"""TaskGraph（黑板/工作记忆）单元测试——拓扑排序契约。

契约（与 2026-09 优化前行为一致，复杂度 O(V²logV) -> O(V+E)）：
- 依赖在前；初始就绪层按插入序稳定输出
- 未知依赖 id 忽略；重复依赖不重复产出
- 循环依赖：剩余节点按插入序兜底追加（不崩溃）
"""
from router_system.memory import TaskGraph, TaskNode


def _node(nid: str, deps=()) -> TaskNode:
    return TaskNode(id=nid, kind="solve", domain="general", query="q", deps=list(deps))


def test_topo_chain_order():
    g = TaskGraph()
    g.add_node(_node("a"))
    g.add_node(_node("b", ["a"]))
    g.add_node(_node("c", ["b"]))
    assert [n.id for n in g.topo_order()] == ["a", "b", "c"]


def test_topo_diamond_initial_ready_by_insertion():
    """菱形依赖：初始就绪层按插入序。"""
    g = TaskGraph()
    g.add_node(_node("s"))
    g.add_node(_node("y", ["s"]))   # 先插入 y
    g.add_node(_node("x", ["s"]))
    g.add_node(_node("t", ["x", "y"]))
    order = [n.id for n in g.topo_order()]
    assert order == ["s", "y", "x", "t"]


def test_topo_independent_nodes_keep_insertion_order():
    g = TaskGraph()
    g.add_node(_node("n3"))
    g.add_node(_node("n1"))
    g.add_node(_node("n2"))
    assert [n.id for n in g.topo_order()] == ["n3", "n1", "n2"]


def test_topo_unknown_dep_ignored():
    g = TaskGraph()
    g.add_node(_node("a", ["不存在的依赖"]))
    assert [n.id for n in g.topo_order()] == ["a"]


def test_topo_cycle_fallback_by_insertion():
    g = TaskGraph()
    g.add_node(_node("p", ["q"]))
    g.add_node(_node("q", ["p"]))
    g.add_node(_node("r"))
    order = [n.id for n in g.topo_order()]
    # r 无依赖先行；p/q 成环按插入序兜底
    assert order == ["r", "p", "q"]


def test_topo_duplicate_deps_counted_once_in_output():
    """重复依赖边不产生重复输出节点。"""
    g = TaskGraph()
    g.add_node(_node("a"))
    g.add_node(_node("b", ["a", "a"]))
    assert [n.id for n in g.topo_order()] == ["a", "b"]