<?php declare(strict_types=1);

namespace Orbit\Module;

use Orbit\Module;
use Orbit\Request;
use Orbit\Response;

/**
 * Static files server module
 *
 * @uses Module
 * @package Orbit
 */
class Statics extends Module
{
    const WORLD_READABLE = 0x0004;

    /**
     * Handle a request and generate a proper response
     *
     * @param Request $request The request object
     */
    public function handle(Request $request): array
    {
        $response = new Response();
        $real_root_dir = realpath($this->config->root_dir);
        $resource_path = rtrim($real_root_dir, "/") . $request->path;

        // Check if within the server root
        // getAbsolutePath will translate any '..' in the path
        $realpath = self::getAbsolutePath($resource_path);
        if ($realpath && strpos($realpath, $real_root_dir) !== 0) {
            $response->setStatus(Response::STATUS_PERMANENT_FAILURE);
            $response->setMeta("Invalid location");
            return [false, $response];
        }

        if (is_dir($resource_path)) {
            // If missing the final slash, issue a redirect
            if ($resource_path[-1] != "/") {
                $response->setStatus(Response::STATUS_REDIRECT_PERMANENT);
                $response->setMeta($request->getUrlAppendPath('/'));
                return [false, $response];
            }

            // Check if index file exists
            if (file_exists($resource_path . DIRECTORY_SEPARATOR . $this->config->index_file)) {
                $resource_path = $resource_path . DIRECTORY_SEPARATOR . $this->config->index_file;
            } else {
                if (!$this->config->enable_directory_index) {
                    $response->setStatus(Response::STATUS_NOT_FOUND);
                    $response->setMeta('Path not available');
                    return [false, $response];
                } else {
                    $response->setStatus(Response::STATUS_SUCCESS);
                    $response->setMeta('text/gemini');
                    $response->setBody($this->makeDirectoryIndex($resource_path, $real_root_dir));
                    return [true, $response];
                }
            }
        }

        // File exists and is world readable
        if (file_exists($resource_path) && self::isWorldReadable($resource_path)) {
            $response->setStatus(Response::STATUS_SUCCESS);

            $pathinfo = pathinfo($resource_path);

            if (isset($pathinfo['extension'])) {
                $meta = $this->getCustomMimeFromFileExtension($pathinfo['extension']);
                if (!$meta) {
                    $meta = mime_content_type($resource_path);
                }
            } else {
                // Use finfo_file to detect type
                $meta = finfo_file(finfo_open(FILEINFO_MIME), $resource_path);
            }

            $response->setMeta($meta);
            $response->setStaticFile($resource_path);
        } else {
            $response->setStatus(Response::STATUS_NOT_FOUND);
            $response->setMeta('Not found!');
        }

        return [true, $response];
    }

    /**
     * Get mime type from file extension for custom types
     *
     * @param string $extension
     * @return string
     */
    public function getCustomMimeFromFileExtension($extension): string
    {
        switch ($extension) {
        case 'gmi':
        case 'gemini':
            return 'text/gemini';
            break;
        case 'md':
        case 'markdown':
            return 'text/gemini';
            break;
        case 'ans':
        case 'ansi':
            return 'text/x-ansi';
            break;
        default:
            return '';
        }
    }

    /**
     * Make a directory index suitable as response content
     *
     * @param string $path Current path
     * @param string $root Root path on disk of the server
     * @return string
     */
    public function makeDirectoryIndex($path, $root): string
    {
        $files = glob($path . "*");

        $body = "# Directory listing " . str_replace($root, '', $path) . "/\n\n";

        if ($path != $root . "/") {
            // If not already at root, provide option to go up one parent
            $body .= "=> " . str_replace($root, '', dirname($path)) . "/ ..\n";
        }

        foreach ($files as $file) {
            $relative_path = str_replace($path, '', $file);

            $is_dir = false;
            if (is_dir($file)) {
                $is_dir = true;
                $size = '';
            } else {
                $size = filesize($file);
            }

            $body .= sprintf(
                "=> %s%s %s%s%s\n",
                urlencode($relative_path),
                ($is_dir ? '/' : ''),
                $relative_path,
                ($is_dir ? '/' : ''),
                ($size ? " ($size)" : '')
            );
        }

        return $body;
    }

    /**
     * Report whether a given file is world readable or not
     *
     * @param string $file The file to check
     * @return bool
     */
    public static function isWorldReadable(string $file): bool
    {
        return (bool)(fileperms($file) & self::WORLD_READABLE);
    }

    /**
     * Get an absolute path for a filename
     *
     * Translates .. and . to the real locations. The reason I am not using
     * realpath() to do it is it resolves symlinks
     *
     * @param string $path
     * @return string
     */
    public static function getAbsolutePath($path): string
    {
        $path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);
        $parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
        $absolutes = [];

        foreach ($parts as $part) {
            if ('.' == $part) {
                continue;
            }
            if ('..' == $part) {
                array_pop($absolutes);
            } else {
                $absolutes[] = $part;
            }
        }

        return "/" . implode(DIRECTORY_SEPARATOR, $absolutes);
    }
}