"""Tests for the textutil module."""

from __future__ import annotations

import pytest

from vibe_bot.textutil import split_message


def test_split_message_empty() -> None:
    assert split_message("") == []


def test_split_message_short_text_single_chunk() -> None:
    assert split_message("hello") == ["hello"]


def test_split_message_exact_limit() -> None:
    text = "a" * 1900
    chunks = split_message(text)
    assert chunks == [text]
    assert len(chunks) == 1


def test_split_message_just_over_limit_no_newline() -> None:
    text = "a" * 1901
    chunks = split_message(text)
    assert "".join(chunks) == text
    assert all(len(c) <= 1900 for c in chunks)
    assert chunks == ["a" * 1900, "a"]


def test_split_message_no_newlines_long() -> None:
    text = "x" * 5000
    chunks = split_message(text)
    assert "".join(chunks) == text
    assert all(len(c) <= 1900 for c in chunks)


def test_split_message_respects_newlines() -> None:
    # Many short lines spanning several chunks: boundaries fall on newlines.
    text = "\n".join(f"line {i}" for i in range(1, 501))
    chunks = split_message(text)
    assert "".join(chunks) == text
    assert all(len(c) <= 1900 for c in chunks)
    assert len(chunks) > 1
    # Every chunk except the last ends on a newline (split at a line boundary).
    for chunk in chunks[:-1]:
        assert chunk.endswith("\n")


def test_split_message_long_line_hard_split() -> None:
    # A single line longer than the limit must be hard-split.
    text = "a" * 5000 + "\n" + "short"
    chunks = split_message(text)
    assert "".join(chunks) == text
    assert all(len(c) <= 1900 for c in chunks)


def test_split_message_emoji_round_trip() -> None:
    # Multi-codepoint emoji at split boundaries must not corrupt on join.
    text = "hello 🌍 world 👨‍👩‍👧‍👦 end " * 500
    for limit in (1, 10, 100, 1900):
        chunks = split_message(text, limit)
        assert "".join(chunks) == text
        assert all(len(c) <= limit for c in chunks)


def test_split_message_property_round_trip_corpus() -> None:
    corpus = [
        "",
        "a",
        "a" * 1900,
        "a" * 1901,
        "line1\nline2\nline3",
        "para one\n\npara two\n\npara three",
        "no newline " * 1000,
        "emoji 🎉 " * 1000,
        "👨‍👩‍👧‍👦" * 2000,
        "mixed 🌍 text and 日本語 and emoji 🎊 here",
        # NFD combining marks (e + U+0301, a + U+0308) straddle split points.
        "cafe\u0301 " * 1000,
        "a\u0308\u0301 b\u0327\u0301 c\u0308 " * 1000,
        # Code spans with backticks and spaces.
        "`inline code` and `x = 1` spans " * 500,
        "``double backtick`` `single` " * 500,
    ]
    for text in corpus:
        for limit in (1, 5, 100, 1900):
            chunks = split_message(text, limit)
            assert "".join(chunks) == text, f"round-trip failed for limit={limit}"
            assert all(len(c) <= limit for c in chunks)


def test_split_message_exact_multiple_of_limit() -> None:
    """Input that is an exact multiple of the limit splits into full chunks."""
    for limit in (1, 5, 100, 1900):
        text = "z" * (limit * 4)
        chunks = split_message(text, limit)
        assert "".join(chunks) == text
        assert len(chunks) == 4
        assert all(len(c) == limit for c in chunks)


def test_split_message_limit_must_be_positive() -> None:
    with pytest.raises(ValueError):
        split_message("hello", 0)
    with pytest.raises(ValueError):
        split_message("hello", -5)