//! Palette contrast tests, mirroring bezel's `tests/theme.rs`: each light text
//! token must land within ~0.5 of its dark counterpart's contrast ratio
//! against its own background, and the primary text must keep the ratio the
//! palette was tuned for.

use gpui::Hsla;
use theme::{Brand, ThemeColors, ThemeMode, Tint, contrast_ratio, flatten};

// The shipped palette's measured floors (AppKit-style ink, per bezel):
// text/bg is 14.4:1 dark and 15.1:1 light, muted lands near 6.3 dark and
// 4.0 light, and faint sits below 3:1 in both appearances by design.
const TEXT_RATIO: f32 = 13.9;
const MUTED_RATIO: f32 = 3.9;
const FAINT_RATIO: f32 = 1.8;
const TEXT_PARITY: f32 = 0.7;

fn ratio(fg: Hsla, bg: Hsla) -> f32 {
    contrast_ratio(flatten(fg, bg), bg)
}

#[test]
fn text_keeps_its_contrast() {
    for appearance in [ThemeMode::Dark, ThemeMode::Light] {
        let colors = ThemeColors::for_appearance(appearance);
        assert!(
            ratio(colors.text, colors.bg) >= TEXT_RATIO,
            "{appearance:?}: text on bg = {}",
            ratio(colors.text, colors.bg)
        );
        assert!(
            ratio(colors.text, colors.surface) >= TEXT_RATIO,
            "{appearance:?}: text on surface"
        );
        assert!(
            ratio(colors.text_muted, colors.bg) >= MUTED_RATIO,
            "{appearance:?}: muted on bg = {}",
            ratio(colors.text_muted, colors.bg)
        );
        assert!(
            ratio(colors.text_faint, colors.bg) >= FAINT_RATIO,
            "{appearance:?}: faint on bg = {}",
            ratio(colors.text_faint, colors.bg)
        );
    }
}

#[test]
fn light_matches_dark_contrast() {
    let dark = ThemeColors::for_appearance(ThemeMode::Dark);
    let light = ThemeColors::for_appearance(ThemeMode::Light);

    // Primary text keeps near-parity across appearances. Muted and faint do
    // not (the light values sit further from the background by design, see
    // Ink::APPKIT); their floors are asserted in `text_keeps_its_contrast`.
    let pairs = [
        ("text/bg", dark.text, dark.bg, light.text, light.bg),
        (
            "text/surface",
            dark.text,
            dark.surface,
            light.text,
            light.surface,
        ),
    ];
    for (name, dark_fg, dark_bg, light_fg, light_bg) in pairs {
        let dark_ratio = ratio(dark_fg, dark_bg);
        let light_ratio = ratio(light_fg, light_bg);
        let delta = (dark_ratio - light_ratio).abs();
        assert!(
            delta <= TEXT_PARITY,
            "{name}: light deviates by {delta} (dark {dark_ratio:.3}, light {light_ratio:.3})"
        );
    }
}

#[test]
fn default_brand_is_a_no_op() {
    let brand = Brand::default();
    assert!(brand.is_default());
    for appearance in [ThemeMode::Dark, ThemeMode::Light] {
        let base = ThemeColors::for_appearance(appearance);
        let branded = brand.branded(appearance);
        assert_eq!(
            base, branded,
            "{appearance:?}: default brand must not move the palette"
        );
    }
}

#[test]
fn brand_tint_rotates_greys_and_keeps_semantics() {
    let brand = Brand {
        tint: Tint::new(257.417, 0.046),
        accent: Tint::new(276.935, 0.182),
        ..Brand::default()
    };
    let base = ThemeColors::for_appearance(ThemeMode::Dark);
    let branded = brand.branded(ThemeMode::Dark);

    assert_ne!(branded.bg, base.bg, "bg takes the tint");
    assert_ne!(branded.accent, base.accent, "accent takes the accent hue");
    assert_eq!(
        branded.danger, base.danger,
        "danger is semantic and keeps its hue"
    );
    assert_eq!(
        branded.warning, base.warning,
        "warning is semantic and keeps its hue"
    );
}

#[test]
fn warning_wash_carries_its_label() {
    // warning_muted is a translucent amber wash, so the label pairing is
    // measured against the plate flattened onto the content plane.
    for appearance in [ThemeMode::Dark, ThemeMode::Light] {
        let colors = ThemeColors::for_appearance(appearance);
        let plate = flatten(colors.warning_muted, colors.bg);
        assert!(
            ratio(colors.warning, plate) >= 3.0,
            "{appearance:?}: warning on warning_muted = {}",
            ratio(colors.warning, plate)
        );
    }
}