from fractions import Fraction
from itertools import chain

import pytest

from textual._resolve import resolve, resolve_fraction_unit
from textual.css.scalar import Scalar
from textual.geometry import Size
from textual.widget import Widget


def test_resolve_empty():
    assert resolve([], 10, 1, Size(20, 10), Size(80, 24)) == []


@pytest.mark.parametrize(
    "scalars,total,gutter,result",
    [
        (["10"], 100, 0, [(0, 10)]),
        (
            ["10", "20"],
            100,
            0,
            [(0, 10), (10, 20)],
        ),
        (
            ["10", "20"],
            100,
            1,
            [(0, 10), (11, 20)],
        ),
        (
            ["10", "1fr"],
            100,
            1,
            [(0, 10), (11, 89)],
        ),
        (
            ["1fr", "1fr"],
            100,
            0,
            [(0, 50), (50, 50)],
        ),
        (
            ["3", "1fr", "1fr", "1"],
            100,
            1,
            [(0, 3), (4, 46), (51, 47), (99, 1)],
        ),
    ],
)
def test_resolve(scalars, total, gutter, result):
    assert (
        resolve(
            [Scalar.parse(scalar) for scalar in scalars],
            total,
            gutter,
            Size(40, 20),
            Size(80, 24),
        )
        == result
    )


def test_resolve_fraction_unit():
    """Test resolving fraction units in combination with minimum widths."""
    widget1 = Widget()
    widget2 = Widget()
    widget3 = Widget()

    widget1.styles.width = "1fr"
    widget1.styles.min_width = 20

    widget2.styles.width = "2fr"
    widget2.styles.min_width = 10

    widget3.styles.width = "1fr"

    styles = (widget1.styles, widget2.styles, widget3.styles)

    # Try with width 80.
    # Fraction unit should one fourth of width
    assert resolve_fraction_unit(
        styles,
        Size(80, 24),
        Size(80, 24),
        Fraction(80),
        resolve_dimension="width",
    ) == Fraction(20)

    # Try with width 50
    # First widget is fixed at 20
    # Remaining three widgets have 30 to play with
    # Fraction is 10
    assert resolve_fraction_unit(
        styles,
        Size(80, 24),
        Size(80, 24),
        Fraction(50),
        resolve_dimension="width",
    ) == Fraction(10)

    # Try with width 35
    # First widget fixed at 20
    # Fraction is 5
    assert resolve_fraction_unit(
        styles,
        Size(80, 24),
        Size(80, 24),
        Fraction(35),
        resolve_dimension="width",
    ) == Fraction(5)

    # Try with width 32
    # First widget fixed at 20
    # Second widget is fixed at 10
    # Remaining widget has all the space
    # Fraction is 2
    assert resolve_fraction_unit(
        styles,
        Size(80, 24),
        Size(80, 24),
        Fraction(32),
        resolve_dimension="width",
    ) == Fraction(2)


@pytest.mark.xfail(reason="https://github.com/Textualize/textual/issues/2502")
def test_resolve_issue_2502():
    """Test https://github.com/Textualize/textual/issues/2502"""

    widgets_fr = [Widget() for _ in range(50)]
    widgets_min_width = [Widget() for _ in range(50)]

    for widget in widgets_fr:
        widget.styles.width = "1fr"
        widget.styles.min_width = 3

    for widget in widgets_min_width:
        widget.styles.width = 0

    styles = (
        widget.styles
        for widget in chain.from_iterable(zip(widgets_fr, widgets_min_width))
    )

    assert isinstance(
        resolve_fraction_unit(
            styles, Size(80, 24), Size(80, 24), Fraction(10), resolve_dimension="width"
        ),
        Fraction,
    )