<?php

namespace NoccyLabs\React\Http2\Frame;

class SettingsFrame extends Frame
{
    const SETTINGS_HEADER_TABLE_SIZE = 0x1;
    const SETTINGS_ENABLE_PUSH = 0x2;
    const SETTINGS_MAX_CONCURRENT_STREAMS = 0x3;
    const SETTINGS_INITIAL_WINDOW_SIZE = 0x4;
    const SETTINGS_MAX_FRAME_SIZE = 0x5;
    const SETTINGS_MAX_HEADER_LIST_SIZE = 0x6;

    protected int $frameType = self::FRAME_SETTINGS;

    protected array $settings = [];

    /**
     * Set a setting to a specific value. This method intentionally does not do any bounds
     * checking on the setting id to allow for extensions.
     * 
     * @param int $setting
     * @param int $value
     * @return self
     */
    public function set(int $setting, int $value): self
    {
        $this->settings[$setting] = $value;
        return $this;
    }

    public function get(int $setting): ?int
    {
        return $this->settings[$setting]??null;
    }

    public function toBinary(): string
    {
        $packed = '';
        foreach ($this->settings as $setting=>$value) {
            $packed .= pack('vV', $setting, $value);
        }
        return $packed;
    }

    public function fromBinary(string $data): void
    {
        for ($n = 0; $n < strlen($data) - 3; $n = $n + 3) {
            $unpacked = unpack('vsetting/Vvalue', substr($data,$n,3));
            $this->set($unpacked['setting'], $unpacked['value']);
        }
    }
}