"""Tests for the settings.local.toml overlay loader.

The overlay is the dev-side path for keeping host-specific secrets
(notably `[database].url`) out of the tracked `settings.toml` without
forcing every interactive shell to export env vars. The footgun this
test suite guards against: a one-key local override (e.g. a single
`[database] url = "..."`) silently wiping every other key in that
section. The merge is section-level, not shallow.
"""

from __future__ import annotations

from pathlib import Path

import pytest


# ---------------------------------------------------------------------------
# Pure-Python: _overlay_sections
# ---------------------------------------------------------------------------


def test_overlay_preserves_sibling_keys_in_overlapping_section():
    """The exact regression target — local `url` must not wipe `pool_size`."""
    from second_brain.config import _overlay_sections

    base = {"database": {"url": "", "pool_size": 5}}
    local = {"database": {"url": "postgresql://x"}}

    out = _overlay_sections(base, local)
    assert out["database"]["url"] == "postgresql://x"
    assert out["database"]["pool_size"] == 5


def test_overlay_section_only_in_base_survives():
    from second_brain.config import _overlay_sections

    base = {"database": {"url": "a"}, "scheduler": {"interval": 30}}
    local = {"database": {"url": "b"}}

    out = _overlay_sections(base, local)
    assert out["scheduler"] == {"interval": 30}
    assert out["database"]["url"] == "b"


def test_overlay_section_only_in_local_appears():
    from second_brain.config import _overlay_sections

    base = {"database": {"url": "a"}}
    local = {"embeddings": {"ollama_url": "http://x"}}

    out = _overlay_sections(base, local)
    assert out["database"] == {"url": "a"}
    assert out["embeddings"] == {"ollama_url": "http://x"}


def test_overlay_scalar_in_overlay_replaces_dict_in_base():
    """Non-dict overlay values replace outright — no merge attempt."""
    from second_brain.config import _overlay_sections

    base = {"feature": {"a": 1, "b": 2}}
    local = {"feature": "off"}  # scalar wins outright

    out = _overlay_sections(base, local)
    assert out["feature"] == "off"


def test_overlay_dict_in_overlay_replaces_scalar_in_base():
    from second_brain.config import _overlay_sections

    base = {"feature": "off"}
    local = {"feature": {"a": 1}}

    out = _overlay_sections(base, local)
    assert out["feature"] == {"a": 1}


def test_overlay_empty_overlay_is_identity():
    from second_brain.config import _overlay_sections

    base = {"database": {"url": "a", "pool_size": 5}}
    assert _overlay_sections(base, {}) == base
    assert _overlay_sections(base, None) == base


def test_overlay_only_merges_one_level():
    """Doc: the overlay is section-level. Nested dicts inside a section
    replace, not deep-merge. This pins the documented depth."""
    from second_brain.config import _overlay_sections

    base = {"db": {"url": "a", "pool": {"min": 1, "max": 10}}}
    local = {"db": {"pool": {"max": 20}}}

    out = _overlay_sections(base, local)
    # pool replaced wholesale — `min` does NOT survive. This is deliberate.
    assert out["db"]["pool"] == {"max": 20}
    assert out["db"]["url"] == "a"


# ---------------------------------------------------------------------------
# load_config: end-to-end with real TOML files on disk
# ---------------------------------------------------------------------------


def _write(path: Path, body: str) -> None:
    path.write_text(body, encoding="utf-8")


@pytest.fixture(autouse=True)
def _reset_config():
    """Drop the cached singleton before/after each test so overlay state
    doesn't leak between cases."""
    from second_brain.config import reset_config_singleton

    reset_config_singleton()
    yield
    reset_config_singleton()


def test_load_config_picks_up_sibling_local_overlay(tmp_path):
    from second_brain.config import load_config

    base = tmp_path / "settings.toml"
    local = tmp_path / "settings.local.toml"
    _write(
        base,
        '[database]\nurl = ""\n\n[embeddings]\nollama_url = "http://ollama:11434"\nmodel = "nomic-embed-text"\n',
    )
    _write(
        local,
        '[database]\nurl = "postgresql+psycopg://lovebug:x@127.0.0.1:5433/petalbrain"\n\n[embeddings]\nollama_url = "http://127.0.0.1:11434"\n',
    )

    cfg = load_config(base)
    # url from local wins; default model survives (not in local).
    assert cfg.database["url"].startswith("postgresql+psycopg://")
    assert cfg.embeddings["ollama_url"] == "http://127.0.0.1:11434"
    assert cfg.embeddings["model"] == "nomic-embed-text"


def test_load_config_no_local_overlay_is_inert(tmp_path):
    from second_brain.config import load_config

    base = tmp_path / "settings.toml"
    _write(base, '[database]\nurl = "from-base"\n')

    cfg = load_config(base)
    assert cfg.database["url"] == "from-base"


def test_load_config_local_overlay_at_explicit_path(tmp_path):
    """Doc: when an explicit (or SECOND_BRAIN_CONFIG) path is used, the
    overlay sibling is resolved next to THAT path — not next to the
    repo's config dir."""
    from second_brain.config import load_config

    subdir = tmp_path / "etc"
    subdir.mkdir()
    base = subdir / "settings.toml"
    local = subdir / "settings.local.toml"
    _write(base, '[database]\nurl = "base"\n')
    _write(local, '[database]\nurl = "overlay-wins"\n')

    cfg = load_config(base)
    assert cfg.database["url"] == "overlay-wins"