import asyncio
from collections.abc import Iterable
import contextlib
from typing import Any, ClassVar
from typing_extensions import Self

from tortoise.backends.base.client import BaseDBAsyncClient
from tortoise.exceptions import IntegrityError, MultipleObjectsReturned
from tortoise.models import Model as TortoiseModel

from zhenxun.services.cache import CacheRoot
from zhenxun.services.log import logger
from zhenxun.utils.enum import DbLockType

from .config import LOG_COMMAND, db_model
from .utils import with_db_timeout


class Model(TortoiseModel):
    """
    增强的ORM基类，解决锁嵌套问题
    """

    # sem_data[cls][lock_type] 可以是 Semaphore（全局）
    # 或 dict[key, Semaphore]（按键）
    sem_data: ClassVar[dict[type["Model"], dict[DbLockType, Any]]] = {}
    # 跟踪当前协程持有的锁集合 {(cls, lock_type, lock_key), ...}
    _current_locks: ClassVar[
        dict[int, set[tuple[type["Model"], DbLockType, Any | None]]]
    ] = {}

    def __init_subclass__(cls, **kwargs):
        super().__init_subclass__(**kwargs)
        if cls.__module__ not in db_model.models:
            db_model.models.append(cls.__module__)

        if func := getattr(cls, "_run_script", None):
            db_model.script_method.append((cls.__module__, func))

    @classmethod
    def get_cache_type(cls) -> str | None:
        """获取缓存类型"""
        return getattr(cls, "cache_type", None)

    @classmethod
    def get_cache_key_field(cls) -> str | tuple[str]:
        """获取缓存键字段"""
        return getattr(cls, "cache_key_field", "id")

    @classmethod
    def get_cache_key(cls, instance) -> str | None:
        """获取缓存键

        参数:
            instance: 模型实例

        返回:
            str | None: 缓存键，如果无法获取则返回None
        """
        from zhenxun.services.cache.config import COMPOSITE_KEY_SEPARATOR

        key_field = cls.get_cache_key_field()

        if isinstance(key_field, tuple):
            # 多字段主键
            key_parts = []
            for field in key_field:
                if hasattr(instance, field):
                    value = getattr(instance, field, None)
                    key_parts.append(value if value is not None else "")
                else:
                    # 如果缺少任何必要的字段，返回None
                    key_parts.append("")

            # 如果没有有效参数，返回None
            return COMPOSITE_KEY_SEPARATOR.join(key_parts) if key_parts else None
        elif hasattr(instance, key_field):
            value = getattr(instance, key_field, None)
            return str(value) if value is not None else None

        return None

    @classmethod
    def get_semaphore(cls, lock_type: DbLockType, lock_key: Any | None = None):
        """
        获取信号量

        设计约定（弃用 enable_lock，仅通过 lock_fields 控制是否启用锁）:
        - 如果未配置 lock_fields，或其中不存在对应 lock_type，则不加锁
        - 如果 lock_fields[lock_type] 配置了按字段的锁（如 tuple[str, ...]），
          则调用处按字段值生成 lock_key，在此为不同 lock_key
          分配不同信号量，实现「按键」互斥
        - 如仅需全局锁，可在 lock_fields 中声明该 lock_type，
          且在 _lock_context 传入 lock_key=None
        """
        lock_fields: dict[DbLockType, Any] = getattr(cls, "lock_fields", {}) or {}
        # 未在 lock_fields 中声明的 lock_type 不加锁
        if lock_type not in lock_fields:
            return None

        cls_sem = cls.sem_data.setdefault(cls, {})

        # 配置了按字段的锁并且提供了具体的 lock_key 时，使用「按键」锁
        if lock_key is not None:
            keyed = cls_sem.setdefault(lock_type, {})
            if not isinstance(keyed, dict):
                # 兼容历史数据，重置为按键字典
                keyed = {}
                cls_sem[lock_type] = keyed
            if lock_key not in keyed:
                keyed[lock_key] = asyncio.Semaphore(1)
            return keyed[lock_key]

        # 默认全局锁
        sem = cls_sem.get(lock_type)
        if not isinstance(sem, asyncio.Semaphore):
            sem = asyncio.Semaphore(1)
            cls_sem[lock_type] = sem
        return sem

    @classmethod
    def _require_lock(cls, lock_type: DbLockType, lock_key: Any | None) -> bool:
        """检查是否需要真正加锁"""
        task_id = id(asyncio.current_task())
        held = cls._current_locks.get(task_id)
        if not held:
            return True
        # 同一协程内，如果已经持有完全相同的一把锁
        # （同一模型 + 同一 lock_type + 同一 lock_key），视为重入，
        # 不再重复加锁，避免自锁
        return (cls, lock_type, lock_key) not in held

    @classmethod
    @contextlib.asynccontextmanager
    async def _lock_context(cls, lock_type: DbLockType, lock_key: Any | None = None):
        """带重入检查的锁上下文"""
        task_id = id(asyncio.current_task())
        need_lock = cls._require_lock(lock_type, lock_key)

        if not need_lock:
            # 已经持有这把锁，直接透传，支持可重入
            yield
            return

        sem = cls.get_semaphore(lock_type, lock_key)
        if not sem:
            # 对于未启用锁的场景，直接继续执行
            yield
            return

        lock_id = (cls, lock_type, lock_key)
        held = cls._current_locks.setdefault(task_id, set())
        held.add(lock_id)
        try:
            async with sem:
                yield
        finally:
            # 安全移除当前锁记录
            held.discard(lock_id)
            if not held:
                cls._current_locks.pop(task_id, None)

    @classmethod
    async def create(
        cls, using_db: BaseDBAsyncClient | None = None, **kwargs: Any
    ) -> Self:
        """创建数据（使用CREATE锁）"""
        lock_fields: dict[DbLockType, Any] = getattr(cls, "lock_fields", {}) or {}
        lock_key = None
        if field := lock_fields.get(DbLockType.CREATE):
            if isinstance(field, tuple):
                key_tuple = tuple(kwargs.get(f) for f in field)
                lock_key = key_tuple if any(v is not None for v in key_tuple) else None
            else:
                lock_key = kwargs.get(field)

        async with cls._lock_context(DbLockType.CREATE, lock_key):
            # 直接调用父类的_create方法避免触发save的锁
            result = await super().create(using_db=using_db, **kwargs)
            if cache_type := cls.get_cache_type():
                await CacheRoot.invalidate_cache(cache_type, cls.get_cache_key(result))
            return result

    @classmethod
    async def get_or_create(
        cls,
        defaults: dict | None = None,
        using_db: BaseDBAsyncClient | None = None,
        **kwargs: Any,
    ) -> tuple[Self, bool]:
        """获取或创建数据（无锁版本，依赖数据库约束）"""
        result = await super().get_or_create(
            defaults=defaults, using_db=using_db, **kwargs
        )
        if cache_type := cls.get_cache_type():
            await CacheRoot.invalidate_cache(cache_type, cls.get_cache_key(result[0]))
        return result

    @classmethod
    async def update_or_create(
        cls,
        defaults: dict | None = None,
        using_db: BaseDBAsyncClient | None = None,
        **kwargs: Any,
    ) -> tuple[Self, bool]:
        """更新或创建数据（优化版本，减少锁等待）"""
        lock_fields: dict[DbLockType, Any] = getattr(cls, "lock_fields", {}) or {}
        lock_key = None
        if field := lock_fields.get(DbLockType.UPSERT):
            if isinstance(field, tuple):
                key_tuple = tuple(kwargs.get(f) for f in field)
                lock_key = key_tuple if any(v is not None for v in key_tuple) else None
            else:
                lock_key = kwargs.get(field)

        async with cls._lock_context(DbLockType.UPSERT, lock_key):
            try:
                # 优化：先尝试无锁查询，大部分情况数据已存在
                if obj := await cls.get_or_none(**kwargs):
                    if defaults:
                        await obj.update_from_dict(defaults)
                        # 只更新指定字段，减少写操作
                        await obj.save(update_fields=list(defaults.keys()))
                    if cache_type := cls.get_cache_type():
                        await CacheRoot.invalidate_cache(
                            cache_type, cls.get_cache_key(obj)
                        )
                    return obj, False

                # 数据不存在，尝试创建（依赖数据库唯一约束）
                try:
                    obj = await super().create(
                        using_db=using_db, **kwargs, **(defaults or {})
                    )
                    if cache_type := cls.get_cache_type():
                        await CacheRoot.invalidate_cache(
                            cache_type, cls.get_cache_key(obj)
                        )
                    return obj, True
                except IntegrityError:
                    # 并发创建冲突，重新获取并更新
                    obj = await cls.get(**kwargs)
                    if defaults:
                        await obj.update_from_dict(defaults)
                        await obj.save(update_fields=list(defaults.keys()))
                    if cache_type := cls.get_cache_type():
                        await CacheRoot.invalidate_cache(
                            cache_type, cls.get_cache_key(obj)
                        )
                    return obj, False
            except IntegrityError:
                # 处理极端情况下的唯一约束冲突
                obj = await cls.get(**kwargs)
                return obj, False

    async def save(
        self,
        using_db: BaseDBAsyncClient | None = None,
        update_fields: Iterable[str] | None = None,
        force_create: bool = False,
        force_update: bool = False,
    ):
        """保存数据（根据操作类型自动选择锁）"""
        lock_type = (
            DbLockType.CREATE
            if getattr(self, "id", None) is None
            else DbLockType.UPDATE
        )
        async with self._lock_context(lock_type):
            await super().save(
                using_db=using_db,
                update_fields=update_fields,
                force_create=force_create,
                force_update=force_update,
            )
            if cache_type := getattr(self, "cache_type", None):
                await CacheRoot.invalidate_cache(
                    cache_type, self.__class__.get_cache_key(self)
                )

    async def delete(self, using_db: BaseDBAsyncClient | None = None):
        cache_type = getattr(self, "cache_type", None)
        key = self.__class__.get_cache_key(self) if cache_type else None
        # 执行删除操作
        await super().delete(using_db=using_db)

        # 清除缓存
        if cache_type:
            await CacheRoot.invalidate_cache(cache_type, key)

    @classmethod
    async def safe_get_or_none(
        cls,
        *args,
        using_db: BaseDBAsyncClient | None = None,
        clean_duplicates: bool = True,
        **kwargs: Any,
    ) -> Self | None:
        """安全地获取一条记录或None，处理存在多个记录时返回最新的那个
        注意，默认会删除重复的记录，仅保留最新的

        参数:
            *args: 查询参数
            using_db: 数据库连接
            clean_duplicates: 是否删除重复的记录，仅保留最新的
            **kwargs: 查询参数

        返回:
            Self | None: 查询结果，如果不存在返回None
        """
        try:
            # 先尝试使用 get_or_none 获取单个记录
            try:
                return await with_db_timeout(
                    cls.get_or_none(*args, using_db=using_db, **kwargs),
                    operation=f"{cls.__name__}.get_or_none",
                    source="DataBaseModel",
                )
            except MultipleObjectsReturned:
                # 如果出现多个记录的情况，进行特殊处理
                logger.warning(
                    f"{cls.__name__} safe_get_or_none 发现多个记录: {kwargs}",
                    LOG_COMMAND,
                )

                # 查询所有匹配记录
                records = await with_db_timeout(
                    cls.filter(*args, **kwargs).all(),
                    operation=f"{cls.__name__}.filter.all",
                    source="DataBaseModel",
                )

                if not records:
                    return None

                # 如果需要清理重复记录
                if clean_duplicates and hasattr(records[0], "id"):
                    # 按 id 排序
                    records = sorted(
                        records, key=lambda x: getattr(x, "id", 0), reverse=True
                    )
                    for record in records[1:]:
                        try:
                            await with_db_timeout(
                                record.delete(),
                                operation=f"{cls.__name__}.delete_duplicate",
                                source="DataBaseModel",
                            )
                            logger.info(
                                f"{cls.__name__} 删除重复记录:"
                                f" id={getattr(record, 'id', None)}",
                                LOG_COMMAND,
                            )
                        except Exception as del_e:
                            logger.error(f"删除重复记录失败: {del_e}")
                    return records[0]
                # 如果不需要清理或没有 id 字段，则返回最新的记录
                if hasattr(cls, "id"):
                    return await with_db_timeout(
                        cls.filter(*args, **kwargs).order_by("-id").first(),
                        operation=f"{cls.__name__}.filter.order_by.first",
                        source="DataBaseModel",
                    )
                # 如果没有 id 字段，则返回第一个记录
                return await with_db_timeout(
                    cls.filter(*args, **kwargs).first(),
                    operation=f"{cls.__name__}.filter.first",
                    source="DataBaseModel",
                )
        except asyncio.TimeoutError:
            logger.error(
                f"数据库操作超时: {cls.__name__}.safe_get_or_none", LOG_COMMAND
            )
            return None
        except Exception as e:
            # 其他类型的错误则继续抛出
            logger.error(
                f"数据库操作异常: {cls.__name__}.safe_get_or_none, {e!s}", LOG_COMMAND
            )
            raise