<?php
// RangeHeader.php
// Created: 2022-02-14
// Updated: 2022-02-27

namespace Index\Http\Headers;

use stdClass;
use Index\Http\HttpHeader;

class RangeHeader {
    private string $unit;
    private array $ranges;

    public function __construct(string $unit, array $ranges) {
        $this->unit = $unit;
        $this->ranges = $ranges;
    }

    public function getUnit(): string {
        return $this->unit;
    }

    public function isBytes(): bool {
        return $this->unit === 'bytes';
    }

    public function getRanges(): array {
        return $this->ranges;
    }

    public static function parse(HttpHeader $header): RangeHeader {
        $parts = explode('=', trim($header->getFirstLine()), 2);
        $unit = trim($parts[0]);

        $ranges = [];
        $rawRanges = explode(',', $parts[1] ?? '', 2);

        foreach($rawRanges as $raw) {
            $raw = explode('-', trim($raw), 2);
            $start = trim($raw[0]);
            $end = trim($raw[1] ?? '');

            $ranges[] = $range = new stdClass;

            if($start === '' && is_numeric($end)) {
                $range->type = 'suffix-length';
                $range->length = intval($end);
            } elseif(is_numeric($start) && $end === '') {
                $range->type = 'start';
                $range->start = intval($start);
            } else {
                $range->type = 'range';
                $range->start = intval($start);
                $range->end = intval($end);
            }
        }

        return new RangeHeader($unit, $ranges);
    }
}