fission-core 0.3.0

use fission_core::Runtime;
use fission_layout::TextMeasurer;
use std::sync::Arc;
use unicode_segmentation::UnicodeSegmentation;

struct MockMeasurer;

impl TextMeasurer for MockMeasurer {
    fn measure(&self, text: &str, font_size: f32, _available_width: Option<f32>) -> (f32, f32) {
        // Simple mock: 10px per char
        let width = text.chars().count() as f32 * 10.0;
        (width, font_size)
    }
    fn hit_test(
        &self,
        text: &str,
        _font_size: f32,
        _available_width: Option<f32>,
        x: f32,
        _y: f32,
    ) -> usize {
        let char_width = 10.0;
        if x <= 0.0 {
            return 0;
        }
        let char_idx = (x / char_width).round() as usize;
        let mut byte_offset = 0;
        for (idx, g) in text.grapheme_indices(true).take(char_idx) {
            byte_offset = idx + g.len();
        }
        byte_offset
    }
    fn get_line_metrics(
        &self,
        text: &str,
        font_size: f32,
        available_width: Option<f32>,
    ) -> Vec<fission_layout::LineMetric> {
        vec![fission_layout::LineMetric {
            start_index: 0,
            end_index: text.len(),
            baseline: font_size,
            height: font_size,
            width: self.measure(text, font_size, available_width).0,
        }]
    }
    fn get_caret_position(
        &self,
        text: &str,
        font_size: f32,
        _available_width: Option<f32>,
        caret_index: usize,
    ) -> (f32, f32) {
        let char_width = 10.0;
        let x = text
            .graphemes(true)
            .take(caret_index)
            .map(|g| g.len())
            .sum::<usize>() as f32
            * char_width;
        let y = font_size; // Baseline
        (x, y)
    }
}

#[test]
fn test_caret_hit_test_precise() {
    let measurer = Arc::new(MockMeasurer);
    let runtime = Runtime::default().with_measurer(measurer);

    let text = "Hello";
    let font_size = 16.0;
    let viewport_x = 0.0;
    let viewport_w = 100.0;
    let content_w = 50.0;
    let scroll_offset = 0.0;

    // "H"  0-10
    // "e" 10-20
    // "l" 20-30
    // "l" 30-40
    // "o" 40-50

    // Click at 4.0 (Left of center of 'H') -> 0
    assert_eq!(
        runtime.caret_from_point_in_text(
            text,
            font_size,
            viewport_x,
            viewport_w,
            content_w,
            scroll_offset,
            4.0
        ),
        0
    );

    // Click at 6.0 (Right of center of 'H') -> 1
    assert_eq!(
        runtime.caret_from_point_in_text(
            text,
            font_size,
            viewport_x,
            viewport_w,
            content_w,
            scroll_offset,
            6.0
        ),
        1
    );

    // Click at 14.0 (Left of center of 'e') -> 1
    assert_eq!(
        runtime.caret_from_point_in_text(
            text,
            font_size,
            viewport_x,
            viewport_w,
            content_w,
            scroll_offset,
            14.0
        ),
        1
    );

    // Click at 16.0 (Right of center of 'e') -> 2
    assert_eq!(
        runtime.caret_from_point_in_text(
            text,
            font_size,
            viewport_x,
            viewport_w,
            content_w,
            scroll_offset,
            16.0
        ),
        2
    );

    // Click at 55.0 (Past end)
    assert_eq!(
        runtime.caret_from_point_in_text(
            text,
            font_size,
            viewport_x,
            viewport_w,
            content_w,
            scroll_offset,
            55.0
        ),
        5
    );
}