use cosmic_text::{Attrs, Buffer, FontSystem, Metrics, Shaping};

// Test for https://github.com/pop-os/cosmic-text/issues/364
//
// Empty lines at the start/end of a span should use that span's line height,
// not the buffer's default line height.
#[test]
fn empty_lines_use_span_metrics() {
    let mut font_system = FontSystem::new();

    let metrics = Metrics::new(32.0, 44.0);
    let mut buffer = Buffer::new(&mut font_system, metrics);
    let mut buffer = buffer.borrow_with(&mut font_system);

    let attrs = Attrs::new();
    let small_attrs = attrs.clone().metrics(Metrics::relative(8.0, 1.2));

    // The empty lines from \n\n at start and end should use 8.0 * 1.2 = 9.6 line height.
    // All newlines are inside the small_attrs span so the empty lines are clearly within it.
    buffer.set_rich_text(
        [
            ("Before", attrs.clone()),
            ("\n\n\nSmall\n\n", small_attrs),
            ("After", attrs.clone()),
        ],
        &attrs,
        Shaping::Advanced,
        None,
    );
    buffer.set_size(Some(500.0), Some(500.0));

    let line_heights: Vec<f32> = buffer.layout_runs().map(|run| run.line_height).collect();

    // line_heights should be:
    // [0] "Before"   -> 44.0 (buffer default)
    // [1] "" (empty)  -> 9.6  (small span metrics: 8.0 * 1.2)
    // [2] "" (empty)  -> 9.6  (small span metrics: 8.0 * 1.2)
    // [3] "Small"     -> 9.6  (small span metrics from glyphs)
    // [4] "" (empty)  -> 9.6  (small span metrics: 8.0 * 1.2)
    // [5] "After"     -> 44.0 (buffer default)
    assert_eq!(
        line_heights.len(),
        6,
        "expected 6 layout runs, got {}",
        line_heights.len()
    );
    assert!(
        (line_heights[0] - 44.0).abs() < 0.1,
        "line 0 should use buffer default: {}",
        line_heights[0]
    );
    assert!(
        (line_heights[1] - 9.6).abs() < 0.1,
        "line 1 (empty) should use span metrics: {}",
        line_heights[1]
    );
    assert!(
        (line_heights[2] - 9.6).abs() < 0.1,
        "line 2 (empty) should use span metrics: {}",
        line_heights[2]
    );
    assert!(
        (line_heights[4] - 9.6).abs() < 0.1,
        "line 4 (empty) should use span metrics: {}",
        line_heights[4]
    );
    assert!(
        (line_heights[5] - 44.0).abs() < 0.1,
        "line 5 should use buffer default: {}",
        line_heights[5]
    );
}