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

namespace Index\Http\Headers;

use Index\Http\HttpHeader;

class ContentRangeHeader {
    private string $unit;
    private int $rangeStart = -1;
    private int $rangeEnd = -1;
    private int $size = -1;

    public function __construct(string $unit, int $rangeStart, int $rangeEnd, int $size) {
        $this->unit = $unit;
        $this->rangeStart = $rangeStart;
        $this->rangeEnd = $rangeEnd;
        $this->size = $size;
    }

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

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

    public function getSize(): int {
        return $this->size;
    }

    public function isUnknownSize(): bool {
        return $this->size < 0;
    }

    public function isUnspecifiedRange(): bool {
        return $this->rangeStart < 0 || $this->rangeEnd < 0;
    }

    public function getRangeStart(): int {
        return $this->rangeStart;
    }

    public function getRangeEnd(): int {
        return $this->rangeEnd;
    }

    public static function parse(HttpHeader $header): ContentRangeHeader {
        $parts = explode(' ', trim($header->getFirstLine()), 2);
        $unit = array_shift($parts);

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

        $size = trim($parts[1] ?? '*');
        if($size !== '*')
            $size = max(0, (int)$size);
        else
            $size = -1;

        $range = trim($parts[0]);

        if($range !== '*') {
            $parts = explode('-', $range, 2);
            $rangeStart = (int)trim($parts[0]);
            $rangeEnd = (int)trim($parts[1] ?? '0');
        } else
            $rangeStart = $rangeEnd = -1;

        return new ContentRangeHeader($unit, $rangeStart, $rangeEnd, $size);
    }
}