"""Use-case registry.

Adding a use case is a two-line change:

  1. Write ``ix/use_cases/<name>.py`` exporting
     ``Request(BaseModel)`` (with ``use_case_name``, ``default_model``,
     ``system_prompt``) and ``<Response>(BaseModel)`` with the extraction
     schema.
  2. Add ``"<name>": (Request, <Response>)`` to :data:`REGISTRY` below.

No import-time side effects in use-case modules — registration is explicit
so the load order is obvious and tests can patch the registry cleanly.
"""

from __future__ import annotations

from pydantic import BaseModel

from ix.errors import IXErrorCode, IXException
from ix.use_cases.bank_statement_header import BankStatementHeader
from ix.use_cases.bank_statement_header import Request as BankStatementHeaderRequest

REGISTRY: dict[str, tuple[type[BaseModel], type[BaseModel]]] = {
    "bank_statement_header": (BankStatementHeaderRequest, BankStatementHeader),
}


def get_use_case(name: str) -> tuple[type[BaseModel], type[BaseModel]]:
    """Look up a registered use case by name.

    Raises :class:`IXException` with :attr:`IXErrorCode.IX_001_001` when the
    name is not in the registry — the offending name is embedded in the
    ``detail`` for log-scrape.
    """
    try:
        return REGISTRY[name]
    except KeyError as exc:
        raise IXException(IXErrorCode.IX_001_001, detail=name) from exc


__all__ = ["REGISTRY", "get_use_case"]