"""Reading and checking wav deliverables."""
from __future__ import annotations

import hashlib
import os
import urllib.request
from pathlib import Path

import numpy as np
from scipy.io import wavfile


def resolve_output(output: str, json_dir: Path, cache_dir: Path | None = None) -> Path:
    """Return a local path for a solution output, downloading URLs into cache_dir."""
    if output.startswith("http://") or output.startswith("https://"):
        cache_dir = cache_dir or Path(os.environ.get("CHALLENGE_CACHE", ".challenge-cache"))
        cache_dir.mkdir(parents=True, exist_ok=True)
        name = hashlib.sha256(output.encode()).hexdigest()[:16] + ".wav"
        dest = cache_dir / name
        if not dest.exists():
            urllib.request.urlretrieve(output, dest)
        return dest
    p = (json_dir / output).resolve()
    return p


def read_wav(path: Path, spec: dict) -> np.ndarray:
    """Read a wav and check it against the challenge's output spec. Returns float64 samples (mono)."""
    rate, data = wavfile.read(path)
    problems = []
    if rate != spec["sample_rate_hz"]:
        problems.append(f"sample rate {rate} != {spec['sample_rate_hz']}")
    if spec.get("sample_format") == "float32" and data.dtype != np.float32:
        problems.append(f"sample format {data.dtype} != float32")
    channels = 1 if data.ndim == 1 else data.shape[1]
    if channels != spec["channels"]:
        problems.append(f"channels {channels} != {spec['channels']}")
    n = data.shape[0]
    if n != spec["num_samples"]:
        problems.append(f"num samples {n} != {spec['num_samples']}")
    if not np.all(np.isfinite(data)):
        problems.append("non-finite samples")
    if problems:
        raise ValueError(f"{path}: " + "; ".join(problems))
    if data.ndim > 1:
        data = data[:, 0]
    return data.astype(np.float64)


def write_wav(path: Path, samples: np.ndarray, sample_rate: int) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    wavfile.write(path, sample_rate, np.asarray(samples, dtype=np.float32))