"""L1: SQL formula evidence -- concept->formula units (spec D14b).

A concept (e.g. 'fascia pediatrica') maps to a SQL formula (CASE WHEN ...) that
derives it from physical columns. These are reusable, reviewable units: the gate
surfaces a candidate formula, the reviewer approves or rejects it (recorded via
concept_formula_approved / concept_formula_rejected), and approved formulas are
part of the schema-linking artifact. The store is frontmatter-YAML + SQL body.
"""
from pathlib import Path

import pytest

from tht.evidence.formula_store import ConceptFormula, retrieve_formula, save_formula


def test_formula_retrieval_by_concept(tmp_path):
    f = ConceptFormula(
        concept="fascia pediatrica",
        columns=["data_nascita"],
        sql="CASE WHEN age < 18 THEN 'pediatrica' ELSE 'adulto' END",
        status="reviewed",
        sources=["src1"],
    )
    save_formula(tmp_path, f)
    results = retrieve_formula(tmp_path, "fascia pediatrica")
    assert len(results) == 1
    assert results[0].sql.startswith("CASE WHEN")
    assert results[0].concept == "fascia pediatrica"
    assert results[0].status == "reviewed"
    assert "data_nascita" in results[0].columns


def test_save_and_reload_roundtrip_preserves_sql_body(tmp_path):
    f = ConceptFormula(
        concept="fascia pediatrica",
        columns=["data_nascita"],
        sql="CASE\n  WHEN x THEN 1\nEND",
        status="draft",
        sources=[],
    )
    path = save_formula(tmp_path, f)
    assert path.exists()
    # the file is frontmatter YAML + SQL body
    text = path.read_text()
    assert text.startswith("---")
    assert "concept: fascia pediatrica" in text
    assert "CASE" in text  # SQL body preserved


def test_retrieve_multiple_formulas_for_concept(tmp_path):
    # two competing formulas for the same concept (different sources/status)
    save_formula(tmp_path, ConceptFormula(concept="ablazione", columns=["flag"],
                                          sql="SELECT 1", status="draft", sources=["a"]))
    save_formula(tmp_path, ConceptFormula(concept="ablazione", columns=["testo"],
                                          sql="SELECT 2", status="reviewed", sources=["b"]))
    results = retrieve_formula(tmp_path, "ablazione")
    assert len(results) == 2
    statuses = {r.status for r in results}
    assert statuses == {"draft", "reviewed"}


def test_retrieve_empty_when_no_match(tmp_path):
    save_formula(tmp_path, ConceptFormula(concept="altro", columns=["c"],
                                          sql="SELECT 1", status="reviewed", sources=[]))
    assert retrieve_formula(tmp_path, "inesistente") == []


def test_retrieve_empty_on_missing_dir(tmp_path):
    # no formulas dir at all -> empty list, not error
    assert retrieve_formula(tmp_path / "nope", "anything") == []


def test_concept_formula_decision_types_exist():
    import typing
    from tht.decisions import DecisionType
    args = typing.get_args(DecisionType)
    assert "concept_formula_approved" in args
    assert "concept_formula_rejected" in args


def test_concept_formula_default_status(tmp_path):
    # status has a sensible default so an author can write a draft quickly
    f = ConceptFormula(concept="x", columns=["c"], sql="SELECT 1")
    assert f.status == "draft"  # not yet reviewed
    assert f.sources == []