Glassmorphism Generator — Rust source

// Pure glassmorphism CSS builder — deterministic, no DOM.
//
// Language: Rust
// CosmoDev polyglot showcase port of the `glassmorphism-generator` tool.
// Ported from src/lib/glassmorphism.ts — display source, part of CosmoDev's
// polyglot tool pages.
//
// Builds a frosted-glass CSS block from blur / opacity / tint / radius /
// border_opacity (+ optional saturation). Hex tints (#rgb / #rrggbb) are
// validated by hand with is_ascii_hexdigit (no regex crate — stdlib only);
// opacity is clamped to [0,1]; the alpha channel is rounded with
// (x*100).round()/100 and rendered via {} (shortest repr, matching JS
// template literals), so the output matches the live TypeScript lib
// byte-for-byte. Pure stdlib.
//
// Parity note: f64::round() rounds half away from zero — identical to JS
// Math.round for the non-negative alphas produced here (alpha is clamped
// to [0,1] before rounding).

/// Configuration for one glassmorphism declaration block.
pub struct GlassConfig {
    pub blur: f64,
    pub opacity: f64,
    pub tint: String,
    pub radius: f64,
    pub border_opacity: f64,
    pub saturation: Option<f64>, // None => 180.0 (lib default)
}

/// The rendered glassmorphism block plus its full CSS text.
pub struct GlassCss {
    pub background: String,
    pub backdrop_filter: String,
    pub webkit_backdrop_filter: String,
    pub border: String,
    pub border_radius: String,
    pub box_shadow: String,
    pub full_css: String,
}

/// True when every byte is an ASCII hex digit (0-9, a-f, A-F).
fn is_hex(s: &str) -> bool {
    !s.is_empty() && s.bytes().all(|c| c.is_ascii_hexdigit())
}

/// Parse 1-2 hex digits into an integer (base 16); 0 on failure.
fn parse_hex(s: &str) -> i64 {
    i64::from_str_radix(s, 16).unwrap_or(0)
}

/// Parse #rgb or #rrggbb into (r, g, b); None on a bad color.
/// A 3-char hex expands each digit (e.g. "abc" -> "aabbcc"), like CSS.
/// Exactly one leading '#' is stripped, matching the lib's /^#/ replace.
pub fn hex_to_rgb(hex: &str) -> Option<(i64, i64, i64)> {
    let h = hex.trim();
    let h = h.strip_prefix('#').unwrap_or(h);
    if h.len() == 3 && is_hex(h) {
        let expand = |i: usize| parse_hex(&h[i..i + 1].repeat(2));
        Some((expand(0), expand(1), expand(2)))
    } else if h.len() == 6 && is_hex(h) {
        Some((parse_hex(&h[0..2]), parse_hex(&h[2..4]), parse_hex(&h[4..6])))
    } else {
        None
    }
}

/// Format rgba(), clamping + 2-decimal-rounding the alpha.
pub fn rgba(r: i64, g: i64, b: i64, a: f64) -> String {
    let c = a.max(0.0).min(1.0);
    format!("rgba({}, {}, {}, {})", r, g, b, (c * 100.0).round() / 100.0)
}

/// Build the full glassmorphism CSS for a config.
pub fn build_glassmorphism(cfg: &GlassConfig) -> GlassCss {
    let blur = cfg.blur.max(0.0);
    let opacity = cfg.opacity.max(0.0).min(1.0);
    let radius = cfg.radius.max(0.0);
    let border_opacity = cfg.border_opacity.max(0.0).min(1.0);
    let saturation = cfg.saturation.unwrap_or(180.0);
    let (r, g, b) = hex_to_rgb(&cfg.tint).unwrap_or((255, 255, 255));

    let background = rgba(r, g, b, opacity);
    let backdrop_filter = format!("blur({}px) saturate({}%)", blur, saturation);
    let border = format!("1px solid {}", rgba(255, 255, 255, border_opacity));
    let border_radius = format!("{}px", radius);
    let box_shadow = "0 8px 32px 0 rgba(31, 38, 135, 0.37)".to_string();

    let full_css = format!(
        "background: {};\n\
         -webkit-backdrop-filter: {};\n\
         backdrop-filter: {};\n\
         border-radius: {};\n\
         border: {};\n\
         box-shadow: {};",
        background, backdrop_filter, backdrop_filter, border_radius, border, box_shadow
    );

    GlassCss {
        background,
        backdrop_filter: backdrop_filter.clone(),
        webkit_backdrop_filter: backdrop_filter,
        border,
        border_radius,
        box_shadow,
        full_css,
    }
}

fn main() {
    let cfg = GlassConfig {
        blur: 10.0,
        opacity: 0.3,
        tint: "#ffffff".to_string(),
        radius: 12.0,
        border_opacity: 0.2,
        saturation: None,
    };
    println!("{}", build_glassmorphism(&cfg).full_css);
}