"""L0: db/introspect against a known schema (testcontainers).
Verifies the ported introspection returns the right tables, columns, types, comments,
FKs, and indexes from a real Postgres catalog.
"""
import pytest

from tht.db.introspect import IntrospectionError, introspect

pytestmark = [pytest.mark.l0]


def test_introspect_returns_known_tables(admin_engine):
    schema = introspect(admin_engine, "testdb", "dw")
    assert set(schema.tables.keys()) == {"dim_pazienti", "dim_periodi", "fct_ricoveri"}
    assert schema.db_schema == "dw"


def test_introspect_columns_types_and_comments(admin_engine):
    schema = introspect(admin_engine, "testdb", "dw")
    pazienti = schema.tables["dim_pazienti"]
    assert set(pazienti.columns.keys()) == {"id_paziente", "nome", "citta"}
    assert pazienti.columns["id_paziente"].pk is True
    assert pazienti.columns["id_paziente"].nullable is False
    assert "bigint" in pazienti.columns["id_paziente"].type.lower()
    assert pazienti.comment == "Anagrafica pazienti"
    assert pazienti.columns["citta"].comment == "Comune di residenza"


def test_introspect_enum_detected(admin_engine):
    schema = introspect(admin_engine, "testdb", "dw")
    tipo_col = schema.tables["fct_ricoveri"].columns["tipo"]
    assert tipo_col.is_enum is True


def test_introspect_foreign_keys(admin_engine):
    schema = introspect(admin_engine, "testdb", "dw")
    ricoveri = schema.tables["fct_ricoveri"]
    fk_tables = {fk.ref_table for fk in ricoveri.foreign_keys}
    assert "dim_pazienti" in fk_tables
    assert "dim_periodi" in fk_tables
    # the composite FK to dim_periodi (anno, mese)
    periodi_fk = [fk for fk in ricoveri.foreign_keys if fk.ref_table == "dim_periodi"]
    assert periodi_fk
    assert set(periodi_fk[0].columns) == {"anno", "mese"}


def test_introspect_indexes(admin_engine):
    schema = introspect(admin_engine, "testdb", "dw")
    # composite PK on dim_periodi (anno, mese)
    periodi = schema.tables["dim_periodi"]
    pk_indexes = [i for i in periodi.indexes if i.primary]
    assert pk_indexes, "dim_periodi should have a primary index"
    assert set(pk_indexes[0].columns) == {"anno", "mese"}


def test_introspect_nonexistent_schema_raises(admin_engine):
    with pytest.raises(IntrospectionError):
        introspect(admin_engine, "testdb", "nonexistent_schema")