From f7373e877e500d3389152032294fd0c3585e911d Mon Sep 17 00:00:00 2001
From: Piotr Markiewicz <piotr.markiewicz@vaimo.com>
Date: Fri, 25 Apr 2025 10:20:20 +0200
Subject: [PATCH] Added Excessive Parameters List rule

---
 README.md                                     | 10 +++-
 extension.neon                                | 21 ++++++-
 src/Rules/ExcessiveParameterListRule.php      | 60 +++++++++++++++++++
 tests/ExcessiveParameterListRuleTest.php      | 51 ++++++++++++++++
 tests/fixtures/ExcessiveParameterListRule.php | 59 ++++++++++++++++++
 5 files changed, 199 insertions(+), 2 deletions(-)
 create mode 100644 src/Rules/ExcessiveParameterListRule.php
 create mode 100644 tests/ExcessiveParameterListRuleTest.php
 create mode 100644 tests/fixtures/ExcessiveParameterListRule.php

diff --git a/README.md b/README.md
index e237fe1..4867589 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Set of additional PHPStan rules
 
 *PHPMD rules*
 - check for boolean argument flag
-- more coming soon ...
+- maximum number of parameters (default 10)
 
 ## Installation
 
@@ -19,4 +19,12 @@ Edit your phpstan configuration file and add
 ```
 includes:
     - vendor/pmarki/phpstan-rules/extension.neon
+```
+
+Additional configuration:
+```
+parameters:
+    pmarki:
+        excessiveParameterListRule:
+            maxNumberOfParameters: 10
 ```
\ No newline at end of file
diff --git a/extension.neon b/extension.neon
index 6990faa..b26cedc 100644
--- a/extension.neon
+++ b/extension.neon
@@ -18,4 +18,23 @@ services:
 	-
 	    class: PMarki\PHPStanRules\Rules\BooleanArgumentFlagRule
 	    tags:
-	        - phpstan.rules.rule
\ No newline at end of file
+	        - phpstan.rules.rule
+	-
+	    class: PMarki\PHPStanRules\Rules\ExcessiveParameterListRule
+	    arguments:
+	        maxNumberOfParameters: %pmarki.excessiveParameterListRule.maxNumberOfParameters%
+	    tags:
+	        - phpstan.rules.rule
+
+parameters:
+    pmarki:
+        excessiveParameterListRule:
+            maxNumberOfParameters: 10
+
+parametersSchema:
+    pmarki: structure([
+        excessiveParameterListRule: structure([
+            maxNumberOfParameters: int(),
+        ])
+    ])
+
diff --git a/src/Rules/ExcessiveParameterListRule.php b/src/Rules/ExcessiveParameterListRule.php
new file mode 100644
index 0000000..ecbb3f7
--- /dev/null
+++ b/src/Rules/ExcessiveParameterListRule.php
@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PMarki\PHPStanRules\Rules;
+
+use PhpParser\Node;
+use PhpParser\Node\FunctionLike;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use PMarki\PHPStanRules\Utils\Ancestors;
+
+/**
+ * @implements Rule<FunctionLike>
+ */
+class ExcessiveParameterListRule implements Rule
+{
+    public function __construct(
+        private readonly Ancestors $ancestors,
+        private readonly int $maxNumberOfParameters,
+    ) {
+    }
+
+    public function getNodeType(): string
+    {
+        return FunctionLike::class;
+    }
+
+    /**
+     * @return array<int, \PHPStan\Rules\RuleError>
+     */
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (!$node instanceof FunctionLike) {
+            return [];
+        }
+
+        if ($node->name instanceof Node\Identifier && $this->ancestors->methodInherited($node->name->name, $scope)) {
+            return [];
+        }
+
+        $numberOfParams = count($node->getParams());
+        if ($numberOfParams > $this->maxNumberOfParameters) {
+            return [
+                RuleErrorBuilder::message(
+                    sprintf(
+                        'Too many parameters in function declaration, expected %s, found %s.',
+                        $this->maxNumberOfParameters,
+                        $numberOfParams,
+                    )
+                )->tip('Create a new object to wrap the numerous parameters.')
+                    ->identifier('extraExcessiveParameterList')
+                    ->build(),
+            ];
+        }
+
+        return [];
+    }
+}
diff --git a/tests/ExcessiveParameterListRuleTest.php b/tests/ExcessiveParameterListRuleTest.php
new file mode 100644
index 0000000..d597218
--- /dev/null
+++ b/tests/ExcessiveParameterListRuleTest.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PMarki\PHPStanRules\Tests;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+use PMarki\PHPStanRules\Rules\ExcessiveParameterListRule;
+use PMarki\PHPStanRules\Utils\Ancestors;
+
+class ExcessiveParameterListRuleTest extends RuleTestCase
+{
+    private const MAX_NUMBER_OF_PARAMS = 10;
+    private const TIP = "\n    💡 Create a new object to wrap the numerous parameters.";
+
+    public function testExcessiveParameterListRule(): void
+    {
+        $this->analyse(
+            [
+                __DIR__ . '/fixtures/ExcessiveParameterListRule.php',
+            ],
+            [
+                [
+                    sprintf(
+                        "Too many parameters in function declaration, expected %s, found 11.%s",
+                        self::MAX_NUMBER_OF_PARAMS,
+                        self::TIP,
+                    ),
+                    6,
+                ],
+                [
+                    sprintf(
+                        "Too many parameters in function declaration, expected %s, found 11.%s",
+                        self::MAX_NUMBER_OF_PARAMS,
+                        self::TIP,
+                    ),
+                    34,
+                ],
+            ],
+        );
+    }
+
+    protected function getRule(): Rule
+    {
+        return new ExcessiveParameterListRule(
+            new Ancestors(),
+            self::MAX_NUMBER_OF_PARAMS,
+        );
+    }
+}
diff --git a/tests/fixtures/ExcessiveParameterListRule.php b/tests/fixtures/ExcessiveParameterListRule.php
new file mode 100644
index 0000000..911ee4f
--- /dev/null
+++ b/tests/fixtures/ExcessiveParameterListRule.php
@@ -0,0 +1,59 @@
+<?php
+namespace ExcessiveParameterListRule;
+
+class ExcessiveParameterListRule
+{
+    private function tooLong(
+        $a1,
+        $a2,
+        $a3,
+        $a4,
+        $a5,
+        $a6,
+        $a7,
+        $a8,
+        $a9,
+        $a10,
+        $a11,
+    ) {}
+
+    private function good(
+        $a1,
+        $a2,
+        $a3,
+        $a4,
+        $a5,
+        $a6,
+        $a7,
+        $a8,
+        $a9,
+        $a10,
+    ) {}
+}
+
+function tooLong(
+    $a1,
+    $a2,
+    $a3,
+    $a4,
+    $a5,
+    $a6,
+    $a7,
+    $a8,
+    $a9,
+    $a10,
+    $a11,
+) {}
+
+function good(
+    $a1,
+    $a2,
+    $a3,
+    $a4,
+    $a5,
+    $a6,
+    $a7,
+    $a8,
+    $a9,
+    $a10,
+) {}
\ No newline at end of file