PocketMineでFormを扱うサンプル。動作未確認。

form.php

<?php

declare(strict_types=1);

class selectForm implements \pocketmine\form\Form
{
    
    public function handleResponse(\pocketmine\Player $player, $data): void
    {
        if ($data === null) {
            $player->sendMessage("フォームが閉じられました");
            return;
        }
        switch ($data) {
            case 0:
                //名前の設定が押された
                $player->sendForm(new nameSettingForm());
                return;
        }
        //何も該当しなかった場合
        throw new \pocketmine\form\FormValidationException();
    }
    
    public function jsonSerialize()
    {
        return [
            "type" => "form",
            "title" => "選択フォーム",
            "content" => "選択してください",
            "buttons" => [
                [
                    "text" => "名前の設定",
                ],
            ],
        ];
    }
    
}

class nameSettingForm implements \pocketmine\form\Form
{
    
    public function handleResponse(\pocketmine\Player $player, $data): void
    {
        //保存したりする処理を書く
        
        $player->sendForm(new successForm(new selectForm(), "名前の設定が完了しました！"));
    }
    
    public function jsonSerialize()
    {
        return [
            "type" => "custom_form",
            "title" => "名前設定フォーム",
            "content" => [
                [
                    "type" => "input",
                    "text" => "名前を入力",
                ],
            ],
        ];
    }
    
}

class successForm implements \pocketmine\form\Form
{
    
    /** @var \pocketmine\form\Form */
    private $back;
    
    /** @var string */
    private $message;
    
    public function __construct(\pocketmine\form\Form $back, string $message)
    {
        $this->back = $back;
        $this->message = $message;
    }
    
    public function handleResponse(\pocketmine\Player $player, $data): void
    {
        if ($data === null) {
            $player->sendMessage("フォームが閉じられました");
            return;
        }
        if ($data === false) {
            //戻るボタンが押された
            $player->sendForm($this->back);
            return;
        } else if ($data === true) {
            //閉じるボタンが押された
            return;
        }
        throw new \pocketmine\form\FormValidationException();
    }
    
    public function jsonSerialize()
    {
        return [
            "type" => "modal",
            "title" => "完了しました",
            "content" => $this->message,
            "button1" => "戻る",
            "button2" => "閉じる",
        ];
    }
    
}