(function() {
    // ボタン群を包むコンテナのID
    const CONTAINER_ID = 'yt-swift-control-container';

    function updateSpeedButtonStyle(btn, rate) {
        if (rate === 2) {
            btn.style.backgroundColor = "#ff0000";
            btn.style.color = "#ffffff";
            btn.style.fontWeight = "bold";
            btn.innerHTML = '2.0x';
        } else {
            btn.style.backgroundColor = "rgba(255, 255, 255, 0.1)";
            btn.style.color = "#ffffff";
            btn.style.fontWeight = "normal";
            btn.innerHTML = '1.0x';
        }
    }

    function createControlBtn(text, title, onClick) {
        const btn = document.createElement('button');
        btn.className = 'ytp-button';
        btn.innerHTML = text;
        btn.title = title;
        btn.style.width = 'auto';
        btn.style.minWidth = '45px';
        btn.style.height = '30px';
        btn.style.marginTop = '8px';
        btn.style.marginRight = '5px';
        btn.style.borderRadius = '4px';
        btn.style.fontSize = '12px';
        btn.style.display = 'inline-flex';
        btn.style.alignItems = 'center';
        btn.style.justifyContent = 'center';
        btn.style.transition = 'background-color 0.2s';
        btn.style.verticalAlign = 'top';
        btn.onclick = onClick;
        return btn;
    }

    function injectControls() {
        const controls = document.querySelector('.ytp-right-controls');
        if (!controls || document.getElementById(CONTAINER_ID)) return;

        const container = document.createElement('div');
        container.id = CONTAINER_ID;
        container.style.display = 'inline-flex';
        container.style.marginRight = '10px';
        container.style.verticalAlign = 'top';

        const video = document.querySelector('video');

        // 1. 10秒巻き戻しボタン
        const prevBtn = createControlBtn('←10', '10秒巻き戻す', () => {
            if (video) video.currentTime -= 10;
        });

        // 2. 速度切り替えボタン
        const speedBtn = createControlBtn('1.0x', '再生速度を1x/2xで切り替え', () => {
            if (video) {
                const newRate = video.playbackRate === 1 ? 2 : 1;
                video.playbackRate = newRate;
                updateSpeedButtonStyle(speedBtn, newRate);
            }
        });
        updateSpeedButtonStyle(speedBtn, video ? video.playbackRate : 1);

        // 3. 10秒スキップボタン
        const nextBtn = createControlBtn('10→', '10秒スキップ', () => {
            if (video) video.currentTime += 10;
        });

        container.appendChild(prevBtn);
        container.appendChild(speedBtn);
        container.appendChild(nextBtn);
        controls.prepend(container);
    }

    const observer = new MutationObserver(injectControls);
    observer.observe(document.body, { childList: true, subtree: true });
})();