"""TDD — Phase 4 of issue #40: dedup intel provider BFS into _load_commit_walk.

P4-1  Structural — each provider delegates to _load_commit_walk; no inline BFS
P4-2  Behavioural — _load_commit_walk returns correct BFS order for a 4-commit chain
P4-3  Behavioural — _load_commit_walk respects max_walk cap
"""
from __future__ import annotations

import inspect
from types import SimpleNamespace
from unittest.mock import AsyncMock, MagicMock

import pytest


# ---------------------------------------------------------------------------
# P4-1  Structural — each provider delegates to _load_commit_walk
# ---------------------------------------------------------------------------

def test_p4_1_coupling_provider_delegates_to_load_commit_walk() -> None:
    """CouplingProvider.compute must call _load_commit_walk; no inline walk_dag."""
    from musehub.services import musehub_intel_providers as mod

    src = inspect.getsource(mod.CouplingProvider.compute)
    assert "_load_commit_walk" in src, (
        "CouplingProvider.compute must delegate to _load_commit_walk."
    )
    assert "walk_dag" not in src, (
        "CouplingProvider.compute still has an inline walk_dag call."
    )


def test_p4_1_entangle_provider_delegates_to_load_commit_walk() -> None:
    """EntangleProvider.compute must call _load_commit_walk; no inline walk_dag."""
    from musehub.services import musehub_intel_providers as mod

    src = inspect.getsource(mod.EntangleProvider.compute)
    assert "_load_commit_walk" in src, (
        "EntangleProvider.compute must delegate to _load_commit_walk."
    )
    assert "walk_dag" not in src, (
        "EntangleProvider.compute still has an inline walk_dag call."
    )


def test_p4_1_velocity_provider_delegates_to_load_commit_walk() -> None:
    """VelocityProvider.compute must call _load_commit_walk; no inline walk_dag."""
    from musehub.services import musehub_intel_providers as mod

    src = inspect.getsource(mod.VelocityProvider.compute)
    assert "_load_commit_walk" in src, (
        "VelocityProvider.compute must delegate to _load_commit_walk."
    )
    assert "walk_dag" not in src, (
        "VelocityProvider.compute still has an inline walk_dag call."
    )


# ---------------------------------------------------------------------------
# Helpers for behavioural tests
# ---------------------------------------------------------------------------

def _row(commit_id: str, parent_ids: list[str]) -> None:
    return SimpleNamespace(commit_id=commit_id, parent_ids=parent_ids)


def _make_session(rows: list[SimpleNamespace]) -> MagicMock:
    """Fake session whose execute() returns an iterable of row SimpleNamespaces."""
    session = MagicMock()
    session.execute = AsyncMock(return_value=rows)
    return session


# ---------------------------------------------------------------------------
# P4-2  Behavioural — correct BFS order for a 4-commit diamond
# ---------------------------------------------------------------------------

@pytest.mark.asyncio
async def test_p4_2_load_commit_walk_bfs_order() -> None:
    """_load_commit_walk returns commits in BFS order for a diamond graph.

    Diamond:  A → B, A → C;  B → D;  C → D.
    BFS from A: [A, B, C, D] (level-by-level).
    """
    from musehub.services.musehub_intel_providers import _load_commit_walk

    rows = [
        _row("A", ["B", "C"]),
        _row("B", ["D"]),
        _row("C", ["D"]),
        _row("D", []),
    ]
    session = _make_session(rows)

    result = await _load_commit_walk(session, "repo1", "A", max_walk=100)

    assert result == ["A", "B", "C", "D"], (
        f"Expected BFS order [A, B, C, D], got {result}"
    )


# ---------------------------------------------------------------------------
# P4-3  Behavioural — max_walk cap
# ---------------------------------------------------------------------------

@pytest.mark.asyncio
async def test_p4_3_load_commit_walk_max_walk_cap() -> None:
    """_load_commit_walk stops after max_walk commits have been collected.

    Linear chain: A→B→C→D→E.  max_walk=3 → [A, B, C].
    """
    from musehub.services.musehub_intel_providers import _load_commit_walk

    rows = [
        _row("A", ["B"]),
        _row("B", ["C"]),
        _row("C", ["D"]),
        _row("D", ["E"]),
        _row("E", []),
    ]
    session = _make_session(rows)

    result = await _load_commit_walk(session, "repo1", "A", max_walk=3)

    assert len(result) == 3, f"Expected exactly 3 commits, got {len(result)}"
    assert result == ["A", "B", "C"], f"Expected [A, B, C], got {result}"