<?php

declare(strict_types=1);

namespace Plugin\AzuraCastOnDemandHls\Service;

use Plugin\AzuraCastOnDemandHls\Config;
use RuntimeException;

final readonly class CachePaths
{
    public function __construct(private Config $config)
    {
    }

    public function root(string $stationTempDirectory): string
    {
        return rtrim($stationTempDirectory, DIRECTORY_SEPARATOR)
            . DIRECTORY_SEPARATOR . $this->config->cacheDirectory;
    }

    public function sessions(string $stationTempDirectory): string
    {
        return $this->root($stationTempDirectory) . '/sessions';
    }

    public function assets(string $stationTempDirectory): string
    {
        return $this->root($stationTempDirectory) . '/assets';
    }

    public function locks(string $stationTempDirectory): string
    {
        return $this->root($stationTempDirectory) . '/locks';
    }

    public function asset(string $stationTempDirectory, string $cacheKey): string
    {
        if (1 !== preg_match('/^[a-f0-9]{64}$/D', $cacheKey)) {
            throw new RuntimeException('Unsafe cache key.');
        }
        return $this->assets($stationTempDirectory) . '/' . $cacheKey;
    }

    public function ensure(string $stationTempDirectory): void
    {
        $directories = [
            $this->root($stationTempDirectory) => 0755,
            $this->sessions($stationTempDirectory) => 0700,
            $this->assets($stationTempDirectory) => 0755,
            $this->locks($stationTempDirectory) => 0700,
        ];
        foreach ($directories as $directory => $mode) {
            if (is_link($directory)) {
                throw new RuntimeException('Refusing to use a symlinked HLS cache directory.');
            }
            // Another request may create the same directory after is_dir().
            // Suppress that benign E_WARNING, then verify the final state.
            if (!is_dir($directory) && !@mkdir($directory, $mode, true) && !is_dir($directory)) {
                throw new RuntimeException('Could not create the HLS cache directory.');
            }
            chmod($directory, $mode);
        }
    }
}