from decimal import Decimal

import pytest

from voice_transcriptor.services.chunking import (
    calculate_chunk_boundaries,
    source_timestamp,
    total_chunk_duration,
)


@pytest.mark.parametrize(
    ("total", "chunk", "overlap", "expected"),
    [
        ("600", "900", "15", [("0", "600")]),
        ("900", "900", "15", [("0", "900")]),
        ("1800", "900", "15", [("0", "900"), ("885", "1785"), ("1770", "1800")]),
        ("901.25", "900", "15", [("0", "900"), ("885", "901.25")]),
        ("1800", "900", "0", [("0", "900"), ("900", "1800")]),
    ],
)
def test_chunk_boundaries_keep_context_and_exact_final_end(
    total: str, chunk: str, overlap: str, expected: list[tuple[str, str]]
) -> None:
    boundaries = calculate_chunk_boundaries(total, chunk, overlap)
    assert [(str(item.start_seconds), str(item.end_seconds)) for item in boundaries] == expected


def test_overlap_is_included_in_total_generated_audio_duration() -> None:
    boundaries = calculate_chunk_boundaries("1800", "900", "15")
    assert total_chunk_duration(boundaries) == Decimal("1830")


def test_local_timestamp_maps_to_exact_source_offset() -> None:
    boundary = calculate_chunk_boundaries("1800", "900", "15")[1]
    assert source_timestamp(boundary, "12.5") == Decimal("897.5")


def test_many_hour_recording_ends_exactly_at_source_duration() -> None:
    boundaries = calculate_chunk_boundaries("28800.125", "900", "15")
    assert boundaries[-1].end_seconds == Decimal("28800.125")


@pytest.mark.parametrize(
    ("total", "chunk", "overlap"),
    [("0", "900", "15"), ("10", "0", "0"), ("10", "10", "10"), ("10", "10", "-1")],
)
def test_invalid_chunk_configuration_is_rejected(total: str, chunk: str, overlap: str) -> None:
    with pytest.raises(ValueError):
        calculate_chunk_boundaries(total, chunk, overlap)