implement SearchUsers use case

backend/app/User/EloquentUserRepository.php

@@ -43,6 +43,25 @@ class EloquentUserRepository implements UserRepository
         return $model === null ? null : $this->toDomain($model);
     }
 
+    /**
+     * @return User[]
+     */
+    public function search(string $query): array
+    {
+        $like = strtolower($query).'%';
+        $models = UserModel::query()
+            ->whereRaw('LOWER(display_name) LIKE ?', [$like])
+            ->orWhereRaw('LOWER(email) LIKE ?', [$like])
+            ->orderBy('display_name')
+            ->get();
+
+        return $models->map(
+            function (UserModel $model) {
+                return $this->toDomain($model);
+            },
+        )->all();
+    }
+
     /**
      * @throws RuntimeException
      */

backend/app/User/UseCases/SearchUsers/SearchUsers.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace App\User\UseCases\SearchUsers;
+
+use App\Exceptions\BadRequestException;
+use App\User\User;
+use App\User\UserRepository;
+
+class SearchUsers
+{
+    public function __construct(
+        private UserRepository $userRepo,
+    ) {}
+
+    /**
+     * @return User[]
+     *
+     * @throws BadRequestException
+     */
+    public function execute(SearchUsersRequest $request): array
+    {
+        $query = trim($request->query);
+        if ($query === '') {
+            throw new BadRequestException('query is required');
+        }
+
+        return $this->userRepo->search($query);
+    }
+}

backend/app/User/UseCases/SearchUsers/SearchUsersRequest.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App\User\UseCases\SearchUsers;
+
+class SearchUsersRequest
+{
+    public function __construct(
+        public string $query,
+    ) {}
+}

backend/app/User/UserRepository.php

@@ -15,4 +15,9 @@ interface UserRepository
     public function findByDisplayName(string $displayName): ?User;
 
     public function update(User $user): User;
+
+    /**
+     * @return User[]
+     */
+    public function search(string $query): array;
 }

backend/tests/Fakes/FakeUserRepository.php

@@ -63,6 +63,36 @@ class FakeUserRepository implements UserRepository
         return null;
     }
 
+    /**
+     * @return User[]
+     */
+    public function search(string $query): array
+    {
+        $needle = strtolower($query);
+        $results = [];
+        foreach ($this->existingUsers as $user) {
+            $displayName = strtolower($user->getDisplayName());
+            $email = strtolower($user->getEmail()->value());
+            if (
+                str_starts_with($displayName, $needle)
+                || str_starts_with($email, $needle)
+            ) {
+                $results[] = $this->copy($user);
+            }
+        }
+        usort(
+            $results,
+            function (User $left, User $right) {
+                return strcmp(
+                    $left->getDisplayName(),
+                    $right->getDisplayName(),
+                );
+            },
+        );
+
+        return $results;
+    }
+
     /**
      * @throws RuntimeException
      */