import logging
import re

from aiogram import F, Router
from aiogram.filters import Command
from aiogram.types import CallbackQuery, InlineKeyboardButton, InlineKeyboardMarkup, Message
from telethon import TelegramClient
from telethon.errors import (
    ChannelInvalidError,
    ChannelPrivateError,
    FloodWaitError,
    UsernameInvalidError,
    UsernameNotOccupiedError,
)

from bot.models import ReportType
from bot.services.analyzer import analyze_channel
from bot.services.chunker import chunk_messages
from bot.services.fetcher import fetch_channel_messages
from bot.services.formatter import split_report

log = logging.getLogger(__name__)
router = Router()

# channel_username -> store temporarily per user for callback
_pending: dict[int, str] = {}


def _extract_channel(text: str) -> str | None:
    text = text.strip()
    # @username
    m = re.match(r"@(\w+)", text)
    if m:
        return m.group(1)
    # https://t.me/username
    m = re.match(r"https?://t\.me/(\w+)", text)
    if m:
        return m.group(1)
    # bare username
    if re.match(r"^\w+$", text):
        return text
    return None


def _report_keyboard() -> InlineKeyboardMarkup:
    return InlineKeyboardMarkup(
        inline_keyboard=[
            [InlineKeyboardButton(text=rt.label, callback_data=f"report:{rt.value}")]
            for rt in ReportType
        ]
    )


@router.message(Command("analyze"))
async def cmd_analyze(message: Message) -> None:
    args = (message.text or "").split(maxsplit=1)
    if len(args) < 2:
        await message.answer(
            "Please provide a channel: <code>/analyze @channel</code>",
            parse_mode="HTML",
        )
        return

    channel = _extract_channel(args[1])
    if not channel:
        await message.answer("Could not parse channel name. Use @username or t.me/username.")
        return

    _pending[message.from_user.id] = channel
    await message.answer(
        f"Channel: <b>@{channel}</b>\n\nChoose report type:",
        parse_mode="HTML",
        reply_markup=_report_keyboard(),
    )


@router.callback_query(F.data.startswith("report:"))
async def on_report_type(callback: CallbackQuery) -> None:
    await callback.answer()

    user_id = callback.from_user.id
    channel = _pending.pop(user_id, None)
    if not channel:
        await callback.message.answer("Session expired. Please run /analyze again.")
        return

    report_value = callback.data.split(":", 1)[1]
    report_type = ReportType(report_value)

    telethon_client: TelegramClient = callback.message.bot.__dict__.get("_telethon_client")
    if not telethon_client:
        # Fallback: try dispatcher data
        from aiogram import Dispatcher
        # Access via bot's dispatcher isn't directly available in callback,
        # so we store it on the bot instance in __main__.py
        await callback.message.answer("Internal error: Telethon client not configured.")
        return

    status_msg = await callback.message.answer(
        f"Starting <b>{report_type.label}</b> for @{channel}...\n\n"
        "Fetching messages...",
        parse_mode="HTML",
    )

    async def update_status(text: str) -> None:
        try:
            await status_msg.edit_text(
                f"<b>{report_type.label}</b> for @{channel}\n\n{text}",
                parse_mode="HTML",
            )
        except Exception:
            pass

    try:
        messages, stats = await fetch_channel_messages(telethon_client, channel)
    except (ChannelPrivateError, ChannelInvalidError):
        await status_msg.edit_text("Channel is private or does not exist.")
        return
    except (UsernameInvalidError, UsernameNotOccupiedError):
        await status_msg.edit_text("Channel username not found.")
        return
    except FloodWaitError as e:
        await status_msg.edit_text(f"Rate limited by Telegram. Retry in {e.seconds}s.")
        return
    except Exception as e:
        log.exception("Failed to fetch channel %s", channel)
        await status_msg.edit_text(f"Failed to fetch channel: {e}")
        return

    if not messages:
        await status_msg.edit_text("No text messages found in this channel.")
        return

    await update_status(f"Fetched {len(messages)} messages. Chunking...")

    chunks = chunk_messages(messages)
    await update_status(f"{len(messages)} messages in {len(chunks)} chunks. Analyzing...")

    try:
        report = await analyze_channel(
            report_type=report_type,
            chunks=chunks,
            channel_title=stats["title"],
            channel_username=stats.get("username"),
            subscribers=stats.get("subscribers"),
            msg_count=len(messages),
            on_progress=update_status,
        )
    except Exception as e:
        log.exception("Analysis failed for %s", channel)
        await status_msg.edit_text(f"Analysis failed: {e}")
        return

    await update_status("Sending report...")

    parts = split_report(report)
    for part in parts:
        try:
            await callback.message.answer(part, parse_mode="HTML")
        except Exception:
            # Fallback: send without formatting
            await callback.message.answer(part)

    try:
        await status_msg.delete()
    except Exception:
        pass