Initial implementation for Symfony1 composer-plugin installer

Author: thePanz

composer.json

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+{
+    "name": "friendsofsymfony1/symfony1-installer-plugin",
+    "type": "composer-plugin",
+    "license": "MIT",
+    "autoload": {
+        "psr-4": {"Symfony1\\Composer\\": "src/"}
+    },
+    "extra": {
+        "class": "Symfony1\\Composer\\InstallerPlugin"
+    },
+    "require": {
+        "php": "^7.4 || ^8.0",
+        "composer-plugin-api": "^2.8"
+    },
+    "require-dev": {
+        "composer/composer": "^2.8"
+    }
+}

src/Installer.php

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+<?php
+
+namespace Symfony1\Composer;
+
+use Composer\Installer\LibraryInstaller;
+use Composer\Package\PackageInterface;
+
+class Installer extends LibraryInstaller
+{
+    public function getInstallPath(PackageInterface $package): string
+    {
+        $prettyName = $package->getPrettyName();
+        if (str_contains($prettyName, '/')) {
+            $name = explode('/', $prettyName)[1];
+        } else {
+            $name = $prettyName;
+        }
+
+        $camelCaseName = preg_replace_callback('/-([a-z])/', static fn($m) => strtoupper($m[1]), $name);
+
+        return 'plugins/'.$camelCaseName;
+    }
+
+    public function supports($packageType): bool
+    {
+        return 'symfony1-plugin' === $packageType;
+    }
+}

src/InstallerPlugin.php

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+<?php
+
+namespace Symfony1\Composer;
+
+use Composer\Composer;
+use Composer\IO\IOInterface;
+use Composer\Plugin\PluginInterface;
+
+class InstallerPlugin implements PluginInterface
+{
+    public function activate(Composer $composer, IOInterface $io): void
+    {
+        $installer = new Installer($io, $composer);
+        $composer->getInstallationManager()->addInstaller($installer);
+    }
+
+    public function deactivate(Composer $composer, IOInterface $io): void
+    {
+        $installer = new Installer($io, $composer);
+        $composer->getInstallationManager()->removeInstaller($installer);
+    }
+
+    public function uninstall(Composer $composer, IOInterface $io): void
+    {
+    }
+}