"""Tests for chord_file_to_midi() in src/midi_export.py.

Fixture: tests/fixtures/midi_export_test.chord
  4 bars, 4/4 sub=4, C major, no function tag.
  Chords: C Am7 F G7 (each held 4 positions = one whole bar).

Expected MIDI structure:
  instruments[0] "Chords": 3+4+3+4 = 14 notes, pitches in octave 4–5 [60, 83]
  instruments[1] "Bass":   4 notes (one per chord event), pitches in octave 2 [36, 47]
"""

from pathlib import Path

import pretty_midi
import pytest

from src.midi_export import chord_file_to_midi

FIXTURES = Path(__file__).parent / "fixtures"
TEST_CHORD = FIXTURES / "midi_export_test.chord"


# ---------------------------------------------------------------------------
# Shared fixture — export once, parse back, share across test methods
# ---------------------------------------------------------------------------


@pytest.fixture(scope="module")
def exported(tmp_path_factory: pytest.TempPathFactory) -> pretty_midi.PrettyMIDI:
    out = tmp_path_factory.mktemp("midi") / "out.mid"
    chord_file_to_midi(TEST_CHORD, out)
    return pretty_midi.PrettyMIDI(str(out))


# ---------------------------------------------------------------------------
# Basic output
# ---------------------------------------------------------------------------


class TestOutputFile:
    def test_file_is_created(self, tmp_path):
        out = tmp_path / "out.mid"
        chord_file_to_midi(TEST_CHORD, out)
        assert out.exists() and out.stat().st_size > 0

    def test_midi_is_parseable(self, tmp_path):
        out = tmp_path / "out.mid"
        chord_file_to_midi(TEST_CHORD, out)
        pm = pretty_midi.PrettyMIDI(str(out))
        assert pm is not None


# ---------------------------------------------------------------------------
# Instrument structure
# ---------------------------------------------------------------------------


class TestInstruments:
    def test_two_instruments(self, exported):
        assert len(exported.instruments) == 2

    def test_first_instrument_is_chords(self, exported):
        assert exported.instruments[0].name == "Chords"

    def test_second_instrument_is_bass(self, exported):
        assert exported.instruments[1].name == "Bass"


# ---------------------------------------------------------------------------
# Note counts
# ---------------------------------------------------------------------------


class TestNoteCounts:
    def test_chord_track_note_count(self, exported):
        # C(3) + Am7(4) + F(3) + G7(4) = 14
        assert len(exported.instruments[0].notes) == 14

    def test_bass_track_note_count(self, exported):
        # one bass note per chord event = 4
        assert len(exported.instruments[1].notes) == 4


# ---------------------------------------------------------------------------
# Octave placement
# ---------------------------------------------------------------------------


class TestOctaves:
    def test_chord_notes_in_middle_octave(self, exported):
        # Root anchored at C4=60; triads/7ths add at most 11 st → max B5=83.
        for note in exported.instruments[0].notes:
            assert 60 <= note.pitch <= 83, f"chord pitch {note.pitch} outside [60, 83]"

    def test_bass_notes_in_low_octave(self, exported):
        # Bass anchored at C2=36; highest pitch class B2=47.
        for note in exported.instruments[1].notes:
            assert 36 <= note.pitch <= 47, f"bass pitch {note.pitch} outside [36, 47]"


# ---------------------------------------------------------------------------
# Tempo
# ---------------------------------------------------------------------------


class TestTempo:
    def test_higher_tempo_shortens_duration(self, tmp_path):
        slow = tmp_path / "slow.mid"
        fast = tmp_path / "fast.mid"
        chord_file_to_midi(TEST_CHORD, slow, tempo=90)
        chord_file_to_midi(TEST_CHORD, fast, tempo=180)
        assert (
            pretty_midi.PrettyMIDI(str(slow)).get_end_time()
            > pretty_midi.PrettyMIDI(str(fast)).get_end_time()
        )