<?php

declare(strict_types=1);

namespace App\Helpers;

use FilesystemIterator;
use Generator;
use RecursiveDirectoryIterator;
use RecursiveIteratorIterator;
use SplFileInfo;

class EnumExtractor
{
    private string $namespace;

    private string $directory;

    public function __construct(string $namespace, string $directory)
    {
        $this->namespace = mb_trim($namespace, '\\').'\\';
        $this->directory = mb_rtrim($directory, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR;
    }

    /**
     * Executes the extraction process and returns an array of actual Enum objects.
     */
    public function extract(): array
    {
        $enumObjects = [];

        foreach ($this->getPhpFiles() as $file) {
            $className = $this->resolveClassName($file->getPathname());

            $this->loadClassIfNeeded($className, $file->getPathname());

            if (enum_exists($className)) {
                // $className::cases() returns an array of the actual Enum objects
                // e.g., [App\Enums\Status::Active, App\Enums\Status::Inactive]
                $enumObjects[$className] = $className::cases();
            }
        }

        return $enumObjects;
    }

    /**
     * Yields only PHP files from the target directory.
     */
    private function getPhpFiles(): Generator
    {
        $iterator = new RecursiveIteratorIterator(
            new RecursiveDirectoryIterator($this->directory, FilesystemIterator::SKIP_DOTS)
        );

        /** @var SplFileInfo $file */
        foreach ($iterator as $file) {
            if ('php' === $file->getExtension()) {
                yield $file;
            }
        }
    }

    /**
     * Converts a physical file path to a fully qualified PSR-4 class name.
     */
    private function resolveClassName(string $filePath): string
    {
        // Strip the base directory from the path
        $relativePath = str_replace($this->directory, '', $filePath);

        // Normalize slashes and remove the .php extension
        $normalizedPath = str_replace([DIRECTORY_SEPARATOR, '/', '.php'], ['\\', '\\', ''], $relativePath);

        return $this->namespace.mb_ltrim($normalizedPath, '\\');
    }

    /**
     * Requires the file into memory if it hasn't been autoloaded yet.
     */
    private function loadClassIfNeeded(string $className, string $filePath): void
    {
        if (! class_exists($className, false)
            && ! enum_exists($className, false)
            && ! interface_exists($className, false)
        ) {
            require_once $filePath;
        }
    }
}