import pytest
from rdkit import Chem

from macro_lactone_toolkit import (
    AmbiguousMacrolactoneError,
    MacroLactoneAnalyzer,
    MacrolactoneDetectionError,
    MacrolactoneFragmenter,
)

from .helpers import build_ambiguous_smiles, build_macrolactone


@pytest.mark.parametrize("ring_size", [12, 14, 16, 20])
def test_analyzer_detects_supported_ring_sizes(ring_size: int):
    built = build_macrolactone(ring_size)
    analyzer = MacroLactoneAnalyzer()

    assert analyzer.get_valid_ring_sizes(built.smiles) == [ring_size]


def test_analyzer_rejects_non_lactone_macrocycle():
    analyzer = MacroLactoneAnalyzer()

    assert analyzer.get_valid_ring_sizes("C1CCCCCCCCCCC1") == []


def test_fragmenter_auto_numbers_ring_with_expected_positions():
    built = build_macrolactone(16, {5: "methyl"})
    result = MacrolactoneFragmenter().number_molecule(built.mol)

    assert result.ring_size == 16
    assert result.position_to_atom == built.position_to_atom
    assert set(result.position_to_atom) == set(range(1, 17))
    assert result.atom_to_position == {
        atom_idx: position for position, atom_idx in built.position_to_atom.items()
    }

    carbonyl_atom = built.mol.GetAtomWithIdx(result.position_to_atom[1])
    assert carbonyl_atom.GetSymbol() == "C"
    assert any(
        bond.GetBondType() == Chem.BondType.DOUBLE and bond.GetOtherAtom(carbonyl_atom).GetSymbol() == "O"
        for bond in carbonyl_atom.GetBonds()
    )

    ester_oxygen = built.mol.GetAtomWithIdx(result.position_to_atom[2])
    assert ester_oxygen.GetSymbol() == "O"


def test_fragmenter_requires_explicit_ring_size_for_ambiguous_molecule():
    ambiguous_smiles = build_ambiguous_smiles()

    with pytest.raises(AmbiguousMacrolactoneError):
        MacrolactoneFragmenter().number_molecule(ambiguous_smiles)


def test_fragmenter_raises_for_missing_macrolactone():
    with pytest.raises(MacrolactoneDetectionError):
        MacrolactoneFragmenter().number_molecule("CCO")


def test_explicit_ring_size_selects_requested_ring():
    built = build_macrolactone(14)
    result = MacrolactoneFragmenter(ring_size=14).number_molecule(built.smiles)

    assert result.ring_size == 14


def test_explicit_ring_size_rejects_wrong_ring():
    built = build_macrolactone(12)

    with pytest.raises(MacrolactoneDetectionError):
        MacrolactoneFragmenter(ring_size=16).number_molecule(built.smiles)