"""
Historical price backfill for already-relevant posts.

Important safety rule:
  This job only fills missing price fields. It must NEVER rewrite the post's
  semantic classification (`relevant`, `sentiment`, signal direction) from a
  keyword heuristic, otherwise historical truth rows become a mixed dataset of
  AI-scored rows + script-guessed rows.
"""

import asyncio
import logging
from datetime import datetime, timezone, timedelta
from typing import Optional

import httpx
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings
from app.models import Post

logger = logging.getLogger(__name__)

# 每次从 Binance 拉多少分钟的 1m K 线（覆盖 1h 涨跌幅计算需要至少 60 根）
FETCH_WINDOW_MINUTES = 90


async def _fetch_klines(symbol: str, start_ms: int, limit: int = 90) -> list:
    url = (
        f"{settings.binance_rest_url}/api/v3/klines"
        f"?symbol={symbol}&interval=1m&startTime={start_ms}&limit={limit}"
    )
    async with httpx.AsyncClient(timeout=15) as client:
        resp = await client.get(url)
        resp.raise_for_status()
    return resp.json()


def _price_at(klines: list, target_ms: int) -> Optional[float]:
    """找最接近 target_ms 的收盘价"""
    best = None
    best_diff = float("inf")
    for row in klines:
        diff = abs(row[0] - target_ms)
        if diff < best_diff:
            best_diff = diff
            best = float(row[4])  # close
    return best


def _pct_change(klines: list, from_ms: int, delta_minutes: int) -> Optional[float]:
    from_price = _price_at(klines, from_ms)
    to_price = _price_at(klines, from_ms + delta_minutes * 60 * 1000)
    if from_price and to_price and from_price != 0:
        return round((to_price - from_price) / from_price * 100, 4)
    return None


async def backfill_price_impact(db_session_factory, asset: str = "BTC") -> None:
    """Fill price-impact fields for posts that are already relevant.

    The semantic label must come from the original analyzer, not from this
    backfill job. This task only enriches rows with price-at-post and
    subsequent returns.
    """
    symbol = "BTCUSDT" if asset == "BTC" else "ETHUSDT"

    async with db_session_factory() as db:
        # Only touch rows whose semantic classification already exists.
        result = await db.execute(
            select(Post)
            .where(Post.relevant == True)
            .where(Post.price_at_post == None)
            .where(Post.price_impact_asset == asset)
            .order_by(Post.published_at.asc())
        )
        posts = result.scalars().all()

    logger.info("找到 %d 条帖子需要价格回溯 (asset=%s)", len(posts), asset)
    if not posts:
        return

    saved = 0
    errors = 0

    for i, post in enumerate(posts):
        try:
            published_at = post.published_at
            if published_at.tzinfo is None:
                published_at = published_at.replace(tzinfo=timezone.utc)

            start_ms = int(published_at.timestamp() * 1000)

            # 拉 Binance 历史价格
            klines = await _fetch_klines(symbol, start_ms, limit=FETCH_WINDOW_MINUTES)

            price_at_post = _price_at(klines, start_ms)
            m5 = _pct_change(klines, start_ms, 5)
            m15 = _pct_change(klines, start_ms, 15)
            m1h = _pct_change(klines, start_ms, 60)

            # 更新帖子
            async with db_session_factory() as db:
                result = await db.execute(select(Post).where(Post.id == post.id))
                p = result.scalar_one_or_none()
                if p:
                    p.price_at_post = price_at_post
                    p.price_impact_m5 = m5
                    p.price_impact_m15 = m15
                    p.price_impact_m1h = m1h
                    await db.commit()
                    saved += 1

            if (i + 1) % 20 == 0:
                logger.info("进度: %d/%d 已处理，已保存 %d 条", i + 1, len(posts), saved)

            # 避免触发 Binance 限速（1200 requests/min）
            await asyncio.sleep(0.1)

        except Exception as exc:
            errors += 1
            logger.error("帖子 id=%d 回溯失败: %s", post.id, exc)
            await asyncio.sleep(1)

    logger.info("✅ 价格回溯完成: 共处理 %d 条，成功 %d 条，失败 %d 条", len(posts), saved, errors)