"""
app.py
──────
FastAPI application serving CogTraceEnv as an OpenEnv HTTP API.

Endpoints:
  GET  /                → Interactive demo UI
  POST /reset           → Observation
  POST /step            → {observation, reward, done, info}
  GET  /state           → EnvState
  GET  /tasks           → list of available tasks
  GET  /health          → {"status": "ok"}
  GET  /openenv.yaml    → serve the spec file
"""

from __future__ import annotations

import os
import random
from typing import Optional

from fastapi import FastAPI, HTTPException
from fastapi.responses import PlainTextResponse, HTMLResponse
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel

from cognitive_env import CogTraceEnv
from patient_simulator import PatientConfig
from models import Action

app = FastAPI(
    title="CogTraceEnv",
    description="OpenEnv environment for Alzheimer's cognitive monitoring",
    version="1.0.0",
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

# Global env instance (single-session server)
_env: Optional[CogTraceEnv] = None

# ─── Request/Response models ──────────────────────────────────────────────────

class ResetRequest(BaseModel):
    true_stage: Optional[int] = None
    episode_length: int = 30
    decline_rate: float = 0.01
    noise_level: float = 1.0
    seed: Optional[int] = None
    patient_id: str = "patient_001"
    anomaly_day: Optional[int] = None
    anomaly_duration: int = 5

class StepRequest(BaseModel):
    action: int  # 0–3

# ─── Routes ───────────────────────────────────────────────────────────────────

@app.get("/", response_class=HTMLResponse)
def serve_demo():
    demo_path = os.path.join(os.path.dirname(__file__), "..", "demo.html")
    if not os.path.exists(demo_path):
        raise HTTPException(status_code=404, detail="demo.html not found")
    with open(demo_path) as f:
        return f.read()


@app.get("/health")
def health():
    return {"status": "ok", "env": "CogTraceEnv-v1"}


@app.post("/reset")
def reset(req: ResetRequest = ResetRequest()):
    global _env
    stage = req.true_stage if req.true_stage is not None else random.randint(1, 3)
    cfg = PatientConfig(
        true_stage=stage,
        episode_length=req.episode_length,
        decline_rate=req.decline_rate,
        noise_level=req.noise_level,
        seed=req.seed,
        patient_id=req.patient_id,
        anomaly_day=req.anomaly_day,
        anomaly_duration=req.anomaly_duration,
    )
    _env = CogTraceEnv(config=cfg)
    obs = _env.reset()
    return obs.model_dump()


@app.post("/step")
def step(req: StepRequest):
    if _env is None:
        raise HTTPException(status_code=400, detail="Call /reset first.")
    try:
        action = Action(action=req.action)
        obs, reward, terminated, truncated, info = _env.step(action)
        return {
            "observation": obs.model_dump(),
            "reward":      float(reward) if isinstance(reward, (int, float)) else reward.model_dump(),
            "done":        terminated or truncated,
            "terminated":  terminated,
            "truncated":   truncated,
            "info":        info.model_dump(),
        }
    except RuntimeError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Internal Server Error: {str(e)}")


@app.get("/state")
def state():
    if _env is None:
        raise HTTPException(status_code=400, detail="Call /reset first.")
    return _env.state().model_dump()


@app.get("/tasks")
def list_tasks():
    return {
        "tasks": [
            {
                "id": "task1_easy",
                "name": "Cognitive Stage Classification",
                "difficulty": "easy",
                "description": (
                    "Given one snapshot of behavioral metrics, "
                    "predict the patient's Alzheimer's stage (0–4)."
                ),
            },
            {
                "id": "task2_medium",
                "name": "Anomaly Timing Detection",
                "difficulty": "medium",
                "description": (
                    "Observe 7 days of signals. Raise an alert on "
                    "the day you detect an anomaly."
                ),
            },
            {
                "id": "task3_hard",
                "name": "Full Triage Episode",
                "difficulty": "hard",
                "description": (
                    "Manage a 30-step episode, balancing sensitivity "
                    "and specificity across declining patient trajectories."
                ),
            },
        ]
    }


@app.get("/openenv.yaml", response_class=PlainTextResponse)
def serve_yaml():
    yaml_path = os.path.join(os.path.dirname(__file__), "..", "openenv.yaml")
    if not os.path.exists(yaml_path):
        raise HTTPException(status_code=404, detail="openenv.yaml not found")
    with open(yaml_path) as f:
        return f.read()


# ── Entry point ───────────────────────────────────────────────────────────────

if __name__ == "__main__":
    import uvicorn
    uvicorn.run("server.app:app", host="0.0.0.0", port=7860, reload=False)