"""IMP-56 (#90) u5 — Step 12 ``text_overrides`` apply unit tests.

Synthetic — exercises ``_apply_text_overrides_to_zones`` directly without
running the full Phase Z 22-step pipeline. The helper is decoupled from
``MdxSection`` / ``CompositionUnit`` graphs and only consumes a minimal
``[{position, slot_payload}, ...]`` zone list, so a synthetic fixture is
sufficient to lock the contract.

Coverage axes (Stage 2 plan u5 + Stage 1 binding contract) :

  - sanitized batch : malformed text_path / non-string value drops per-row
    (mirrors ``image_id_stamper.build_image_overrides_style`` u7 tolerance).
  - stale path : frame swap / layout regression → ``skipped``, not error.
  - raw_content preservation : helper never touches ``debug_zones`` / unit
    graph (asserted by zero-mutation on an out-of-band sentinel mapping).
  - audit shape : ``applied`` / ``skipped`` / ``per_zone`` keys present and
    counts consistent with the input batch.
  - empty / ``None`` override input is a no-op (empty audit).

Fully synthetic per Codex generalization guardrail (MOCK_ prefix).
NO real catalog template_id / frame_id, NO ``v4_full32_result.yaml``
dependency.
"""
from __future__ import annotations

import pytest

from src.phase_z2_pipeline import _apply_text_overrides_to_zones


# ─── Synthetic fixture helpers ──────────────────────────────────────


def _zone(position: str, slot_payload: dict) -> dict:
    """Minimal zone dict mirroring the Step 12 ``zones_data[i]`` shape."""
    return {
        "position": position,
        "template_id": "MOCK_T_phase_z2_text_overrides",
        "slot_payload": slot_payload,
        "content_weight": 1.0,
        "min_height_px": 200,
    }


# ─── Case 1 : happy path — list[str] slot mutation ────────────────────


def test_apply_replaces_list_line_in_place():
    zones = [
        _zone("top", {"slot_title": ["original headline"], "slot_body": ["a", "b", "c"]}),
        _zone("bottom", {"slot_caption": ["caption A"]}),
    ]
    overrides = {
        "top": {"slot_title.0": "edited headline", "slot_body.1": "edited B"},
    }

    audit = _apply_text_overrides_to_zones(overrides, zones)

    assert zones[0]["slot_payload"]["slot_title"] == ["edited headline"]
    assert zones[0]["slot_payload"]["slot_body"] == ["a", "edited B", "c"]
    # bottom zone untouched (no override entry)
    assert zones[1]["slot_payload"]["slot_caption"] == ["caption A"]
    assert audit["applied"] == 2
    assert audit["skipped"] == 0
    assert audit["per_zone"] == [{"position": "top", "applied": 2, "skipped": 0}]


# ─── Case 2 : stale text_path — frame swap / layout regression ────────


def test_stale_text_path_skipped_silently():
    """Absent slot_key + out-of-range line_index both count as skipped, not errors."""
    zones = [_zone("top", {"slot_title": ["only one line"]})]
    overrides = {
        "top": {
            "slot_title.0": "ok",           # applied
            "slot_title.99": "out of range", # skipped (idx > len)
            "slot_missing.0": "stale frame", # skipped (slot absent)
        },
    }

    audit = _apply_text_overrides_to_zones(overrides, zones)

    assert zones[0]["slot_payload"]["slot_title"] == ["ok"]
    assert "slot_missing" not in zones[0]["slot_payload"]
    assert audit["applied"] == 1
    assert audit["skipped"] == 2
    assert audit["per_zone"][0] == {"position": "top", "applied": 1, "skipped": 2}


# ─── Case 3 : malformed input — per-entry tolerance ────────────────────


def test_malformed_entries_dropped_in_validate():
    """Non-string value / malformed text_path drop in ``validate_text_overrides``."""
    zones = [_zone("top", {"slot_title": ["original", "second"]})]
    overrides = {
        "top": {
            "slot_title.0": "good",        # kept
            "slot_title.bad": "ignored",   # dropped (non-int idx)
            "slot_title.1": 123,           # dropped (non-str value)
            "no_dot": "ignored",           # dropped (missing '.')
        },
        "": {"slot_title.0": "empty zone id dropped"},  # zone_id sanitization
        123: {"slot_title.0": "non-string zone id dropped"},
    }

    audit = _apply_text_overrides_to_zones(overrides, zones)

    # only the well-formed entry applied
    assert zones[0]["slot_payload"]["slot_title"] == ["good", "second"]
    assert audit["applied"] == 1
    assert audit["skipped"] == 0


# ─── Case 4 : raw_content preservation invariant ──────────────────────


def test_raw_content_sentinel_untouched():
    """Helper must not mutate anything outside ``zone['slot_payload']``.

    Out-of-band fields (mirror of ``debug_zones[i].source_section_ids`` /
    MdxSection graph) stay byte-identical — Stage 1 binding contract.
    """
    raw_sentinel = ["MOCK_S1", "MOCK_S2"]
    zones = [_zone("top", {"slot_title": ["original"]})]
    zones[0]["source_section_ids_sentinel"] = raw_sentinel  # out-of-band
    zones[0]["raw_content_sentinel"] = "- original bullet\n- second\n"

    _apply_text_overrides_to_zones({"top": {"slot_title.0": "edited"}}, zones)

    assert zones[0]["source_section_ids_sentinel"] is raw_sentinel  # same object
    assert zones[0]["source_section_ids_sentinel"] == ["MOCK_S1", "MOCK_S2"]
    assert zones[0]["raw_content_sentinel"] == "- original bullet\n- second\n"


# ─── Case 5 : empty / None batch is no-op ──────────────────────────────


@pytest.mark.parametrize("payload", [None, {}, {"top": {}}, {"missing_zone": {"slot.0": "x"}}])
def test_empty_or_irrelevant_batch_is_noop(payload):
    zones = [_zone("top", {"slot_title": ["unchanged"]})]
    audit = _apply_text_overrides_to_zones(payload, zones)

    assert zones[0]["slot_payload"]["slot_title"] == ["unchanged"]
    assert audit["applied"] == 0
    assert audit["skipped"] == 0


# ─── Case 6 : zone without slot_payload skipped (defensive) ───────────


def test_zone_without_slot_payload_skipped():
    zones = [{"position": "top"}]  # no slot_payload key (defensive contract)
    audit = _apply_text_overrides_to_zones({"top": {"slot.0": "x"}}, zones)
    assert audit["per_zone"] == []
    assert audit["applied"] == 0
    assert audit["skipped"] == 0