Started work on user slugs

Related to #2525

database/migrations/2021_03_08_215138_add_user_slug.php

@@ -0,0 +1,50 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Support\Str;
+
+class AddUserSlug extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->string('slug', 250);
+        });
+
+        $slugMap = [];
+        DB::table('users')->cursor()->each(function ($user) use (&$slugMap) {
+            $userSlug = Str::slug($user->name);
+            while (isset($slugMap[$userSlug])) {
+                $userSlug = Str::slug($user->name . Str::random(4));
+            }
+            $slugMap[$userSlug] = true;
+
+            DB::table('users')
+                ->where('id', $user->id)
+                ->update(['slug' => $userSlug]);
+        });
+
+        Schema::table('users', function (Blueprint $table) {
+            $table->unique('slug');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->dropColumn('slug');
+        });
+    }
+}