"""
server.py — FastAPI HTTP wrapper for OpenEnv Warehouse
=======================================================
Exposes the environment over HTTP so the HF Space validator can ping /reset.
Also provides full step/state/grade endpoints for remote evaluation.

Endpoints:
  POST /reset          → initial observation (validator pings this)
  POST /step           → step the environment
  GET  /state          → current internal state
  POST /grade          → run grader on current state
  GET  /health         → liveness check
"""

import os
import sys
from typing import Any, Dict, Optional
from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse
from pydantic import BaseModel

# Ensure the current directory is in the path
sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

# UPDATED IMPORTS: Removing folder prefixes
from warehouse_env import WarehouseEnv, Action, ActionType
from graders import grade as run_grade

app = FastAPI(
    title="OpenEnv Warehouse",
    description="Warehouse inventory management benchmark for autonomous agents.",
    version="1.0.0",
)

# One env instance per task — keyed by task_id
_envs: Dict[str, WarehouseEnv] = {}
VALID_TASKS = ["triage_alerts", "resolve_stockout", "optimize_replenishment"]
DEFAULT_SEED = int(os.getenv("ENV_SEED", "42"))


def _get_env(task_id: str) -> WarehouseEnv:
    if task_id not in _envs:
        _envs[task_id] = WarehouseEnv(task_id=task_id, seed=DEFAULT_SEED)
    return _envs[task_id]


# ── Request bodies ────────────────────────────────────────────────────

class ResetRequest(BaseModel):
    task_id: str = "triage_alerts"
    seed: Optional[int] = None


class StepRequest(BaseModel):
    task_id: str = "triage_alerts"
    action: Dict[str, Any]


class GradeRequest(BaseModel):
    task_id: str = "triage_alerts"


# ── Endpoints ─────────────────────────────────────────────────────────

@app.get("/health")
def health():
    return {"status": "ok", "env": "openenv-warehouse", "version": "1.0.0"}


@app.post("/reset")
def reset(req: ResetRequest = ResetRequest()):
    """
    Reset the environment and return the initial observation.
    The validator pings this endpoint with POST /reset and expects HTTP 200.
    """
    if req.task_id not in VALID_TASKS:
        raise HTTPException(
            status_code=400,
            detail=f"Unknown task_id '{req.task_id}'. Choose from {VALID_TASKS}",
        )
    seed = req.seed if req.seed is not None else DEFAULT_SEED
    env = WarehouseEnv(task_id=req.task_id, seed=seed)
    _envs[req.task_id] = env
    obs = env.reset()
    return JSONResponse(
        status_code=200,
        content={
            "task_id": req.task_id,
            "seed": seed,
            "observation": obs.model_dump(),
        },
    )


@app.post("/step")
def step(req: StepRequest):
    """Execute one action and return (observation, reward, done, info)."""
    if req.task_id not in VALID_TASKS:
        raise HTTPException(status_code=400, detail=f"Unknown task_id '{req.task_id}'")
    env = _get_env(req.task_id)
    try:
        action = Action(**req.action)
    except Exception as exc:
        raise HTTPException(status_code=422, detail=f"Invalid action: {exc}")
    try:
        obs, reward, done, info = env.step(action)
    except RuntimeError as exc:
        raise HTTPException(status_code=409, detail=str(exc))
    return {
        "observation": obs.model_dump(),
        "reward": reward.model_dump(),
        "done": done,
        "info": info,
    }


@app.get("/state")
def state(task_id: str = "triage_alerts"):
    """Return current full internal state (includes ground-truth, for graders)."""
    if task_id not in VALID_TASKS:
        raise HTTPException(status_code=400, detail=f"Unknown task_id '{task_id}'")
    env = _get_env(task_id)
    return env.state()


@app.post("/grade")
def grade(req: GradeRequest):
    """Run the programmatic grader on the current state and return score."""
    if req.task_id not in VALID_TASKS:
        raise HTTPException(status_code=400, detail=f"Unknown task_id '{req.task_id}'")
    env = _get_env(req.task_id)
    score, explanation = run_grade(req.task_id, env.state())
    return {"task_id": req.task_id, "score": score, "explanation": explanation}


@app.get("/tasks")
def list_tasks():
    return {"tasks": VALID_TASKS}