<?php

namespace App\Http\Resources\File;

use Illuminate\Http\Request;
use Illuminate\Http\Resources\Json\ResourceCollection;

class FileCollection extends ResourceCollection
{
    /**
     * Transform the resource collection into an array.
     *
     * @return array<int|string, mixed>
     */
    public function toArray(Request $request): array
    {
        return [
            'data' => FileResource::collection($this->collection),
            'pagination' => [
                'current_page' => $this->currentPage(),
                'from' => $this->firstItem(),
                'last_page' => $this->lastPage(),
                'per_page' => $this->perPage(),
                'to' => $this->lastItem(),
                'total' => $this->total(),
                'has_more_pages' => $this->hasMorePages(),
            ],
            'summary' => [
                'total_files' => $this->collection->count(),
                'total_size' => $this->collection->sum('size_bytes'),
                'total_size_formatted' => $this->formatBytes($this->collection->sum('size_bytes')),
                'categories' => $this->getCategoryStats(),
            ],
        ];
    }

    /**
     * Calculate category statistics from the collection
     */
    private function getCategoryStats(): array
    {
        $categories = [];

        foreach ($this->collection as $file) {
            $pathParts = explode('/', $file->storage_uri);
            $category = $pathParts[count($pathParts) - 3] ?? 'general';

            if (!isset($categories[$category])) {
                $categories[$category] = [
                    'count' => 0,
                    'total_size' => 0,
                    'files' => []
                ];
            }

            $categories[$category]['count']++;
            $categories[$category]['total_size'] += $file->size_bytes ?? 0;
            $categories[$category]['files'][] = $file->file_name;
        }

        // Format sizes
        foreach ($categories as $category => &$stats) {
            $stats['total_size_formatted'] = $this->formatBytes($stats['total_size']);
            // Remove file list to avoid too much data in collection
            unset($stats['files']);
        }

        return $categories;
    }

    /**
     * Format bytes to human readable format
     */
    private function formatBytes(int $bytes, int $precision = 2): string
    {
        if ($bytes === 0) {
            return '0 B';
        }

        $units = ['B', 'KB', 'MB', 'GB', 'TB'];
        $base = 1024;
        $factor = floor((strlen($bytes) - 1) / 3);

        return sprintf("%.{$precision}f", $bytes / pow($base, $factor)) . ' ' . $units[$factor];
    }
}