<?php
declare(strict_types=1);

/**
 * How much of the disk an account may take (#427): 1 GB for its uploads, its projects and their
 * snapshots together. Administrators have no limit; the router does not ask for them.
 *
 * Only a write that makes an account larger is refused, so one that is full can still save a smaller
 * project or delete files. Pixel cels are kept apart: they belong to nobody and are small by rule
 * (`PixelStore::MAX_BYTES`).
 */
final class Quota
{
    public const BYTES = 1024 * 1024 * 1024;

    /** The upload folders that are counted, each with a folder per account. */
    private const KINDS = ['textures', 'fonts', 'sounds', 'videos'];

    public function __construct(
        private readonly string $data,
        private readonly int $limit = self::BYTES,
    ) {}

    /** Bytes `$owner` takes up: everything in their upload folder, their projects and their snapshots. */
    public function usage(string $owner, string $folder): int
    {
        $bytes = 0;
        if (preg_match('/^' . UserStore::FOLDER_PATTERN . '$/', $folder)) {
            foreach (self::KINDS as $kind) {
                $bytes += self::sizeOf("{$this->data}/{$kind}/{$folder}");
            }
        }
        $projects = new Store("{$this->data}/projects", $owner);
        foreach ($projects->listOf($owner) as $project) {
            $bytes += (int) @filesize("{$this->data}/projects/{$project['id']}.json");
            $bytes += self::sizeOf("{$this->data}/snapshots/{$project['id']}");
        }
        return $bytes;
    }

    /** Why `$adding` more bytes do not fit, or null when they do (or add nothing). */
    public function refusal(string $owner, string $folder, int $adding): ?string
    {
        if ($adding <= 0) {
            return null;
        }
        $used = $this->usage($owner, $folder);
        if ($used + $adding <= $this->limit) {
            return null;
        }
        return sprintf(
            'Not enough space: this account uses %s of its %s',
            self::megabytes($used),
            self::megabytes($this->limit),
        );
    }

    private static function megabytes(int $bytes): string
    {
        return number_format($bytes / 1024 / 1024, $bytes < 10 * 1024 * 1024 ? 1 : 0, '.', '') . ' MB';
    }

    private static function sizeOf(string $dir): int
    {
        if (!is_dir($dir)) {
            return 0;
        }
        $bytes = 0;
        $files = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir, FilesystemIterator::SKIP_DOTS));
        foreach ($files as $file) {
            if ($file->isFile()) {
                $bytes += $file->getSize();
            }
        }
        return $bytes;
    }
}