server/app.py

from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from fastapi.responses import JSONResponse
import asyncio
import json
from typing import Optional

from models import Observation, Action, Reward, State, StepResult, TaskDifficulty
from server.contextflow_environment import ContextFlowEnvironment


app = FastAPI(title="ContextFlow OpenEnv")

connections: dict[str, WebSocket] = {}
environments: dict[str, ContextFlowEnvironment] = {}


@app.get("/")
async def root():
    return {"message": "ContextFlow OpenEnv Environment", "version": "1.0.0"}


@app.get("/health")
async def health():
    return {"status": "healthy"}


@app.post("/reset")
async def reset(difficulty: Optional[str] = "medium"):
    try:
        difficulty_enum = TaskDifficulty(difficulty.lower())
    except ValueError:
        difficulty_enum = TaskDifficulty.MEDIUM
    
    env = ContextFlowEnvironment(task_difficulty=difficulty_enum)
    observation = env.reset()
    
    env_id = observation.episode_id
    environments[env_id] = env
    
    return {
        "observation": observation.model_dump(),
        "episode_id": env_id,
    }


@app.post("/step")
async def step(action: Action):
    if not action.episode_id or action.episode_id not in environments:
        return JSONResponse(
            status_code=400,
            content={"error": "Invalid or missing episode_id"}
        )
    
    env = environments[action.episode_id]
    result = env.step(action)
    
    if result.done:
        del environments[action.episode_id]
    
    return result.model_dump()


@app.get("/state/{episode_id}")
async def get_state(episode_id: str):
    if episode_id not in environments:
        return JSONResponse(
            status_code=404,
            content={"error": "Episode not found"}
        )
    
    env = environments[episode_id]
    return env.state().model_dump()


@app.websocket("/ws/{episode_id}")
async def websocket_endpoint(websocket: WebSocket, episode_id: str):
    await websocket.accept()
    connections[episode_id] = websocket
    
    if episode_id not in environments:
        await websocket.send_json({"error": "Episode not found"})
        await websocket.close()
        return
    
    try:
        while True:
            data = await websocket.receive_text()
            message = json.loads(data)
            
            if message["type"] == "reset":
                difficulty = message.get("difficulty", "medium")
                env = ContextFlowEnvironment(task_difficulty=TaskDifficulty(difficulty))
                observation = env.reset()
                environments[episode_id] = env
                await websocket.send_json({
                    "type": "reset",
                    "observation": observation.model_dump()
                })
            
            elif message["type"] == "step":
                if episode_id not in environments:
                    await websocket.send_json({"error": "Episode not found"})
                    continue
                
                env = environments[episode_id]
                action = Action(**message["action"])
                result = env.step(action)
                
                if result.done:
                    del environments[episode_id]
                
                await websocket.send_json({
                    "type": "step",
                    "result": result.model_dump()
                })
            
            elif message["type"] == "state":
                if episode_id not in environments:
                    await websocket.send_json({"error": "Episode not found"})
                    continue
                
                env = environments[episode_id]
                await websocket.send_json({
                    "type": "state",
                    "state": env.state().model_dump()
                })
    
    except WebSocketDisconnect:
        pass
    finally:
        if episode_id in connections:
            del connections[episode_id]


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)