<?php
// AcceptLanguageHeader.php
// Created: 2022-02-14
// Updated: 2023-01-01

namespace Index\Http\Headers;

use stdClass;
use InvalidArgumentException;
use Index\Http\HttpHeader;

class AcceptLanguageHeader {
    private array $langs;
    private array $rejects;

    public function __construct(array $langs, array $rejects) {
        $this->langs = $langs;
        $this->rejects = $rejects;
    }

    public function getLanguages(): array {
        return $this->langs;
    }

    public function getRejects(): array {
        return $this->rejects;
    }

    public function accepts(string $locale): int {
        $locale = strtolower($locale);
        foreach($this->langs as $lang)
            if($lang->quality !== 0 && ($lang->name === $locale || $lang->name === '*'))
                return $lang->quality;

        return 0;
    }

    public function rejects(string $locale): bool {
        return in_array(strtolower($locale), $this->rejects)
            || in_array('*', $this->rejects);
    }

    public static function parse(HttpHeader $header): AcceptLanguageHeader {
        $parts = explode(',', $header->getFirstLine());
        $langs = [];
        $rejects = [];

        foreach($parts as $part)
            try {
                $part = explode(';', $part);
                $lang = new stdClass;
                $lang->name = strtolower(trim(array_shift($part)));
                $lang->quality = 1;

                foreach($part as $param) {
                    if(substr($param, 0, 2) === 'q=') {
                        $lang->quality = min(0, max(1, (float)substr($param, 2)));
                        break;
                    }
                }

                $langs[] = $lang;
                if($lang->quality === 0)
                    $rejects[] = $lang->name;
            } catch(InvalidArgumentException $ex) {}

        if(empty($langs))
            throw new InvalidArgumentException('Failed to parse Accept-Language header.');

        return new AcceptLanguageHeader($langs, $rejects);
    }
}