<?php

namespace App\Services;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Storage;

class DiskSpaceService
{
    /**
     * Snapshot of free/used space for the recordings storage volume.
     *
     * @return array{
     *     total_bytes: int,
     *     free_bytes: int,
     *     used_bytes: int,
     *     used_percent: float,
     *     free_percent: float,
     *     total_human: string,
     *     free_human: string,
     *     used_human: string
     * }|null
     */
    public function snapshot(?string $path = null): ?array
    {
        $path ??= Storage::disk('local')->path('');

        if (! is_dir($path)) {
            @mkdir($path, 0755, true);
        }

        /** @var array{total_bytes: int, free_bytes: int, used_bytes: int, used_percent: float, free_percent: float, total_human: string, free_human: string, used_human: string}|null */
        return Cache::remember(
            'disk-space:'.md5($path),
            now()->addSeconds(30),
            fn () => $this->measure($path),
        );
    }

    /**
     * @return array{
     *     total_bytes: int,
     *     free_bytes: int,
     *     used_bytes: int,
     *     used_percent: float,
     *     free_percent: float,
     *     total_human: string,
     *     free_human: string,
     *     used_human: string
     * }|null
     */
    private function measure(string $path): ?array
    {
        $total = @disk_total_space($path);
        $free = @disk_free_space($path);

        if ($total === false || $free === false || $total <= 0) {
            return null;
        }

        $totalBytes = (int) $total;
        $freeBytes = (int) max(0, $free);
        $usedBytes = (int) max(0, $totalBytes - $freeBytes);
        $usedPercent = round(($usedBytes / $totalBytes) * 100, 1);
        $freePercent = round(($freeBytes / $totalBytes) * 100, 1);

        return [
            'total_bytes' => $totalBytes,
            'free_bytes' => $freeBytes,
            'used_bytes' => $usedBytes,
            'used_percent' => $usedPercent,
            'free_percent' => $freePercent,
            'total_human' => $this->formatBytes($totalBytes),
            'free_human' => $this->formatBytes($freeBytes),
            'used_human' => $this->formatBytes($usedBytes),
        ];
    }

    /**
     * Human-readable byte size without requiring the intl extension.
     */
    private function formatBytes(int $bytes): string
    {
        $units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB'];
        $value = (float) max(0, $bytes);
        $unit = 0;

        while ($value >= 1024 && $unit < count($units) - 1) {
            $value /= 1024;
            $unit++;
        }

        $precision = $unit === 0 ? 0 : 1;

        return number_format($value, $precision).' '.$units[$unit];
    }
}