"""IMP-52 (#80) u9 — backend tests for the argparse persistence fallback.

Stage 2 u9 scope (per the Exit Report):

1. Per-axis fill        — file value flows through when CLI omits the axis.
2. CLI-wins             — CLI value beats file value on the same axis.
3. No-file noop         — missing file → ``run_phase_z2_mvp1`` gets all-None.
4. Corrupt-file warn    — invalid JSON / non-object → stderr warning + skip.
5. Invalid stem warn    — ``Path(args.mdx_path).stem`` rejected by validator
                          → warning + fallback skipped wholesale.

We exec the ``if __name__ == "__main__"`` block of
``src.phase_z2_pipeline`` directly inside the module's namespace, after
(a) monkeypatching ``src.user_overrides_io.DEFAULT_OVERRIDES_ROOT`` to a
tmp directory and (b) replacing ``run_phase_z2_mvp1`` with a recording
stub. This exercises the production fallback verbatim without the cost
of a real pipeline invocation.
"""
from __future__ import annotations

import ast
import json
import sys
from pathlib import Path
from typing import Any

import pytest

import src.phase_z2_pipeline as _pz2
import src.user_overrides_io as _io


# -- harness ---------------------------------------------------------------


def _exec_main_block(
    captured: dict[str, Any], argv: list[str], monkeypatch
) -> None:
    """Run the ``__main__`` body of phase_z2_pipeline.py with a fake
    ``run_phase_z2_mvp1`` so its kwargs are observable."""

    def _fake_run(
        mdx_path,
        run_id,
        *,
        override_layout=None,
        override_frames=None,
        override_zone_geometries=None,
        override_section_assignments=None,
    ):
        captured["mdx_path"] = mdx_path
        captured["run_id"] = run_id
        captured["override_layout"] = override_layout
        captured["override_frames"] = override_frames
        captured["override_zone_geometries"] = override_zone_geometries
        captured["override_section_assignments"] = override_section_assignments

    monkeypatch.setattr(_pz2, "run_phase_z2_mvp1", _fake_run)
    monkeypatch.setattr(sys, "argv", argv)

    src_path = Path(_pz2.__file__)
    source = src_path.read_text(encoding="utf-8")
    tree = ast.parse(source)
    for node in tree.body:
        if (
            isinstance(node, ast.If)
            and isinstance(node.test, ast.Compare)
            and isinstance(node.test.left, ast.Name)
            and node.test.left.id == "__name__"
        ):
            block = ast.Module(body=node.body, type_ignores=[])
            exec(compile(block, str(src_path), "exec"), _pz2.__dict__)
            return
    raise AssertionError("no `if __name__ == '__main__'` block found")


def _redirect_overrides_root(tmp_path: Path, monkeypatch) -> None:
    """Redirect the on-disk persistence root so tests never touch
    ``data/user_overrides/``."""
    monkeypatch.setattr(_io, "DEFAULT_OVERRIDES_ROOT", tmp_path)


def _write_full_payload(tmp_path: Path, stem: str = "03") -> Path:
    path = tmp_path / f"{stem}.json"
    path.write_text(
        json.dumps(
            {
                "layout": "sidebar-right",
                "frames": {"03-1": "frame_file_a", "03-1+03-2": "frame_file_b"},
                "zone_geometries": {
                    "top": {"x": 0.0, "y": 0.0, "w": 1.0, "h": 0.3},
                    "bottom": {"x": 0.0, "y": 0.3, "w": 1.0, "h": 0.7},
                },
                "zone_sections": {
                    "top": ["03-1"],
                    "bottom": ["03-2", "03-3"],
                },
            }
        ),
        encoding="utf-8",
    )
    return path


# -- 1. no-file noop -------------------------------------------------------


def test_no_overrides_file_passes_none_overrides(tmp_path, monkeypatch):
    _redirect_overrides_root(tmp_path, monkeypatch)
    captured: dict[str, Any] = {}
    _exec_main_block(captured, ["src.phase_z2_pipeline", "03.mdx"], monkeypatch)

    assert captured["override_layout"] is None
    assert captured["override_frames"] is None
    assert captured["override_zone_geometries"] is None
    assert captured["override_section_assignments"] is None
    # MDX path / run_id propagate untouched.
    assert captured["mdx_path"] == Path("03.mdx")
    assert captured["run_id"] is None


# -- 2. file fills every axis when CLI is empty ----------------------------


def test_file_only_fills_all_four_axes_when_cli_empty(tmp_path, monkeypatch):
    _redirect_overrides_root(tmp_path, monkeypatch)
    _write_full_payload(tmp_path, "03")

    captured: dict[str, Any] = {}
    _exec_main_block(captured, ["src.phase_z2_pipeline", "03.mdx"], monkeypatch)

    assert captured["override_layout"] == "sidebar-right"
    assert captured["override_frames"] == {
        "03-1": "frame_file_a",
        "03-1+03-2": "frame_file_b",
    }
    assert captured["override_zone_geometries"] == {
        "top": {"x": 0.0, "y": 0.0, "w": 1.0, "h": 0.3},
        "bottom": {"x": 0.0, "y": 0.3, "w": 1.0, "h": 0.7},
    }
    assert captured["override_section_assignments"] == {
        "top": ["03-1"],
        "bottom": ["03-2", "03-3"],
    }


# -- 3. CLI beats file on the same axis -----------------------------------


def test_cli_layout_overrides_file_layout(tmp_path, monkeypatch):
    _redirect_overrides_root(tmp_path, monkeypatch)
    _write_full_payload(tmp_path, "03")

    captured: dict[str, Any] = {}
    _exec_main_block(
        captured,
        ["src.phase_z2_pipeline", "03.mdx", "--override-layout", "two-column"],
        monkeypatch,
    )

    # layout from CLI; remaining axes still filled from file.
    assert captured["override_layout"] == "two-column"
    assert captured["override_frames"] == {
        "03-1": "frame_file_a",
        "03-1+03-2": "frame_file_b",
    }
    assert captured["override_zone_geometries"] is not None
    assert captured["override_section_assignments"] is not None


def test_cli_frames_overrides_file_frames(tmp_path, monkeypatch):
    _redirect_overrides_root(tmp_path, monkeypatch)
    _write_full_payload(tmp_path, "03")

    captured: dict[str, Any] = {}
    _exec_main_block(
        captured,
        [
            "src.phase_z2_pipeline",
            "03.mdx",
            "--override-frame",
            "03-1=cli_frame_x",
        ],
        monkeypatch,
    )

    # CLI ``frames`` payload wholly replaces file ``frames`` (per-axis win).
    assert captured["override_frames"] == {"03-1": "cli_frame_x"}
    # Other axes still come from the file.
    assert captured["override_layout"] == "sidebar-right"
    assert captured["override_zone_geometries"] is not None
    assert captured["override_section_assignments"] is not None


# -- 4. corrupt / non-object file warns and skips fallback ----------------


def test_corrupt_json_warns_and_skips_fallback(tmp_path, monkeypatch, capsys):
    _redirect_overrides_root(tmp_path, monkeypatch)
    (tmp_path / "03.json").write_text("{ not valid json", encoding="utf-8")

    captured: dict[str, Any] = {}
    _exec_main_block(captured, ["src.phase_z2_pipeline", "03.mdx"], monkeypatch)

    err = capsys.readouterr().err
    assert "failed to read" in err
    # ``or None`` collapses empty dicts back to None on the call site.
    assert captured["override_layout"] is None
    assert captured["override_frames"] is None
    assert captured["override_zone_geometries"] is None
    assert captured["override_section_assignments"] is None


def test_non_object_top_level_warns_and_skips_fallback(
    tmp_path, monkeypatch, capsys
):
    _redirect_overrides_root(tmp_path, monkeypatch)
    (tmp_path / "03.json").write_text("[1, 2, 3]", encoding="utf-8")

    captured: dict[str, Any] = {}
    _exec_main_block(captured, ["src.phase_z2_pipeline", "03.mdx"], monkeypatch)

    err = capsys.readouterr().err
    assert "not a JSON object" in err
    assert captured["override_layout"] is None
    assert captured["override_frames"] is None
    assert captured["override_zone_geometries"] is None
    assert captured["override_section_assignments"] is None


# -- 5. invalid MDX stem warns and skips fallback wholesale ---------------


def test_invalid_mdx_stem_warns_and_skips_fallback(
    tmp_path, monkeypatch, capsys
):
    _redirect_overrides_root(tmp_path, monkeypatch)
    # Seed a file the loader would otherwise consume; the invalid stem must
    # short-circuit before any read happens.
    _write_full_payload(tmp_path, "03")

    captured: dict[str, Any] = {}
    # ``Path(".hidden.mdx").stem`` == ".hidden" → leading dot → InvalidOverrideKey.
    _exec_main_block(
        captured, ["src.phase_z2_pipeline", ".hidden.mdx"], monkeypatch
    )

    err = capsys.readouterr().err
    assert "cannot derive persistence key" in err
    assert captured["override_layout"] is None
    assert captured["override_frames"] is None
    assert captured["override_zone_geometries"] is None
    assert captured["override_section_assignments"] is None


# -- 6. per-axis partial fill (file fills only what CLI omits) ------------


def test_per_axis_partial_fill_mixes_cli_and_file(tmp_path, monkeypatch):
    """File carries frames + zone_geometries; CLI supplies layout only.

    Expected: ``override_layout`` = CLI value, ``override_frames`` and
    ``override_zone_geometries`` = file values, ``override_section_assignments``
    = None (neither side provided it).
    """
    _redirect_overrides_root(tmp_path, monkeypatch)
    (tmp_path / "03.json").write_text(
        json.dumps(
            {
                "frames": {"03-1": "frame_only_file"},
                "zone_geometries": {
                    "top": {"x": 0.0, "y": 0.0, "w": 1.0, "h": 0.5},
                },
            }
        ),
        encoding="utf-8",
    )

    captured: dict[str, Any] = {}
    _exec_main_block(
        captured,
        [
            "src.phase_z2_pipeline",
            "03.mdx",
            "--override-layout",
            "sidebar-right",
        ],
        monkeypatch,
    )

    assert captured["override_layout"] == "sidebar-right"
    assert captured["override_frames"] == {"03-1": "frame_only_file"}
    assert captured["override_zone_geometries"] == {
        "top": {"x": 0.0, "y": 0.0, "w": 1.0, "h": 0.5},
    }
    assert captured["override_section_assignments"] is None