from pathlib import Path
from importlib import resources

import click
import yaml

from docforge.nav import load_nav_spec
from docforge.nav import resolve_nav
from docforge.nav import MkDocsNavEmitter


def _load_template(template: Path | None) -> dict:
    if template is not None:
        if not template.exists():
            raise click.FileError(str(template), hint="Template not found")
        return yaml.safe_load(template.read_text(encoding="utf-8"))

    # Load built-in default
    text = (
        resources.files("docforge.templates")
        .joinpath("mkdocs.sample.yml")
        .read_text(encoding="utf-8")
    )
    return yaml.safe_load(text)


@click.command("mkdocs")
@click.option(
    "--docs-dir",
    type=click.Path(path_type=Path),
    default=Path("docs"),
)
@click.option(
    "--nav",
    "nav_file",
    type=click.Path(path_type=Path),
    default=Path("docforge.nav.yml"),
)
@click.option(
    "--template",
    type=click.Path(path_type=Path),
    default=None,
    help="Override the built-in mkdocs template",
)
@click.option(
    "--out",
    type=click.Path(path_type=Path),
    default=Path("mkdocs.yml"),
)
def mkdocs_cmd(
    docs_dir: Path,
    nav_file: Path,
    template: Path | None,
    out: Path,
) -> None:
    """Generate mkdocs.yml from nav spec and template."""

    if not nav_file.exists():
        raise click.FileError(str(nav_file), hint="Nav spec not found")

    # Load nav spec
    spec = load_nav_spec(nav_file)

    # Resolve nav
    resolved = resolve_nav(spec, docs_dir)

    # Emit mkdocs nav
    nav_block = MkDocsNavEmitter().emit(resolved)

    # Load template (user or built-in)
    data = _load_template(template)

    # Inject nav
    data["nav"] = nav_block

    # Write output
    out.write_text(
        yaml.safe_dump(data, sort_keys=False),
        encoding="utf-8",
    )

    click.echo(f"mkdocs.yml written to {out}")