"""Tests para build_join_graph."""

from build_join_graph import build_join_graph


def _star_fks():
    """Esquema en estrella: orders apunta a customers y a products."""
    return [
        {
            "from_table": "orders",
            "from_col": "customer_id",
            "to_table": "customers",
            "to_col": "id",
            "inclusion": 1.0,
            "cardinality": "many-to-one",
        },
        {
            "from_table": "orders",
            "from_col": "product_id",
            "to_table": "products",
            "to_col": "id",
            "inclusion": 0.98,
            "cardinality": "many-to-one",
        },
    ]


def test_star_schema_roles_and_hub():
    g = build_join_graph(_star_fks())
    nodes = {n["table"]: n for n in g["nodes"]}

    assert nodes["orders"]["role"] == "fact"
    assert nodes["orders"]["out_degree"] == 2
    assert nodes["orders"]["in_degree"] == 0

    assert nodes["customers"]["role"] == "dimension"
    assert nodes["customers"]["in_degree"] == 1
    assert nodes["customers"]["out_degree"] == 0

    assert nodes["products"]["role"] == "dimension"

    # orders es el hub (mayor out_degree).
    assert g["hubs"][0] == "orders"


def test_two_edges_built():
    g = build_join_graph(_star_fks())
    assert len(g["edges"]) == 2
    pairs = {(e["from_table"], e["to_table"]) for e in g["edges"]}
    assert pairs == {("orders", "customers"), ("orders", "products")}


def test_mermaid_contains_tables_and_arrows():
    g = build_join_graph(_star_fks())
    m = g["mermaid"]
    assert "orders" in m
    assert "customers" in m
    assert "products" in m
    assert "-->" in m
    # Etiqueta de columnas en la arista.
    assert "customer_id->id" in m


def test_bridge_role():
    # order_items apunta a orders y products, y nadie le apunta -> fact en este
    # subgrafo. Para forzar bridge, hacemos que reciba tambien una FK.
    fks = [
        {"from_table": "shipments", "from_col": "order_item_id",
         "to_table": "order_items", "to_col": "id",
         "inclusion": 1.0, "cardinality": "many-to-one"},
        {"from_table": "order_items", "from_col": "product_id",
         "to_table": "products", "to_col": "id",
         "inclusion": 1.0, "cardinality": "many-to-one"},
    ]
    g = build_join_graph(fks)
    nodes = {n["table"]: n for n in g["nodes"]}
    assert nodes["order_items"]["role"] == "bridge"
    assert nodes["order_items"]["in_degree"] == 1
    assert nodes["order_items"]["out_degree"] == 1


def test_standalone_node_from_tables_list():
    g = build_join_graph(_star_fks(), tables=["orders", "customers", "products", "audit_log"])
    nodes = {n["table"]: n for n in g["nodes"]}
    assert "audit_log" in nodes
    assert nodes["audit_log"]["role"] == "standalone"
    assert nodes["audit_log"]["out_degree"] == 0
    assert nodes["audit_log"]["in_degree"] == 0
    # El nodo aislado aparece declarado en el mermaid.
    assert "audit_log" in g["mermaid"]


def test_empty_list_does_not_crash():
    g = build_join_graph([])
    assert g["nodes"] == []
    assert g["edges"] == []
    assert g["hubs"] == []
    assert g["mermaid"].startswith("graph LR")


def test_none_input_does_not_crash():
    g = build_join_graph(None)
    assert g["edges"] == []
    assert "graph LR" in g["mermaid"]


def test_malformed_entries_skipped():
    fks = [
        {"from_table": "a", "from_col": "x", "to_table": "b", "to_col": "y"},
        {"from_table": "a"},          # falta to_table -> se ignora
        "not a dict",                  # no es dict -> se ignora
        {"to_table": "b"},             # falta from_table -> se ignora
    ]
    g = build_join_graph(fks)
    assert len(g["edges"]) == 1
    assert g["edges"][0]["from_table"] == "a"


def test_does_not_mutate_input():
    fks = _star_fks()
    snapshot = [dict(fk) for fk in fks]
    build_join_graph(fks)
    assert fks == snapshot