import asyncio
from dataclasses import dataclass
from datetime import UTC, datetime
from typing import Any, Protocol

from pydantic import BaseModel, ValidationError

from app.core.contracts import RequestContext, SourceReference, ToolCallRecord
from app.core.errors import (
    DependencyUnavailableError,
    ForbiddenAgentError,
    UpstreamTimeoutError,
    ValidationAgentError,
)
from app.infrastructure.db import SessionFactory
from app.model.audit import InteractionAudit


class ToolHandler(Protocol):
    async def __call__(self, arguments: BaseModel, context: RequestContext) -> Any: ...


@dataclass(frozen=True)
class ToolDefinition:
    name: str
    input_model: type[BaseModel]
    handler: ToolHandler
    required_permission: str
    allowed_roles: tuple[str, ...]
    read_only: bool = True
    timeout_seconds: float = 5


@dataclass(frozen=True)
class ToolExecution:
    output: Any
    record: ToolCallRecord
    references: tuple[SourceReference, ...] = ()


class ToolRegistry:
    def __init__(self) -> None:
        self._tools: dict[str, ToolDefinition] = {}

    def register(self, definition: ToolDefinition) -> None:
        if definition.name in self._tools:
            raise ValidationAgentError("工具名称重复")
        if not definition.read_only:
            raise ValidationAgentError("Agent 公共工具仅允许只读")
        self._tools[definition.name] = definition

    def get(self, name: str) -> ToolDefinition:
        definition = self._tools.get(name)
        if definition is None:
            raise ForbiddenAgentError("工具未注册")
        return definition


class ToolExecutor:
    def __init__(self, registry: ToolRegistry) -> None:
        self.registry = registry

    async def execute(
        self, *, name: str, arguments: dict[str, Any], intent: str,
        configured_tools: dict[str, tuple[str, ...]], context: RequestContext,
    ) -> ToolExecution:
        definition = self.registry.get(name)
        # 把三种"用不了"分开，并且**审计写详细、异常给通用**：
        #
        # 原先前两种情况共用一句"工具不在当前意图白名单"，运维无法判断该去补发布配置、
        # 还是该改白名单内容——本项目已经因此踩坑两次（客服、风控的意图码都要求三处对齐，
        # 而缺配置时是静默失败关闭）。权限与角色两处也只说"缺少工具权限"，不说是哪一个。
        #
        # 细节只进审计：异常 message 会随 API 响应返回给调用方，
        # 白名单内容、权限码、角色集属于内部配置，不该出现在客户可见的响应里。
        reason = ""
        detail = ""
        configured = configured_tools.get(intent, ())
        if name not in configured:
            if not configured:
                # 白名单为空。**注意**：经过 governance 装配后，"意图完全没配"与"配了空列表"
                # 在这里无法区分——governance 会为每个 supported_intent 预填条目，所以
                # `intent not in configured_tools` 这个判断在真实链路上永远不会成立
                # （这一点是端到端跑探针才发现的，单元测试里手工构造空 dict 掩盖了它）。
                # 好在两者的运维动作相同：都该去看 agent_tools 里 <agent_type>:<intent>
                # 这一项，所以合并成一句准确的话，不假装能区分。
                reason = "该意图未配置工具白名单"
                detail = (
                    f"意图 {intent!r} 的工具白名单为空：发布配置里没有为它配置任何工具"
                    f"（agent_tools / <agent_type>:{intent}），工具失败关闭"
                )
            else:
                reason = "工具不在当前意图白名单"
                detail = (
                    f"工具 {name!r} 不在意图 {intent!r} 的白名单 {list(configured)} 内"
                )
        elif definition.required_permission not in context.permissions:
            reason = "缺少工具权限"
            detail = f"缺少权限 {definition.required_permission!r}"
        elif not set(definition.allowed_roles).intersection(context.roles):
            reason = "角色不能使用工具"
            detail = (
                f"角色 {list(context.roles)} 与工具允许的角色 "
                f"{list(definition.allowed_roles)} 无交集"
            )
        if reason:
            await self._audit(name, intent, context, "denied", detail)
            raise ForbiddenAgentError(reason)
        try:
            validated = definition.input_model.model_validate(arguments)
        except ValidationError as exc:
            await self._audit(name, intent, context, "denied", "参数校验失败")
            raise ValidationAgentError("工具参数校验失败") from exc
        try:
            async with asyncio.timeout(definition.timeout_seconds):
                output = await definition.handler(validated, context)
        except TimeoutError as exc:
            await self._audit(name, intent, context, "failed", "timeout")
            raise UpstreamTimeoutError("工具调用超时") from exc
        except Exception as exc:
            await self._audit(name, intent, context, "failed", type(exc).__name__)
            raise DependencyUnavailableError("工具调用失败") from exc
        record = ToolCallRecord(
            tool_name=name, status="succeeded",
            input_summary={key: "[redacted]" for key in arguments},
            output_summary={"result_type": type(output).__name__},
        )
        await self._audit(name, intent, context, "succeeded", "ok")
        reference = SourceReference(source_type="tool", source_id=f"{context.trace_id}:{name}",
                                    title=name)
        return ToolExecution(output=output, record=record, references=(reference,))

    async def _audit(
        self, name: str, intent: str, context: RequestContext, status: str, reason: str
    ) -> None:
        async with SessionFactory() as session, session.begin():
            session.add(InteractionAudit(
                actor_type="agent", actor_id=int(context.user_id), portal=context.portal,
                action_type="agent.tool_executed", detail={
                    "tool_name": name, "intent": intent, "status": status,
                    "reason": reason, "trace_id": context.trace_id,
                }, created_at=datetime.now(UTC).replace(tzinfo=None),
            ))