"""External templates registry for md→pdf / md→docx conversion."""

import json
from pathlib import Path

import click

CONFIG_PATH = Path.home() / ".config" / "mytoolkit" / "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 set_root(path: Path) -> Path:
    """Register the templates root directory. Returns the resolved path."""
    resolved = Path(path).expanduser().resolve()
    _write({"dir": str(resolved)})
    return resolved


def get_root() -> Path:
    """Return the registered templates root, or raise UsageError if missing."""
    data = _read()
    raw = data.get("dir")
    if not raw:
        raise click.UsageError(
            "Templates not registered. Run: mytoolkit templates register <path>"
        )
    root = Path(raw)
    if not root.is_dir():
        raise click.UsageError(
            f"Registered templates dir does not exist: {root}\n"
            "Re-run: mytoolkit templates register <path>"
        )
    return 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