app/env/fastapi_app.py

"""FastAPI wrapper for PolyGuardEnv (OpenEnv-style)."""

from __future__ import annotations

import json
import os
from typing import Any, Optional

import uvicorn
from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from pydantic import BaseModel, ConfigDict

from app.common.enums import Difficulty, SubEnvironment
from app.common.types import PolyGuardAction, PolyGuardObservation, PolyGuardState
from app.env.env_core import PolyGuardEnv

app = FastAPI(title="POLYGUARD-RL Env Service", version="0.1.0")
_ENV = PolyGuardEnv()


class ResetRequest(BaseModel):
    model_config = ConfigDict(extra="forbid")
    seed: Optional[int] = None
    difficulty: Optional[Difficulty] = None
    sub_environment: Optional[SubEnvironment] = None
    scenario_id: Optional[str] = None
    patient_id: Optional[str] = None


def _step_payload(observation: dict[str, Any], reward: float, done: bool, info: dict[str, Any]) -> dict[str, Any]:
    reason = str(info.get("termination_reason", "")) if isinstance(info, dict) else ""
    truncated = reason in {"wall_clock_timeout", "step_timeout", "step_budget_exhausted"}
    return {
        "observation": observation,
        "reward": reward,
        "done": done,
        "terminated": done,
        "truncated": truncated,
        "info": info,
    }


@app.get("/health")
def health() -> dict[str, str]:
    return {"status": "healthy"}


@app.post("/env/reset")
def env_reset(request: ResetRequest) -> dict[str, Any]:
    obs = _ENV.reset(
        seed=request.seed,
        difficulty=request.difficulty,
        sub_environment=request.sub_environment,
        scenario_id=request.scenario_id,
        patient_id=request.patient_id,
    )
    return {"observation": obs.model_dump(mode="json")}


@app.post("/env/step")
def env_step(action: dict[str, Any]) -> dict[str, Any]:
    obs, reward, done, info = _ENV.step(action)
    return _step_payload(observation=obs.model_dump(mode="json"), reward=reward, done=done, info=info)


@app.get("/env/state")
def env_state() -> dict[str, Any]:
    return _ENV.get_state()


@app.get("/env/trace")
def env_trace() -> list[dict[str, Any]]:
    return _ENV.get_trace()


@app.get("/env/legal_actions")
def env_legal_actions() -> list[dict[str, Any]]:
    return _ENV.get_legal_actions()


@app.get("/env/reward_breakdown")
def env_reward_breakdown() -> dict[str, Any]:
    return _ENV.get_reward_breakdown()


@app.get("/env/uncertainty")
def env_uncertainty() -> dict[str, Any]:
    return _ENV.get_uncertainty_report().model_dump(mode="json")


@app.get("/env/metadata")
def env_metadata() -> dict[str, Any]:
    return _ENV.get_metadata()


@app.get("/schema")
def schema() -> dict[str, Any]:
    return {
        "action": PolyGuardAction.model_json_schema(),
        "observation": PolyGuardObservation.model_json_schema(),
        "state": PolyGuardState.model_json_schema(),
    }


@app.post("/mcp")
def mcp(payload: dict[str, Any]) -> dict[str, Any]:
    request_id = payload.get("id")
    method = str(payload.get("method", "") or "")
    params = payload.get("params", {}) if isinstance(payload.get("params", {}), dict) else {}

    try:
        if method == "tools/list":
            result = {
                "tools": [
                    {
                        "name": "env.reset",
                        "description": "Reset environment and return initial observation payload.",
                        "inputSchema": {
                            "type": "object",
                            "properties": {
                                "seed": {"type": "integer"},
                                "difficulty": {"type": "string"},
                                "sub_environment": {"type": "string"},
                                "scenario_id": {"type": "string"},
                                "patient_id": {"type": "string"},
                            },
                        },
                    },
                    {
                        "name": "env.step",
                        "description": "Execute a policy action.",
                        "inputSchema": PolyGuardAction.model_json_schema(),
                    },
                    {
                        "name": "env.state",
                        "description": "Get current environment state.",
                        "inputSchema": {"type": "object", "properties": {}},
                    },
                    {
                        "name": "env.metadata",
                        "description": "Get environment metadata.",
                        "inputSchema": {"type": "object", "properties": {}},
                    },
                ]
            }
        elif method == "tools/call":
            tool_name = str(params.get("name", "") or "")
            arguments = params.get("arguments", {}) if isinstance(params.get("arguments"), dict) else {}
            if tool_name == "env.reset":
                request = ResetRequest.model_validate(arguments)
                result = env_reset(request)
            elif tool_name == "env.step":
                result = env_step(arguments)
            elif tool_name == "env.state":
                result = env_state()
            elif tool_name == "env.metadata":
                result = env_metadata()
            else:
                raise ValueError(f"Unknown tool name: {tool_name}")
        elif not method:
            result = {"capabilities": {"tools": True, "ws": True}}
        else:
            raise ValueError(f"Unsupported method: {method}")
        return {"jsonrpc": "2.0", "id": request_id, "result": result}
    except Exception as exc:  # noqa: BLE001
        return {
            "jsonrpc": "2.0",
            "id": request_id,
            "error": {"code": -32000, "message": str(exc)},
        }


# OpenEnv baseline compatibility aliases.
@app.post("/reset")
def reset_alias(request: ResetRequest) -> dict[str, Any]:
    payload = env_reset(request)
    return _step_payload(
        observation=payload["observation"],
        reward=0.5,
        done=False,
        info={"reset": True},
    )


@app.post("/step")
def step_alias(action: dict[str, Any]) -> dict[str, Any]:
    return env_step(action)


@app.get("/state")
def state_alias() -> dict[str, Any]:
    return env_state()


@app.get("/metadata")
def metadata_alias() -> dict[str, Any]:
    return env_metadata()


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket) -> None:
    await websocket.accept()
    try:
        while True:
            raw = await websocket.receive_text()
            message = json.loads(raw)
            msg_type = message.get("type")
            data = message.get("data", {}) or {}
            try:
                if msg_type == "reset":
                    request = ResetRequest.model_validate(data)
                    obs = _ENV.reset(
                        seed=request.seed,
                        difficulty=request.difficulty,
                        sub_environment=request.sub_environment,
                        scenario_id=request.scenario_id,
                        patient_id=request.patient_id,
                    )
                    payload = _step_payload(
                        observation=obs.model_dump(mode="json"),
                        reward=0.5,
                        done=False,
                        info={"reset": True},
                    )
                elif msg_type == "step":
                    obs, reward, done, info = _ENV.step(data)
                    payload = _step_payload(
                        observation=obs.model_dump(mode="json"),
                        reward=reward,
                        done=done,
                        info=info,
                    )
                elif msg_type == "state":
                    payload = _ENV.get_state()
                elif msg_type == "metadata":
                    payload = _ENV.get_metadata()
                else:
                    raise ValueError(f"Unsupported message type: {msg_type}")
                await websocket.send_json({"type": "result", "data": payload})
            except Exception as exc:  # noqa: BLE001
                await websocket.send_json(
                    {
                        "type": "error",
                        "data": {"code": "EXECUTION_ERROR", "message": str(exc)},
                    }
                )
    except WebSocketDisconnect:
        return


def main() -> None:
    host = os.getenv("POLYGUARD_ENV_HOST", "127.0.0.1")
    port = int(os.getenv("POLYGUARD_ENV_PORT", "8100"))
    uvicorn.run("app.env.fastapi_app:app", host=host, port=port, reload=False)


if __name__ == "__main__":
    main()