link shorting

src/server/short_link.rs

@@ -0,0 +1,77 @@
+use dashmap::DashMap;
+use once_cell::sync::Lazy;
+use rand::{Rng, thread_rng};
+
+static LINKS: Lazy<DashMap<String, String>> = Lazy::new(DashMap::new);
+
+const CHARSET: &[u8] = b"abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ#1234567890";
+
+pub async fn add_short_link(long: &str) -> Result<String, ()> {
+    let raw = generate_unique_short_link().await;
+    LINKS.insert(raw.clone(), long.to_string());
+
+    Ok(format!(
+        "omega.tensamin.net/direct/{}",
+        format_with_dashes(&raw)
+    ))
+}
+
+async fn generate_unique_short_link() -> String {
+    loop {
+        let short = generate_short_link().await;
+        if !LINKS.contains_key(&short) {
+            return short;
+        }
+    }
+}
+
+pub async fn generate_short_link() -> String {
+    let len = short_length();
+
+    let mut rng = thread_rng();
+    (0..len)
+        .map(|_| {
+            let idx = rng.gen_range(0..CHARSET.len());
+            CHARSET[idx] as char
+        })
+        .collect()
+}
+
+pub async fn get_short_link(short: &str) -> Result<String, ()> {
+    let normalized = normalize_short(short);
+
+    LINKS.get(&normalized).map(|v| v.value().clone()).ok_or(())
+}
+
+/* ---------------- helpers ---------------- */
+
+fn short_length() -> usize {
+    let count = LINKS.len();
+
+    match count {
+        0..=1_999 => 4,
+        2_000..=999_999 => 8,
+        _ => 12,
+    }
+}
+
+fn format_with_dashes(s: &str) -> String {
+    s.chars()
+        .collect::<Vec<_>>()
+        .chunks(4)
+        .map(|c| c.iter().collect::<String>())
+        .collect::<Vec<_>>()
+        .join("-")
+}
+
+fn normalize_short(input: &str) -> String {
+    input
+        .chars()
+        .filter(|c| *c != '-')
+        .map(|c| match c {
+            'Q' | 'O' => '0',
+            'I' => 'l',
+            _ => c,
+        })
+        .collect()
+}