"""ReliabilityStep — writes provenance_verified + text_agreement (spec §6).

Runs after :class:`~ix.pipeline.genai_step.GenAIStep`. Skips entirely
when provenance is off OR when no provenance data was built (OCR-skipped
text-only request, for example). Otherwise delegates to
:func:`~ix.provenance.apply_reliability_flags`, which mutates each
:class:`~ix.contracts.FieldProvenance` in place and fills the two
summary counters (``verified_fields``, ``text_agreement_fields``) on
``quality_metrics``.

No own dispatch logic — everything interesting lives in the normalisers
+ verifier modules and is unit-tested there.
"""

from __future__ import annotations

from typing import cast

from pydantic import BaseModel

from ix.contracts import RequestIX, ResponseIX
from ix.pipeline.step import Step
from ix.provenance import apply_reliability_flags


class ReliabilityStep(Step):
    """Fills per-field reliability flags on ``response.provenance``."""

    async def validate(self, request_ix: RequestIX, response_ix: ResponseIX) -> bool:
        if not request_ix.options.provenance.include_provenance:
            return False
        return response_ix.provenance is not None

    async def process(
        self, request_ix: RequestIX, response_ix: ResponseIX
    ) -> ResponseIX:
        assert response_ix.provenance is not None  # validate() guarantees

        ctx = response_ix.context
        texts: list[str] = (
            list(getattr(ctx, "texts", []) or []) if ctx is not None else []
        )
        use_case_response_cls = cast(
            type[BaseModel],
            getattr(ctx, "use_case_response", None) if ctx is not None else None,
        )

        apply_reliability_flags(
            provenance_data=response_ix.provenance,
            use_case_response=use_case_response_cls,
            texts=texts,
        )
        return response_ix


__all__ = ["ReliabilityStep"]