From db83565c54a2b97ad9cf3e83314775193876be43 Mon Sep 17 00:00:00 2001
From: Li Zhineng <im@zhineng.li>
Date: Mon, 12 May 2025 19:27:10 +0800
Subject: determine if clean energy

---
 src/RegistrationNumber.php       | 38 +++++++++++++++++++++++++++++++++++++-
 tests/RegistrationNumberTest.php | 20 ++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/src/RegistrationNumber.php b/src/RegistrationNumber.php
index 6e729e3..3f6edcc 100644
--- a/src/RegistrationNumber.php
+++ b/src/RegistrationNumber.php
@@ -134,10 +134,23 @@ final readonly class RegistrationNumber
         'F', 'G', 'H', 'J', 'K',
     ];
 
+    /**
+     * @var string[]
+     */
+    private const array BATTERY_ELECTRIC_LETTERS = [
+        'D', 'A', 'B', 'C', 'E',
+    ];
+
+    public string $region;
+
+    public string $authority;
+
+    public string $sequence;
+
     private function __construct(
         public string $registrationNumber
     ) {
-        //
+        $this->parse($registrationNumber);
     }
 
     public static function make(string $registrationNumber): static
@@ -250,4 +263,27 @@ final readonly class RegistrationNumber
             'The registration number "%s" is invalid.', $registrationNumber
         ));
     }
+
+    private function parse(string $registrationNumber): void
+    {
+        $this->region = mb_substr($registrationNumber, 0, 1);
+        $this->authority = mb_substr($registrationNumber, 1, 1);
+        $this->sequence = mb_substr($registrationNumber, 2);
+    }
+
+    public function isCleanEnergy(): bool
+    {
+        return strlen($this->sequence) === 6;
+    }
+
+    public function isBatteryElectric(): bool
+    {
+        if (! $this->isCleanEnergy()) {
+            return false;
+        }
+
+        $code = mb_substr($this->sequence, 0, 1);
+
+        return in_array($code, self::BATTERY_ELECTRIC_LETTERS);
+    }
 }
diff --git a/tests/RegistrationNumberTest.php b/tests/RegistrationNumberTest.php
index dfb3dd3..fcf5f33 100644
--- a/tests/RegistrationNumberTest.php
+++ b/tests/RegistrationNumberTest.php
@@ -30,6 +30,26 @@ final class RegistrationNumberTest extends TestCase
         RegistrationNumber::make($registrationNumber);
     }
 
+    public function test_is_clean_energy_determines_if_vehicle_is_clean_energy(): void
+    {
+        $this->assertTrue(RegistrationNumber::make('粤ED12345')->isCleanEnergy());
+        $this->assertFalse(RegistrationNumber::make('粤ED1234')->isCleanEnergy());
+    }
+
+    public function test_is_battery_electric_determines_if_vehicle_is_a_fully_electric_vehicle(): void
+    {
+        $this->assertTrue(RegistrationNumber::make('粤ED12345')->isBatteryElectric());
+        $this->assertTrue(RegistrationNumber::make('粤EA12345')->isBatteryElectric());
+        $this->assertTrue(RegistrationNumber::make('粤EB12345')->isBatteryElectric());
+        $this->assertTrue(RegistrationNumber::make('粤EC12345')->isBatteryElectric());
+        $this->assertTrue(RegistrationNumber::make('粤EE12345')->isBatteryElectric());
+        $this->assertFalse(RegistrationNumber::make('粤EF12345')->isBatteryElectric());
+        $this->assertFalse(RegistrationNumber::make('粤EG12345')->isBatteryElectric());
+        $this->assertFalse(RegistrationNumber::make('粤EH12345')->isBatteryElectric());
+        $this->assertFalse(RegistrationNumber::make('粤EJ12345')->isBatteryElectric());
+        $this->assertFalse(RegistrationNumber::make('粤EK12345')->isBatteryElectric());
+    }
+
     /**
      * @return string[]
      */
-- 
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