"""Tests para build_column_dictionary.

Verifica el aplanado de un DatabaseProfile del grupo eda a un diccionario de
columnas buscable: entradas por columna, marca de PII desde el semantic_type,
deteccion de columnas compartidas por nombre (join keys), lectura defensiva y
que la funcion es pura (no muta el input).
"""

import copy
import os
import sys

sys.path.insert(0, os.path.dirname(__file__))

from build_column_dictionary import build_column_dictionary


def _col(name, inferred_type="categorical", semantic_type="", null_pct=0.0,
         distinct_count=10, categorical=None) -> dict:
    """ColumnProfile minimo con las claves del contrato eda usadas por la funcion."""
    return {
        "name": name,
        "physical_type": "VARCHAR",
        "inferred_type": inferred_type,
        "semantic_type": semantic_type,
        "null_pct": null_pct,
        "distinct_count": distinct_count,
        "flags": [],
        "numeric": None,
        "categorical": categorical,
        "datetime": None,
    }


def _db_profile() -> dict:
    """DatabaseProfile de juguete con dos tablas y una columna de join comun."""
    return {
        "db_path": "toy.duckdb",
        "n_tables": 2,
        "table_profiles": [
            {
                "table": "clientes",
                "columns": [
                    _col("customer_id", "numeric", "", 0.0, 1000),
                    _col("email", "text", "email", 0.05, 990),
                    _col(
                        "ciudad",
                        "categorical",
                        "",
                        0.0,
                        3,
                        categorical={
                            "top": [
                                {"value": "Madrid", "count": 5, "pct": 0.5},
                                {"value": "Bilbao", "count": 3, "pct": 0.3},
                            ]
                        },
                    ),
                ],
            },
            {
                "table": "pedidos",
                "columns": [
                    _col("customer_id", "numeric", "", 0.0, 800),
                    _col("iban", "text", "iban", 0.1, 795),
                ],
            },
        ],
    }


# --------------------------------------------------------------------------- #
# Golden
# --------------------------------------------------------------------------- #
def test_golden_flattens_two_tables():
    res = build_column_dictionary(_db_profile())
    assert res["status"] == "ok"
    assert res["n_tables"] == 2
    assert res["n_columns"] == 5
    # Una entrada por columna, con las claves del contrato.
    keys = {
        "table", "column", "inferred_type", "semantic_type",
        "is_pii", "null_pct", "n_distinct", "top_values",
    }
    for e in res["entries"]:
        assert keys.issubset(e.keys())
    # El markdown tiene la tabla y la seccion de join keys.
    assert "## Columnas" in res["markdown"]
    assert "candidatas a join key" in res["markdown"]


# --------------------------------------------------------------------------- #
# PII desde el semantic_type real del grupo
# --------------------------------------------------------------------------- #
def test_pii_flagged_from_semantic_type():
    res = build_column_dictionary(_db_profile())
    pii_cols = {(e["table"], e["column"]) for e in res["pii_columns"]}
    assert ("clientes", "email") in pii_cols
    assert ("pedidos", "iban") in pii_cols
    # customer_id / ciudad NO son PII.
    assert ("clientes", "customer_id") not in pii_cols
    assert ("clientes", "ciudad") not in pii_cols
    # Coherencia entre is_pii en entries y la lista pii_columns.
    assert res["pii_columns"] == [e for e in res["entries"] if e["is_pii"]]


def test_empty_semantic_type_maps_to_none_and_not_pii():
    res = build_column_dictionary(_db_profile())
    ciudad = next(
        e for e in res["entries"]
        if e["table"] == "clientes" and e["column"] == "ciudad"
    )
    assert ciudad["semantic_type"] is None
    assert ciudad["is_pii"] is False


# --------------------------------------------------------------------------- #
# Columnas compartidas por nombre = candidatas a join key
# --------------------------------------------------------------------------- #
def test_shared_column_names_detected_as_join_keys():
    res = build_column_dictionary(_db_profile())
    md = res["markdown"]
    # customer_id aparece en las dos tablas -> listada en la seccion de join keys.
    join_section = md.split("## Columnas\n")[0]
    assert "customer_id" in join_section
    assert "clientes" in join_section and "pedidos" in join_section
    # email solo esta en una tabla -> no aparece en la seccion de join keys.
    assert "email" not in join_section


# --------------------------------------------------------------------------- #
# top_values desde el bloque categorical
# --------------------------------------------------------------------------- #
def test_top_values_from_categorical_block():
    res = build_column_dictionary(_db_profile())
    ciudad = next(e for e in res["entries"] if e["column"] == "ciudad")
    assert ciudad["top_values"] == ["Madrid", "Bilbao"]
    # Columnas sin bloque categorical -> None.
    email = next(e for e in res["entries"] if e["column"] == "email")
    assert email["top_values"] is None


# --------------------------------------------------------------------------- #
# Entrada vacia / malformada -> resultado vacio en ok
# --------------------------------------------------------------------------- #
def test_empty_profile_returns_empty_ok():
    empty = build_column_dictionary({})
    assert empty == {
        "status": "ok", "n_tables": 0, "n_columns": 0,
        "entries": [], "pii_columns": [], "markdown": "",
    }


def test_malformed_input_returns_empty_ok():
    for bad in (None, [], "nope", 42, {"table_profiles": "x"}):
        res = build_column_dictionary(bad)
        assert res["status"] == "ok"
        assert res["n_columns"] == 0
        assert res["entries"] == []
        assert res["markdown"] == ""


def test_missing_keys_read_defensively():
    # TableProfiles y columnas con claves ausentes / basura no rompen.
    profile = {
        "table_profiles": [
            {"table": "t1", "columns": [{"name": "a"}, "no-dict", None]},
            "no-dict",
            {"table": "t2"},  # sin columns
            {"columns": [{}]},  # sin table, columna vacia
        ]
    }
    res = build_column_dictionary(profile)
    assert res["status"] == "ok"
    # t1 (1 col dict valida; "no-dict" y None se saltan) + tabla sin table
    # (1 col {}). t2 no tiene columns -> no cuenta como tabla.
    assert res["n_tables"] == 2
    assert res["n_columns"] == 2
    a = next(e for e in res["entries"] if e["column"] == "a")
    assert a["semantic_type"] is None
    assert a["null_pct"] is None
    assert a["n_distinct"] is None
    assert a["top_values"] is None


# --------------------------------------------------------------------------- #
# Pureza
# --------------------------------------------------------------------------- #
def test_does_not_mutate_input():
    profile = _db_profile()
    snapshot = copy.deepcopy(profile)
    build_column_dictionary(profile)
    assert profile == snapshot