#!/usr/bin/env python3

import os
import re
import argparse
from pathlib import Path


def is_binary(file_path: Path) -> bool:
    """
    Detect binary files by checking for null bytes.
    """
    try:
        with file_path.open("rb") as f:
            chunk = f.read(1024)
            return b"\x00" in chunk
    except Exception:
        return True


def should_exclude(path: Path, exclude_pattern: re.Pattern) -> bool:
    """
    Check if path matches exclusion regex.
    """
    return bool(exclude_pattern.search(str(path)))


def concatenate_files(root_dir: Path, output_file: Path, exclude_regex: str):
    exclude_pattern = re.compile(exclude_regex)

    with output_file.open("w", encoding="utf-8") as outfile:
        for path in root_dir.rglob("*"):
            if not path.is_file():
                continue

            if path.resolve() == output_file.resolve():
                continue

            if should_exclude(path, exclude_pattern):
                continue

            if is_binary(path):
                continue

            try:
                content = path.read_text(encoding="utf-8", errors="replace")
            except Exception:
                continue

            outfile.write(f"===== FILE: {path} =====\n")
            outfile.write(content)
            outfile.write("\n\n")

    print(f"Done. Output written to {output_file}")


def main():
    parser = argparse.ArgumentParser(
        description="Recursively concatenate file contents into a single txt file."
    )
    parser.add_argument(
        "-d",
        "--directory",
        type=str,
        default=".",
        help="Root directory to search (default: current directory)",
    )
    parser.add_argument(
        "-o",
        "--output",
        type=str,
        default="combined_output.txt",
        help="Output file (default: combined_output.txt)",
    )
    parser.add_argument(
        "-e",
        "--exclude",
        type=str,
        default=r"\.git",
        help=r"Regex pattern for exclusions (default: \.git)",
    )

    args = parser.parse_args()

    root_dir = Path(args.directory).resolve()
    output_file = Path(args.output).resolve()

    concatenate_files(root_dir, output_file, args.exclude)


if __name__ == "__main__":
    main()