import collections
import logging
import os
import sys
import threading
import time
from contextlib import asynccontextmanager
from pathlib import Path

from dotenv import load_dotenv
from fastapi import Depends, FastAPI, Header, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse, JSONResponse

load_dotenv()

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s | %(levelname)-8s | %(message)s",
    datefmt="%H:%M:%S",
    handlers=[logging.StreamHandler(sys.stdout)],
)
log = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Configuration
# ---------------------------------------------------------------------------
PORT          = int(os.environ.get("PORT", 8000))
API_KEY       = os.environ.get("API_KEY", "")
MODEL_VERSION = os.environ.get("MODEL_VERSION", "v1.0.0")
HF_TOKEN      = os.environ.get("HF_TOKEN", "")
DEVICE        = os.environ.get("DEVICE", "cpu")

# Rate limiting — spec Section 5 / error code 429
RATE_LIMIT_REQUESTS = int(os.environ.get("RATE_LIMIT_REQUESTS", 60))
RATE_LIMIT_WINDOW_S = int(os.environ.get("RATE_LIMIT_WINDOW_S", 60))
_rate_buckets: dict          = {}
_rate_lock:    threading.Lock = threading.Lock()

ONNX_PATH       = Path("models/onnx/immuniwatch_classifier.onnx")
THRESHOLDS_PATH = Path("models/onnx/thresholds.json")
CONFIG_PATH     = Path("models/onnx/model_config.json")
LORA_REPO       = "AHFIDAILabs/immuniwatch-lora-classifier"

# Uptime tracking — used by /health
_start_time = time.time()


# ---------------------------------------------------------------------------
# Model file download — runs at startup on HuggingFace Spaces
# Downloads ONNX files from the model repo if not present locally.
# On local dev they already exist in models/onnx/ (gitignored).
# ---------------------------------------------------------------------------
def _download_model_files() -> None:
    files = [
        ("immuniwatch_classifier.onnx",      ONNX_PATH),
        ("immuniwatch_classifier.onnx.data", ONNX_PATH.parent / "immuniwatch_classifier.onnx.data"),
        ("thresholds.json",                  THRESHOLDS_PATH),
        ("model_config.json",                CONFIG_PATH),
    ]
    missing = [(fname, path) for fname, path in files if not path.exists()]
    if not missing:
        return

    log.info("Downloading %d model file(s) from %s ...", len(missing), LORA_REPO)
    try:
        from huggingface_hub import hf_hub_download
        for fname, path in missing:
            log.info("  -> %s", fname)
            path.parent.mkdir(parents=True, exist_ok=True)
            hf_hub_download(
                repo_id=   LORA_REPO,
                filename=  fname,
                local_dir= str(path.parent),
                token=     HF_TOKEN or None,
            )
        log.info("Model files ready.")
    except Exception as exc:
        log.error("Model download failed: %s", exc)
        log.error("Upload ONNX files to %s on HuggingFace Hub first.", LORA_REPO)


# ---------------------------------------------------------------------------
# Startup
# ---------------------------------------------------------------------------
def _start_ingestion_worker() -> None:
    bluesky_handle = os.environ.get("BLUESKY_HANDLE", "")
    youtube_key    = os.environ.get("YOUTUBE_API_KEY", "")
    if not bluesky_handle and not youtube_key:
        log.info("No connector credentials — ingestion worker not started.")
        return
    try:
        from src.ingestion.direct_runner import run as run_ingestion
        t = threading.Thread(target=run_ingestion, daemon=True, name="ingestion-worker")
        t.start()
        log.info("Ingestion worker started in background thread.")
    except Exception as exc:
        log.warning("Ingestion worker failed to start: %s", exc)


@asynccontextmanager
async def lifespan(app: FastAPI):
    from src.models.classifier import load as load_classifier
    from src.intelligence.rag import preload_embedder

    log.info("Starting ImmuniWatch ML Service v%s", MODEL_VERSION)
    _download_model_files()
    load_classifier(
        onnx_path=      str(ONNX_PATH),
        thresholds_path=str(THRESHOLDS_PATH),
        config_path=    str(CONFIG_PATH),
        tokenizer_repo= LORA_REPO,
        hf_token=       HF_TOKEN or None,
    )
    preload_embedder()
    _start_ingestion_worker()
    log.info("Service ready on port %d", PORT)
    yield
    log.info("Service shutting down.")


# ---------------------------------------------------------------------------
# App
# ---------------------------------------------------------------------------
app = FastAPI(
    title="ImmuniWatch Nigeria — ML Service",
    version=MODEL_VERSION,
    lifespan=lifespan,
    docs_url="/docs",
    redoc_url=None,
)

# ---------------------------------------------------------------------------
# CORS — allow any origin so the local dashboard (file://) can call the API
# ---------------------------------------------------------------------------
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=False,
    allow_methods=["*"],
    allow_headers=["*"],
)


# ---------------------------------------------------------------------------
# Authentication — per spec Section 4
# Never log the key value — only log presence or absence
# ---------------------------------------------------------------------------
def _check_rate_limit(key: str) -> tuple:
    now = time.time()
    with _rate_lock:
        if key not in _rate_buckets:
            _rate_buckets[key] = collections.deque()
        bucket = _rate_buckets[key]
        while bucket and bucket[0] < now - RATE_LIMIT_WINDOW_S:
            bucket.popleft()
        if len(bucket) >= RATE_LIMIT_REQUESTS:
            retry_after = int(RATE_LIMIT_WINDOW_S - (now - bucket[0])) + 1
            return False, retry_after
        bucket.append(now)
        return True, 0


async def require_api_key(x_ml_api_key: str = Header(default=None)):
    if x_ml_api_key is None:
        log.warning("Rejected — X-ML-API-Key header absent")
        raise HTTPException(status_code=401,
                            detail="X-ML-API-Key header is required")
    if x_ml_api_key != API_KEY:
        log.warning("Rejected — X-ML-API-Key invalid")
        raise HTTPException(status_code=401, detail="Invalid API key")

    allowed, retry_after = _check_rate_limit(x_ml_api_key)
    if not allowed:
        raise HTTPException(
            status_code=429,
            detail="Rate limit exceeded",
            headers={"Retry-After": str(retry_after)},
        )


# ---------------------------------------------------------------------------
# GET / — root info endpoint, no auth required
# ---------------------------------------------------------------------------
@app.get("/")
async def root():
    return {
        "service":     "ImmuniWatch Nigeria ML Service",
        "version":     MODEL_VERSION,
        "status":      "running",
        "docs":        "/docs",
        "health":      "/health",
        "dashboard":   "/dashboard",
        "classify":    "POST /classify",
        "batch":       "POST /classify/batch",
    }


# ---------------------------------------------------------------------------
# GET /dashboard — serve the HTML dashboard, no auth required
# ---------------------------------------------------------------------------
@app.get("/dashboard", include_in_schema=False)
async def dashboard():
    path = Path("dashboard.html")
    if not path.exists():
        raise HTTPException(status_code=404, detail="Dashboard not found")
    return FileResponse(path, media_type="text/html")


# ---------------------------------------------------------------------------
# GET /health — no auth required, must respond in < 10ms
# ---------------------------------------------------------------------------
@app.get("/health")
async def health():
    from src.models.classifier import is_loaded

    if not is_loaded():
        return JSONResponse(
            status_code=503,
            content={"status": "unavailable", "reason": "model loading"},
        )
    return {
        "status":        "ok",
        "model_loaded":  True,
        "model_version": MODEL_VERSION,
        "device":        DEVICE,
        "uptime_s":      int(time.time() - _start_time),
    }


# ---------------------------------------------------------------------------
# Register all other routes with API key authentication
# ---------------------------------------------------------------------------
from src.api.routes import router  # noqa: E402

app.include_router(router, dependencies=[Depends(require_api_key)])