"""积分服务层 — 积分账户、扣减、充值、流水、每日免费额度 (#1895)

直接操作 SQLAlchemy session，不走 Repository 抽象层，简化事务处理。
"""

from __future__ import annotations

import logging
import uuid
from datetime import UTC, datetime, timedelta
from typing import Any

from sqlalchemy.orm import Session

from packages.domain.points_rules import (
    DAILY_FREE_CLIP_LIMIT,
    POINTS_PACKAGES,
)

logger = logging.getLogger(__name__)


# ── 延迟导入模型（避免循环/顺序依赖） ────────────────────────────────────


def _get_models():
    """延迟获取积分相关模型类。"""
    from packages.adapters.sqlalchemy_impl.models import (
        DailyUsageRecordModel,
        PointsAccountModel,
        PointsOrderModel,
        PointsTransactionModel,
        UserModel,
    )

    return (
        PointsAccountModel,
        PointsTransactionModel,
        PointsOrderModel,
        DailyUsageRecordModel,
        UserModel,
    )


def _get_redis_client():
    """获取 Redis 客户端，用于每日额度缓存。"""
    try:
        import redis as redis_lib
        from app.config import settings

        return redis_lib.from_url(settings.REDIS_URL, decode_responses=True)
    except Exception:
        return None


class PointsService:
    """积分核心服务。"""

    # ──────────────── 账户管理 ────────────────

    def get_or_create_account(self, user_id: str, db: Session) -> dict[str, Any]:
        """获取或创建积分账户，返回账户快照。"""
        PointsAccountModel, _, _, _, _ = _get_models()

        account = db.query(PointsAccountModel).filter(PointsAccountModel.user_id == user_id).first()
        if account is None:
            account = PointsAccountModel(
                id=uuid.uuid4().hex,
                user_id=user_id,
                balance=0,
                total_earned=0,
                total_spent=0,
            )
            db.add(account)
            db.flush()

        return {
            "id": account.id,
            "user_id": account.user_id,
            "balance": account.balance,
            "total_earned": account.total_earned,
            "total_spent": account.total_spent,
        }

    # ──────────────── 余额检查 ────────────────

    def check_balance(self, user_id: str, amount: int, db: Session) -> dict[str, Any]:
        """检查余额是否足够。"""
        account_data = self.get_or_create_account(user_id, db)
        balance = account_data["balance"]
        return {
            "sufficient": balance >= amount,
            "balance": balance,
            "required": amount,
            "remaining_after": balance - amount,
        }

    # ──────────────── 积分扣减（事务性） ────────────────

    def deduct_points(
        self,
        user_id: str,
        amount: int,
        source: str,
        db: Session,
        description: str = "",
        ref_id: str = "",
    ) -> dict[str, Any]:
        """扣减积分（事务性：SELECT FOR UPDATE → 检查余额 → 扣减 → 流水 → 同步用户表）。

        Returns:
            {"success": True/False, "balance": int, "transaction_id": str|None}
        """
        PointsAccountModel, PointsTransactionModel, _, _, UserModel = _get_models()

        try:
            # 1. 行锁获取账户
            account = (
                db.query(PointsAccountModel).filter(PointsAccountModel.user_id == user_id).with_for_update().first()
            )
            if account is None:
                account = PointsAccountModel(
                    id=uuid.uuid4().hex,
                    user_id=user_id,
                    balance=0,
                    total_earned=0,
                    total_spent=0,
                )
                db.add(account)
                db.flush()

            # 2. 检查余额
            if account.balance < amount:
                return {
                    "success": False,
                    "balance": account.balance,
                    "transaction_id": None,
                }

            # 3. 扣减余额
            account.balance -= amount
            account.total_spent += amount

            # 4. 创建流水
            txn_id = uuid.uuid4().hex
            txn = PointsTransactionModel(
                id=txn_id,
                user_id=user_id,
                account_id=account.id,
                type="deduct",
                source=source,
                amount=amount,
                balance_after=account.balance,
                description=description or f"积分扣减: {source}",
                ref_id=ref_id,
            )
            db.add(txn)

            # 5. 同步用户表 points_balance
            db.execute(
                UserModel.__table__.update()
                .where(UserModel.__table__.c.id == user_id)
                .values(points_balance=account.balance)
            )

            db.commit()
            return {
                "success": True,
                "balance": account.balance,
                "transaction_id": txn_id,
            }

        except Exception:
            db.rollback()
            logger.exception(
                "积分扣减失败: user_id=%s, amount=%d, source=%s",
                user_id,
                amount,
                source,
            )
            return {"success": False, "balance": 0, "transaction_id": None}

    # ──────────────── 积分增加 ────────────────

    def add_points(
        self,
        user_id: str,
        amount: int,
        source: str,
        db: Session,
        description: str = "",
        ref_id: str = "",
    ) -> dict[str, Any]:
        """增加积分（充值/赠送/退款）。"""
        PointsAccountModel, PointsTransactionModel, _, _, UserModel = _get_models()

        try:
            account = (
                db.query(PointsAccountModel).filter(PointsAccountModel.user_id == user_id).with_for_update().first()
            )
            if account is None:
                account = PointsAccountModel(
                    id=uuid.uuid4().hex,
                    user_id=user_id,
                    balance=0,
                    total_earned=0,
                    total_spent=0,
                )
                db.add(account)
                db.flush()

            account.balance += amount
            account.total_earned += amount

            txn_id = uuid.uuid4().hex
            txn = PointsTransactionModel(
                id=txn_id,
                user_id=user_id,
                account_id=account.id,
                type="add",
                source=source,
                amount=amount,
                balance_after=account.balance,
                description=description or f"积分增加: {source}",
                ref_id=ref_id,
            )
            db.add(txn)

            db.execute(
                UserModel.__table__.update()
                .where(UserModel.__table__.c.id == user_id)
                .values(points_balance=account.balance)
            )

            db.commit()
            return {
                "success": True,
                "balance": account.balance,
                "transaction_id": txn_id,
            }

        except Exception:
            db.rollback()
            logger.exception(
                "积分增加失败: user_id=%s, amount=%d, source=%s",
                user_id,
                amount,
                source,
            )
            return {"success": False, "balance": 0, "transaction_id": None}

    # ──────────────── 积分退还 ────────────────

    def refund_points(
        self,
        user_id: str,
        amount: int,
        source: str,
        db: Session,
        ref_id: str = "",
        description: str = "",
    ) -> dict[str, Any]:
        """退还积分（业务失败回退）。内部调用 add_points，source 前缀 refund:。"""
        return self.add_points(
            user_id=user_id,
            amount=amount,
            source=f"refund:{source}",
            db=db,
            description=description or f"积分退还: {source}",
            ref_id=ref_id,
        )

    # ──────────────── 流水查询 ────────────────

    def get_transactions(
        self,
        user_id: str,
        db: Session,
        page: int = 1,
        page_size: int = 20,
        type_filter: str | None = None,
        source_filter: str | None = None,
        start_date: datetime | None = None,
        end_date: datetime | None = None,
    ) -> dict[str, Any]:
        """查询积分流水（分页+筛选）。"""
        _, PointsTransactionModel, _, _, _ = _get_models()

        query = db.query(PointsTransactionModel).filter(PointsTransactionModel.user_id == user_id)

        if type_filter:
            query = query.filter(PointsTransactionModel.type == type_filter)
        if source_filter:
            query = query.filter(PointsTransactionModel.source == source_filter)
        if start_date:
            query = query.filter(PointsTransactionModel.created_at >= start_date)
        if end_date:
            query = query.filter(PointsTransactionModel.created_at <= end_date)

        total = query.count()
        items = (
            query.order_by(PointsTransactionModel.created_at.desc())
            .offset((page - 1) * page_size)
            .limit(page_size)
            .all()
        )

        return {
            "items": [
                {
                    "id": item.id,
                    "type": item.type,
                    "source": item.source,
                    "amount": item.amount,
                    "balance_after": item.balance_after,
                    "description": item.description,
                    "ref_id": item.ref_id,
                    "created_at": (item.created_at.isoformat() if item.created_at else None),
                }
                for item in items
            ],
            "total": total,
            "page": page,
            "page_size": page_size,
        }

    # ──────────────── 每日免费混剪额度 ────────────────

    def _daily_key(self, user_id: str) -> str:
        """生成 Redis 每日额度 key。格式: daily_usage:{user_id}:{YYYYMMDD}:free_clip"""
        today = datetime.now(UTC).strftime("%Y%m%d")
        return f"daily_usage:{user_id}:{today}:free_clip"

    def check_daily_free_clip(self, user_id: str, db: Session) -> bool:
        """检查今日是否还有免费混剪额度。

        优先查 Redis，Redis 不可用时降级到 DB。
        """
        redis_client = _get_redis_client()
        if redis_client:
            try:
                key = self._daily_key(user_id)
                current = redis_client.get(key)
                if current is None:
                    return True
                return int(current) < DAILY_FREE_CLIP_LIMIT
            except Exception:
                logger.warning("Redis 不可用，降级到 DB 查询每日额度")

        # 降级到 DB
        _, _, _, DailyUsageRecordModel, _ = _get_models()
        today_start = datetime.now(UTC).replace(hour=0, minute=0, second=0, microsecond=0)
        record = (
            db.query(DailyUsageRecordModel)
            .filter(
                DailyUsageRecordModel.user_id == user_id,
                DailyUsageRecordModel.usage_type == "free_clip",
                DailyUsageRecordModel.usage_date >= today_start,
            )
            .first()
        )
        if record is None:
            return True
        return record.count < DAILY_FREE_CLIP_LIMIT

    def record_daily_free_clip(self, user_id: str, db: Session) -> bool:
        """记录使用一次免费混剪。

        先 INCR Redis；如果超限回退 Redis。DB 使用 upsert 语义（唯一约束）。
        """
        redis_client = _get_redis_client()
        if redis_client:
            try:
                key = self._daily_key(user_id)
                new_count = redis_client.incr(key)
                if new_count == 1:
                    redis_client.expire(key, 48 * 3600)  # TTL 48h
                if new_count <= DAILY_FREE_CLIP_LIMIT:
                    return True
                # 超限，回退 Redis
                redis_client.decr(key)
            except Exception:
                logger.warning("Redis 不可用，降级到 DB 记录每日额度")

        # 降级/兜底到 DB（upsert 语义）
        _, _, _, DailyUsageRecordModel, _ = _get_models()
        today_start = datetime.now(UTC).replace(hour=0, minute=0, second=0, microsecond=0)

        record = (
            db.query(DailyUsageRecordModel)
            .filter(
                DailyUsageRecordModel.user_id == user_id,
                DailyUsageRecordModel.usage_type == "free_clip",
                DailyUsageRecordModel.usage_date >= today_start,
            )
            .first()
        )

        if record is None:
            if DAILY_FREE_CLIP_LIMIT <= 0:
                return False
            record = DailyUsageRecordModel(
                id=uuid.uuid4().hex,
                user_id=user_id,
                usage_type="free_clip",
                usage_date=datetime.now(UTC),
                count=1,
            )
            db.add(record)
        else:
            if record.count >= DAILY_FREE_CLIP_LIMIT:
                return False
            record.count += 1

        db.commit()
        return True

    def get_daily_usage(self, user_id: str, db: Session) -> dict[str, Any]:
        """查询今日免费额度使用情况。"""
        redis_client = _get_redis_client()
        used = 0

        if redis_client:
            try:
                key = self._daily_key(user_id)
                val = redis_client.get(key)
                used = int(val) if val else 0
            except Exception:
                pass

        if used == 0:
            # 从 DB 查
            _, _, _, DailyUsageRecordModel, _ = _get_models()
            today_start = datetime.now(UTC).replace(hour=0, minute=0, second=0, microsecond=0)
            record = (
                db.query(DailyUsageRecordModel)
                .filter(
                    DailyUsageRecordModel.user_id == user_id,
                    DailyUsageRecordModel.usage_type == "free_clip",
                    DailyUsageRecordModel.usage_date >= today_start,
                )
                .first()
            )
            used = record.count if record else 0

        now = datetime.now(UTC)
        tomorrow = (now + timedelta(days=1)).replace(hour=0, minute=0, second=0, microsecond=0)

        return {
            "free_clips_used": used,
            "free_clips_limit": DAILY_FREE_CLIP_LIMIT,
            "free_clips_remaining": max(0, DAILY_FREE_CLIP_LIMIT - used),
            "reset_at": tomorrow.isoformat(),
        }

    # ──────────────── 订单管理 ────────────────

    def create_order(
        self,
        user_id: str,
        order_type: str,
        product_code: str,
        db: Session,
    ) -> dict[str, Any]:
        """创建积分充值或会员购买订单。

        Args:
            order_type: "points" 或 "membership"
            product_code: 积分包 code (如 "starter_pack") 或会员类型 (如 "monthly")
        """
        _, _, PointsOrderModel, _, _ = _get_models()

        amount_cents = 0
        points_amount = 0
        if order_type == "points":
            package = POINTS_PACKAGES.get(product_code)
            if not package:
                raise ValueError(f"Unknown points package: {product_code}")
            amount_cents = package["price_cents"]
            points_amount = package["points"]
        elif order_type == "membership":
            from packages.domain.points_rules import MEMBERSHIP_PRICES

            membership = MEMBERSHIP_PRICES.get(product_code)
            if not membership:
                raise ValueError(f"Unknown membership type: {product_code}")
            amount_cents = membership["price_cents"]
        else:
            raise ValueError(f"Unknown order type: {order_type}")

        order = PointsOrderModel(
            id=uuid.uuid4().hex,
            user_id=user_id,
            order_type=order_type,
            product_code=product_code,
            amount_cents=amount_cents,
            original_amount_cents=amount_cents,
            points_amount=points_amount,
            status="pending",
        )
        db.add(order)
        db.commit()

        return {
            "id": order.id,
            "order_type": order.order_type,
            "product_code": order.product_code,
            "amount_cents": order.amount_cents,
            "status": order.status,
            "created_at": (order.created_at.isoformat() if order.created_at else None),
        }

    def confirm_payment(
        self,
        order_id: str,
        payment_id: str,
        db: Session,
    ) -> dict[str, Any]:
        """确认支付 → 更新订单状态 → 发放积分或会员。"""
        _, _, PointsOrderModel, _, UserModel = _get_models()

        try:
            order = db.query(PointsOrderModel).filter(PointsOrderModel.id == order_id).with_for_update().first()
            if order is None:
                return {"success": False, "message": "订单不存在"}
            if order.status != "pending":
                return {"success": False, "message": f"订单状态异常: {order.status}"}

            # 更新订单状态
            order.status = "paid"
            order.payment_id = payment_id
            order.paid_at = datetime.now(UTC)

            if order.order_type == "points":
                # 发放积分
                self.add_points(
                    user_id=order.user_id,
                    amount=order.points_amount,
                    source=f"recharge:{order.product_code}",
                    db=db,
                    description=f"积分充值: {order.product_code}",
                    ref_id=order.id,
                )
            elif order.order_type == "membership":
                # 激活会员
                from packages.domain.points_rules import MEMBERSHIP_PRICES

                membership = MEMBERSHIP_PRICES.get(order.product_code, {})
                duration_days = membership.get("duration_days", 30)

                user = db.query(UserModel).filter(UserModel.id == order.user_id).first()
                if user:
                    now = datetime.now(UTC)
                    current_expires = user.member_expires_at or now
                    if current_expires < now:
                        current_expires = now
                    user.member_expires_at = current_expires + timedelta(days=duration_days)
                    user.member_type = order.product_code
                    user.is_member = True

            db.commit()
            return {
                "success": True,
                "message": "支付确认成功",
                "order_id": order_id,
            }

        except Exception:
            db.rollback()
            logger.exception("确认支付失败: order_id=%s", order_id)
            return {"success": False, "message": "确认支付异常"}