from __future__ import annotations

from datetime import datetime, UTC
from typing import Any

from yuxi.channels.models import (
    ChannelIdentity,
    ChannelMessage,
    ChannelType,
    ChatType,
    EventType,
    MentionsInfo,
    MessageType,
)

from .irc_parser import (
    ParsedIRCMessage,
    extract_nick,
    parse_badges,
    parse_emotes,
    make_irc_message_id,
)

_FILTERED_NOTICE_MSG_IDS = frozenset(
    {
        "subs_on",
        "subs_off",
        "emote_only_on",
        "emote_only_off",
        "slow_on",
        "slow_off",
        "followers_on",
        "followers_off",
        "r9k_on",
        "r9k_off",
        "host_on",
        "host_off",
    }
)

_EVENT_MAP: dict[str, str] = {
    "sub": "subscription",
    "resub": "resubscription",
    "subgift": "subscription_gift",
    "anonsubgift": "anonymous_subscription_gift",
    "submysterygift": "subscription_mystery_gift",
    "raid": "raid",
    "ritual": "ritual",
    "announcement": "announcement",
}

_SKIP_COMMANDS = frozenset({"JOIN", "PART", "HOSTTARGET", "ROOMSTATE", "USERSTATE"})


def _make_identity(
    channel_user_id: str,
    channel_chat_id: str,
    channel_message_id: str | None = None,
) -> ChannelIdentity:
    return ChannelIdentity(
        channel_id="twitch",
        channel_type=ChannelType.TWITCH,
        channel_user_id=channel_user_id,
        channel_chat_id=channel_chat_id,
        channel_message_id=channel_message_id,
    )


def _make_timestamp(tmi_sent_ts: str | None) -> datetime:
    ts = int(tmi_sent_ts or "0")
    if ts:
        return datetime.fromtimestamp(ts / 1000, tz=UTC)
    return datetime.now(UTC)


def resolve_mentions(content: str, bot_username: str | None = None) -> MentionsInfo:
    mentioned: list[str] = []
    is_bot_mentioned = False
    bot_lower = bot_username.lower() if bot_username else None
    for word in content.split():
        if word.startswith("@"):
            name = word[1:].rstrip(",.")
            mentioned.append(name)
            if bot_lower and name.lower() == bot_lower:
                is_bot_mentioned = True
    return MentionsInfo(
        mentioned_user_ids=mentioned,
        is_bot_mentioned=is_bot_mentioned,
    )


def normalize_irc_message(parsed: ParsedIRCMessage) -> ChannelMessage | None:
    command = parsed.command
    tags = parsed.tags

    # ---- PRIVMSG: 普通聊天消息 ----
    if command == "PRIVMSG":
        channel = parsed.params[0] if parsed.params else ""
        user_id = tags.get("user-id") or extract_nick(parsed.prefix)
        message_id = tags.get("id") or tags.get("tmi-sent-ts") or make_irc_message_id(user_id)

        identity = _make_identity(user_id, channel, message_id)

        bits = int(tags.get("bits", "0"))
        badges = parse_badges(tags.get("badges", ""))
        emotes = parse_emotes(tags.get("emotes", ""), parsed.trailing)

        metadata: dict[str, Any] = {
            "display_name": tags.get("display-name", user_id),
            "color": tags.get("color"),
            "badges": badges,
            "emotes": emotes,
            "bits": bits,
            "is_mod": tags.get("mod") == "1",
            "is_subscriber": tags.get("subscriber") == "1",
            "is_turbo": tags.get("turbo") == "1",
            "user_type": tags.get("user-type"),
            "tmi_sent_ts": tags.get("tmi-sent-ts"),
        }

        return ChannelMessage(
            identity=identity,
            event_type=EventType.MESSAGE_RECEIVED,
            message_type=MessageType.TEXT,
            chat_type=ChatType.GROUP,
            content=parsed.trailing,
            mentions=resolve_mentions(parsed.trailing),
            metadata=metadata,
            timestamp=_make_timestamp(tags.get("tmi-sent-ts")),
        )

    # ---- USERNOTICE: 订阅/赠礼/Raid/新人 ----
    if command == "USERNOTICE":
        msg_id = tags.get("msg-id", "")
        channel = parsed.params[0] if parsed.params else ""
        user_id = tags.get("user-id", "system")
        message_id = tags.get("id") or make_irc_message_id(user_id, tags.get("tmi-sent-ts"))

        identity = _make_identity(user_id, channel, message_id)

        metadata = {
            "event": _EVENT_MAP.get(msg_id, msg_id),
            "display_name": tags.get("display-name", user_id),
            "msg_param_sub_plan": tags.get("msg-param-sub-plan"),
            "msg_param_months": tags.get("msg-param-cumulative-months"),
            "msg_param_recipient": tags.get("msg-param-recipient-user-name"),
            "msg_param_gift_count": tags.get("msg-param-gift-months"),
            "msg_param_viewer_count": tags.get("msg-param-viewerCount"),
            "system_msg": tags.get("system-msg", parsed.trailing),
        }

        return ChannelMessage(
            identity=identity,
            event_type=EventType.SYSTEM_EVENT,
            message_type=MessageType.TEXT,
            chat_type=ChatType.GROUP,
            content=tags.get("system-msg", parsed.trailing),
            metadata=metadata,
            timestamp=_make_timestamp(tags.get("tmi-sent-ts")),
        )

    # ---- CLEARCHAT: 消息删除/用户 timeout ----
    if command == "CLEARCHAT":
        channel = parsed.params[0] if parsed.params else ""
        target_user = tags.get("target-user-id", "") or parsed.trailing
        ban_duration = tags.get("ban-duration", "0")

        return ChannelMessage(
            identity=_make_identity(target_user, channel),
            event_type=EventType.MESSAGE_DELETED,
            message_type=MessageType.TEXT,
            chat_type=ChatType.GROUP,
            content="",
            metadata={
                "event": "clearchat",
                "ban_duration_sec": int(ban_duration),
            },
            timestamp=datetime.now(UTC),
        )

    # ---- WHISPER: 私信 ----
    if command == "WHISPER":
        user_id = tags.get("user-id") or extract_nick(parsed.prefix)
        message_id = tags.get("message-id") or make_irc_message_id(user_id)
        identity = _make_identity(user_id, f"#whisper_{user_id}", message_id)
        display_name = tags.get("display-name", user_id)

        metadata: dict[str, Any] = {
            "display_name": display_name,
            "color": tags.get("color"),
            "badges": parse_badges(tags.get("badges", "")),
            "emotes": parse_emotes(tags.get("emotes", ""), parsed.trailing),
            "thread_id": tags.get("thread-id"),
        }

        return ChannelMessage(
            identity=identity,
            event_type=EventType.MESSAGE_RECEIVED,
            message_type=MessageType.TEXT,
            chat_type=ChatType.DIRECT,
            content=parsed.trailing,
            mentions=resolve_mentions(parsed.trailing),
            metadata=metadata,
            timestamp=_make_timestamp(tags.get("tmi-sent-ts")),
        )

    # ---- NOTICE: 系统通知 ----
    if command == "NOTICE":
        channel = parsed.params[0] if parsed.params else ""
        msg_id = tags.get("msg-id", "")

        if msg_id in _FILTERED_NOTICE_MSG_IDS:
            return None

        return ChannelMessage(
            identity=_make_identity("twitch_system", channel),
            event_type=EventType.SYSTEM_EVENT,
            message_type=MessageType.TEXT,
            chat_type=ChatType.GROUP,
            content=parsed.trailing,
            metadata={"event": "notice", "msg_id": msg_id},
            timestamp=datetime.now(UTC),
        )

    # ---- PING → 内部处理 ----
    if command == "PING":
        return None

    # ---- JOIN/PART/HOSTTARGET/ROOMSTATE/USERSTATE → 内部状态 ----
    if command in _SKIP_COMMANDS:
        return None

    return None