"""按照执行策略把 action 路由到脚本、MCP 或 fake runner。"""

from __future__ import annotations

from .constants import ALLOWED_ACTIONS, HOME_ACTIONS, NODE_ACTIONS
from .models import AgentState, BackendName, ExecutionStrategy, ActionResult


def build_action_backends(strategy: ExecutionStrategy) -> dict[str, BackendName]:
    """根据执行策略生成每个 action 对应的后端类型。"""
    if strategy == "fake":
        return {action: "fake" for action in ALLOWED_ACTIONS}
    if strategy == "script_only":
        return {action: "script" for action in ALLOWED_ACTIONS}
    if strategy == "hybrid_node_mcp":
        routes: dict[str, BackendName] = {action: "script" for action in HOME_ACTIONS}
        routes.update({action: "mcp" for action in NODE_ACTIONS})
        return routes
    raise ValueError(f"未知执行策略: {strategy}")


class ActionRouter:
    """统一的 action 调度器，屏蔽脚本、MCP 和 fake 后端差异。"""

    def __init__(self, *, script_runner, mcp_runner=None, fake_runner=None) -> None:
        """保存各类 runner，运行时按 state 中的路由表选择后端。"""
        self.script_runner = script_runner
        self.mcp_runner = mcp_runner
        self.fake_runner = fake_runner

    def run_action(self, state: AgentState, action: str, **kwargs) -> ActionResult:
        """执行一个 action，并返回统一的 ActionResult。"""
        backend = state.action_backends.get(action)
        if not backend:
            raise ValueError(f"action 未配置路由: {action}")
        if backend == "script":
            return self.script_runner.run(
                action,
                params=state.params,
                script_entry=state.script_entry,
                config_path=state.config_path,
                trace_file_path=state.trace_file_path,
                **kwargs,
            )
        if backend == "mcp":
            if self.mcp_runner is None:
                raise RuntimeError(f"action 需要 MCP runner: {action}")
            mcp_kwargs = dict(kwargs)
            hash_code = mcp_kwargs.pop("hash_code", None) or state.hash_code
            node_url = mcp_kwargs.pop("node_url", None) or state.node_url
            return self.mcp_runner.run(
                action,
                params=state.params,
                hash_code=hash_code,
                node_url=node_url,
                **mcp_kwargs,
            )
        if self.fake_runner is None:
            raise RuntimeError(f"action 需要 fake runner: {action}")
        return self.fake_runner.run(action, params=state.params, **kwargs)