"""Validate pipeline outputs before Make stamps are touched."""

from __future__ import annotations

import argparse
import sys
import zipfile
from pathlib import Path

import polars as pl


def _failures_for_file(path: Path) -> list[str]:
    if not path.exists():
        return [f"{path}: missing"]
    if not path.is_file():
        return [f"{path}: not a file"]
    try:
        size = path.stat().st_size
    except OSError as exc:
        return [f"{path}: unreadable metadata: {exc}"]
    if size <= 0:
        return [f"{path}: empty file"]
    return []


def _failures_for_dir(path: Path) -> list[str]:
    if not path.exists():
        return [f"{path}: missing"]
    if not path.is_dir():
        return [f"{path}: not a directory"]
    try:
        if not any(not child.name.startswith(".") for child in path.iterdir()):
            return [f"{path}: empty directory"]
    except OSError as exc:
        return [f"{path}: unreadable directory: {exc}"]
    return []


def _failures_for_parquet(path: Path) -> list[str]:
    failures = _failures_for_file(path)
    if failures:
        return failures
    try:
        row_count = pl.scan_parquet(path).select(pl.len()).collect().item()
    except Exception as exc:
        return [f"{path}: unreadable parquet: {exc}"]
    if row_count <= 0:
        return [f"{path}: parquet has no rows"]
    return []


def _failures_for_zip(path: Path) -> list[str]:
    failures = _failures_for_file(path)
    if failures:
        return failures
    if not zipfile.is_zipfile(path):
        return [f"{path}: unreadable zip"]
    try:
        with zipfile.ZipFile(path) as archive:
            if not archive.namelist():
                return [f"{path}: zip has no members"]
    except Exception as exc:
        return [f"{path}: unreadable zip: {exc}"]
    return []


def _split_glob(spec: str) -> tuple[Path, str]:
    if "::" not in spec:
        raise argparse.ArgumentTypeError(
            f"{spec!r} must use BASE::PATTERN, for example data::**/*.csv"
        )
    base, pattern = spec.split("::", 1)
    if not base or not pattern:
        raise argparse.ArgumentTypeError(f"{spec!r} must include BASE and PATTERN")
    return Path(base), pattern


def _matched_files(spec: str) -> tuple[Path, str, list[Path]]:
    base, pattern = _split_glob(spec)
    if not base.exists():
        return base, pattern, []
    return base, pattern, sorted(path for path in base.glob(pattern) if path.is_file())


def _failures_for_glob(spec: str) -> list[str]:
    base, pattern, paths = _matched_files(spec)
    if not paths:
        return [f"{base}: no files matched {pattern!r}"]

    failures: list[str] = []
    for path in paths:
        failures.extend(_failures_for_file(path))
    return failures


def _failures_for_zip_glob(spec: str) -> list[str]:
    base, pattern, paths = _matched_files(spec)
    if not paths:
        return [f"{base}: no zip files matched {pattern!r}"]

    failures: list[str] = []
    for path in paths:
        failures.extend(_failures_for_zip(path))
    return failures


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--file", action="append", default=[], type=Path)
    parser.add_argument("--dir", action="append", default=[], type=Path)
    parser.add_argument("--parquet", action="append", default=[], type=Path)
    parser.add_argument("--zip", action="append", default=[], type=Path)
    parser.add_argument(
        "--glob",
        action="append",
        default=[],
        help="Require at least one non-empty file matching BASE::PATTERN",
    )
    parser.add_argument(
        "--zip-glob",
        action="append",
        default=[],
        help="Require at least one readable zip matching BASE::PATTERN",
    )
    args = parser.parse_args()

    failures: list[str] = []
    for path in args.file:
        failures.extend(_failures_for_file(path))
    for path in args.dir:
        failures.extend(_failures_for_dir(path))
    for path in args.parquet:
        failures.extend(_failures_for_parquet(path))
    for path in args.zip:
        failures.extend(_failures_for_zip(path))
    for spec in args.glob:
        failures.extend(_failures_for_glob(spec))
    for spec in args.zip_glob:
        failures.extend(_failures_for_zip_glob(spec))

    if failures:
        print("Output validation failed:", file=sys.stderr)
        for failure in failures:
            print(f"  - {failure}", file=sys.stderr)
        return 1

    return 0


if __name__ == "__main__":
    raise SystemExit(main())