refactor: replace slug generation with CRC32 + base62

app/controllers/link.cr

@@ -27,16 +27,7 @@ module App::Controllers::Link
       link.id = UUID.v4.to_s
       link.url = url
       link.user = user
-
-      attempts = 0
-      loop do
-        slug = SlugService.generate_base64(url, 5 + attempts)
-        unless Database.get_by(Link, slug: slug)
-          link.slug = slug
-          break
-        end
-        attempts += 1
-      end
+      link.slug = SlugService.shorten_url(url)
 
       changeset = Database.insert(link)
       if !changeset.valid?

app/services/slug.cr

@@ -1,9 +1,11 @@
 require "digest"
+require "base64"
 
 module App::Services::SlugService
-  def self.generate_base64(link : String, size : Int32) : String
-    hash = Digest::SHA256.digest(link)
-    base64_encoded = Base64.urlsafe_encode(hash).strip.tr("+/", "")
-    base64_encoded[0, size]
+  def self.shorten_url(url : String) : String
+    crc32_hash = Digest::CRC32.digest(url)
+    base62_encoded = Base64.urlsafe_encode(crc32_hash).strip.tr("-_=", "")
+
+    base62_encoded
   end
 end