#!/usr/bin/env python3
"""Stats for PV sensors (Type 4) with heavy tails / regime changes."""

import argparse
import csv
import gzip
import json
from pathlib import Path
from typing import Dict, List


def parse_args():
    base_dir = Path(__file__).resolve().parent
    parser = argparse.ArgumentParser(description="PV stats.")
    parser.add_argument("--generated", default=str(base_dir / "results" / "generated.csv"))
    parser.add_argument("--reference", default=str(base_dir / "config.json"))
    parser.add_argument("--features", default="", help="comma-separated list")
    parser.add_argument("--config", default=str(base_dir / "config.json"))
    parser.add_argument("--out", default=str(base_dir / "results" / "pv_stats.json"))
    parser.add_argument("--max-rows", type=int, default=200000)
    return parser.parse_args()


def resolve_reference_glob(ref_arg: str) -> str:
    ref_path = Path(ref_arg)
    if ref_path.suffix == ".json":
        cfg = json.loads(ref_path.read_text(encoding="utf-8"))
        data_glob = cfg.get("data_glob") or cfg.get("data_path") or ""
        if not data_glob:
            raise SystemExit("reference config has no data_glob/data_path")
        combined = ref_path.parent / data_glob
        if "*" in str(combined) or "?" in str(combined):
            return str(combined)
        return str(combined.resolve())
    return str(ref_path)


def read_series(path: Path, cols: List[str], max_rows: int) -> Dict[str, List[float]]:
    vals = {c: [] for c in cols}
    opener = gzip.open if str(path).endswith(".gz") else open
    with opener(path, "rt", newline="") as fh:
        reader = csv.DictReader(fh)
        for i, row in enumerate(reader):
            for c in cols:
                try:
                    vals[c].append(float(row[c]))
                except Exception:
                    pass
            if max_rows > 0 and i + 1 >= max_rows:
                break
    return vals


def quantile_stats(series: List[float]):
    if not series:
        return {"q05": None, "q50": None, "q95": None, "tail_ratio": None}
    xs = sorted(series)
    n = len(xs)
    def q(p):
        idx = int(round(p * (n - 1)))
        idx = max(0, min(n - 1, idx))
        return xs[idx]
    q05 = q(0.05)
    q50 = q(0.5)
    q95 = q(0.95)
    tail_ratio = (q95 - q50) / (q50 - q05) if (q50 - q05) != 0 else None
    return {"q05": q05, "q50": q50, "q95": q95, "tail_ratio": tail_ratio}


def main():
    args = parse_args()
    features = [f.strip() for f in args.features.split(",") if f.strip()]
    if not features and Path(args.config).exists():
        cfg = json.loads(Path(args.config).read_text(encoding="utf-8"))
        features = cfg.get("type4_features", []) or []
    if not features:
        raise SystemExit("no features specified for pv_stats")

    gen_vals = read_series(Path(args.generated), features, args.max_rows)
    ref_glob = resolve_reference_glob(args.reference)
    ref_paths = sorted(Path(ref_glob).parent.glob(Path(ref_glob).name))
    if not ref_paths:
        raise SystemExit(f"no reference files matched: {ref_glob}")
    real_vals = {c: [] for c in features}
    for p in ref_paths:
        vals = read_series(p, features, args.max_rows)
        for c in features:
            real_vals[c].extend(vals[c])

    out = {"features": features, "generated": {}, "reference": {}}
    for c in features:
        out["generated"][c] = quantile_stats(gen_vals[c])
        out["reference"][c] = quantile_stats(real_vals[c])

    out_path = Path(args.out)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    out_path.write_text(json.dumps(out, indent=2), encoding="utf-8")
    print("wrote", out_path)


if __name__ == "__main__":
    main()