From cb8ad9567a940db0434b9ca8991422ac9d2ce795 Mon Sep 17 00:00:00 2001
From: Li Zhineng <im@zhineng.li>
Date: Mon, 28 Apr 2025 17:53:19 +0800
Subject: region manager

---
 src/RegionException.php     | 10 ++++++++
 src/RegionManager.php       | 58 +++++++++++++++++++++++++++++++++++++++++++++
 tests/RegionManagerTest.php | 52 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 src/RegionException.php
 create mode 100644 src/RegionManager.php
 create mode 100644 tests/RegionManagerTest.php

diff --git a/src/RegionException.php b/src/RegionException.php
new file mode 100644
index 0000000..f33adec
--- /dev/null
+++ b/src/RegionException.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zhineng\Region;
+
+final class RegionException extends \Exception
+{
+    //
+}
diff --git a/src/RegionManager.php b/src/RegionManager.php
new file mode 100644
index 0000000..9b8b969
--- /dev/null
+++ b/src/RegionManager.php
@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zhineng\Region;
+
+final class RegionManager
+{
+    /**
+     * @param  array<string, string>  $codeToName
+     * @param  array<string, int[]>  $relationships
+     * @param  array<int, int[]>  $topLevels
+     */
+    public function __construct(
+        private array $codeToName,
+        private array $relationships,
+        private array $topLevels
+    ) {
+        //
+    }
+
+    public static function createFromBuiltIn(): static
+    {
+        return new self(
+            require __DIR__.'/../resources/code-to-name.php',
+            require __DIR__.'/../resources/relationships.php',
+            require __DIR__.'/../resources/top-levels.php'
+        );
+    }
+
+    public function getName(int $code): string
+    {
+        return $this->codeToName[$this->groupKey($code)]
+            ?? throw new RegionException('The region code does not exist.');
+    }
+
+    /**
+     * @return int[]
+     */
+    public function getTopLevelNodes(): array
+    {
+        return $this->topLevels;
+    }
+
+    /**
+     * @return int[]
+     */
+    public function getNodes(int $code): array
+    {
+        return $this->relationships[$this->groupKey($code)]
+            ?? throw new RegionException('Could not find any nodes under the region code.');
+    }
+
+    private function groupKey(int $code): string
+    {
+        return '_'.$code;
+    }
+}
diff --git a/tests/RegionManagerTest.php b/tests/RegionManagerTest.php
new file mode 100644
index 0000000..2536a7c
--- /dev/null
+++ b/tests/RegionManagerTest.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zhineng\Region\Tests;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use Zhineng\Region\RegionException;
+use Zhineng\Region\RegionManager;
+
+#[CoversClass(RegionManager::class)]
+final class RegionManagerTest extends TestCase
+{
+    public function test_name_resolution(): void
+    {
+        $manager = new RegionManager(
+            ['_110000' => '北京市'],
+            [],
+            []
+        );
+        $this->assertSame('北京市', $manager->getName(110000));
+    }
+
+    public function test_name_resolution_with_non_existent_code(): void
+    {
+        $this->expectException(RegionException::class);
+        $this->expectExceptionMessage('The region code does not exist.');
+        $manager = new RegionManager([], [], []);
+        $manager->getName(110000);
+    }
+
+    public function test_top_level_nodes_resolution(): void
+    {
+        $manager = new RegionManager([], [], [1, 2, 3]);
+        $this->assertSame([1, 2, 3], $manager->getTopLevelNodes());
+    }
+
+    public function test_nodes_resolution(): void
+    {
+        $manager = new RegionManager([], ['_1' => [2]], []);
+        $this->assertSame([2], $manager->getNodes(1));
+    }
+
+    public function test_nodes_resolution_with_non_existent_code(): void
+    {
+        $this->expectException(RegionException::class);
+        $this->expectExceptionMessage('Could not find any nodes under the region code.');
+        $manager = new RegionManager([], [], []);
+        $manager->getNodes(1);
+    }
+}
-- 
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