#!/usr/bin/env python3
"""Filesystem and I/O helpers for the intrusion-detection system."""

from __future__ import annotations

import csv
import gzip
import json
import os
import re
from typing import Any, Iterable, Iterator, Sequence

ANSI_RE = re.compile(r"\x1b\[[0-9;]*m")


# -- directory --------------------------------------------------------------

def validate_dir(path: str, need_write: bool = False) -> str:
    if not os.path.exists(path):
        raise FileNotFoundError(f"path does not exist: {path}")
    if not os.path.isdir(path):
        raise NotADirectoryError(f"path is not a directory: {path}")
    if not os.access(path, os.R_OK):
        raise PermissionError(f"path not readable: {path}")
    if need_write and not os.access(path, os.W_OK):
        raise PermissionError(f"path not writable: {path}")
    return path


def ensure_dirs(*paths: str) -> None:
    for p in paths:
        os.makedirs(p, exist_ok=True)


# -- log discovery ----------------------------------------------------------

def find_logs(path: str, pattern: re.Pattern | None = None,
              suffixes: Sequence[str] = (),
              exclude_prefixes: Sequence[str] = ()) -> list[str]:
    """List matching log file names (not full paths), sorted."""
    out = []
    for name in os.listdir(path):
        if not os.path.isfile(os.path.join(path, name)):
            continue
        if any(name.startswith(p) for p in exclude_prefixes):
            continue
        if pattern is not None and not pattern.match(name):
            continue
        if suffixes and not name.endswith(tuple(suffixes)):
            continue
        out.append(name)
    return sorted(out)


def read_lines(path: str) -> Iterator[str]:
    """Yield ANSI-stripped, newline-stripped lines. Transparently gunzips."""
    opener = gzip.open if path.endswith(".gz") else open
    with opener(path, "rt", encoding="utf-8", errors="replace") as f:
        for line in f:
            yield ANSI_RE.sub("", line.rstrip("\r\n"))


# -- writers ----------------------------------------------------------------

def write_csv(path: str, header: Sequence[str],
              rows: Iterable[Sequence[Any]]) -> str:
    with open(path, "w", newline="", encoding="utf-8") as f:
        w = csv.writer(f)
        w.writerow(header)
        w.writerows(rows)
    return path


def write_json(path: str, obj: Any) -> str:
    with open(path, "w", encoding="utf-8") as f:
        json.dump(obj, f, indent=2, default=str)
    return path


def write_lines(path: str, lines: Iterable[str]) -> str:
    with open(path, "w", encoding="utf-8") as f:
        for line in lines:
            f.write(line + "\n")
    return path