"""The one module in `core/` that knows about Typer.

**Why this is not a violation of the layering.** The invariant D-263 states is
that typer/click appear only in `main.py` and `router.py` — and its purpose is
that a *service* must never know it was called from a CLI. A shared group class
is transport by definition; the alternative is copying the same subclass into
every `router.py`, where the copies drift and only some domains end up
enumerating their verbs. So the invariant is refined rather than broken:

    no typer/click in service.py, schemas.py or helpers.py — ever.
    transport lives in main.py, router.py, and this module.

Keep that bound. If something here stops being about *transport*, it belongs
somewhere else.
"""

from __future__ import annotations

import typer
from typer.core import TyperGroup


class ReachDomainGroup(TyperGroup):
    """A domain group whose unknown-verb error names the verbs that exist.

    Click's default is `No such command 'x'` — which tells you that you are
    wrong without telling you what would be right. That is the closed-set gap
    D-263 measured in pql (an invalid status rejected without naming the six
    valid ones), and the fix is nearly free: the verb list is already registered
    on the group, so enumerating it costs a sort.
    """

    def resolve_command(self, ctx: typer.Context, args: list[str]):
        if args and self.get_command(ctx, args[0]) is None:
            listed = ", ".join(sorted(self.list_commands(ctx)))
            ctx.fail(f"unknown command {args[0]!r}\n\nChoose one of: {listed}")
        return super().resolve_command(ctx, args)


def domain(name: str, help: str) -> typer.Typer:
    """Build a domain's Typer app with the house settings applied.

    Every domain router should use this rather than calling `typer.Typer`
    directly, so the settings that are easy to forget are not per-router
    decisions:

    - `cls=ReachDomainGroup` so unknown verbs enumerate.
    - `rich_markup_mode=None` — load-bearing, not cosmetic: it keeps `rich` and
      `pygments` off the import path, and stops typer drawing box-art help even
      when stdout is a pipe, which would litter hook logs.
    - `no_args_is_help` so a bare `reach <domain>` says what it can do.

    Note the caller still needs a `@app.callback()` on the router: Typer
    collapses a single-command app into a bare command, and without the callback
    `reach <domain> <verb>` fails with "unexpected extra argument".
    """
    return typer.Typer(
        name=name,
        help=help,
        cls=ReachDomainGroup,
        no_args_is_help=True,
        add_completion=False,
        rich_markup_mode=None,
    )