import os
import asyncio
import logging
from datetime import datetime, timezone
from typing import Optional
from telethon import TelegramClient
from db.repository import Repository
from core.metrics import POSTS_PUBLISHED_TOTAL, QUEUE_POSTS_GAUGE

logger = logging.getLogger(__name__)

SESSION_DIR = os.getenv("SESSION_DIR", "/app/sessions" if os.path.exists("/app") else "/projects/telegram-bots/copykar/sessions")

class PublisherService:
    def __init__(
        self,
        repo: Repository,
        api_id: Optional[int] = None,
        api_hash: Optional[str] = None,
        session_name: Optional[str] = None,
        bot_token: Optional[str] = None,
    ):
        self.repo = repo
        self.api_id = api_id or int(os.getenv("API_ID", "0"))
        self.api_hash = api_hash or os.getenv("API_HASH", "")
        self.bot_token = bot_token or os.getenv("BOT_TOKEN")
        self.session_name = session_name or os.path.join(SESSION_DIR, "publisher.session")
        os.makedirs(os.path.dirname(self.session_name), exist_ok=True)
        self.client = TelegramClient(self.session_name, self.api_id, self.api_hash)
        self._running = False
        self._task: Optional[asyncio.Task] = None

    async def start(self):
        logger.info("Starting Publisher Service...")
        if self.bot_token:
            await self.client.start(bot_token=self.bot_token)
        else:
            await self.client.start()
        logger.info("Publisher Service connected successfully.")

        self._running = True
        self._task = asyncio.create_task(self._publisher_loop())

    async def _publisher_loop(self):
        while self._running:
            try:
                await self._process_pending_queues()
            except Exception as e:
                logger.error(f"Error in publisher loop: {e}", exc_info=True)
            await asyncio.sleep(15)

    async def _process_pending_queues(self):
        targets = await self.repo.get_active_targets()
        now = datetime.now(timezone.utc)

        pending_count = len(await self.repo.get_posts_by_status("approved", limit=5000))
        QUEUE_POSTS_GAUGE.labels(status="approved").set(pending_count)

        for target in targets:
            if target.last_post_time:
                last_post = target.last_post_time
                if last_post.tzinfo is None:
                    last_post = last_post.replace(tzinfo=timezone.utc)
                diff_minutes = (now - last_post).total_seconds() / 60.0
                if diff_minutes < target.post_interval_min:
                    continue

            post = await self.repo.get_next_approved_post_for_target(target.id)
            if not post:
                continue

            try:
                publish_text = post.ai_text or post.raw_text or ""
                if post.media_path and os.path.exists(post.media_path):
                    await self.client.send_file(
                        target.channel_id,
                        file=post.media_path,
                        caption=publish_text,
                        parse_mode="markdown"
                    )
                else:
                    await self.client.send_message(
                        target.channel_id,
                        publish_text,
                        parse_mode="markdown"
                    )

                await self.repo.mark_post_published(post.id)
                await self.repo.update_target_last_post(target.id)
                POSTS_PUBLISHED_TOTAL.labels(target_channel_id=str(target.channel_id)).inc()
                logger.info(f"Successfully published post {post.id} to target channel {target.title} ({target.channel_id})")
            except Exception as e:
                logger.error(f"Failed to publish post {post.id} to target {target.channel_id}: {e}", exc_info=True)

    async def stop(self):
        self._running = False
        if self._task:
            self._task.cancel()
        if self.client.is_connected():
            await self.client.disconnect()
            logger.info("Publisher Service disconnected.")