"""
AURIS startup script — downloads model artifacts from HuggingFace Hub
before the API server starts.

Usage (in Dockerfile CMD):
    python startup.py && uvicorn app.main:app --host 0.0.0.0 --port 7860

Environment variables:
    HF_TOKEN          — HuggingFace access token (optional for public repos)
    AURIS_MODELS_REPO — HF repo ID, default: Rthur2003/auris-models
    MODELS_DIR        — Local destination, default: /app/models
    SKIP_MODEL_DOWNLOAD — Set to "1" to skip (for local dev)
"""

from __future__ import annotations

import os
import sys
import time
from pathlib import Path

REPO_ID   = os.getenv("AURIS_MODELS_REPO", "Rthur2003/auris-models")
MODELS_DIR = Path(os.getenv("MODELS_DIR", "/app/models"))
HF_TOKEN  = os.getenv("HF_TOKEN") or os.getenv("HUGGING_FACE_HUB_TOKEN")
SKIP      = os.getenv("SKIP_MODEL_DOWNLOAD", "0") == "1"

# Files that must exist for the API to work
REQUIRED_FILES = [
    "auris_classifier_v1.pkl",
    "feature_scaler_v1.pkl",
    "feature_columns_v1.json",
    "feature_stats_v1.json",
    "training_results.json",
    "deep_learning_results.json",
    "model_lightgbm.pkl",
    "model_xgboost.pkl",
    "model_random_forest.pkl",
    "model_gradient_boosting.pkl",
    "model_svm_rbf.pkl",
    "model_mlp_neural_network.pkl",
    "model_logistic_regression.pkl",
    "model_dl_deep_mlp_512_256_128_64.pkl",
    "model_dl_1d_cnn.pkl",
    "model_dl_residual_mlp_3_blocks.pkl",
    "model_dl_attention_mlp.pkl",
    "wav2vec2_auris_v1.pt",
]

# Large files that are optional (wav2vec2 tower works without wav2vec2)
OPTIONAL_FILES = {
    "wav2vec2_auris_v1.pt",
}


def _already_downloaded() -> bool:
    """Return True if all required non-optional files already exist."""
    missing = [
        f for f in REQUIRED_FILES
        if f not in OPTIONAL_FILES and not (MODELS_DIR / f).exists()
    ]
    if missing:
        print(f"[startup] Missing files: {missing}")
        return False
    return True


def download_models() -> None:
    if SKIP:
        print("[startup] SKIP_MODEL_DOWNLOAD=1 — skipping download.")
        return

    MODELS_DIR.mkdir(parents=True, exist_ok=True)

    if _already_downloaded():
        print("[startup] All required model files already present — skipping download.")
        return

    print(f"[startup] Downloading models from {REPO_ID} → {MODELS_DIR}")
    t0 = time.time()

    try:
        from huggingface_hub import hf_hub_download, list_repo_files
    except ImportError:
        print("[startup] huggingface_hub not installed — pip install huggingface-hub")
        sys.exit(1)

    kwargs = {"repo_id": REPO_ID, "repo_type": "model"}
    if HF_TOKEN:
        kwargs["token"] = HF_TOKEN

    # Get list of files in the repo
    try:
        repo_files = list(list_repo_files(**{k: v for k, v in kwargs.items() if k != "token"},
                                          token=HF_TOKEN))
    except Exception as e:
        print(f"[startup] Cannot list repo files: {e}")
        print("[startup] Trying to download known files directly...")
        repo_files = REQUIRED_FILES

    errors: list[str] = []
    for filename in REQUIRED_FILES:
        dest = MODELS_DIR / filename
        if dest.exists():
            print(f"[startup]   skip  {filename} (exists)")
            continue

        is_optional = filename in OPTIONAL_FILES
        if filename not in repo_files and is_optional:
            print(f"[startup]   skip  {filename} (not in repo, optional)")
            continue
        try:
            print(f"[startup]   dl    {filename} ...", end=" ", flush=True)
            path = hf_hub_download(
                filename=filename,
                local_dir=str(MODELS_DIR),
                **kwargs,
            )
            print(f"OK ({Path(path).stat().st_size / 1024 / 1024:.1f} MB)")
        except Exception as e:
            if is_optional:
                print(f"SKIP (optional: {e})")
            else:
                print(f"ERROR: {e}")
                errors.append(f"{filename}: {e}")

    elapsed = time.time() - t0
    print(f"[startup] Download complete in {elapsed:.1f}s")

    if errors:
        print(f"[startup] FATAL — {len(errors)} required file(s) failed:")
        for err in errors:
            print(f"  - {err}")
        print("[startup] Set AURIS_MODELS_REPO and HF_TOKEN env vars if repo is private.")
        sys.exit(1)


if __name__ == "__main__":
    download_models()
    print("[startup] Ready.")