from __future__ import annotations

import json
import re

from yuxi.channels.models import Attachment, MessageType

_MENTION_RE = re.compile(r"@(\w[\w.-]*)")
_URL_RE = re.compile(r"https?://[^\s<>\"')\]}]+")


def _parse_json_field(data: dict, field: str) -> dict:
    value = data.get(field, "")
    if isinstance(value, str):
        try:
            return json.loads(value)
        except (json.JSONDecodeError, TypeError):
            return {}
    return value if isinstance(value, dict) else {}


def parse_post_json(data: dict) -> dict:
    return _parse_json_field(data, "post")


def parse_channel_json(data: dict) -> dict:
    return _parse_json_field(data, "channel")


def extract_mentions(text: str) -> list[str]:
    if not text:
        return []
    return _MENTION_RE.findall(text)


def check_bot_mentioned(text: str, bot_username: str) -> bool:
    if not text or not bot_username:
        return False
    return f"@{bot_username}" in text.casefold()


def extract_urls(text: str) -> list[str]:
    if not text:
        return []
    return _URL_RE.findall(text)


def detect_message_type(post_data: dict) -> MessageType:
    file_ids = post_data.get("file_ids", [])
    if file_ids:
        return MessageType.FILE
    return MessageType.TEXT


def extract_attachments(post_data: dict) -> list[Attachment]:
    file_ids = post_data.get("file_ids", [])
    if not file_ids:
        return []
    return [Attachment(type="file", file_id=fid) for fid in file_ids]