"""Tests for the CJK-aware composer cursor offset."""

import pytest
from textual.app import App, ComposeResult

from deerflow.tui.widgets.composer import ComposerInput


class _Harness(App):
    def compose(self) -> ComposeResult:
        yield ComposerInput(id="c")


@pytest.mark.asyncio
async def test_cursor_offset_after_cjk_has_no_off_by_one():
    app = _Harness()
    async with app.run_test() as pilot:
        await pilot.pause()
        comp = app.query_one("#c", ComposerInput)
        comp.value = "总结一下"  # 4 wide chars = 8 cells
        comp.cursor_position = len(comp.value)
        # Stock Input would report 9 here (unconditional +1); the fix reports 8,
        # so the hardware/IME cursor sits exactly after the last character.
        assert comp._cursor_offset == 8


@pytest.mark.asyncio
async def test_cursor_offset_mid_text_is_unchanged():
    app = _Harness()
    async with app.run_test() as pilot:
        await pilot.pause()
        comp = app.query_one("#c", ComposerInput)
        comp.value = "总结一下"
        comp.cursor_position = 3  # not at end -> 3 wide chars = 6 cells
        assert comp._cursor_offset == 6


@pytest.mark.asyncio
async def test_cursor_offset_ascii_end_is_exact():
    app = _Harness()
    async with app.run_test() as pilot:
        await pilot.pause()
        comp = app.query_one("#c", ComposerInput)
        comp.value = "abcd"
        comp.cursor_position = 4
        assert comp._cursor_offset == 4