, call_args, remaining_val)
        if not ok:
            return
        elif self.__mb_arg_fallthrough__ and len(self.__mb_subcommands__) > 0:
            ok, res = await self.__call_subcommand__(evt, call_args, remaining_val)
            if ok:
                return res
            elif self.__mb_require_subcommand__:
                await evt.reply(self.__mb_full_help__)
                return

        if self.__mb_must_consume_args__ and remaining_val.strip():
            await evt.reply(self.__mb_full_help__)
            return

        if self.__bound_instance__:
            return await self.__mb_func__(self.__bound_instance__, evt, **call_args)
        return await self.__mb_func__(evt, **call_args)

    async def __call_subcommand__(
        self, evt: MaubotMessageEvent, call_args: Dict[str, Any], remaining_val: str
    ) -> Tuple[bool, Any]:
        command, remaining_val = _split_in_two(remaining_val.strip(), " ")
        for subcommand in self.__mb_subcommands__:
            if subcommand.__mb_is_command_match__(subcommand.__bound_instance__, command):
                return True, await subcommand(
                    evt, _existing_args=call_args, remaining_val=remaining_val
                )
        return False, None

    async def __parse_args__(
        self, evt: MaubotMessageEvent, call_args: Dict[str, Any], remaining_val: str
    ) -> Tuple[bool, str]:
        for arg in self.__mb_arguments__:
            try:
                remaining_val, call_args[arg.name] = arg.match(
                    remaining_val.strip(), evt=evt, instance=self.__bound_instance__
                )
                if arg.required and call_args[arg.name] is None:
                    raise ValueError("Argument required")
            except ArgumentSyntaxError as e:
                await evt.reply(e.message + (f"\n{self.__mb_usage__}" if e.show_usage else ""))
                return False, remaining_val
            except ValueError:
                await evt.reply(self.__mb_usage__)
                return False, remaining_val
        return True, remaining_val

    @property
    def __mb_full_help__(self) -> str:
        usage = self.__mb_usage_without_subcommands__ + "\n\n"
        if not self.__mb_require_subcommand__:
            usage += f"* {self.__mb_prefix__} {self.__mb_usage_args__} - {self.__mb_help__}\n"
        usage += "\n".join(cmd.__mb_usage_inline__ for cmd in self.__mb_subcommands__)
        return usage

    @property
    def __mb_usage_args__(self) -> str:
        arg_usage = " ".join(
            f"<{arg.label}>" if arg.required else f"[{arg.label}]" for arg in self.__mb_arguments__
        )
        if self.__mb_subcommands__ and self.__mb_arg_fallthrough__:
            arg_usage += " " + self.__mb_usage_subcommand__
        return arg_usage

    @property
    def __mb_usage_subcommand__(self) -> str:
        return f"<subcommand> [...]"

    @property
    def __mb_name__(self) -> str:
        return self.__mb_get_name__(self.__bound_instance__)

    @property
    def __mb_prefix__(self) -> str:
        if self.__mb_parent__:
            return (
                f"!{self.__mb_parent__.__mb_get_name__(self.__bound_instance__)} "
                f"{self.__mb_name__}"
            )
        return f"!{self.__mb_name__}"

    @property
    def __mb_usage_inline__(self) -> str:
        if not self.__mb_arg_fallthrough__:
            return (
                f"* {self.__mb_name__} {self.__mb_usage_args__} - {self.__mb_help__}\n"
                f"* {self.__mb_name__} {self.__mb_usage_subcommand__}"
            )
        return f"* {self.__mb_name__} {self.__mb_usage_args__} - {self.__mb_help__}"

    @property
    def __mb_subcommands_list__(self) -> str:
        return f"**Subcommands:** {', '.join(sc.__mb_name__ for sc in self.__mb_subcommands__)}"

    @property
    def __mb_usage_without_subcommands__(self) -> str:
        if not self.__mb_arg_fallthrough__:
            if not self.__mb_arguments__:
                return f"**Usage:** {self.__mb_prefix__} [subcommand] [...]"
            return (
                f"**Usage:** {self.__mb_prefix__} {self.__mb_usage_args__}"
                f" _OR_ {self.__mb_prefix__} {self.__mb_usage_subcommand__}"
            )
        return f"**Usage:** {self.__mb_prefix__} {self.__mb_usage_args__}"

    @property
    def __mb_usage__(self) -> str:
        if len(self.__mb_subcommands__) > 0:
            return f"{self.__mb_usage_without_subcommands__}  \n{self.__mb_subcommands_list__}"
        return self.__mb_usage_without_subcommands__

    def subcommand(
        self,
        name: PrefixType = None,
        *,
        help: str = None,
        aliases: AliasesType = None,
        required_subcommand: bool = True,
        arg_fallthrough: bool = True,
    ) -> CommandHandlerDecorator:
        def decorator(func: Union[CommandHandler, CommandHandlerFunc]) -> CommandHandler:
            if not isinstance(func, CommandHandler):
                func = CommandHandler(func)
            new(
                name,
                help=help,
                aliases=aliases,
                require_subcommand=required_subcommand,
                arg_fallthrough=arg_fallthrough,
            )(func)
            func.__mb_parent__ = self
            func.__mb_event_handler__ = False
            self.__mb_subcommands__.append(func)
            return func

        return decorator


def new(
    name: PrefixType = None,
    *,
    help: str = None,
    aliases: AliasesType = None,
    event_type: EventType = EventType.ROOM_MESSAGE,
    msgtypes: Iterable[MessageType] = None,
    require_subcommand: bool = True,
    arg_fallthrough: bool = True,
    must_consume_args: bool = True,
) -> CommandHandlerDecorator:
    def decorator(func: Union[CommandHandler, CommandHandlerFunc]) -> CommandHandler:
        if not isinstance(func, CommandHandler):
            func = CommandHandler(func)
        func.__mb_help__ = help
        if name:
            if callable(name):
                if len(inspect.getfullargspec(name).args) == 0:
                    func.__mb_get_name__ = lambda self: name()
                else:
                    func.__mb_get_name__ = name
            else:
                func.__mb_get_name__ = lambda self: name
        else:
            func.__mb_get_name__ = lambda self: func.__mb_func__.__name__.replace("_", "-")
        if callable(aliases):
            if len(inspect.getfullargspec(aliases).args) == 1:
                func.__mb_is_command_match__ = lambda self, val: aliases(val)
            else:
                func.__mb_is_command_match__ = aliases
        elif isinstance(aliases, (list, set, tuple)):
            func.__mb_is_command_match__ = lambda self, val: (
                val == func.__mb_get_name__(self) or val in aliases
            )
        else:
            func.__mb_is_command_match__ = lambda self, val: val == func.__mb_get_name__(self)
        # Decorators are executed last to first, so we reverse the argument list.
        func.__mb_arguments__.reverse()
        func.__mb_require_subcommand__ = require_subcommand
        func.__mb_arg_fallthrough__ = arg_fallthrough
        func.__mb_must_consume_args__ = must_consume_args
        func.__mb_event_types__ = {event_type}
        if msgtypes:
            func.__mb_msgtypes__ = msgtypes
        return func

    return decorator


class ArgumentSyntaxError(ValueError):
    def __init__(self, message: str, show_usage: bool = True) -> None:
        super().__init__(message)
        self.message = message
        self.show_usage = show_usage


class Argument(ABC):
    def __init__(
        self, name: str, label: str = None, *, required: bool = False, pass_raw: bool = False
    ) -> None:
        self.name = name
        self.label = label or name
        self.required = required
        self.pass_raw = pass_raw

    @abstractmethod
    def match(self, val: str, **kwargs) -> Tuple[str, Any]:
        pass

    def __call__(self, func: Union[CommandHandler, CommandHandlerFunc]) -> CommandHandler:
        if not isinstance(func, CommandHandler):
            func = CommandHandler(func)
        func.__mb_arguments__.append(self)
        return func


class RegexArgument(Argument):
    def __init__(
        self,
        name: str,
        label: str = None,
        *,
        required: bool = False,
        pass_raw: bool = False,
        matches: str = None,
    ) -> None:
        super().__init__(name, label, required=required, pass_raw=pass_raw)
        matches = f"^{matches}" if self.pass_raw else f"^{matches}$"
        self.regex = re.compile(matches)

    def match(self, val: str, **kwargs) -> Tuple[str, Any]:
        orig_val = val
        if not self.pass_raw:
            val = re.split(r"\s", val, 1)[0]
        match = self.regex.match(val)
        if match:
            return (
                orig_val[: match.start()] + orig_val[match.end() :],
                match.groups() or val[match.start() : match.end()],
            )
        return orig_val, None


class CustomArgument(Argument):
    def __init__(
        self,
        name: str,
        label: str = None,
        *,
        required: bool = False,
        pass_raw: bool = False,
        matcher: Callable[[str], Any],
    ) -> None:
        super().__init__(name, label, required=required, pass_raw=pass_raw)
        self.matcher = matcher

    def match(self, val: str, **kwargs) -> Tuple[str, Any]:
        if self.pass_raw:
            return self.matcher(val)
        orig_val = val
        val = re.split(r"\s", val, 1)[0]
        res = self.matcher(val)
        if res is not None:
            return orig_val[len(val) :], res
        return orig_val, None


class SimpleArgument(Argument):
    def match(self, val: str, **kwargs) -> Tuple[str, Any]:
        if self.pass_raw:
            return "", val
        res = re.split(r"\s", val, 1)[0]
        return val[len(res) :], res


def argument(
    name: str,
    label: str = None,
    *,
    required: bool = True,
    matches: Optional[str] = None,
    parser: Optional[Callable[[str], Any]] = None,
    pass_raw: bool = False,
) -> CommandHandlerDecorator:
    if matches:
        return RegexArgument(name, label, required=required, matches=matches, pass_raw=pass_raw)
    elif parser:
        return CustomArgument(name, label, required=required, matcher=parser, pass_raw=pass_raw)
    else:
        return SimpleArgument(name, label, required=required, pass_raw=pass_raw)


def passive(
    regex: Union[str, Pattern],
    *,
    msgtypes: Sequence[MessageType] = (MessageType.TEXT,),
    field: Callable[[MaubotMessageEvent], str] = lambda evt: evt.content.body,
    event_type: EventType = EventType.ROOM_MESSAGE,
    multiple: bool = False,
    case_insensitive: bool = False,
    multiline: bool = False,
    dot_all: bool = False,
) -> PassiveCommandHandlerDecorator:
    if not isinstance(regex, Pattern):
        flags = re.RegexFlag.UNICODE
        if case_insensitive:
            flags |= re.IGNORECASE
        if multiline:
            flags |= re.MULTILINE
        if dot_all:
            flags |= re.DOTALL
        regex = re.compile(regex, flags=flags)

    def decorator(func: CommandHandlerFunc) -> CommandHandlerFunc:
        combine = None
        if hasattr(func, "__mb_passive_orig__"):
            combine = func
            func = func.__mb_passive_orig__

        @event.on(event_type)
        @functools.wraps(func)
        async def replacement(self, evt: MaubotMessageEvent = None) -> None:
            if not evt and isinstance(self, MaubotMessageEvent):
                evt = self
                self = None
            if evt.sender == evt.client.mxid:
                return
            elif msgtypes and evt.content.msgtype not in msgtypes:
                return
            data = field(evt)
            if multiple:
                val = [
                    (data[match.pos : match.endpos], *match.groups())
                    for match in regex.finditer(data)
                ]
            else:
                match = regex.search(data)
                if match:
                    val = (data[match.pos : match.endpos], *match.groups())
                else:
                    val = None
            if val:
                if self:
                    await func(self, evt, val)
                else:
                    await func(evt, val)

        if combine:
            orig_replacement = replacement

            @event.on(event_type)
            @functools.wraps(func)
            async def replacement(self, evt: MaubotMessageEvent = None) -> None:
                await asyncio.gather(combine(self, evt), orig_replacement(self, evt))

        replacement.__mb_passive_orig__ = func

        return replacement

    return decorator