Implement euph color hashing

src/euph.rs

@@ -1,6 +1,8 @@
 pub mod api;
 mod conn;
 mod room;
+mod util;
 
 pub use conn::{Joined, Joining, Status};
 pub use room::Room;
+pub use util::{hue, nick_color, nick_style};

src/euph/util.rs

@@ -0,0 +1,48 @@
+use crossterm::style::{Color, ContentStyle, Stylize};
+use palette::{FromColor, Hsl, RgbHue, Srgb};
+
+fn normalize(text: &str) -> String {
+    // TODO Remove emoji names?
+    text.chars()
+        .filter(|&c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
+        .map(|c| c.to_ascii_lowercase())
+        .collect()
+}
+
+/// A re-implementation of [euphoria's nick hue hashing algorithm][0].
+///
+/// [0]: https://github.com/euphoria-io/heim/blob/master/client/lib/hueHash.js
+fn hue_hash(text: &str, offset: i64) -> u8 {
+    let mut val = 0_i32;
+    for char in text.chars() {
+        let char_val = (char as i32).wrapping_mul(439) % 256;
+        val = val.wrapping_mul(33).wrapping_add(char_val);
+    }
+
+    let val: i64 = val as i64 + 2_i64.pow(31);
+    ((val + offset) % 255) as u8
+}
+
+const GREENIE_OFFSET: i64 = 148 - 192; // 148 - hue_hash("greenie", 0)
+
+pub fn hue(text: &str) -> u8 {
+    let normalized = normalize(text);
+    if normalized.is_empty() {
+        hue_hash(text, GREENIE_OFFSET)
+    } else {
+        hue_hash(&normalized, GREENIE_OFFSET)
+    }
+}
+
+pub fn nick_color(nick: &str) -> (u8, u8, u8) {
+    let hue = RgbHue::from(hue(nick) as f32);
+    let color = Hsl::new(hue, 1.0, 0.72);
+    Srgb::from_color(color)
+        .into_format::<u8>()
+        .into_components()
+}
+
+pub fn nick_style(nick: &str) -> ContentStyle {
+    let (r, g, b) = nick_color(nick);
+    ContentStyle::default().bold().with(Color::Rgb { r, g, b })
+}