style: add wp coding standards and fix issues

.gitattributes

@@ -15,3 +15,4 @@
 
 /composer.lock export-ignore
 /phpstan.neon export-ignore
+/.phpcs.xml export-ignore

.github/workflows/backend.yml

@@ -0,0 +1,35 @@
+name: PHPCS and PHPStan Check
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "**.php"
+  pull_request:
+    paths:
+      - "**.php"
+
+jobs:
+  phpcs:
+    name: Run PHPCS
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: 🐘 Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "8.1"
+
+      - name: 📥 Install PHP dependencies
+        uses: ramsey/composer-install@v2
+        with:
+          composer-options: "--classmap-authoritative"
+
+      - name: ✨ PHPCS
+        run: composer analyse:phpcs
+
+      - name: 🧐 PHPStan
+        run: composer analyse:phpstan

.phpcs.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0"?>
+<ruleset name="Custom">
+    <file>.</file>
+    <exclude-pattern>/vendor/*</exclude-pattern>
+    <exclude-pattern>/node_modules/*</exclude-pattern>
+    <exclude-pattern>/src/*</exclude-pattern>
+    <exclude-pattern>/build/*</exclude-pattern>
+    <exclude-pattern>/*.js</exclude-pattern>
+
+    <config name="minimum_wp_version" value="6.3"/>
+    <arg name="basepath" value="."/>
+
+    <rule ref="WordPress">
+        <exclude name="Universal.Arrays.DisallowShortArraySyntax"/>
+        <exclude name="WordPress.Files.FileName.NotHyphenatedLowercase"/>
+        <exclude name="WordPress.Files.FileName.InvalidClassFileName"/>
+        <exclude name="Squiz.Commenting.FileComment.Missing"/>
+        <exclude name="Squiz.Commenting.ClassComment.Missing"/>
+        <exclude name="Squiz.Commenting.FunctionComment.Missing"/>
+        <exclude name="Generic.Commenting.DocComment.MissingShort"/>
+        <exclude name="WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode"/>
+        <exclude name="WordPress.NamingConventions.ValidHookName.UseUnderscores"/>
+        <exclude name="WordPress.WP.AlternativeFunctions.json_encode_json_encode"/>
+        <exclude name="WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents"/>
+    </rule>
+</ruleset>

composer.json

@@ -15,15 +15,19 @@
   },
   "require-dev": {
     "szepeviktor/phpstan-wordpress": "^v1.3",
-    "phpstan/extension-installer": "^1.3"
+    "phpstan/extension-installer": "^1.3",
+    "wp-coding-standards/wpcs": "^3.0"
   },
   "config": {
     "allow-plugins": {
-      "phpstan/extension-installer": true
+      "phpstan/extension-installer": true,
+      "dealerdirect/phpcodesniffer-composer-installer": true
     }
   },
   "scripts": {
     "analyse:phpstan": "phpstan analyse",
-    "clear-cache:phpstan": "phpstan clear-result-cache"
+    "clear-cache:phpstan": "phpstan clear-result-cache",
+    "analyse:phpcs": "phpcs",
+    "format": "phpcbf"
   }
 }