clean: removed unused function + small fixme

src/main.rs

@@ -1,10 +1,7 @@
 mod cli;
 
 use clap::Parser;
-use std::{
-    collections::{HashMap, HashSet},
-    num::ParseIntError,
-};
+use std::collections::{HashMap, HashSet};
 
 use dotenv::dotenv;
 use image::{DynamicImage, GenericImageView, Rgb};
@@ -16,19 +13,6 @@ use crate::cli::Cli;
 type ColourSet = HashMap<u8, HashMap<u8, HashSet<u8>>>;
 type Colour = Rgb<u8>;
 
-pub fn decode_hex(s: &str) -> Result<Colour, Box<dyn std::error::Error>> {
-    let u8s: Vec<u8> = (0..s.len())
-        .step_by(2)
-        .map(|i| u8::from_str_radix(&s[i..i + 2], 16))
-        .collect::<Result<Vec<u8>, ParseIntError>>()?;
-
-    let rgb: [u8; 3] = u8s
-        .try_into()
-        .map_err(|_| <&str as Into<String>>::into("Hex string must decode to exactly 3 bytes"))?;
-
-    Ok(Rgb(rgb))
-}
-
 fn extract_colours(img: DynamicImage) -> ColourSet {
     let mut out: ColourSet = HashMap::new();
     for (_x, _y, p) in img.pixels() {
@@ -51,17 +35,17 @@ fn extract_colours_set(img: DynamicImage) -> HashSet<Rgb<u8>> {
 
 fn closest_colour(colour: &Colour, all: &ColourSet) -> Option<Colour> {
     // use redmean to calculate the distance between colours
-    // inevitably O(len(all))
     let mut closest: Option<Colour> = None;
     let mut dist: f32 = f32::MAX;
+
+    let (colour_r, colour_g, colour_b) = (colour[0] as f32, colour[1] as f32, colour[2] as f32);
     for (r, gbs) in all.iter() {
-        let r_bar = 0.5 * (*r as f32 + colour[0] as f32); //FIXME (low priority): i dont like the
-        //clunky as f32s everywhere
-        let r_squared = (*r as f32 - colour[0] as f32) * (*r as f32 - colour[0] as f32);
+        let r_bar = 0.5 * (*r as f32 + colour_r);
+        let r_squared = (*r as f32 - colour_r) * (*r as f32 - colour_r);
         for (g, bs) in gbs.iter() {
-            let g_squared = (*g as f32 - colour[1] as f32) * (*g as f32 - colour[1] as f32);
+            let g_squared = (*g as f32 - colour_g) * (*g as f32 - colour_g);
             for b in bs {
-                let b_squared = (*b as f32 - colour[2] as f32) * (*b as f32 - colour[2] as f32);
+                let b_squared = (*b as f32 - colour_b) * (*b as f32 - colour_b);
                 let delta = (2.0 + r_bar / 256.0) * r_squared
                     + 4.0 * g_squared
                     + (2.0 + (255.0 - r_bar) / 256.0) * b_squared;