from __future__ import annotations

from pathlib import Path

import pytest

from vibe.core.types import ImageAttachment, LLMMessage, Role


@pytest.fixture()
def image_a(tmp_path: Path) -> ImageAttachment:
    p = tmp_path / "a.png"
    p.write_bytes(b"\x89PNG")
    return ImageAttachment(path=p, alias="a.png", mime_type="image/png")


@pytest.fixture()
def image_b(tmp_path: Path) -> ImageAttachment:
    p = tmp_path / "b.png"
    p.write_bytes(b"\x89PNG")
    return ImageAttachment(path=p, alias="b.png", mime_type="image/png")


def _msg(content: str, images: list[ImageAttachment] | None = None) -> LLMMessage:
    return LLMMessage(role=Role.assistant, content=content, images=images)


def test_merge_prefers_self_images_when_present(
    image_a: ImageAttachment, image_b: ImageAttachment
) -> None:
    merged = _msg("hi", images=[image_a]) + _msg(" there", images=[image_b])
    assert merged.images == [image_a]


def test_merge_falls_back_to_other_when_self_is_none(image_b: ImageAttachment) -> None:
    merged = _msg("hi") + _msg(" there", images=[image_b])
    assert merged.images == [image_b]


def test_merge_preserves_explicit_empty_self_images_over_other(
    image_b: ImageAttachment,
) -> None:
    # An explicit `[]` (intentional clearing) must NOT silently inherit
    # `other.images`. Truthy/falsy-based merging would have flipped this.
    merged = _msg("hi", images=[]) + _msg(" there", images=[image_b])
    assert merged.images == []


def test_merge_yields_none_when_both_sides_are_none() -> None:
    merged = _msg("hi") + _msg(" there")
    assert merged.images is None