import json
from fastapi import APIRouter, HTTPException
from app.config import STATE_PATH, BACKGROUND_PATH, energy_axis, NUM_CHANNELS
import numpy as np

router = APIRouter()


@router.get("/current")
async def get_current_spectrum():
    """Current accumulated spectrum with energy axis."""
    if not STATE_PATH.exists():
        raise HTTPException(status_code=503, detail="Monitor not started yet")

    try:
        with open(STATE_PATH) as f:
            state = json.load(f)
    except (json.JSONDecodeError, OSError):
        raise HTTPException(status_code=503, detail="Monitor state file corrupt")

    return {
        "timestamp": state.get("timestamp", ""),
        "connected": state.get("connected", False),
        "cumulated_live_time_s": state.get("cumulated_live_time_s", 0),
        "cumulated_live_time_h": state.get("cumulated_live_time_h", 0),
        "cps": state.get("cps", 0),
        "total_counts": state.get("total_counts", 0),
        "background_subtracted": state.get("background_subtracted", False),
        "isotopes_detected": state.get("isotopes_detected", []),
        "channels": list(range(NUM_CHANNELS)),
        "energy_kev": energy_axis(),
        "counts": state.get("counts", [0] * 1024)[:NUM_CHANNELS],
    }


@router.get("/difference")
async def get_difference_spectrum():
    """Background-subtracted spectrum (net signal)."""
    if not STATE_PATH.exists():
        raise HTTPException(status_code=503, detail="Monitor not started yet")

    try:
        with open(STATE_PATH) as f:
            state = json.load(f)
    except (json.JSONDecodeError, OSError):
        raise HTTPException(status_code=503, detail="Monitor state file corrupt")

    counts = np.array(state.get("counts", [0] * 1024), dtype=np.float64)[:NUM_CHANNELS]
    live_time = state.get("cumulated_live_time_s", 0)

    if live_time <= 0:
        raise HTTPException(status_code=503, detail="No live time data yet")

    rate = counts / live_time

    if BACKGROUND_PATH.exists():
        bg_data = np.load(str(BACKGROUND_PATH), allow_pickle=True).item()
        bg_counts = bg_data["counts"].astype(np.float64)[:NUM_CHANNELS]
        bg_live_time = float(bg_data["duration"])
        bg_rate = bg_counts / bg_live_time
        net_rate = np.clip(rate - bg_rate, 0, None)
        net_counts = net_rate * live_time
        bg_available = True
    else:
        net_counts = counts
        bg_available = False

    return {
        "timestamp": state.get("timestamp", ""),
        "cumulated_live_time_s": live_time,
        "background_subtracted": bg_available,
        "channels": list(range(NUM_CHANNELS)),
        "energy_kev": energy_axis(),
        "counts": [round(float(c), 1) for c in net_counts],
        "raw_counts": state.get("counts", [])[:NUM_CHANNELS],
    }