<?php

namespace App\Services\Utils;

use App\Contracts\Utils\FindClassesInNamespaceContract;
use Illuminate\Support\Str;
use Symfony\Component\Finder\Finder;

class FindClassesInNamespace implements FindClassesInNamespaceContract
{
    /**
     * @var Finder
     */
    protected $finder;

    /**
     * @var array
     */
    protected $namespacePathMap;

    /**
     * FindClassesInNamespace constructor.
     * @param Finder $finder
     */
    public function __construct(Finder $finder)
    {
        $this->finder = $finder;
        $this->namespacePathMap = [
            'App' => base_path('app'),
            'Gazelkin' => base_path('src')
        ];
    }

    /**
     * @param string $namespace
     * @return \Traversable&string[]
     */
    public function find(string $namespace): \Traversable
    {
        $pathPrefix = $this->getPathPrefix($namespace);
        $path = $this->makePathFromNamespace($pathPrefix, $namespace);

        foreach ($this->findFiles($path) as $file) {
            yield Str::after(
                str_replace(['/', '.php'], ['\\', ''], $file->getPathname()),
                $pathPrefix . DIRECTORY_SEPARATOR
            );
        }
    }

    /**
     * @param string $namespace
     * @return string
     */
    private function getPathPrefix(string $namespace): string
    {
        foreach ($this->namespacePathMap as $prefix => $path) {
            if (Str::startsWith($namespace, $prefix)) {
                return $path;
            }
        }

        throw new \InvalidArgumentException('Unknown namespace');
    }

    /**
     * @param string $pathPrefix
     * @param string $namespace
     * @return string
     */
    private function makePathFromNamespace(string $pathPrefix, string $namespace): string
    {
        $path = str_replace('\\', '/', $namespace);

        return $pathPrefix . '/' . $path;
    }

    /**
     * @param $path
     * @return \Traversable&\SplFileInfo[]
     */
    private function findFiles($path): \Traversable
    {
        return $this->finder->files()->in($path)->name('*.php');
    }
}