"""用户个性化配置应用服务。"""

from __future__ import annotations

import json
from functools import partial
from typing import Optional, Protocol, Union

from app.application.database import AsyncDatabaseExecutor
from app.schemas.common import JsonData
from app.schemas.types import UserConfigKey

# Agent 助手形象私有数据的用户配置 key 前缀，完整 key 为 AgentPetState.<plugin_id>.<pet_key>
AGENT_PET_STATE_KEY_PREFIX = "AgentPetState."
# 助手形象私有数据按紧凑 JSON 的 UTF-8 字节计算的上限，只承载位置、偏好等小块状态
AGENT_PET_STATE_MAX_BYTES = 16 * 1024


class UserConfigurationValueTooLargeError(ValueError):
    """用户配置值超出该 key 允许的序列化大小。"""


def validate_user_configuration_value(key: Union[str, UserConfigKey], value: JsonData) -> None:
    """校验写入值是否满足 key 的约束，目前仅限制助手形象私有数据的大小。"""
    key_name = key.value if isinstance(key, UserConfigKey) else key
    if not key_name.startswith(AGENT_PET_STATE_KEY_PREFIX):
        return
    size = len(json.dumps(value, ensure_ascii=False, separators=(",", ":")).encode("utf-8"))
    if size > AGENT_PET_STATE_MAX_BYTES:
        raise UserConfigurationValueTooLargeError(
            f"助手形象数据序列化后为 {size} 字节，超过 {AGENT_PET_STATE_MAX_BYTES} 字节上限"
        )


class UserConfigurationRepository(Protocol):
    """用户配置数据端口。"""

    def get(
        self,
        username: str,
        key: Union[str, UserConfigKey],
    ) -> JsonData:
        """读取用户配置。"""

    def set(
        self,
        username: str,
        key: Union[str, UserConfigKey],
        value: JsonData,
    ) -> None:
        """写入用户配置。"""

    def publish_rename(self, previous_name: str, current_name: str) -> None:
        """在用户改名提交后迁移进程级配置快照。"""

    def publish_delete(self, username: str) -> None:
        """在用户删除提交后移除进程级配置快照。"""


class UserConfigurationService:
    """编排用户个性化配置读写。"""

    def __init__(
        self,
        repository: UserConfigurationRepository,
        *,
        async_executor: Optional[AsyncDatabaseExecutor] = None,
    ) -> None:
        """注入用户配置数据端口及可选的异步事务执行能力。"""
        self._repository = repository
        self._async_executor = async_executor

    def get(
        self,
        username: str,
        key: Union[str, UserConfigKey],
    ) -> JsonData:
        """读取用户配置。"""
        return self._repository.get(username=username, key=key)

    def set(
        self,
        username: str,
        key: Union[str, UserConfigKey],
        value: JsonData,
    ) -> None:
        """写入用户配置，值超出 key 约束时抛出 ``UserConfigurationValueTooLargeError``。"""
        validate_user_configuration_value(key, value)
        self._repository.set(username=username, key=key, value=value)

    async def async_set(
        self,
        username: str,
        key: Union[str, UserConfigKey],
        value: JsonData,
    ) -> None:
        """异步写入用户配置，并等待数据库提交或回滚完成；值超出 key 约束时不落库并抛错。"""
        if self._async_executor is None:
            raise RuntimeError("用户配置异步数据库执行端口尚未配置")
        validate_user_configuration_value(key, value)
        await self._async_executor.run(partial(self._repository.set, username=username, key=key, value=value))

    async def rename(self, previous_name: str, current_name: str) -> None:
        """异步发布已提交的用户名配置迁移。"""
        if self._async_executor is None:
            raise RuntimeError("用户配置异步数据库执行端口尚未配置")
        await self._async_executor.run(partial(self._repository.publish_rename, previous_name, current_name))

    async def delete(self, username: str) -> None:
        """异步发布已提交的用户名配置删除。"""
        if self._async_executor is None:
            raise RuntimeError("用户配置异步数据库执行端口尚未配置")
        await self._async_executor.run(partial(self._repository.publish_delete, username))


_configured_user_configuration: Optional[UserConfigurationService] = None


def configure_user_configuration(service: UserConfigurationService) -> None:
    """由启动组合根登记用户配置服务。"""
    global _configured_user_configuration
    _configured_user_configuration = service


def reset_user_configuration() -> None:
    """清除当前 lifespan 的用户配置服务，避免重复启动复用旧实例。"""
    global _configured_user_configuration
    _configured_user_configuration = None


def get_configured_user_configuration() -> UserConfigurationService:
    """返回启动阶段登记的用户配置服务。"""
    if _configured_user_configuration is None:
        raise RuntimeError("用户配置服务尚未配置")
    return _configured_user_configuration