"""Templates registry for md→pdf / md→docx conversion."""

import importlib.resources as resources
import json
import os
from pathlib import Path

import click

_HOME = Path(os.environ.get("MYTOOLKIT_HOME", Path.home() / ".mytoolkit"))
CONFIG_PATH = _HOME / "templates.json"


def _read() -> dict:
    if not CONFIG_PATH.exists():
        return {}
    with open(CONFIG_PATH, encoding="utf-8") as f:
        return json.load(f)


def _write(data: dict) -> None:
    CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
    with open(CONFIG_PATH, "w", encoding="utf-8") as f:
        json.dump(data, f, indent=2, ensure_ascii=False)
        f.write("\n")


def _package_root() -> Path:
    """Return the templates directory bundled with the package."""
    return Path(str(resources.files("mytoolkit") / "templates"))


def set_root(path: Path) -> Path:
    """Register an external templates root directory (override bundled templates)."""
    resolved = Path(path).expanduser().resolve()
    _write({"dir": str(resolved)})
    return resolved


def get_root() -> Path:
    """Return the active templates root.

    Uses the externally registered path if it exists and is valid; otherwise
    falls back to the templates directory bundled with the package.
    """
    data = _read()
    raw = data.get("dir")
    if raw:
        root = Path(raw)
        if root.is_dir():
            return root
    return _package_root()


def get_md_to_pdf_root() -> Path:
    sub = get_root() / "md-to-pdf"
    if not sub.is_dir():
        raise click.UsageError(f"Subdirectory missing: {sub}")
    return sub


def get_md_to_docx_root() -> Path:
    sub = get_root() / "md-to-docx"
    if not sub.is_dir():
        raise click.UsageError(f"Subdirectory missing: {sub}")
    return sub