#!/usr/bin/env python3
# file: scripts/audit_rust_blank_lines.py
# version: 1

"""Audit blank-line spacing in explicitly selected Rust sources."""

from __future__ import annotations

import argparse
import pathlib
import re
import sys

from _rust_audit_common import line_depths, mask_source, selected_files

_BODY = re.compile(r"^\s*(?:(?:pub(?:\([^)]*\))?|async|const|unsafe|extern|default)\s+)*(fn|struct|enum)\b")


def audit_file(path: pathlib.Path) -> list[str]:
    """Check successive empty lines and empty function/struct/enum body lines."""

    text = path.read_text(encoding="utf-8")
    lines = text.splitlines()
    masked, protected = mask_source(text)
    masked_lines = masked.splitlines()
    depths = line_depths(masked)
    errors: list[str] = []
    previous_blank = False
    pending: tuple[str, int] | None = None
    active: tuple[str, int] | None = None

    for number, (original, code, depth) in enumerate(zip(lines, masked_lines, depths, strict=True), 1):
        blank = not original.strip() and number not in protected
        if blank and previous_blank:
            errors.append(f"{path}:{number}: consecutive blank Rust source lines")
        previous_blank = blank

        if active is not None and depth <= active[1]:
            active = None
        if active is not None and blank:
            errors.append(f"{path}:{number}: blank line inside {active[0]} body")

        if active is None and pending is None:
            match = _BODY.match(code)
            if match is not None:
                pending = (match.group(1), depth)
        if pending is not None:
            if "{" in code:
                active = pending
                pending = None
            elif ";" in code:
                pending = None
    return errors


def main() -> int:
    """Run the read-only spacing audit on explicitly selected Rust files."""

    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("paths", nargs="+", help="Rust files or directories to inspect")
    args = parser.parse_args()
    files, errors = selected_files(args.paths)
    if errors or not files:
        for error in errors or ["no Rust files selected"]:
            print(f"Rust blank-line audit: {error}", file=sys.stderr)
        return 2
    for path in files:
        try:
            errors.extend(audit_file(path))
        except (OSError, UnicodeError) as error:
            print(f"Rust blank-line audit: cannot read {path}: {error}", file=sys.stderr)
            return 2
    for error in errors:
        print(error, file=sys.stderr)
    if errors:
        print(f"Rust blank-line audit: {len(errors)} error(s) across {len(files)} file(s)", file=sys.stderr)
        return 1
    print(f"Rust blank-line audit: clean ({len(files)} file(s))")
    return 0


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