#!/usr/bin/env python3
"""Validate the standardized PDENNEval dataset package."""

from __future__ import annotations

import argparse
import hashlib
import json
import math
import sys
from pathlib import Path

import h5py
import numpy as np


REPO_ROOT = Path(__file__).resolve().parents[1]
DATA_ROOT = REPO_ROOT / "data"
CHECKSUM_PATH = REPO_ROOT / "files_sha256.jsonl"

EXPECTED_FILES = {
    "1D_Burgers_Sols_Nu0.001.hdf5": {
        "datasets": {
            "tensor": {"ndim": 3, "dtype": "float32"},
            "x-coordinate": {"ndim": 1, "dtype": "float32"},
            "t-coordinate": {"ndim": 1, "dtype": "float32"},
        },
        "attrs": {"Nu": 0.001},
    },
    "2D_DarcyFlow_beta0.1_Train.hdf5": {
        "datasets": {
            "tensor": {"ndim": 4, "dtype": "float32"},
            "nu": {"ndim": 3, "dtype": "float32"},
            "x-coordinate": {"ndim": 1, "dtype": "float32"},
            "y-coordinate": {"ndim": 1, "dtype": "float32"},
        },
        "attrs": {"beta": 0.1},
    },
    "1D_Advection_Sols_beta1.0.hdf5": {
        "datasets": {
            "tensor": {"ndim": 3, "dtype": "float32"},
            "x-coordinate": {"ndim": 1, "dtype": "float32"},
            "t-coordinate": {"ndim": 1, "dtype": "float32"},
        },
        "attrs": {},
    },
}


def fail(message: str) -> None:
    print(f"[FAIL] {message}")
    raise SystemExit(1)


def ok(message: str) -> None:
    print(f"[OK] {message}")


def warn(message: str) -> None:
    print(f"[WARN] {message}")


def sha256_file(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def as_float(value: object) -> float | None:
    try:
        return float(value)
    except (TypeError, ValueError):
        return None


def validate_hdf5_file(path: Path, spec: dict[str, object]) -> None:
    if not path.is_file():
        fail(f"missing expected HDF5 file: {path}")
    with h5py.File(path, "r") as handle:
        for attr_name, expected in spec.get("attrs", {}).items():
            actual = as_float(handle.attrs.get(attr_name))
            if actual is None or not math.isclose(actual, float(expected), rel_tol=1e-6, abs_tol=1e-12):
                fail(f"{path.name} attr {attr_name!r} expected {expected}, got {handle.attrs.get(attr_name)!r}")
        for dataset_name, dataset_spec in spec["datasets"].items():
            if dataset_name not in handle:
                fail(f"{path.name} missing dataset {dataset_name!r}")
            dataset = handle[dataset_name]
            if dataset.ndim != dataset_spec["ndim"]:
                fail(f"{path.name}/{dataset_name} ndim expected {dataset_spec['ndim']}, got {dataset.ndim}")
            if str(dataset.dtype) != dataset_spec["dtype"]:
                fail(f"{path.name}/{dataset_name} dtype expected {dataset_spec['dtype']}, got {dataset.dtype}")
            if any(dim <= 0 for dim in dataset.shape):
                fail(f"{path.name}/{dataset_name} has invalid shape {dataset.shape}")
            probe = np.asarray(dataset[0])
            if not np.isfinite(probe).all():
                fail(f"{path.name}/{dataset_name} first slice contains non-finite values")
        ok(f"{path.name} HDF5 schema is readable")


def verify_checksums(full_hash: bool) -> None:
    if not CHECKSUM_PATH.exists():
        warn(f"checksum manifest is not present: {CHECKSUM_PATH}")
        return
    records = [json.loads(line) for line in CHECKSUM_PATH.read_text(encoding="utf-8").splitlines() if line.strip()]
    if not records:
        fail("checksum manifest is empty")
    for record in records:
        path = REPO_ROOT / record["path"]
        if not path.is_file():
            fail(f"checksum entry points to missing file: {path}")
        size = path.stat().st_size
        if size != record["size"]:
            fail(f"size mismatch for {path}: expected {record['size']}, got {size}")
        if full_hash:
            digest = sha256_file(path)
            if digest != record["sha256"]:
                fail(f"sha256 mismatch for {path}")
    mode = "size+sha256" if full_hash else "size"
    ok(f"checksum manifest verified in {mode} mode: {len(records)} files")


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--full-hash", action="store_true", help="verify SHA256 for all large HDF5 files")
    args = parser.parse_args()

    if not DATA_ROOT.is_dir():
        fail(f"dataset data root does not exist: {DATA_ROOT}")
    for filename, spec in EXPECTED_FILES.items():
        validate_hdf5_file(DATA_ROOT / filename, spec)
    verify_checksums(args.full_hash)
    ok("dataset validation completed")
    return 0


if __name__ == "__main__":
    sys.exit(main())