#!/usr/bin/env python3
"""Safely create one direct child in the configured knowledge vault."""

from __future__ import annotations

import json
import sys
from pathlib import Path


def fail(message: str) -> int:
    print(message, file=sys.stderr)
    return 1


def child_name(raw: str) -> str | None:
    name = raw.strip()
    if not name or name in {".", ".."} or "/" in name or "\\" in name or "\0" in name:
        return None
    if name.startswith("."):
        return None
    return name


def main() -> int:
    if len(sys.argv) != 5:
        return fail("usage: create-entry.py VAULT KIND CURRENT_DIRECTORY NAME")
    raw_vault, kind, current_directory, raw_name = sys.argv[1:]
    vault = Path(raw_vault).expanduser().resolve()
    if not vault.is_dir():
        return fail(f"vault does not exist: {vault}")
    if kind not in {"note", "directory"}:
        return fail("kind must be note or directory")
    current = (vault / current_directory).resolve()
    if current != vault and vault not in current.parents:
        return fail("current directory escaped the vault")
    if not current.is_dir():
        return fail("current directory no longer exists")

    name = child_name(raw_name)
    if name is None:
        return fail("use a non-hidden direct name without slashes")
    if kind == "note" and not name.lower().endswith(".md"):
        name += ".md"
    target = (current / name).resolve()
    if target.parent != current:
        return fail("target escaped the current directory")

    try:
        if kind == "directory":
            target.mkdir()
        else:
            title = target.stem
            with target.open("x", encoding="utf-8") as handle:
                handle.write(f"# {title}\n")
    except FileExistsError:
        return fail(f"already exists: {name}")
    except OSError as error:
        return fail(f"cannot create {name}: {error}")

    relative = target.relative_to(vault).as_posix()
    json.dump(
        {
            "kind": kind,
            "relative": relative,
            "name": name,
            "absolute": str(target),
        },
        sys.stdout,
    )
    return 0


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